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Patent
China University of Petroleum - Beijing | Date: 2016-09-07

The present invention provides a multi-detecting depth nuclear magnetic resonance logging tool and probe, and an antenna excitation method, the probe of nuclear magnetic resonance logging tool includes: a housing, a magnet and an antenna array apparatus; the magnet is fixedly arranged in the housing; the antenna array apparatus includes at least two groups of antenna arrays distributed along circumference of the magnet, and each group of antenna arrays include N layers of independently fed antennas; k-th layer antenna is arranged between the magnet and (k+1)-th layer antenna, k=1, 2, . . . N1; the antenna is fixed on a support, and the support is fixedly connected to the housing. In the present invention, stratum information detection at different azimuth angles is achieved by exciting different antenna arrays, so that circumferential recognizing capability of nuclear magnetic resonance logging tool probe is improved and three-dimensional (radial, axial and circumferential) stratum detection is achieved.


Patent
China University of Petroleum - Beijing | Date: 2016-09-07

The present invention provides a three dimensional nuclear magnetic resonance logging instrument based on multiple antenna excitation, including: a probe, an excitation transmitter and a bearing component; the probe includes magnet and multiple antennas arranged at outer side of the magnet, and the multiple antenna individually and independently provide feed; a holding cavity is provided in the bearing component, and the excitation transmitter is fixed in the holding cavity; and the excitation transmitter includes a transmitter framework and an excitation circuit; the transmitter framework and the bearing component are fixedly connected; and the excitation circuit is fixed on the transmitter framework, and is electrically connected with each of the multiple antennas for feeding the multiple antennas.


The present invention provides a nuclear magnetic resonance logging instrument probe with double-layered magnets and an antenna excitation method, the nuclear magnetic resonance logging instrument probe includes: a probe framework and a shielding layer arranged in the probe framework; a plurality of main magnets are provided above and below the shielding layer, respectively; central axes of the main magnets are parallel with each other, and distances between the central axes of each of the main magnets and a central axis of the probe framework are the same; a distance between central axes of any two main magnets is not smaller than a first preset value; and an antenna is provided at outer side of each main magnety. In the present invention, circumferential recognizing capability of the nuclear magnetic resonance logging instrument probe can be improved and three-dimensional (radial, axial and circumferential) stratum detection can be achieved.


The present invention provides a nuclear magnetic resonance logging instrument probe with multi-layered magnet and an antenna excitation method, the nuclear magnetic resonance logging instrument probe includes a probe skeleton, multiple magnet assemblies and a plurality of antennas; the probe skeleton is of a cylindrical shape, multiple magnet assemblies are distributed in the circumferential direction of the probe skeleton; the magnet assembly includes at least two layers of magnet arranged from top to bottom, the magnet is magnetized in a radial direction, two adjacent layers of magnet are magnetized in opposite directions; an antenna is arranged outside each magnet assembly, multiple antennas are independently fed. In the nuclear magnetic resonance logging instrument probe and antenna excitation method, through exciting different antennas, detection of stratum information at different azimuth angles is realized, which improves circumferential resolution of the probe, realize stratum detection in three dimensions along radius, axis and circumference.


The present invention provides a three-dimensional nuclear magnetic resonance logging instrument probe, a logging instrument and an antenna excitation method, where the probe includes: a probe framework, a magnet and an antenna; four magnets are uniformly distributed along a circumference of the probe framework, the magnets are magnetized in a radial direction of the probe framework, two magnets placed opposite to each other are magnetized from outside to inside, and the other two magnets placed opposite to each other are magnetized from inside to outside; in the probe framework, each of the magnets is provided with independently fed antennas; antennas corresponding to each of the magnets comprise a left antenna provided on one side of the corresponding magnet and a right antenna provided on the other side of the corresponding magnet; the left antenna and the right antenna corresponding to each magnet are electrically connected.


Patent
China University of Petroleum - Beijing | Date: 2016-09-07

The present invention provides a multi-azimuth nuclear magnetic resonance logging instrument and an antenna excitation method, the nuclear magnetic resonance logging instrument includes: a probe framework and a shielding layer arranged in the probe framework; a plurality of main magnets are provided above and below the shielding layer, respectively; central axes of the main magnets are parallel with each other, and distances between the central axes of each of the main magnets and a central axis of the probe framework are the same; a distance between central axes of any two main magnets is not smaller than a first preset value; and an antenna is provided at outer side of each main magnet, and a plurality of the antennas are fed independently. In the present invention, circumferential recognizing capability of the nuclear magnetic resonance logging instrument can be improved and three-dimensional (radial, axial and circumferential) stratum detection can be achieved.


Li Y.,China National Offshore Oil Corporation | Fu N.,China National Offshore Oil Corporation | Zhang Z.,China University of Petroleum - Beijing
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2013

The deepwater area of the northern South China Sea underwent multistage rifting in Paleogene and came into depression stage in Neogene. Lacustrine and transitional source rocks were formed mainly in the rifting period, while marine source rocks developed mainly in the depression stage. The transitional source rock is one of major source rocks in the deepwater area of the northern South China Sea. Oil and gas found in the northern South China Sea are mainly generated from transitional source rocks of Yacheng Formation and Enping Formation, while Zhuhai Formation marine source rock makes an important contribution to oil in the deepwater area of the Zhu II Depression. Natural gas in the Qiongdongnan deepwater area is a typical coal-type gas generated from Yacheng Formation humic source rock, but gas in the Zhu II Depression of the Pearl River Mouth Basin is neither a typical coal-type gas nor an oil-type gas, instead it is a transitional gas generated from Enping Formation humic-sapropel source rock.


Zhang X.,Peking University | Zhang X.,China University of Petroleum - Beijing
Procedia Earth and Planetary Science | Year: 2011

Special elemental sulfurs formed by thermochemical sulfate reduction (TSR) are reported for the first time in the Upper Permian Changxing Formation and the Lower Triassic Feixianguan Formation, Northeastern Sichuan Basin, Southwest China. They occur mainly as single pellets with round morphology, and partly in semi or 'A pellets of 10 to 100 μm in diameter, or form interpenetrating grains. Most of them precipitate at the inner wall of the vugs, oomoldic or inter-granular pores of the dolomitic reservoirs. Petrogenetic sequence analysis demonstrates that they postdate the dolomite formation and cementation, while are prior to the late calcite and quartz cementation The sulfur develops restrictively in the section where pyrobitumen is found, namely in the paleo-oil window, which strongly supports that the crude oil/liquid hydrocarbon had been involved in the TSR. © 2011 Published by Elsevier Ltd.


Xie Y.,China National Offshore Oil Corporation | Liu P.,China National Offshore Oil Corporation | Huang Z.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2012

With the breakthrough made in gas exploration in the high temperature and over-pressured environment of the Yinggehai Basin, this area has thus become the hot spot in present gas exploration. However, there are many uncertainties about the gas pooling patterns there. In view of this, through the analysis of geological conditions and gas pooling process in this area, the main controlling factors of free gas pooling in such high temperature and over-pressured environment of this basin are clarified. The following results are achieved in this study. (1) The hydrocarbon kitchen had a wide area with good quality source rocks, hydrocarbon generation took a long time, and there was a long lag in the time of hydrocarbon expulsion. (2) Such high temperature and over-pressured environment is good for the reservoirs to keep a rather high porosity and permeability. (3) Under closed and half-closed fluid system for a long time in this basin, multiple sealing rocks are well developed and favorable for gas accumulation and preservation. (4) In those half-closed high temperature and over-pressured fluid system in the diapiric structural zones of the middle and deep basin, water-soluble gas migrates, releases, and accumulates, as a result, a gas pool has come into being. Such evidences have been found in several water-soluble gas reservoirs in this basin. This study provides guidance for further gas exploration in the Yinggehai Basin.


Tang L.,China University of Petroleum - Beijing | Cui M.,China National Offshore Oil Corporation
Petroleum Science | Year: 2012

Hydrocarbon preservation conditions have restricted exploration in the Middle and Upper Yangtze, and structural deformation and fluid activity have played an important role in the origin and preservation of oil and gas. In order to study that how the deformation and fluid activity impact the hydrocarbon preservation, we did some field work and collected some calcite vein samples for analysis of deformation periods using acoustic emission and fluid inclusions. Combined with previous studies, the strata distribution, tectonic deformation and fluid characteristics show that there are three structural belts in the study area: East Sichuan, West Hunan and Hubei and the northwestern periphery of the Xuefeng Uplift, and that their tectonic deformation style, fluid inclusion characteristics and hydrocarbon preservation are different. The breakthrough thrusts were well developed in the anticline core, and a lot of hydrocarbon inclusions were found in calcite veins around the thrusts in East Sichuan. The breakthrough thrusts were only in the syncline core in West Hunan and Hubei, and the brine inclusions did not contain hydrocarbon in calcite veins around the thrusts. Many breakthrough thrusts were found in the northwestern periphery of the Xuefeng Uplift, where there were only rare calcite veins. The deformation and hydrocarbon inclusion indicated that when there was no fault breakthrough in East Sichuan, the Paleozoic covered by the Triassic regional cap was good for hydrocarbon preservation. The strata above the Lower Paleozoic were denuded, and lots of brine inclusions and deep infiltration of surface water were found in the West Hunan and Hubei, so only the part of the syncline area with a well developed Silurian regional cap had good preservation conditions. Intense tectonic movements and denudation were widely developed in the northwestern periphery of the Xuefeng Uplift, where there were only paleo-reservoirs, non-hydrocarbon fluid activity and poor preservation conditions. © 2012 China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg.


Sun J.,CAS Beijing National Laboratory for Molecular | Gao T.,CAS Beijing National Laboratory for Molecular | Song X.,CAS Beijing National Laboratory for Molecular | Zhao Y.,Peking University | And 9 more authors.
Journal of the American Chemical Society | Year: 2014

High-quality monolayer graphene was synthesized on high-K dielectric single crystal SrTiO3 (STO) substrates by a facile metal-catalyst-free chemical vapor deposition process. The as-grown graphene sample was suitable for fabricating a high performance field-effect transistor (FET), followed by a far lower operation voltage compared to that of a SiO2-gated FET and carrier motilities of approximately 870-1050 cm2·V -1·s-1 in air at rt. The directly grown high-quality graphene on STO makes it a perfect candidate for designing transfer-free, energy-saving, and batch production of FET arrays. © 2014 American Chemical Society.


Hou Q.,Peking University | Hou Q.,Petrochina | Zhao Z.,Petrochina | Huang Z.,China University of Petroleum - Beijing
Petroleum Exploration and Development | Year: 2011

To further understand the accumulation mechanism and distribution rules of deep basin oil, the laboratory physical simulation experiment is conducted for water-sealed oil in sand columns of different grain sizes, and the water-sealed oil mechanism and the accumulation threshold of deep basin oil are analyzed. Stable deep basin oil can be formed under laboratory conditions. The accumulation threshold of deep basin oil mainly depends on the pore throat radius of oil-bearing sand layer as well as the oil/water interfacial tension and strata dip under such conditions. The accumulation threshold and its main controlling factors of the deep basin reservoir in the Fuyang oil layer are studied, and the prediction model of deep basin reservoir boundaries is established: the porosity is less than 11%, the permeability is less than 1×10 -3 μm 2, the largest pore throat radius is less than 6.2 μm, and the burial depth is 1800-2100 m, located at the lower positions of syncline or slope, and good source rock in Qing-1 Member is developed, with obviously abnormal pressure. Three " sweet spot" areas favorable for deep basin oil in the Songliao Basin are determined, namely south Liangjing area, east Haituozi area, and west Qian'an area. The predicted deep basin oil potential in these three areas is 0.317 billion tons. The total proved resources of deep basin oil in the Songliao Basin are 1.575 billion tons, with good exploration potential. © 2011 Research Institute of Petroleum Exploration & Development, PetroChina.


Ge L.,University of California at Riverside | Ge L.,China University of Petroleum - Beijing | Zuo F.,University of California at Riverside | Liu J.,University of California at Riverside | And 5 more authors.
Journal of Physical Chemistry C | Year: 2012

Novel CdS quantum dot (QD)-coupled graphitic carbon nitride (g-C 3N 4) photocatalysts were synthesized via a chemical impregnation method and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. The effect of CdS content on the rate of visible light photocatalytic hydrogen evolution was investigated for different CdS loadings using platinum as a cocatalyst in methanol aqueous solutions. The synergistic effect of g-C 3N 4 and CdS QDs leads to efficient separation of the photogenerated charge carriers and, consequently, enhances the visible light photocatalytic H 2 production activity of the materials. The optimal CdS QD content is determined to be 30 wt %, and the corresponding H 2 evolution rate was 17.27 μmol·h -1 under visible light irradiation,∼9 times that of pure g-C 3N 4. A possible photocatalytic mechanism of the CdS/g-C 3N 4 composite is proposed and corroborated by photoluminescence spectroscopy and photoelectrochemical curves. © 2012 American Chemical Society.


Chen X.,University of Science and Technology Beijing | Feng C.,University of Science and Technology Beijing | Wu Z.L.,Beijing Normal University | Yang F.,China University of Petroleum - Beijing | And 4 more authors.
Applied Physics Letters | Year: 2014

This paper reports the interfacial oxygen migration effect and its induced magnetic anisotropy evolution in Pt/Co/MgO/Pt films. During depositing the MgO layer, oxygen atoms from the MgO combine with the neighboring Co atoms, leading to the formation of CoO at the Co/MgO interface. Meanwhile, the films show in-plane magnetic anisotropy (IMA). After annealing, most of the oxygen atoms in CoO migrate back to the MgO layer, resulting in obvious improvement of Co/MgO interface and the enhancement of effective Co-O orbital hybridization. These favor the evolution of magnetic anisotropy from IMA to perpendicular magnetic anisotropy (PMA). The oxygen migration effect is achieved by the redox reaction at the Co/MgO interface. On the contrary, the transfer from IMA to PMA cannot be observed in Pt/Co/Pt films due to the lack of interfacial oxygen migration. © 2014 AIP Publishing LLC.


Gao Y.,Nankai University | Zhou Q.,China University of Petroleum - Beijing | Xie G.,Henan Institute of Science and Technology | Yao Z.,National Marine Environmental Monitoring Center
Journal of Separation Science | Year: 2012

Present study described a simple, environmental benign, easy to operate, and determination method for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil, and tebuconazole. The method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction coupled to HPLC with ultraviolet detector. In the enrichment procedure, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM] [PF6] was used as the extraction solvent. Variable affecting parameters such as the volume of [C8MIM][PF6], temperature, extraction time, centrifuging time, and salting-out effect have been optimized in detail. Under the optimal conditions, this method has been found to have good linear relationship in the concentration range of 1.0-100 μg/L and excellent detection sensitivity with LODs (S/N = 3) in the range of 0.32-0.79 μg/L. Precisions of proposed method were in the range of 3.7-5.9% for intraday and 7.8-11.0% for interday (RSDs, n = 6). The proposed method was used for the analysis of real water samples and good spiked recoveries at two different spiked levels were achieved in the range of 84.6-102%. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu W.,University of Miami | Liu W.,China University of Petroleum - Beijing | Yang Q.D.,University of Miami | Mohammadizadeh S.,University of Miami | Su X.Y.,Peking University
International Journal for Numerical Methods in Engineering | Year: 2014

SUMMARY: This paper presents an augmentation method that enables bilinear finite elements to efficiently and accurately account for arbitrary, multiple intra-elemental discontinuities in 2D solids. The augmented finite element method (A-FEM) employs four internal nodes to account for the crack displacements due to an intra-elemental weak or strong discontinuity, and it permits repeated elemental augmentation to include multiple interactive cracks. It thus enables a unified treatment of damage evolution from a weak discontinuity to a strong discontinuity, and to multiple interactive cohesive cracks, all within a single bilinear element that employs standard external nodal DoFs only. A novel elemental condensation procedure has been developed to solve the internal nodal DoFs as functions of the external nodal DoFs for any irreversible, piece-wise linear cohesive laws. It leads to a fully condensed elemental equilibrium equation with mathematical exactness, eliminating the need for nonlinear equilibrium iterations at elemental level. The new A-FEM's high-fidelity simulation capabilities to interactive cohesive crack formation and propagation in homogeneous, and heterogeneous solids have been demonstrated through several challenging numerical examples. It is shown that the proposed A-FEM, empowered by the new elemental condensation procedure, is numerically very efficient, accurate, and robust. © 2014 John Wiley & Sons, Ltd.


Zhao H.,China University of Petroleum - Beijing | Bai Y.,China University of Petroleum - Beijing | Bai Y.,China National Offshore Oil Corporation
International Journal of Energy Research | Year: 2014

A new way of energy saving for existing coal-fired power plant that uses low-or medium-temperature solar energy as assistant heat source was proposed to generate "green" electricity. This paper has built the mathematical models of the solar-aided power generation system focusing on the NZK600-16.7/538/538 units. Based on the combination of the first and second law of thermodynamics, the thermodynamic performance of different components of the integrated system was evaluated under the changing operating condition aiming at different substitution options for turbine bleed streams. It has been found that the efficiency of the solar heat to electricity enhances with the increase of the load and the replaced extraction level. Additionally, when the second extraction is replaced, the effect is the best, which makes the power output increase around 6.13% or the coal consumption rate decrease 13.14 g/(kW · h) under 100%THA load and CO2 emission reduce about 32.76 g/(kW · h), while the energy and exergy efficiencies of the integrated system are 39.35% and 39.12%, respectively. The results provide not only theory basis and scientific support for the design of solar-aided coal-fired power plants, but also a new way of energy saving and optimization for the units. Copyright © 2014 John Wiley & Sons, Ltd.


Hao F.,China University of Petroleum - Beijing | Zhou X.,China National Offshore Oil Corporation | Zhu Y.,Zhejiang University | Zou H.,China University of Petroleum - Beijing | Yang Y.,China University of Petroleum - Beijing
Marine and Petroleum Geology | Year: 2010

This paper discusses origin and charging directions of oil fields on the Shaleitian Uplift, Bohai Bay basin. The Shaleitian Uplift is a footwall uplift surrounded by three sags containing mature source rocks. The origins of the four oil fields on the Shaleitian Uplift, both in terms of source rock intervals and in terms of generative kitchens, were studied using biomarker distributions for 61 source rock samples and 27 oil samples. Hierarchical cluster analysis using 12 parameters known to be effective indicators of organic matter input and/or depositional conditions allowed the identification of six oil types or classes. These six oil classes could then be linked to three distinct source rock intervals ranging in age from 43.0 Ma to 30.3 Ma. The third member (43.0-38.0 Ma in age) and first member (35.8-32.8 Ma) of the Eocene Shahejie Formation, and the third member of the Oligocene Dongying Formation (32.8-30.3 Ma) each sourced one class of oil. The other three classes represent mixtures of oil generated from multiple source rock intervals. Traps on the Shaleitian Uplift were charged in the east by oil generated from the Eocene Shahejie Formation in the Bozhong Sag, in the southeast by oil generated from the Eocene Shahejie and then Oligocene Dongying formations in the southwestern part of the Bozhong Sag and/or in the eastern part of the Shanan Sag, and in the southwest by oil generated from the Eocene Shahejie Formation in the western part of the Shanan Sag. The estimated migration distances range from less than 5 km to about 20 km. The compositional heterogeneity within fields and multiple-parameter comparisons between oils from nearby wells in different fields have proven to be a powerful tool to determine the in-filling histories of oil fields in cases where multiple source rock intervals and multiple generative kitchens exist. © 2010 Elsevier Ltd.


Gong C.,China University of Petroleum - Beijing | Wang Y.,China University of Petroleum - Beijing | Zhu W.,China National Offshore Oil Corporation | Li W.,British Petroleum | Xu Q.,China National Offshore Oil Corporation
AAPG Bulletin | Year: 2013

A series of short and steep unidirectionally migrating deepwater channels, which are typically without levees and migrate progressively northeastward, are identified in the Baiyun depression, Pearl River Mouth Basin. Using three-dimensional seismic and well data, the current study documents their morphology, internal architecture, and depositional history, and discusses the distribution and depositional controls on the bottom current-reworked sands within these channels. Unidirectionally migrating deep-water channels consist of different channel-complex sets (CCSs) that are, overall, short and steep, and their northeastern walls are, overall, steeper than their southwestern counterparts. Within each CCS, bottom current-reworked sands in the lower part grade upward into muddy slumps and debris-flow deposits and, finally, into shale drapes. Three stages of CCSs development are recognized: (1) the early lowstand incision stage, during which intense gravity and/or turbidity flows versus relatively weak along-slope bottom currents of the North Pacific intermediate water (NPIW-BCs] resulted in basal erosional bounding surfaces and limited bottom current-reworked sands; (2) the late lowstand lateral-migration and active-fill stage, with gradual CCS widening and progressively northeastward migration, characterized by reworking of gravity- and/or turbidity-flow deposits by vigorous NPIW-BCs and the CCSs being mainly filled by bottom current-reworked sands and limited slumps and debris-flow deposits; and (3) the transgression abandonment stage, characterized by the termination of the gravity and/or turbidity flows and the CCSs being widely draped by marine shales. These three stages repeated through time, leading to the generation of unidirectionally migrating deep-water channels. The distribution of the bottom current-reworked sands varies both spatially and temporally. Spatially, these sands mainly accumulate along the axis of the unidirectionally migrating deep-water channels and are preferentially deposited to the side toward which the channels migrated. Temporally, these sands mainly accumulated during the late lowstand lateral-migration and active-fill stage. The bottom current-reworked sands developed under the combined action of gravity and/or turbidity flows and alongslope bottom currents of NPIW-BCs. Other factors, including relative sea level fluctuations, sediment supply, and slope configurations, also affected the formation and distribution of these sands. The proposed distribution pattern of the bottom currentreworked sands has practical implications for predicting reservoir occurrence and distribution in bottom current-related channels. Copyright © 2013. The American Association of Petroleum Geologists. All rights reserved.


Li L.,China National Offshore Oil Corporation | Li L.,China University of Petroleum - Beijing | Li X.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2013

The current evaluation methods at home and abroad for the stress sensitivity of low-permeability reservoirs are mainly dominated by core experiments. However, there is a great difference between experimental conditions and actual formation conditions. Therefore, the rock mechanics theory is used to make a dynamic analysis of the reservoir overlying rocks; the calculation method is established of the overlying rocks' stress in the process of reservoir development; on this basis, such a correction factor is presented. According to this study, the current calculation method of overlying rock pressure is in accordance with the fluid mechanics and is fit for studies with fluids as an objective or those with an infinite field. But in reality, those overlying rocks with mutual binding force have a high resistance to flexure and shearing strength. Moreover, the pressure conductive ability is limited in the gas well production process, namely, the overlying rock pressure only affects the pressure drop in a limited area. As a result, a great error occurs in this calculation method, leading to a rather big error in the stress evaluation system. The referred correction factor indicates the resistance of the overlying rocks to flexure and shearing strength, with correction also to the effective stress of porous media; but in the actual experiment, the rock confining pressure is always imposed on the core at a stable value, which is inconsistent with that of the really existed bed rocks. In this respect, the experimental results exaggerate the effect of stress sensitivity to some extent.


Li X.,China National Offshore Oil Corporation | Li H.,China University of Petroleum - Beijing
Journal of Petroleum Science and Engineering | Year: 2013

In the traditional data-driven data mining process, there are huge gaps between the efficient algorithms and intelligent tools as well as the invalidity of knowledge which is obtained by traditional data-driven data mining. Meanwhile, each data in the earth science field contains a solid physical meaning. If there is no corresponding domain knowledge involved in the mining process, the information explored by data-driven data mining will be lack of practicability and not able to effectively solve problems in the earth science area. Therefore, the task-driven data mining is proposed. Additionally, task-driven data mining concepts and principles are elaborated with the help of data mining concepts and techniques. It is divided into seven elements such as data warehousing, data preprocessing, feature subset selection, modeling, model evaluation, model updating and model release. Those constitute a cyclic and iterative process until a predictive model which is capable of effectively achieving the objectives. In order to accurately identify complex lithologies, this paper puts forward a self-organizing feature map neural network based on the task-driven data mining. With the attempt to solve the problem of complex reservoir identification, the decision tree and support vector machine are used to build the fluid predictive model. Meanwhile, the optimization algorithms inclusive of genetic, grid and quadratic are adopted to optimize the important parameters of C-SVC and υ-SVC, such as C, υ and γ, so as to improve the classification performance and generalization ability of the predictive model of support vector machine. The conclusions of fine interpretation are compared with the core analysis data and well testing data. As a result, the accuracy of the complex lithology and reservoir identification is more than 90%. Finally, the paper puts forward the understandings, development prospects and key challenges of task-driven data mining facing. © 2013 Elsevier B.V.


Li J.,China University of Petroleum - Beijing | Guo B.,University of Louisiana at Lafayette | Ling K.,University of North Dakota
Journal of Energy Resources Technology, Transactions of the ASME | Year: 2013

With the downturn in natural gas prices, it is vitally important to reduce the cost of drilling shale gas wells. Gas-percussion drilling has been recently employed in shale gas field development. It increases footage capacity by nearly 60%. However, wellbore erosion by the high-velocity gas has been recognized as a problem that hinders further application of the technology. This paper investigates a potential solution to the problem using a new type of flow-diverting joint (FDJ). The FDJ with exchangeable nozzles can be installed at the shoulder of the drill collar to partially bypass gas flow into the annulus between the drill pipe and open hole. Hydraulics computations with a state-of-the-art computer program indicate that this technique will allow for the use of high-gas injection rate to carry drill cuttings while reducing the gas flow rate through the drill bit. As a result, the gas velocity in the drill collar-open hole annulus can be maintained at a safe level to prevent hole erosion. The reduced gas flow rate through the drill bit also minimizes wellbore enlargement at hole bottom. Sensitivity analyses with the computer program show that the FDJ-nozzle area to bit-nozzle area ratio is directly proportional to the annulus area ratio, and the bypassed flow rate fraction remains constant as drilling progresses. This makes the FDJ system easy to design and practical to use over a long section of hole to be drilled. © 2013 by ASME.


Xu B.,China University of Petroleum - Beijing | Xu B.,University of Adelaide | Haghighi M.,University of Adelaide | Li X.,China University of Petroleum - Beijing | Cooke D.,University of Adelaide
Journal of Petroleum Science and Engineering | Year: 2013

As a result of ultra-low rock permeability and hydraulic fracturing, both shale gas and tight gas production exhibit long-term transient and linear flow behaviour. Previous studies have introduced the type curves for linear flow reservoir and assumed that the production is dominated by the stimulated reservoir volume (SRV). Later the type curves were extended to include the production contribution from un-stimulated region which has been assumed to be a homogeneous system. At present, no type curves have been developed for naturally fractured shale gas/tight gas reservoirs in which the un-stimulated region has double porosity flow behaviour. In the current study, we have developed new analytical solutions for shale gas/tight gas reservoirs with multi-stage fractured horizontal well in order to account for the un-stimulated region as a dual porosity system. The solutions are more general for type curve analysis and applicable in both homogeneous and naturally fractured reservoirs. Numerical models were used to validate the analytical solutions and obtained an excellent agreement. We have also developed new type curves for shale gas/tight gas evaluation. The flow regimes are identified to show linear flow and transition flow alternately, and are more complicated than the assumption of homogeneous un-stimulated reservoir in late period. We have compared the new type curves with the curves based on SRV and Brohi's solutions. It is concluded that the double porosity behaviour of un-stimulated region has a positive effect on production even if the fracture permeability is in the order of matrix permeability and the matrix bulk shape factor is low. © 2013 Elsevier B.V.


Zhang K.,Sinopec | Zhang L.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2013

Unconventional oil and gas exploration and development have moved from behind the scenes to the stage all over the world. To get a better understanding and make a proper decision, we made a discussion on the E & P history and prospect of unconventional natural gas resources such as tight oil and gas, shale oil and gas, etc. The following findings were obtained. a. In current industrial mining, tight oil & gas, in a broad sense, mainly includes tight sandstone oil & gas, shale oil & gas and coalbed methane (CBM) with the same core exploiting technologies-horizontal drilling and hydraulic fracturing. b. In the USA, exploitation has been extending from tight sand hydrocarbons to coalbed methane and shale gas. The decrease of natural gas prices justified the rapid development of shale oil exploitation in recent years, which makes the USA the fastest growing producer of natural gas and oil. c. The up-to-date survey indicates that shale oil and shale gas account for 10% and 32% respectively of the global cumulative assessed hydrocarbon reserves. d. Tight liquids, an outstanding and popular concept worldwide in recent years, are mainly of shale oil including Natural Gas liquids (NGLs) and Light Oil. It suggests that only relatively light oil can be exploited out of tightly reserved oil. Accordingly, it could be named Light Tight Oil or LTO.


Zhang Y.,China University of Petroleum - Beijing | Zhang Y.,University of California at Riverside | He X.,China University of Petroleum - Beijing | He X.,CAS Fujian Institute of Research on the Structure of Matter | And 2 more authors.
Crystal Growth and Design | Year: 2011

Reported here are two three-dimensional CuI cluster-based organic frameworks, (Cu4I4)2(Cu6I 6)(DABCO)6 (1) and (Cu4I3) 2(CN)2(DABCO)3 (2) (DABCO = 1,4-diazabicyclo[2.2.2]octane) constructed from mixed CuI clusters and mixed linear ligands, respectively. Compound 1 displays an unprecedented 4-connected network based on Cu4I4 and Cu6I6 clusters, respectively, as tetrahedral and pseudosquare planar 4-connected nodes, while 2 displays a novel 5-connected BN-type network composed of 5-connected cationic Cu4I3 + clusters linked by mixed cyanide anion CN- and DABCO ligands. The CN- in 2 derives from the solvent CH3CN and adopts a rare μ4- bridging mode. 1 shows chiral symmetry and photoluminescence at 298 K. The mixed strategies prove to be a useful fool to enrich the synthetic chemistry and structural diversity of cluster organic frameworks. © 2010 American Chemical Society.


Chen F.,China University of Petroleum - Beijing | Jiang H.,China University of Petroleum - Beijing | Bai X.,China National Petroleum Corporation | Zheng W.,China National Offshore Oil Corporation
Journal of Industrial and Engineering Chemistry | Year: 2013

Sodium metaborate, a novel alkali, is introduced into alkali/surfactant/polymer (ASP) flooding to solve the negative effects caused by conventional alkalis. Sodium metaborate can reduce the adsorption loss of the surfactant as well as the interfacial tension (IFT). Weak alkali sodium metaborate causes less viscosity reduction compared with strong alkalis. Scale precipitation study shows that sodium metaborate can be effective to avoid the scale precipitation damage. Study results indicate that sodium metaborate result in the highest oil recovery of 56% compared with sodium carbonate and sodium hydroxide, and at the same time avoid the problems caused by conventional alkalis. © 2012 The Korean Society of Industrial and Engineering Chemistry.


Gong C.,China University of Petroleum - Beijing | Wang Y.,China University of Petroleum - Beijing | Zhu W.,China National Offshore Oil Corporation | Li W.,British Petroleum | And 2 more authors.
Marine and Petroleum Geology | Year: 2011

Submarine canyons have been the subject of intense studies in recent years because of their close link to deepwater systems. The Central Canyon is a large unusual submarine canyon in the northwestern margin of the South China Sea, has a total length of about 425 km and is oriented sub-parallel to the continental slope. Using integrated 2D/3D seismic, well log, core, and biostratigraphy data, the current study documents the stratigraphic framework, internal architecture, depositional processes, and controlling factors of the segment of the Central Canyon located in the Qiongdongnan Basin.The integrated analysis shows that the canyon fill consists of four 3rd-order sequences, SQ4, SQ3, SQ2, and SQ1. Each of them is bounded by regionally important erosional surfaces (3rd-order sequence boundaries). Within each 3rd-order sequence there is maximum regressive surface separating a regressive systems tract in the lower part and a transgressive systems tract in the upper part. Nine facies are identified and are further grouped into five depositional units, DU1 through DU5.The canyon evolved through four cut-and-fill stages, with a change from predominantly axial cut-and-fill to primarily side cut-and-fill. Axial cut-and-fill dominated during the first stage, and the slope-subparallel paleo Xisha Trough was intensely eroded by large-scale axial gravity flows. During the second cut-and-fill stage, the Central Canyon experienced both axial and side cut-and-fill. The third stage was dominated by side cut-and-fill. The canyon was eroded and fed by slope channels that transported sandy sediments from the shelf to the north during regression, and was covered by side-derived muddy MTCs during transgression. The last stage was also dominated by side cut-and-fill. The canyon, however, was filled predominantly by side-derived muddy MTCs.Evolution and depositional processes in the Central Canyon were likely controlled by slope-subparallel negative-relief induced by paleo-seafloor morphology, structural inversion of the Red River Fault and the slope-subparallel basement faults. Additionally, Coriolis force, sea-level fluctuations, high sedimentation rate, and rapid progradation of the slope also controlled and influenced the depositional processes, and internal architectures of the canyon. © 2011 Elsevier Ltd.


Wang B.,Tsinghua National Laboratory for Information Sciences and Technology | Wang B.,China University of Petroleum - Beijing
IEEE Geoscience and Remote Sensing Letters | Year: 2016

Sampling irregularity in observed seismic data may cause a significant complexity increase in subsequent processing. Seismic data interpolation helps in removing this sampling irregularity, for which purpose complex-valued curvelet transform is used, but it is time-consuming because of the huge size of observed data. In order to improve efficiency as well as keep interpolation accuracy, I first extract principal frequency components using forward Fourier transform. The size of the principal frequency-space domain data is at least halved compared with that of the original time-space domain data because the complex-valued components of the representation of a real-valued signal (i.e., a complex-valued signal with zero as its imaginary component) exhibit conjugate symmetry in the frequency domain. Then, the projection onto convex projection (POCS) method is used to interpolate frequency-space data based on complex-valued curvelet transform. Finally, interpolated seismic data in the time-space domain can be obtained using inverse Fourier transform. Synthetic data and field data examples show that the efficiency can be improved more than two times and the performance is slightly better in the frequency-space domain compared with the POCS method directly performed in the time-space domain, which demonstrates the validity of the proposed method. © 2016 IEEE.


Xiang W.,National University of Singapore | Xiang W.,China University of Petroleum - Beijing | Lee C.,National University of Singapore
Applied Physics Letters | Year: 2010

Nanoelectromechanical torsion switches are fabricated by using focused ion beam milling on silicon-on-insulator substrate. The device layer thickness of the substrate is 220 nm. A 9 m long and 1.5 m wide suspended silicon cantilever is mechanically connected to peripheral silicon device layer via a silicon torsion spring with the length of 2.4 m and width of 530 nm. After hydrofluoric-acid vapor releasing, the silicon cantilever shows downward deflection. The pull-in voltage is about 5.5 V and the ratio of current measured at the ON/OFF states is over 1000. Moreover, the simulated data of pull-in voltage of torsion switch is in agreement with the experimental result, which will contribute to design of an optimal nanoelectromechanical torsion switch with a driven voltage as low as 1.2 V. According to the preliminary results, this torsion switch with low driven voltage has a great potential for high density non-volatile memory application. © 2010 American Institute of Physics.


Zhou Q.,University of California at Davis | Zhou Q.,China University of Petroleum - Beijing | Ristenpart W.D.,University of California at Davis | Stroeve P.,University of California at Davis
Langmuir | Year: 2011

We report a magnetic technique for altering the apparent contact angle of aqueous droplets deposited on a nanostructured surface. Polymeric tubes with embedded superparamagnetic magnetite (Fe 3O 4) nanoparticles were prepared via layer-by-layer deposition in the 800 nm diameter pores of polycarbonate track-etched (PCTE) membranes. Etching away the original membrane yields a superparamagnetic film composed of mostly vertical tubes attached to a rigid substrate. We demonstrate that the apparent contact angle of pure water droplets deposited on the nanostructured film is highly sensitive to the ante situm strength of an applied magnetic field, decreasing linearly from 117 ± 1.3° at no applied field to 105 ± 0.4° at an applied field of approximately 500 G. Importantly, this decrease in contact angle did not require an inordinately strong magnetic field: a 15° decrease in contact angle was observed even with a standard alnico bar magnet. We interpret the observed contact angle behavior in terms of magnetically induced conformation changes in the film nanostructure, and we discuss the implications for reversibly switching substrates from hydrophilic to hydrophobic via externally tunable magnetic fields. © 2011 American Chemical Society.


Yu G.,China University of Petroleum - Beijing | Yu B.,China University of Petroleum - Beijing | Han D.,China University of Petroleum - Beijing
Applied Thermal Engineering | Year: 2013

The POD-Galerkin reduced-order model is established for the thermal process of the buried oil pipeline, which carries complex and inhomogeneous boundary conditions, including Dirichlet (or first-type), Neumann (or second-type), and Robin (or third-type) boundary conditions. Especially, the treatment of different boundary conditions is given in detail. The implementation of POD-Galerkin reduced-order model on unstructured mesh is also introduced. Subsequently, the thermal processes of batching transportation and commissioning in an oil pipeline are calculated by the established reduced-order model, indicating that the reduced-order model is accurate and efficient. The application of this reduced-order model may provide a convenient and rapid approach for the design and ensuring safe and economic operation of the oil transportation pipeline. © 2012 Elsevier Ltd. All rights reserved.


Liu G.,Xi'an Jiaotong University | Li H.,WISDRI Engineering and Research Incorporation Ltd | Feng X.,Xi'an Jiaotong University | Deng C.,China University of Petroleum - Beijing
AIChE Journal | Year: 2013

The purification reuse/recycle is one effective resource conservation strategy. In this article, a novel conceptual method is proposed to identify the optimal purification feed flow rate (PFFR) and the corresponding maximum hydrogen utility savings (HUS) of the hydrogen network with purification reuse/recycle. In this method, the sources and sink-tie-lines are divided into three regions according to the purified product and purification feed. The quantitative relationship between the HUS and the PFFR is analyzed for the sink-tie-lines and sources of each region. With the quantitative relationship line between the HUS and the PFFR of each source plotted, the quantitative relationship diagram can be obtained and can be used to identify the pinch point and the HUS for a given PFFR. Furthermore, the optimal PFFR and the maximum HUS can be identified easily. Three cases are studied to illustrate the applicability of the proposed method. © 2012 American Institute of Chemical Engineers (AIChE).


Tang Y.,China University of Petroleum - Beijing | Tang Y.,University of Texas at Austin | Obayashi M.,Japan Agency for Marine - Earth Science and Technology | Niu F.,China University of Petroleum - Beijing | And 7 more authors.
Nature Geoscience | Year: 2014

Volcanism that occurs far from plate margins is difficult to explain with the current paradigm of plate tectonics. The Changbaishan volcanic complex, located on the border between China and North Korea, lies approximately 1,300 km away from the Japan Trench subduction zone and is unlikely to result from a mantle plume rising from a thermal boundary layer at the base of the mantle. Here we use seismic images and three-dimensional waveform modelling results obtained from the NECESSArray experiment to identify a slow, continuous seismic anomaly in the mantle beneath Changbaishan. The anomaly extends from just below 660 km depth to the surface beneath Changbaishan and occurs within a gap in the stagnant subducted Pacific Plate. We propose that the anomaly represents hot and buoyant sub-lithospheric mantle that has been entrained beneath the sinking lithosphere of the Pacific Plate and is now escaping through a gap in the subducting slab. We suggest that this subduction-induced upwelling process produces decompression melting that feeds the Changbaishan volcanoes. Subduction-induced upwelling may also explain back-arc volcanism observed at other subduction zones. © 2014 Macmillan Publishers Limited.


Yu H.,China University of Petroleum - Beijing | Yu H.,China National Offshore Oil Corporation | Li S.,China University of Petroleum - Beijing | Jin G.,Beijing Institute of Petrochemical Technology
Energy and Fuels | Year: 2010

Because of high contents of nitrogen, sulfur, and unsaturated hydrocarbons in shale oil, its potential use as a substitute fuel is limited. In this paper, catalytic hydrotreating of the diesel fraction (200-360 °C) from Fushun shale oil was preliminarily investigated in a fixed-bed reactor. Hydrotreating experiments were carried out using various available commercial catalysts, including CoMo/Al2O3, NiW/Al2O3, and NiMoW/Al2O3, at different conditions of temperature, hydrogen pressure, liquid hourly space velocity (LHSV), and ratio of hydrogen/feedstock. The results showed that the NiMoW catalyst was most active for heteroatom removal, in comparison to other catalysts. Under relative mild conditions, it was possible to produce clean diesel from a Fushun shale oil distillate. The produced oil had low contents of sulfur, nitrogen, and alkene, reduced density, and increased cetane number, and it could be used as a more valuable fuel. © 2010 American Chemical Society.


Sun L.,China University of Petroleum - Beijing | Gao D.,China University of Petroleum - Beijing | Zhu K.,Drilling and Production Technology Research Institute
Journal of Natural Gas Science and Engineering | Year: 2012

Casing wear is one of the critical problems in drilling operations for oil and gas field development. It is important to be able to predict the casing wear for offering practical advice on casing wear reduction. Currently the wear-efficiency model and the nonlinear casing wear model are used to predict casing wear. Two full-size casing wear tests were conducted in this study, involving the change in tool joint size. Comparisons of the test data with the casing wear models showed that the casing wear condition coefficient in the nonlinear wear model is slightly affected by the wear time and tool joint size change, which is different from the casing wear factor in the wear-efficiency model. Therefore, the nonlinear wear model should be used to predict the casing wear depth with higher accuracy in complex wells. In addition, it was found that the limestone additives (nonabrasive solids) did not affect the casing wear in the film forming & sealing & low invasion reservoir protection drilling fluid. High concentrations of the nonabrasive solids did not further reduce casing wear after a protective layer was formed. © 2011 Elsevier B.V.


Yang X.,China University of Petroleum - Beijing | Sun C.-Y.,China University of Petroleum - Beijing | Su K.-H.,China University of Petroleum - Beijing | Yuan Q.,China University of Petroleum - Beijing | And 2 more authors.
Energy Conversion and Management | Year: 2012

A middle-scale reactor equipped with 16 thermocouples was used to investigate the formation and dissociation of methane hydrate in sediment in three dimensions. A method was proposed to form hydrate homogeneously distributed in sediment, i.e., using frozen sand instead of wet sand with pore water. With the formed hydrate sample, hydrate dissociation experiment by depressurization was carried out at a constant pressure of 1.0 MPa. It was found that gas hydrate dissociation occurs throughout the hydrate zone, which controlled by both mass transfer and heat transfer throughout the stages. The sharp-interface is hardly found during the hydrate dissociation. The thermal buffering was observed at the temperature of (271.5-272.2) K during the hydrate dissociation process. The ice arisen from hydrate dissociation slows the hydrate dissociation rate below the ice point, which will affect gas production rate. It may be more reasonable that the depressurization method is used in the initial stage and the thermal stimulation method is used in the later stage in the process of gas recovery from hydrate reservoir. © 2011 Elsevier Ltd. All rights reserved.


Liu R.,University of California at Riverside | Zhang Y.,University of California at Riverside | Zhang Y.,China University of Petroleum - Beijing | Zhao X.,University of California at Riverside | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

(Figure Presented) A new pH-responsive hybrid nanogated ensemble has been developed by using acetal group linked gold nanoparticle capped mesoporous silica. The hydrolysis of acetal linker at acidic environment makes the gold nanoparticles work as a gatekeeper to control the release of guest molecules from mesoporous silica under different pH's. © 2010 American Chemical Society.


Duan J.,China University of Petroleum - Beijing | Gong J.,China University of Petroleum - Beijing | Yao H.,China National Offshore Oil Corporation | Deng T.,China University of Petroleum - Beijing | Zhou J.,China University of Petroleum - Beijing
Applied Energy | Year: 2014

A numerical three-dimensional non-isothermal hydrodynamic and thermal modeling based on the unidirectional flow analysis of stratified flow in the circular cross section pipe is developed and tested by experimental data. The model could solve the steady axial momentum equation and heat transfer equation with a low Reynolds number k~. ε model of turbulence for the eddy viscosity. Due to irregular geometry of stratified pipe flow, the equations of the problem are based on a bipolar coordinate system. Grid refinement near the interface and pipe wall is respectively used for an accurate solution near the boundaries. The model is capable of determining pressure drop and liquid height. In addition, wall and interface shear stress, flow field and temperature field for both phases could be predicted successfully. The predicted data of pressure drop, liquid holdup and velocity profile by the model fit well with some available experiment data and one-dimensional model. And the energy equation is solved, and temperature distribution is gained over the flow and compared well with experimental results. In conclusion, the model could have a practical application for estimation of hydrodynamics and thermodynamics in a pipeline. © 2013 Elsevier Ltd.


Zhou Q.,China University of Petroleum - Beijing | Fang Z.,China University of Petroleum - Beijing | Liao X.,Environmental Protection Agency of Guangshan County
Journal of Separation Science | Year: 2015

We describe a highly sensitive micro-solid-phase extraction method for the pre-concentration of six phthalate esters utilizing a TiO2 nanotube array coupled to high-performance liquid chromatography with a variable-wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting-out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3-200 μg/L. The limits of detection were 0.04-0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang H.,China University of Petroleum - Beijing | Guo B.,University of Louisiana at Lafayette | Gang M.,University of Louisiana at Lafayette
Journal of Natural Gas Science and Engineering | Year: 2012

Underbalanced drilling (UBD) has been proven to be an effective means of increasing drilling performance and minimizing formation damage. While UBD with gases (air, nitrogen, natural gas, etc.) gives the highest rate of penetration (ROP), addition of liquid phase significantly reduces ROP. The objective of this study was to understand the mechanism of rock failure that controls the ROP and use the gained knowledge to optimize gas UBD design. An analytical model was developed in this study to calculate the near-wellbore rock stresses induced by the bottom hole pressure and temperature. A numerical model with finite element method was used to verify the results from the analytical model. Both of the analytical model and the numerical model reveal that the rock stress in the bottom hole rock can change from compressive stress in over-balanced conditions to tensile stress in underbalanced conditions, depending on the bottom hole pressure. A new finding from this study is that the temperature-induced stresses in the bottom hole rock can contribute significantly to the stress unbalance and cause rock failure. This paper provides drilling engineers insight and understanding of rock failure mechanics, which are useful for designing bottom hole pressure and gas injection rate to improve UBD performance. © 2011.


Yin X.-Y.,China University of Petroleum - East China | Zhang S.-X.,China National Offshore Oil Corporation | Zhang F.,China University of Petroleum - Beijing
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013

Russell fluid factor is a sensitive indicator for deep reservoir fluid identification. Considering that the seismic data of deep reservoir is lack of large angle information and has low signal-noise-ratio, the Bayesian-based two term elastic impedance inversion and Russell fluid factor direct estimation method are carried out. Firstly, based on the saturated poroelastic media theory, we derive the two term reflection coefficient approximation in terms of Russell fluid factor and P-wave impedance, using which we get the new equation of elastic impedance containing the Russell fluid factor. Secondly, we analyze the precision and applicable condition of the new elastic impedance and the model test shows that it can satisfy the accuracy of small angle incidence. Finally, the Bayesian-based elastic impedance inversion and Russell fluid factor estimation procedure is introduced, the model tests illustrate that the direct estimation method can take full advantage of elastic impedance inversion to have high signal-noise-ratio and practicability, and furthermore, the direct estimation method can diminish negative effect of accumulative error. The real application shows that the direct estimated Russell fluid factor raise the reliability of the deep reservoir fluid identification.


Yang B.,University of Aarhus | Guo C.,University of Aarhus | Jensen C.S.,University of Aalborg | Kaul M.,University of Aarhus | Shang S.,China University of Petroleum - Beijing
Proceedings - International Conference on Data Engineering | Year: 2014

Different uses of a road network call for the consideration of different travel costs: in route planning, travel time and distance are typically considered, and green house gas (GHG) emissions are increasingly being considered. Further, travel costs such as travel time and GHG emissions are time-dependent and uncertain. To support such uses, we propose techniques that enable the construction of a multi-cost, time-dependent, uncertain graph (MTUG) model of a road network based on GPS data from vehicles that traversed the road network. Based on the MTUG, we define stochastic skyline routes that consider multiple costs and time-dependent uncertainty, and we propose efficient algorithms to retrieve stochastic skyline routes for a given source-destination pair and a start time. Empirical studies with three road networks in Denmark and a substantial GPS data set offer insight into the design properties of the MTUG and the efficiency of the stochastic skyline routing algorithms. © 2014 IEEE.


Ni Z.-Y.,China University of Petroleum - Beijing | Li N.,Peking University | Zhang H.,Chinese Academy of science
Geological Journal | Year: 2014

The Xiaoqinling gold field in central China is the second largest orogenic Au province in China. In the Xiaoqinling area, the Dahu Au-Mo deposit is typical because it is one of the five early-discovered large gold deposits, but also unique for its northernmost location and Mo-association. This study shows that the deposit is a fault-controlled lode system formed by a three-stage hydrothermal process. The early-stage pyrite-quartz veins are structurally deformed and broken. The middle-stage molybdenite-pyrite-quartz stockworks (mostly coaxial) infill the cracks of the early-stage veins and minerals. The late-stage open-space filling quartz-carbonate veinlets show a comb-like texture. The early- and late-stage quartz only contains the fluid inclusions of CO2-H2O and H2O-NaCl types, respectively, suggesting an evolution from CO2-rich to CO2-poor; whereas the middle-stage quartz contains fluid inclusions of CO2-H2O, H2O-NaCl, pure CO2 and daughter mineral-bearing types, supporting a boiling fluid system, because they can occur in a microscopic domain of a single crystal, homogenize divergently at similar temperatures clustering between 293 and 410°C, and show contrasting salinities of <13.6wt.% and >26.3wt.% NaCl equiv. The inclusions in early-stage quartz are homogenized at 402-503°C, with salinities of 4.5-10.4wt.% NaCl equiv.; and those in late-stage quartz are homogenized at temperatures of <251°C, with salinities of 14.4-14.8wt.% NaCl equiv. The trapping pressures of inclusions are estimated to be 138-331MPa in the early stage and 78-237MPa in the middle stage, implying that the fluid system alternately fluctuated from lithostatic to hydrostatic, which was controlled by a fault-valve mechanism at depths of >11km and ~7.8km, respectively. Hydrogen and oxygen isotope signatures indicate that the fluids originated from metamorphic devolatilization in the early stage, then mixed with meteoric water in the middle stage, and finally replaced by meteoric water in the late stage. Hence, it is concluded, that metal precipitation at the Dahu deposit was mainly caused by fluid boiling, followed by fluid mixing, along with a trans-compressing at the transitional zone from a magmatic arc to back-arc basin, which resulted from the Triassic northward subduction of the Mian-Lue oceanic slab. © 2014 The Authors. Geological Journal published by John Wiley & Sons Ltd.


Zeng Y.,China University of Petroleum - Beijing | Cai Y.,Environment Canada | Cai Y.,Beijing Normal University | Jia P.,CAS Shenzhen Institutes of Advanced Technology | And 2 more authors.
Expert Systems with Applications | Year: 2012

Demands on fresh water by human beings have been continuously increasing due to population growth, living standard improvement, and economic development. At the same time, many regions are suffering greatly from floods and droughts. Those are the results of ineffective management of water resources due to the associated complexities. In this study, a decision support system (DSS) was developed for supporting integrated water resources management in Daegu city, Republic of Korea. The developed DSS contained four subsystems including database, modelbase, and knowledgebase, as well as general user interface (GUI). It was then connected with the National Water Management Information System (WAMIS). A flow prediction could be conducted through the incorporated HEC-HMS Version 3.0.1. Also, an urban water demand forecasting model was developed using an artificial neural network (ANN) based model. At the same time, a water resources management model based on genetic algorithm (GA) was developed in the DSS, facilitating efficient allocation of water resources among different regions within a city. The result indicated that the developed DSS is very useful to deal with complex water resources management problems and could be further applied to similar cities in South Korea. © 2012 Elsevier Ltd. All rights reserved.


Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Renewable and Sustainable Energy Reviews | Year: 2014

Research interest in the conversion of lignocellulosic biomass into energy and fuels through the pyrolysis process has increased significantly in the last decade as the necessity for a renewable source of carbon has become more evident. For optimal design of pyrolysis reactors, an understanding of the pyrolysis kinetics of lignocellulosic biomass is of fundamental importance. The distributed activation energy model (DAEM) has been usually used to describe the pyrolysis kinetics of lignocellulosic biomass. In this review, we start with the derivation of the DAEM. After an overview of the activation energy distribution and frequency factor in the DAEM, we focus on the numerical calculation and parameter estimation methods of the DAEM. Finally, this review summarizes recent results published in the literature for the application of the DAEM to the pyrolysis kinetics of lignocellulosic biomass. © 2014 Elsevier Ltd.


Wang L.,China University of Petroleum - Beijing | Jia X.,China University of Petroleum - Beijing | Li Y.,China University of Petroleum - Beijing | Yang F.,China University of Petroleum - Beijing | And 4 more authors.
Journal of Materials Chemistry A | Year: 2014

We report a simple procedure for fabricating flexible, free-standing, and magnetic film of GO/CNT-Fe3O4 composites by using a one-pot co-precipitation in situ growth route. Characterizations including X-ray diffraction, Raman spectroscopy, superconducting quantum interference device magnetometry, scanning electron microscopy and transmission electron microscopy have been carried out to investigate the morphology, crystalline structure and magnetic properties of the composites. The layered structure of the as-prepared composites is porous and superparamagnetic. The GO/CNT-Fe3O 4 composites exhibit excellent microwave absorbing properties in the range of 2-18 GHz and are expected to be promising candidates as microwave absorbing materials. © the Partner Organisations 2014.


Chen W.-T.,University of Illinois at Urbana - Champaign | Zhang Y.,University of Illinois at Urbana - Champaign | Zhang J.,University of Illinois at Urbana - Champaign | Zhang J.,China University of Petroleum - Beijing | And 4 more authors.
Applied Energy | Year: 2014

This study explored the feasibility of combining two types of feedstocks, swine manure (SW) and mixed-culture algae (AW) from wastewater treatment systems, for bio-crude oil production via hydrothermal liquefaction. The effect of feedstock combination ratios on the bio-crude oil yields and qualities were investigated. SW to AW ratios (dry weight basis) were 1:3, 1:1 and 3:1 with a total solids content of 25%. Pure SW and AW were also hydrothermally converted at the same reaction condition for comparison. By combining 75% SW with 25% AW, the highest bio-crude oil yield was achieved (35.7% based on dry matter). By mixing 25% SW with 75% AW, the highest heating value (27.5. MJ/kg) was obtained. GC-MS spectra and thermal gravimetric analysis of bio-crude oils revealed that both light oils and heavy crude were produced, averaging 25% and 20% of the bio-crude oil, respectively. Analysis of energy consumption ratios indicated that co-liquefaction of AW and SW is energetically feasible and could be an economically competitive system for bio-crude oil production. © 2014 Elsevier Ltd.


Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Industrial and Engineering Chemistry Research | Year: 2012

A critical study of the use of the iterative linear integral isoconversional method for a parallel reactions process and a successive reactions process has been performed using theoretical simulated nonisothermal data. The activation energies obtained for these complex processes show a strong dependence on the range of heating rates, which is against the assumptions of isoconversional methods. Therefore, a systematic kinetic analysis for discriminating the reactions rather than merely assuming that the activation energy varies with the conversion would be required for understanding the reaction mechanism of these processes. © 2012 American Chemical Society.


Zhang J.,China University of Petroleum - Beijing | Zhang J.,University of Illinois at Urbana - Champaign | Zhang Y.,University of Illinois at Urbana - Champaign
Energy and Fuels | Year: 2014

In this paper, hydrothermal liquefaction (HTL) of microalgae Chlorella pyrenoidosa was conducted for biocrude oil production. The ethanol-water co-solvent was introduced to take advantage of the special properties of supercritical ethanol and hot compressed water. The effects of the ethanol/water mass ratio (R) on the product distribution and characterization were discussed. The co-solvent showed better performance over any constituent mono-solvent, indicating synergistic effects of ethanol and water. The highest biocrude oil yield of 57.3% and the lowest solid residue yield of 9.4% were achieved at R = 5:2. The loading factor was considered as another influencing factor under supercritical conditions. Furthermore, potential reaction pathways for major biomacromolecule monomers in the ethanol-water co-solvent were also proposed on the basis of the gas chromatography-mass spectrometry (GC-MS) analysis of the liquid products. © 2014 American Chemical Society.


Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Bioresource Technology | Year: 2013

The three-parallel-DAEM-reaction model was used to study the slow pyrolysis kinetics of rice straw based on thermogravimetric analysis (TGA) data. The kinetic parameters of the model were calculated using the pattern search method. A comparison between the predicted DTG data and experimental values showed good agreement. The influences of the kinetic parameters on the model for describing the experimental data of rice straw were analyzed by means of local parametric sensitivity analysis. The results indicated that the frequency factor and the mean value of the activation distribution for cellulose decomposition affect the model more strongly than other parameters, followed by the corresponding parameters for hemicellulose and lignin. The sensitivity of the model to the standard deviations of the activation energy distributions for all pseudocomponents is very slight. © 2012 Elsevier Ltd.


Zhang X.,Tsinghua University | Zhang X.,China University of Petroleum - Beijing | Shi H.,Tsinghua University | Shi H.,Technical University Mnchen | Xu B.-Q.,Tsinghua University
Journal of Catalysis | Year: 2011

Hydrogenation of 1,3-butadiene over Au/ZrO2 catalysts with different gold loadings and calcination temperatures was reported. The catalysts were characterized in depth to understand their structure-property relationship. Gold oxidation states and surface hydroxyl groups, which were found to be sensitive to the gold loading, calcination temperature, and treatment with water, were shown to play vital roles in the hydrogenation activity of Au/ZrO2. Continued activity decrease was seen when the density of surface hydroxyl groups was lowered by elevating the pre-calcination temperature of ZrO2. Fully dehydroxylated Au/ZrO2 was essentially inactive, but became very active after partial regeneration of the hydroxyl groups by water treatment. Moreover, the activity of Au/ZrO2 increased with increasing Au3+/Au0 ratio. Isolated Au3+ ions at the support surface showed up to two orders of magnitude higher activity than Au0 atoms on Au particles. Several models are proposed to address the structural features of active sites for H2 activation in Au/ZrO2 catalysts. © 2011 Elsevier Inc. All rights reserved.


Liu R.,CAS Research Center for Eco Environmental Sciences | Liu J.-F.,CAS Research Center for Eco Environmental Sciences | Zhang Z.-M.,CAS Research Center for Eco Environmental Sciences | Zhang L.-Q.,China University of Petroleum - Beijing | And 3 more authors.
Journal of Physical Chemistry Letters | Year: 2014

For their unique properties, core-shell bimetal nanostructures are currently of immense interest. However, their synthesis is not a trivial work, and most works have been conducted on nanoparticles. We report herein a new synthetic tactic for submonolyer-Pt coated ultrathin Au nanowires (NWs). Besides providing a strong electromagnetic field for Raman signal enhancing, the underlined Au NWs markedly enhanced the catalytic activity of Pt atoms through increasing their dispersity and altering their electronic state. The integration of excellent SERS and high catalytic activity within Au@Pt NWs enable it work as platform for catalyzed reaction study. As a proof of principle, the self-organized Au@Pt NWs thin film is employed in operando SERS monitoring of the p-nitrothiophenol reduction process. In addition to providing kinetic data for structure-activity relationship study, the azo-intermidate independent path is also directly witnessed. This synthetic tactic can be extended to other metals, thus offering a general approach to modulate the physical/chemical properties of both core and shell metals. © 2014 American Chemical Society.


Wu W.,Shanghai JiaoTong University | Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Liu R.,Shanghai JiaoTong University
Industrial and Engineering Chemistry Research | Year: 2013

Seven different distributed activation energy model (DAEM) processes, which were used to describe the pyrolysis kinetics of wood, algae, lignin, corn stalk skin, kerogen, cellulose, and coal, were analyzed by means of the Friedman differential isoconversional method. It has been shown that the activation energies obtained from the Friedman method are independent of the heating rate. For all DAEM processes considered, the effect activation energies evaluated by the Friedman isoconversional method showed significant dependence on the conversion. The kinetic parameters obtained by means of the Friedman isoconversional method were used to reconstruct the conversions and rates data. The agreement between the reconstructed data and the data calculated by the DAEM is excellent at the presimulated and extrapolated conditions for all the DAEM processes. This indicates the DAEM process can be taken as an example to check the accuracy of some integral isoconversional methods in the determination of the activation energy. © 2013 American Chemical Society.


Li J.,Xiamen University | Luo Z.-H.,Xiamen University | Luo Z.-H.,Shanghai JiaoTong University | Lan X.-Y.,China University of Petroleum - Beijing | And 2 more authors.
Powder Technology | Year: 2013

A comprehensive three-dimensional (3-D) heterogeneous reactor model was applied to simulate the turbulent gas-solid flow and reaction in a polydisperse fluid catalytic cracking (FCC) riser reactor. In order to describe the hydrodynamics of polydisperse solid catalyst particles and the FCC reaction, the reactor model combined the population balance model of the catalyst with the 14-lump reaction kinetic equations. The reactor model was also used to predict the distributions of system parameters in the complex gas-solid turbulent reacting flow in the riser, such as velocity, temperature and component concentrations. Furthermore, the effect of aggregation and breakage of particles on the catalyst particle size distribution (PSD) in the flow field was also considered in the proposed model. The simulation results showed that the particle breakage is significant in the FCC riser, which causes the particles become smaller. Besides, the simulated product yields considering particle aggregation and breakage agreed well with the on-site data in the plant. © 2013 Elsevier B.V.


Gao Y.,China University of Petroleum - Beijing | Xiao L.-Z.,China University of Petroleum - Beijing | Xie Q.-M.,Chongqing Institute of Geology and Mineral Resources
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2014

In the Phillips-Twomey method, it is essential to find a suitable regular parameter r. The selection of the parameter r remains practically difficult, and is often biased by researcher's subjectivity. Finding a suitable regular parameter r in using Phillips-Twomey method to inverse nuclear magnetic resonance (NMR) logging transverse relaxation time was focused on. The way to finding the suitable r was based on the compromise criterion in BG theory and the r minimal criterion. The inversed transverse relaxation time was also assessed through the resolution matrix and the covariance matrix. Digital simulation and core analysis show that the approach in determining the regular parameter r of the Phillips-Twomey inverse method works very well for the inverse of NMR transverse relaxation time. Core analysis also shows that this method is better than the classical SVD method without subjective bias.


Zhong W.,China University of Petroleum - Beijing | Chi L.,Shanghai JiaoTong University | Luo Y.,China University of Petroleum - Beijing | Zhang Z.,China University of Petroleum - Beijing | And 2 more authors.
Bioresource Technology | Year: 2013

Anaerobic digestion of Taihu blue algae was tested in laboratory scale, continuous feed digesters (hydraulic retention time 10days) at 35°C and various organic loading rates (OLR). The methane production and biomass digestion performed well at OLR below 4.00gVSL-1d-1 but deteriorated as OLR increased due to the increased ammonia concentration, causing inhibition mainly to acetate and propionate degradation. Supplementing corn straw as co-feedstock significantly improved the digestion performance. The optimal C/N ratio for the co-digestion was 20:1 at OLR of 6.00gVSL-1d-1. Methane yield of 234mL CH4 gVS-1 and methane productivity of 1404mL CH4 L-1d-1 were achieved with solid removal of 63%. Compared with the algae alone, the methane productivity was increased by 46% with less accumulation of ammonia and fatty acids. The reactor rate-limiting step was acetate and propionate degradation. © 2013 Elsevier Ltd.


Xia L.,China University of Petroleum - Beijing | Luo D.,China University of Petroleum - Beijing | Luo D.,Chongqing Institute of Geology and Mineral Resources
Journal of Natural Gas Science and Engineering | Year: 2014

Target depth is a key measure of the commercial viability of a shale gas prospect. Although much research has been conducted in the shale gas techno-economic appraisal field, no reports are available on the economic critical depth (ECD) of shale gas resources. The present work aims at establishing a model for calculating the ECD using the break-even analysis-the reverse of calculating the net present value (NPV)-such that the break-even ECD occurs at zero NPV. The ECD is sensitive to production uncertainty, depending on the initial production (IP) rate and the production decline rate. Examples indicate that these have a marked effect on ECD based on current technology, gas price and exploitation policy, with the IP rate having the more pronounced effect. When the IP rate varies between 2.5 and 5.5 × 104 m3/day based on the fitted production decline trend from a pilot area in China, the corresponding ECD varies from 898 m to 3997 m. The ECD is thus able to rule out non-commercial shale gas prospects quickly. © 2014 Elsevier B.V.


Chen W.-T.,University of Illinois at Urbana - Champaign | Zhang Y.,University of Illinois at Urbana - Champaign | Zhang J.,University of Illinois at Urbana - Champaign | Zhang J.,China University of Petroleum - Beijing | And 4 more authors.
Bioresource Technology | Year: 2014

In this study, a mixed-culture algal biomass harvested from a functioning wastewater treatment system (AW) was hydrothermally converted into bio-crude oils. The highest bio-crude oil yield (49% of volatile matter) and the highest energy recovery were obtained at 300. °C with 1. h retention time. The highest heating value of the bio-crude oil was 33.3. MJ/kg, produced at 320. °C and 1. h retention time. Thermogravimetric analysis showed approximately 60% of the bio-crude oils were distilled in the range of 200-550. °C; and the solid residue might be suitable for use in asphalt. GC-MS results indicated that the bio-crude oil contained hydrocarbons and fatty acids, while the aqueous product was rich in organic acids and cyclic amines. The nitrogen recovery (NR) in the bio-crude oil ranged from 8.41% to 16.8%, which was lower than the typical range of 25%-53% from previous studies. © 2013 Elsevier Ltd.


Guo H.,China University of Petroleum - Beijing | Li J.,Howard University | Qian Y.,University of Nebraska at Omaha
IEEE Transactions on Vehicular Technology | Year: 2010

The development of delay-tolerant networks (DTNs) has attracted significant attention in the network research community. In this paper, we propose a new type of DTNa homing-pigeon-based DTN (HoP-DTN). In the HoP-DTN, each node owns a dedicated messenger (called a pigeon). The only form of internode communication is for a pigeon to periodically carry a batch of messages originated at the home node, deliver them to the corresponding destination nodes, and return home. Clearly, given message-expiration times, some messages may not reach their destinations by the deadline. Through analysis and simulations, we study the relationship between key parameters of the system, including average message delay, expiration time, delivery ratio, arrival rate, and batch size of messages. Various simulations have been conducted to demonstrate the accuracy of our analysis. Our theoretical study and simulations present a deep insight into the characteristics of the proposed system. Some interesting observations from simulations are discussed in detail in this paper, and the results demonstrate that our proposed scheme performs better in terms of average message delay, message-delivery ratio, and cost-effectiveness. © 2010 IEEE.


Chen Y.,China University of Petroleum - Beijing | Zhang J.,PowerChina Beijing Engineering Corporation Ltd | Zhang H.,China University of Petroleum - Beijing | Li X.,Dalian University of Technology | Zhou J.,Dalian University of Technology
Ocean Engineering | Year: 2015

Marine risers are important components operating in offshore oil and gas industry. The vortex-induced vibration design of marine risers requires accurate knowledge of natural frequencies and mode shapes. Free vibration of marine risers are re-examined in this paper by means of variational iteration method, which is relatively new technique capable of dealing with eigenvalue problems rather efficiently. Solutions from the variational iteration method are compared to approximate solutions previously proposed in literatures via a numerical example. Furthermore, validation of the technique is demonstrated by comparing experimentally measured natural frequencies of model marine riser with the predicted ones. © 2014 Elsevier Ltd. All rights reserved.


Ma Y.,China University of Petroleum - Beijing | Zhong N.,China University of Petroleum - Beijing | Li D.,Chongqing Institute of Geology and Mineral Resources | Pan Z.,CSIRO | And 2 more authors.
International Journal of Coal Geology | Year: 2015

Gas shales with a high gas content were encountered in the Lower Cambrian Lujiaping Formation in the northeast part of the upper Yangtze area, China. In this area, the tectonic condition is complex and the organic matter is over-matured, so conventional oil and gas exploration have not previously been considered. During a recent shale gas exploration, canister-desorbed gas contents of more than 1m3/t were detected from 490 to 825m depth, with a maximum value of 3.18m3/t at 762m. Hence to understand the mechanism of preservation of the gas is important. The gas shales have a total organic carbon (TOC) content of between 0.44% and 6.91%, and vitrinite-like macerals reflectance (Ro) between 3.3% and 4.3% with type II kerogen. The porosity of 22 gas shale samples ranges between 0.4% and 2.29%, and their permeability is between 6.9×10-5 and 3.8×10-1mD. To investigate the shale's pore structure and its relation to gas storage behavior, we studied the microscopic mechanism of gas preservation using a combination of pore characterization techniques, including focused ion beam-scanning electron microscope (FIB-SEM) imaging, and comparison of gas sorption and free gas storage capacity.Folding, thrusting and subsequent rapid uplifting movements occurred after most of the dry gas had been originally generated, and the present gas is a mixture originated from the cracking of liquid hydrocarbons at high maturity and kerogen pyrolysis in the early hydrocarbon-generation phase. SEM observations, combined with low temperature gas adsorption and mercury injection capillary pressure analyses, show that pores within the organic matter or the mineral particles in the Lujiaping Shale are rare, while the nanometer-sized pores (1-4nm) between organic matter and clay mineral particles, especially in cleavage domains, are greatly developed. Thus the gas in these shales is mainly adsorbed gas due to the limited free gas storage space. This is unlike most other shale gas reservoirs, pores within the organic matter and pores between or within mineral particles are dominant. Moreover, the desorbed gas content correlates well with TOC content and the microporous and mesoporous specific surface area determined by low temperature CO2 and N2, respectively, suggesting that the nanometer-sized pores associated with the organic matter make up the fundamental storage space for this shale. The calculations based on FIB-SEM observation showed that the nanometer-sized intergranular pores have large specific surface areas, with their small pore throat diameters resulting in high capillary pressure. These characteristics have contributed to the preservation of shale gas in this complex tectonic area. © 2014 Elsevier B.V.


Xu H.,Shanghai JiaoTong University | Pop I.,Babes - Bolyai University | You X.-C.,China University of Petroleum - Beijing
International Journal of Heat and Mass Transfer | Year: 2013

The unsteady film flow and heat transfer of nanofluids caused by a linear stretching velocity over a horizonal elastic sheet is investigated. By means of similarity variables, the boundary layer equations describing the momentum and energy conservations are reduced to a set of ordinary differential equations with an unknown constant. The homotopy analysis method (HAM) is then applied to give exact solutions for this particular kind of equations. A linear relationship between the film thickness β and the unsteadiness parameter S is found. Besides, the effects of the unsteadiness parameters S, the solid volume fraction of the nanofluid φ and the Prandtl number Pr on the velocity and the temperature distributions are presented and discussed, respectively. It is found that the usage of nanoparticles in the base fluids can effectively improve on the heat transfer characteristics. © 2013 Elsevier Ltd. All rights reserved.


Xia L.,China University of Petroleum - Beijing | Luo D.,China University of Petroleum - Beijing | Luo D.,Chongqing Institute of Geology and Mineral Resources | Yuan J.,China University of Petroleum - Beijing
Journal of Natural Gas Science and Engineering | Year: 2015

Although there have been discussions regarding the commercial prospect of shale gas in China, no quantitative and convincing analysis regarding its economic viability has been reported. This research aims to explore the future of the shale gas industry in China using a single-well model. This model is established with the DCF (Discounted cash flow) method aiming at getting an average or representative reflection of the economic viability of shale gas. In the model based on data mainly from pilot areas in Sichuan Basin, three scenarios are conducted to discuss the current economy, the short-term prospect, and the future of the shale gas industry. Under the current technological and economic conditions, China's shale gas resources are not worth an investment. However, in the near future, several sweet-spots are promising, particularly with the expectation of higher gas prices and lower drilling and completion costs (D&C costs). Although the sweet-spots are promising, it is difficult to achieve the goal of large-scale development according to the known information if mainly relying on current policy, unless there are sufficient sweet-spots. Hence, we hold a cautiously optimistic attitude towards the future of the shale gas industry. We suggest that the government should spend more on supporting resource surveys and exploration in the initial stages. After identifying the resource status, a more comprehensive development plan with systemic policies conformed to the resource status is warranted, including encouragement of technical innovations, a system for mature shale gas technical service markets, and a market-oriented price. © 2015 Elsevier B.V.


Zhao X.,China University of Petroleum - Beijing | Yin H.,Shanghai JiaoTong University | Zhao Y.,China Resources Power Holdings Company Ltd
Applied Energy | Year: 2015

The power industry is the largest air polluter in China, contributing nearly 40% of CO2 emissions and 60% of SO2 emissions. Under mounting pressure to improve standards of environmental protection, it is imperative that the industry increases the efficiency and environmental performance of power plants in China. We investigate the impacts of three different environmental regulations on efficiency improvement and CO2 reduction: command and control regulations (CCR), market-based regulations (MBR), and government subsidies (GS). We find that MBR and GS have a positive impact on efficiency improvement and CO2 reduction. However, CCR have no significant impacts. This finding has important implications since CCR dominates China's environmental policy. We discuss the policy implications of these findings, such as China should further release the potential of MBR in the power industry, instead of solely relying on CCR; and pay more attention to the coordination of different policy instruments. © 2015 Elsevier Ltd.


Zhang H.,China University of Petroleum - Beijing | Zhang H.,East China Institute of Technology | Chen X.-H.,China University of Petroleum - Beijing
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013

Traditional seismic data sampling must follow the Nyquist sampling theorem, while the field data acquisition can't meet the sampling theorem due to missing traces or exploration cost limit, so there exits data reconstruction problem. In this paper, based on the theory of compressed sensing, we render coherent aliases of regular under-sampling into harmless incoherent random noise using the random under-sampling, effectively turning the reconstruction problem into a much simpler de-noising problem. We introduce the Projections Onto Convex Sets (POCS) algorithm during the process of reconstruction, choosing the square root exponentially decreased threshold, constructing a curvelet-based recovery strategy of 3D seismic data. At the same time, aiming at the deficiency of simple random under-sampling, we introduce the jittered under-sampling, it shares the benefits of random sampling and controls the maximum gap size. Experiments show that reconstruction effect based on curvelet is better than FFT transform and jittered under-sampling is better than random under-sampling. At last, we apply this technology into practical seismic data and obtain a good application.


Wang S.,China University of Petroleum - Beijing | Li X.-Y.,British Geological Survey | Di B.,China University of Petroleum - Beijing | Booth D.,British Geological Survey
Geophysical Research Letters | Year: 2010

P-wave seismic surveys are performed on realistic physical models of a reservoir formed of interbedded sand and shale layers and filled with gas, water, and oil. They show characteristic behaviour which can be used to distinguish between fluids, with significant implications for the interpretation of time-lapse experiments. Discontinuous reflections originate in gas-filled reservoirs, with widely varying amplitude compared to oil-or water-filled reservoirs. Anomalous changes in seismic amplitude difference attributes for reflections within the reservoir are seen for gas/oil substitution. Oil/water substitution results in only weak variations of reservoir elastic properties, thus amplitude difference attributes may be unsuitable for monitoring changes in oil/water saturation. However, direct differences between the time traces are strong. On time-lapse sections, strong amplitude difference anomalies do not necessarily correspond to the region where the fluid variations occur; this is significant for monitoring oil field development by water injection. Copyright © 2010 by the American Geophysical Union.


Li M.,China University of Petroleum - Beijing | Li M.,Beihang University | Liu L.,Beihang University | Li C.-B.,Shenyang University of Technology
Expert Systems with Applications | Year: 2011

Since organizational tacit knowledge such as know-how and experiences usually resides in the owner's brain, consulting the expert is an effective and efficient way to utilize this type of knowledge. However, users are no longer able to effectively find the appropriate experts in the knowledge management system due to the complexity and diversity of the expertise and the knowledge needs. In this paper, an approach to expert recommendation is proposed to assist the user to find the required experts. The method adopts the fuzzy linguistic method to construct the expert profile, that is, to model expert's expertise. In addition, the fuzzy text classifier is used to get the relevant degree of the document to each knowledge area when the document is registered, which is the base of the following user profile construction. Then, the user profile consisting of the time and the relevance factors of the rated documents is constructed to derive the overall knowledge needs level of the user. Consequently, the expert that fulfills the knowledge needs most is recommended based on the similarity between the derived expert profile and the user profile. The developed prototype system, "knowledge management system in aircraft industry company", is introduced and the experimental results show the proposed approach is feasible and effective. © 2011 Elsevier Ltd. All rights reserved.


Yao Y.,Nankai University | Wang Z.,Tianjin Normal University | Zhao S.,Nankai University | Wang D.,Nankai University | And 2 more authors.
Catalysis Today | Year: 2014

A cross-linked sulfonated polyethersulfone supported Ru nanoparticle catalyst was prepared for highly hydrogenation of levulinic acid (LA) into γ-valerolactone (GVL) at mild conditions (3.0 MPa H2 and 70 °C) in aqueous solution. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations show the formation of highly dispersed small (∼3 nm) Ru clusters on the surface of polyethersulfone. Infrared spectroscopy (IR) and acid-base titration indicate the presence of sulfonic groups without the influence of the deposition of Ru species. Polyethersulfone consisted of cross-linked electron -withdrawing group SO2, maintained its intrinsic thermal stability during the hydrogenating reaction process, and its swelling property promoted the adsorption of LA in aqueous solution. The synchronization of sulfonic groups as active sites for esterification process and metal sites for hydrogenation promoted the hydrogenation reactivity. © 2014 Elsevier B.V.


Fan Z.-J.,Harbin Engineering University | Yan J.,Harbin Engineering University | Wei T.,Harbin Engineering University | Ning G.-Q.,China University of Petroleum - Beijing | And 5 more authors.
ACS Nano | Year: 2011

We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li+ storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage. © 2011 American Chemical Society.


Li X.-Y.,British Geological Survey | Li X.-Y.,China University of Petroleum - Beijing | Zhang Y.-G.,Sinopec
Journal of Geophysics and Engineering | Year: 2011

This paper discusses the concepts of multicomponent seismology and how it can be applied to characterize hydrocarbon reservoirs, illustrated using a 3D three-component real-data example from southwest China. Hydrocarbon reservoirs formed from subtle lithological changes, such as stratigraphic traps, may be delineated from changes in P- and S-wave velocities and impedances, whilst hydrocarbon reservoirs containing aligned fractures are anisotropic. Examination of the resultant split shear waves can give us a better definition of their internal structures. Furthermore, frequency-dependent variations in seismic attributes derived from multicomponent data can provide us with vital information about fluid type and distribution. Current practice and various examples have demonstrated the undoubted potential of multicomponent seismic in reservoir characterization. Despite all this, there are still substantial challenges ahead. In particular, the improvement and interpretation of converted-wave imaging are major hurdles that need to be overcome before multicomponent seismic becomes a mainstream technology. © 2011 Nanjing Geophysical Research Institute.


Zheng S.,China University of Petroleum - Beijing | Li C.,China University of Petroleum - Beijing | Qi Y.,Beihang University | Chen L.,China University of Petroleum - Beijing | Chen C.,China University of Petroleum - Beijing
Corrosion Science | Year: 2013

The mechanism of oxide inclusion-induced pitting corrosion in 316L stainless steel exposed to sulphur environments containing chloride ions was investigated by scanning electron microscope analysis, electrochemical measurements and scanning Kelvin probe force microscopy (SKPFM). Two inclusion types were observed. The (Mg,. Al,. Ca)-oxide inclusions play an important role in pitting formation. SKPFM measurement results show that the inclusion sites exhibited a lower surface potential than the matrix. Finally, the schematic representation of the initiation and propagation process of the (Mg,. Al,. Ca)-oxide inclusion-induced pitting corrosion in 316L stainless steel exposed to sulphur environments containing chloride ions was established. © 2012 Elsevier Ltd.


Qi Y.,Beihang University | Luo H.,Beihang University | Zheng S.,China University of Petroleum - Beijing | Chen C.,China University of Petroleum - Beijing | Wang D.,China University of Petroleum - Beijing
Corrosion Science | Year: 2013

The effect of immersion time on the hydrogen content and tensile properties of A350LF2 steel exposed to hydrogen sulphide environments was investigated by immersion tests, hydrogen content measurements and tensile tests. The results show that both hydrogen content and relative tensile strength and plasticity loss increased first and then decreased with increasing immersion time. High mass transfer resistance of corrosion films can be responsible for that hydrogen content decreased after 240. h immersion. A probable mechanism is proposed to interpret the reason for hydrogen content result. The tensile property loss and embrittled region were closely associated with hydrogen content. © 2012 Elsevier Ltd.


Cao P.,Shandong University of Science and Technology | Luo X.,China University of Petroleum - Beijing
Digital Signal Processing: A Review Journal | Year: 2016

The stochastic Newton recursive algorithm is studied for system identification. The main advantage of this algorithm is that it has extensive form and may embrace more performance with flexible parameters. The primary problem is that the sample covariance matrix may be singular with numbers of model parameters and (or) no general input signal; such a situation hinders the identification process. Thus, the main contribution is adopting multi-innovation to correct the parameter estimation. This simple approach has been proven to solve the problem effectively and improve the identification accuracy. Combined with multi-innovation theory, two improved stochastic Newton recursive algorithms are then proposed for time-invariant and time-varying systems. The expressions of the parameter estimation error bounds have been derived via convergence analysis. The consistence and bounded convergence conclusions of the corresponding algorithms are drawn in detail, and the effect from innovation length and forgetting factor on the convergence property has been explained. The final illustrative examples demonstrate the effectiveness and the convergence properties of the recursive algorithms. © 2016 Elsevier Inc.


Lin Q.,China University of Petroleum - Beijing | Yuan H.,Tsinghua University | Biolzi L.,Polytechnic of Milan | Labuz J.F.,University of Minnesota
Engineering Fracture Mechanics | Year: 2014

Fracture tests were performed on sandstone specimens under three-point bending with a variety of notch positions to achieve KII/. KI= 0-12%. At peak load, the maximum crack opening displacement measured by digital image correlation was 45. μm under mixed mode loading and 30. μm under mode I, and these values were used to determine the length of the cohesive zone: 10-12. mm for mixed mode and 5-7. mm for mode I. For mixed mode fracture, the displacement in the cohesive zone was identified to be opening only, while sliding and opening were detected along the remaining length. © 2014 Elsevier Ltd.


Li H.,University of Business and Technology | Sun Q.,Shandong University of Science and Technology | Zhang Q.,China University of Petroleum - Beijing | Wallin F.,University of Business and Technology
Renewable and Sustainable Energy Reviews | Year: 2015

Heating represents the largest proportion of energy use as supplied to consumers across all end energy uses. Therefore, there is huge potential for energy savings in the heating sector in order to reduce the emission of CO2. District heating (DH) has been considered an efficient, environmentally friendly and cost-effective method for heating in buildings, and is playing an important role in the mitigation of climate change. In the interest of fairness and in the highly competitive market the DH companies operate, there is a strong need to develop a novel heat pricing mechanism in order to promote sustainable development of DH systems. In this paper, existing methods and models regarding heat pricing have been reviewed. The features of different pricing mechanisms have been analysed, including advantages and disadvantages. Insights into developing an advanced pricing mechanism for DH systems have been offered. © 2014 Elsevier Ltd. All rights reserved.


Yan J.,Harbin Engineering University | Fan Z.,Harbin Engineering University | Sun W.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | And 5 more authors.
Advanced Functional Materials | Year: 2012

Hierarchical flowerlike nickel hydroxide decorated on graphene sheets has been prepared by a facile and cost-effective microwave-assisted method. In order to achieve high energy and power densities, a high-voltage asymmetric supercapacitor is successfully fabricated using Ni(OH) 2/graphene and porous graphene as the positive and negative electrodes, respectively. Because of their unique structure, both of these materials exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high-voltage region of 0-1.6 V and displays intriguing performances with a maximum specific capacitance of 218.4 F g -1 and high energy density of 77.8 Wh kg -1. Furthermore, the Ni(OH) 2/graphene//porous graphene supercapacitor device exhibits an excellent long cycle life along with 94.3% specific capacitance retained after 3000 cycles. These fascinating performances can be attributed to the high capacitance and the positive synergistic effects of the two electrodes. The impressive results presented here may pave the way for promising applications in high energy density storage systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wu Z.,University of California at Berkeley | Wu Z.,China University of Petroleum - Beijing | Goel S.,University of California at Berkeley | Choi M.,University of California at Berkeley | And 2 more authors.
Journal of Catalysis | Year: 2014

Noble metal clusters (Pt, Pd, Rh, Ir, Re, and Ag) are selectively encapsulated within LTA voids via hydrothermal synthesis using metal precursors with ligands (NH3 for Pt and Ir; ethylenediamine for Pd, Rh, Re and Ag) that prevent their premature precipitation as colloidal oxyhydroxides. Such stability appears to be necessary and sufficient for successful encapsulation of cationic precursors during nucleation and growth of zeolite frameworks. Mean cluster diameters measured by titration of exposed metal atoms (H2 on Pt, Pd, Rh, Ir and Re; O2 on Ag; 1.1-1.8 nm) and by transmission electron microscopy (1.2-1.9 nm) were similar, indicating that cluster surfaces were clean and accessible to molecules used as titrants or reactants. Metal clusters were narrowly distributed in size and stable against sintering and coalescence during oxidative thermal treatments (573-873 K). Encapsulation selectivities were measured from turnover rates for reactions of small and large reactants, specifically hydrogenation of alkenes (ethene and isobutene) and oxidation of alkanols (methanol, ethanol, and isobutanol), which reflect the restricted access to encapsulated clusters by the larger molecules. These encapsulation selectivities, which reflect the ratio of metal surface areas within and outside LTA crystals ranged from 7.5 to 83 for all samples. Confinement within LTA crystals protects clusters from contact with thiophene and allows ethene hydrogenation to proceed at thiophene concentrations that fully suppressed reactivity for metal clusters dispersed on mesoporous SiO 2. These protocols provide a general strategy for encapsulating clusters within small-pore zeolite voids, for which post-synthesis exchange is infeasible. Their successful encapsulation protects such clusters from coalescence and growth and allows them to select reactants and reject poisons based on their molecular size. © 2014 Elsevier Inc. All rights reserved.


Zheng S.,China University of Petroleum - Beijing | Qi Y.,Beihang University | Chen C.,China University of Petroleum - Beijing | Li S.,China University of Petroleum - Beijing
Corrosion Science | Year: 2012

The tensile properties and fracture behaviour of A350LF2 steels after exposure to wet H 2S environments were investigated by corrosion and tensile testing. The results suggest that relative tensile strength and plasticity loss increased as hydrogen concentration increased. Greater tensile property damage occurred in steel that contained more large-size inclusions. When hydrogen was released, the degree of relative strength and plasticity loss decreased. Fractography of the corroded samples exhibited mixed ductile-brittle rupture. Fractured areas with quasi-cleavage features increased with increasing hydrogen concentration. Flakes appeared in the steel with a low sulphur content and low hydrogen concentration. © 2012 Elsevier Ltd.


Qiao W.,China University of Petroleum - Beijing | Yan X.,China University of Petroleum - Beijing | Ye J.,China University of Petroleum - Beijing | Sun Y.,Beihang University | And 2 more authors.
Renewable Energy | Year: 2011

Municipal biomass waste is regarded as new available energy source, although it could cause serious environmental pollution. Generally, biogas recovery by anaerobic digestion was seen as an ideal way to treat biomass waste. Different types of biomass waste have different biogas production potential. In this paper, cow manure, pig manure, municipal sewage sludge, fruit/vegetable waste, and food waste were chosen as typical municipal biomass waste. In addition, hydrothermal pretreatment was used to accelerate digestion and increase biogas production. Biochemical methane potential (BMP) test was used to evaluate biogas production for raw biomass and hydrothermal treated waste. Raw materials of fruit/vegetable and food waste show higher methane production than that of cow manure, pig manure, and municipal sewage sludge. After hydrothermal pretreatment at typical condition (170 °C at 1 h), the biogas production of pig manure, cow manure, fruit/vegetable waste, and municipal sewage sludge increased by 7.8, 13.3, 18.5, and 67.8% respectively. While, for treated food waste, the biogas decrease by 3.4%. The methane yield of pig manure, fruit/vegetable waste, and municipal sewage sludge increased by 14.6, 16.1, and 65.8%, respectively. While, for treated cow manure and food waste, the methane decrease by 6.9% and 7.5%. © 2011 Elsevier Ltd.


Li Q.,CAS Wuhan Institute of Rock and Soil Mechanics | Wei Y.-N.,CAS Wuhan Institute of Rock and Soil Mechanics | Liu G.,CAS Wuhan Institute of Rock and Soil Mechanics | Lin Q.,China University of Petroleum - Beijing
Applied Energy | Year: 2014

CO2 geological storage, when combined with deep saline water recovery (CO2-EWR), not only achieves the relatively secure storage of CO2 that was captured from the coal chemical industry, due to lower pressure, but also enhances saline water for drinking and industrial or agricultural utilization. This storage will undoubtedly become a win-win choice for the enhancement of energy security and for the promotion of regional development in China, particularly for western regions with a relative shortage of water resources and a more fragile ecological environment. In this paper, a three-dimensional injection-extraction model is established that uses the TOUGH2/ECO2N program according to typical formation parameters of a coal chemical industry in the Xinjiang Uyghur Autonomous Region. Numerical results showed that under the guarantee of sufficient water conditions, 1.73×108tons of saline water could be produced when the CO2-EWR is adopted. Well arrangements and formation parameters are also analyzed, and the following conclusions can be drawn: arrangements of pumping wells, such as pumping well number, pumping rate and distance, have considerable influences on the reservoir pressure, and in addition, the sensitivity of pressure on the distance and pumping rate decreases as their values increase. In view of these features, it is necessary to find an optimal point to achieve the best combination of pressure, the leakage time and the amount of dissolution. Formation parameters primarily control the mechanism of CO2 migration and dissolution. Salinity in the salt water has the greatest impact on CO2 dissolution trapping followed by permeability and porosity. The arrival time that is allowable for saline water production primarily depends on porosity followed by the permeability ratio and the arrangements of pumping wells. The reservoir pressure change that is caused by parameters is not obvious compared with setting pumping wells. Overall, CO2-EWR technology is a potential strategic choice for China, particularly in western regions. Additionally, the analysis results provide a reliable guide and reference for CO2 storage site selection, as well as the practical arrangements of wells. © 2013 Elsevier Ltd.


Fan Z.,Harbin Engineering University | Yan J.,Harbin Engineering University | Wei T.,Harbin Engineering University | Zhi L.,National Center for Nanosciences and Technology of China | And 3 more authors.
Advanced Functional Materials | Year: 2011

Asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte. Due to the high capacitances and excellent rate performances of graphene/MnO2 and ACN, as well as the synergistic effects of the two electrodes, such asymmetric cell exhibits superior electrochemical performances. An optimized asymmetric supercapacitor can be cycled reversibly in the voltage range of 0-1.8 V, and exhibits maximum energy density of 51.1 Wh kg-1, which is much higher than that of MnO2//DWNT cell (29.1 Wh kg-1). Additionally, graphene/MnO2//ACN asymmetric supercapacitor exhibits excellent cycling durability, with 97% specific capacitance retained even after 1000 cycles. These encouraging results show great potential in developing energy storage devices with high energy and power densities for practical applications. A novel asymmetric supercapacitor based on graphene/MnO2 and activated carbon nanofibers (ACN) as the positive and negative electrodes, respectively, has been developed in aqueous Na2SO4 electrolyte solution. More interestingly, the asymmetric supercapacitor exhibits a maximum energy density of 51.1 Wh kg-1 and excellent cycling durability, with 97% specific capacitance retained even after 1000 cycles. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang J.,Heriot - Watt University | Zhang J.,China University of Petroleum - Beijing
Fuel | Year: 2014

Some coal seam is well known for its three low characteristics: low permeability, low reservoir pressure and low gas saturation. Thus stimulation measures must be taken during coalbed methane development stage to enhance its recovery. Hydraulic fracturing transformation technology is an effective method for increasing coalbed methane production. This paper presents a two-phase, 3D flow and hydraulic fracturing model of dual-porosity media based on the theories of oil-gas geology and mechanics of flow through porous media. Correspondingly, a finite difference numerical model has been developed and applied successfully to a coalbed methane reservoir. Well test data from one western China basin is utilized for simulation. Results show that hydraulic fracturing promotes desorption and diffusion of coalbed methane which in turn substantially increases production of coalbed methane. © 2014 Elsevier Ltd. All rights reserved.


Zhang J.,Heriot - Watt University | Zhang J.,China University of Petroleum - Beijing | Bian X.,Sinopec
Fuel | Year: 2014

A Gum fracturing fluid compatible fracture stabilizers was selected through experimental evaluation in the former research. The simulation experiments show that the flow conductivity of fractures could be maintained by fracture stabilizer, and the number of intrusive particles in the proppant processed by stabilizers was significantly reduced. The dosage of the fracture stabilizer was optimized according to comprehensive experiments of long term conductivity and sand control effect under condition of bilinear flow. Results showing that conductivity decreases over time and reaches steady state after 5 days. The conductivity reduction decreases with the increase of stabilizer mass fraction. After a comprehensive evaluation, fracture stabilizer of 3-5% mass fraction is recommended. © 2014 Elsevier Ltd. All rights reserved.


Cao P.,Shandong University of Science and Technology | Luo X.,China University of Petroleum - Beijing
Asian Journal of Control | Year: 2016

The stochastic Newton recursive algorithm is studied for dual-rate system identification. Owing to a lack of intersample measurements, the single-rate model cannot be identified directly. The auxiliary model technique is adopted to provide the intersample estimations to guarantee the recursion process continues. Intersample estimations have a great influence on the convergence of parameter estimations, and one-step innovation may lead to a large fluctuation or even divergence during the recursion. In the meantime, the sample covariance matrix may appear singular. The recursive process would cease for these reasons. In order to guarantee the recursion process and to also improve estimation accuracy, multi-innovation is utilized for correcting the parameter estimations. Combining the auxiliary model and multi-innovation theory, the auxiliary-model-based multi-innovation stochastic Newton recursive algorithm is proposed for time-invariant dual-rate systems. The consistency of this algorithm is analyzed in detail. The final simulations confirm the effectiveness of the proposed algorithm. © 2016 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd.


Yang M.,China University of Technology | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Honeychem | Liu G.,China University of Technology
Industrial and Engineering Chemistry Research | Year: 2014

Introducing purification devices into hydrogen systems can enhance the extent of hydrogen reuse. The economic performance of a purification device depends on its appropriate placement within a hydrogen system. This work presents an improved version of a previously published graphical method for integrating purification processes in hydrogen systems. A mathematical method is deduced for calculating the maximum hydrogen utility savings potential of a hydrogen system with purification reuse. The improved graphical method is able to handle the constraints of concentration and flow rate of a purification process when targeting the maximum hydrogen utility savings. The proposed method can be used for analyzing purification processes with any feed concentration. The graphical method is tested on two case studies. © 2014 American Chemical Society.


Sun J.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing | Wang Y.,China University of Petroleum - Beijing | Deng C.,China University of Petroleum - Beijing | Chu K.H.,Honeychem
Energy | Year: 2014

Centrifugal pumps are widely used in cooling water systems to transport cooling water to its users. They are installed in the header line of the feed pipe, constituting a main pump network. The pressure head of the main pumps must be large enough to satisfy the pressure heads of all coolers. The pressure drop of parallel branch pipes must be balanced by reducing the opening of valves for some coolers, incurring an energy penalty on some pumps. To attain energy savings, this paper proposes an auxiliary pump network whereby auxiliary pumps are installed in parallel branch pipes. A superstructure-based mathematical model is developed to optimize the total cost of the main and auxiliary pump networks. The optimal number of auxiliary pumps and their installation locations are determined by solving the model with a simulated annealing algorithm. The effectiveness of the model is tested by a case study based on the cooling water network of a refinery. © 2014 Elsevier Ltd.


Li M.,China University of Petroleum - Beijing | Jin L.,China University of Petroleum - Beijing | Wang J.,Beihang University
Applied Soft Computing Journal | Year: 2014

Knowledge management system (KMS) is crucial for organization knowledge management. In order to help the evaluation and selection of KMS from the user's perspective, a new multiple criteria decision making (MCDM) method combining quality function deployment (QFD) with technique for order preference by similarity to an ideal solution (TOPSIS) in intuitionistic fuzzy environment is proposed. In the method, the customer criteria and system criteria for KMS selection are required. These two kinds of criteria are established from the user's perspective and the designer's perspective respectively. Customers give their linguistic opinions about the importance of the customer criteria and the rating of alternatives with respect to the customer criterion. Analysts give their linguistic opinions about the relationship between the customer criteria and the system criteria, and the correlation between the system criteria. After the aggregation of linguistic opinions in intuitionistic fuzzy environment, the customers' opinions are transformed into the rating of the weight of system criteria and rating of the alternatives concerning the system criteria by the QFD. Afterwards the alternatives are ranked according to system criteria by TOPSIS method in intuitionistic fuzzy environment and the best alternative is determined. In the end an example is provided to illustrate the applicability of the proposed method. © 2014 Elsevier B.V. All rights reserved.


Sun Y.,Beihang University | Wang D.,Beihang University | Yan J.,Beihang University | Qiao W.,China University of Petroleum - Beijing | And 2 more authors.
Waste Management | Year: 2014

The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2-0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion. © 2013 Elsevier Ltd.


Patent
China University of Petroleum - Beijing and Kms Oil Field Chemicals & Technical Services Ltd. Beijing | Date: 2016-07-13

A synthesis method for degradable material(s) (DM) which can be used in oil and gas field operations. The method involves using two, three, four or five polymer and chain extenders, including poly glycolic acid (PGA), polycaprolactone (PCL), polylactic acid (PLA), poly (butylene succinate) (PBS) and poly(3-hydroxybutyrate) (PHA), to synthesize a resin alloy through the melt mixing reaction method, which can be used in oil and gas field operations. The proposed DM can be prepared into flake, powder, granules, and ball shapes, or by one of the pure PGA, PCL, PLA, PBS and PHA, into flake, powder, granule and ball shapes, which can be further used in all kinds of operations (drilling, well completion, workover and acidizing fracturing) in oil and gas fields, such as temporary plugging to protect a reservoir, temporary plugging of perforation holes, construction intervals, etc. The DMs are fully degradable and cause almost no damage to formations.


Jia X.,Tsinghua University | Jia X.,China University of Petroleum - Beijing | Cheng Y.,University of California at Los Angeles | Lu Y.,University of California at Los Angeles | Wei F.,Tsinghua University
ACS Nano | Year: 2014

Rational design of electrode materials is essential but still a challenge for lithium-ion batteries. Herein, we report the design and fabrication of a class of nanocomposite architecture featured by hierarchically structured composite particles that are built from iron oxide nanocrystals and carbon nanotubes. An aerosol spray drying process was used to synthesize this architecture. Such nanoarchitecture enhanced the ion transport and conductivity that are required for high-power anodes. The large volume changes of the anodes during lithium insertion and extraction are accommodated by the particle's resilience and internal porosity. High reversible capacities, excellent rate capability, and stable performance are attained. The synthesis process is simple and broadly applicable, providing a general approach toward high-performance energy storage materials. (Figure Presented). © 2014 American Chemical Society.


Kaiser M.J.,Louisiana State University | Liu M.,China University of Petroleum - Beijing
Marine Structures | Year: 2014

Decommissioning is the final stage in the life cycle of an offshore structure, where all wells are plugged and abandoned, the platform and associated facilities are removed, and the seafloor cleared of all obstructions created by the operations. From 1989 to 2012, 15 structures in water depth greater than 400ft were decommissioned in the U.S. Gulf of Mexico, but none of the project cost have been publicly released. The purpose of this paper is to apply work decomposition algorithms developed by ProServ Offshore to estimate cost for well plugging and abandonment, conductor severance and removal, pipeline abandonment, umbilical and flowline removal, and platform removal for the 53 deepwater fixed platforms and compliant towers in the Gulf of Mexico circa January 2013. Decommissioning cost estimates are presented by stage and operator. Bullwinkle and Pompano are expected to be the most expensive fixed platform decommissioning projects in the Gulf of Mexico estimated at $265 million and $203 million, respectively. Total undiscounted decommissioning liability for the asset class is estimated to be $2.4 billion. © 2014 Elsevier Ltd.


Yan H.,CAS Institute of Geology and Geophysics | Liu Y.,China University of Petroleum - Beijing | Zhang H.,CGGveritas
Exploration Geophysics | Year: 2013

With advanced computational power, prestack reverse-time migration (RTM) is being used increasingly in seismic imaging. The accuracy and efficiency of RTM strongly depends on the algorithms used for numerical solutions of wave equations. Hence, how to solve the wave equation accurately and rapidly is very important in the process of RTM. In this paper, in order to improve the accuracy of the numerical solution, we use a time-space domain staggered-grid finite-difference (SFD) method to solve the acoustic wave equation, and develop a new acoustic prestack RTM scheme based on this time-space domain high-order SFD. Synthetic and real data tests demonstrate that the RTM scheme improves the imaging quality significantly compared with the conventional SFD RTM. Meanwhile, in the process of wavefield extrapolation, we apply adaptive variable-length spatial operators to compute spatial derivatives to decrease computational costs effectively with little reduction of the accuracy of the numerical solutions. © 2013 ASEG.


Chen Y.,United Information Technology | Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University
Geophysical Journal International | Year: 2013

While inversion of seismic velocity from receiver function data could be instable due to its intrinsic non-linearity and non-uniqueness, improper stacking of receiver function could also introduce significant biases to the resulting velocity structure. In a distance section of receiver functions, the Moho Ps conversion and the two reverberations possess a positive and negative moveout, respectively. Stacking receiver functions without moveout correction could significantly reduce and distort the amplitude and waveform of these phases. Inversion with these incorrectly stacked receiver functions will thus inevitably introduce artefacts to the resulting velocity structure. In this study, we have improved the inversion procedure in two ways. First, we introduce a ray-parameter based (RPB) stacking method to correctly construct receiver function data for inversion. Specifically we develop a 'four-pin' method that accounts for the moveout effect of the converted and reverberated phases in stacking individual receiver functions recorded at various distances. Secondly, we divide the receiver function trace into conversion and reverberation windows and assign different weights between the two windows in the inversion. More weight is given to the Ps conversion window in resolving the shallow structure, which can be nearly fixed in the successive inversion of deeper structure. We also employ other pre-conditioning proposed by previous studies, such as balancing the receiver function data being filtered with different Gaussian filters, smoothing the velocity model and further regulating the model based on existing information. We compute synthetic receiver functions at distances between 30° and 90° from a target model and then use the RPB stacking method to generate the input data for various inversions (iterative linear) with different initial models. Our inversions with enhanced pre-conditioning and RPB stacked data demonstrate a good capability in recovering the target model from generally more stable iterations. Applying these techniques to two broad-band stations in China indicates that the improvements on data stacking and inversion can eliminate potential stacking-induced artefacts, and yield models more consistent with surface geology. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.


Qiu N.,China University of Petroleum - Beijing | Chang J.,China University of Petroleum - Beijing | Zuo Y.,China University of Petroleum - Beijing | Wang J.,CAS Institute of Geology and Geophysics | Li H.,Sinopec
AAPG Bulletin | Year: 2012

The Tarim Basin is one of the richest basins in oil and gas resources in China. The Cambrian and Middle-Upper Ordovician strata are the most important source rocks. Previous early Paleozoic thermal histories have led to varied hypotheses on the evolution of the lower Paleozoic source rocks, causing a significant impact on petroleum exploration in the basin. A new Paleozoic thermal history of the Tarim Basin was reconstructed in this article using the integrated thermal indicators of apatite and zircon (uranium-thorium)/helium ages, apatite fission tracks, and equivalent vitrinite reflectance data. The modeled results indicate that different parts of the basin experienced widely differing early Paleozoic thermal gradient evolution. The eastern and central regions of the basin experienced a decreasing thermal gradient evolution from 37 to 39°C/km during the Cambrian and Ordovician to 35 to 36°C/km in the Silurian, whereas the northwestern region of the basin had an increasing early Paleozoic thermal gradient evolution from 28 to 32°C/km in the Cambrian to 30 to 34°C/km in the Ordovician and Silurian. The Lower Cambrian thermal gradient resulted from the higher thermal conductivity of the 800- to 1000-m (2625- to 3280-ft) thickness of gypsum and salt in the Cambrian strata. The basin experienced an intracratonic phase during the late Paleozoic and a foreland basin phase during the Mesozoic and Cenozoic, with the thermal gradient decreasing to the present-day value of 20 to 25°C/km. The sensitivity of thermal modeling by the best-fit method is less than ±5% in our study, and the differences of the early Paleozoic thermal gradient evolution in different regions of the basin may result in differential maturation of lower Paleozoic source rocks. The maturity histories of the source rocks, modeled based on the new thermal histories, indicate that the lower Paleozoic source rocks in most areas of the basin matured rapidly and reached the late mature to dry-gas stage during the Paleozoic but experienced slower maturation during the Mesozoic and Cenozoic. These new data on the Paleozoic thermal history and lower Paleozoic source rock maturity histories of the Tarim Basin provide new insights to guide oil and gas exploration of the basin. Copyright ©2012. The American Association of Petroleum Geologists. All rights reserved.


Da Silva M.L.B.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária | Cantao M.E.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária | Mezzari M.P.,University of West Santa Catarina | Ma J.,China University of Petroleum - Beijing | Nossa C.W.,Rice University
Microbial Ecology | Year: 2015

Microbial communities from two field-scale swine wastewater treatment plants (WWTPs) were assessed by pyrosequencing analyses of bacterial and archaeal 16S ribosomal DNA (rDNA) fragments. Effluent samples from secondary (anaerobic covered lagoons and upflow anaerobic sludge blanket [UASB]) and tertiary treatment systems (open-pond natural attenuation lagoon and air-sparged nitrification-denitrification tank followed by alkaline phosphorus precipitation process) were analyzed. A total of 56,807 and 48,859 high-quality reads were obtained from bacterial and archaeal libraries, respectively. Dominant bacterial communities were associated with the phylum Firmicutes, Bacteroidetes, Proteobacteria, or Actinobacteria. Bacteria and archaea diversity were highest in UASB effluent sample. Escherichia, Lactobacillus, Bacteroides, and/or Prevotella were used as indicators of putative pathogen reduction throughout the WWTPs. Satisfactory pathogen reduction was observed after the open-pond natural attenuation lagoon but not after the air-sparged nitrification/denitrification followed by alkaline phosphorus precipitation treatment processes. Among the archaeal communities, 80 % of the reads was related to hydrogeno-trophic methanogens Methanospirillum. Enrichment of hydrogenotrophic methanogens detected in effluent samples from the anaerobic covered lagoons and UASB suggested that CO2 reduction with H2 was the dominant methanogenic pathway in these systems. Overall, the results served to improve our current understanding of major microbial communities’ changes downgradient from the pen and throughout swine WWTP as a result of different treatment processes. © 2014, Springer Science+Business Media New York.


Liu S.,China University of Petroleum - Beijing | Guo D.,Tsinghua University | Xie G.,Tsinghua University
Tribology Letters | Year: 2013

A microbubble phenomenon induced by micro-oscillation in the grease lubricating film confined within a nanogap between a highly polished steel ball and a smooth glass disc has been observed with an interferometer. Experimental results show that when the micro-oscillation frequency is a constant value, the microbubble number increases with the micro-oscillation amplitude. When the micro-oscillation amplitude is a constant value, the microbubble number increases with the micro-oscillation frequency when the latter is lower than the critical value and decreases with the micro-oscillation frequency when it is higher than the critical value. Theoretical models and analyses have been used to discuss the bubble formation and describe the characteristics of bubble movement. © 2013 The Author(s).


Xu C.,Tsinghua University | Meng X.,China University of Petroleum - Beijing
Sensors and Actuators, A: Physical | Year: 2013

The effects of different geometrical factors such as the jet nozzle exit width, feedback channel width, oscillator depth, and the oscillating chamber shape on the feedback fluidic oscillator performance were investigated experimentally. A characteristic curve relating to only the oscillation frequency f and Reynolds number Re was found to be insensitive to the oscillator configurations and is expressed as f (Hz) = 6.05 exp(-α/3.30) + 14.5 exp(-α/0.859) + 0.669, where α = ln(Re)/f. The characteristic curve can be used to determine the Reynolds number and thereby the flowrate through the oscillators according to the detected oscillation frequency. © 2012 Elsevier B.V.


Mohr S.H.,University of Technology, Sydney | Wang J.,China University of Petroleum - Beijing | Ellem G.,University of Newcastle | Ward J.,University of South Australia | Giurco D.,University of Technology, Sydney
Fuel | Year: 2014

Detailed projections of world fossil fuel production including unconventional sources were created by country and fuel type to estimate possible future fossil fuel production. Four critical countries (China, USA, Canada and Australia) were examined in detail with projections made on the state/province level. Ultimately Recoverable Resources (URR) for fossil fuels were estimated for three scenarios: Low = 48.4 ZJ, Best Guess (BG) = 75.7 ZJ, High = 121.5 ZJ. The scenarios were developed using Geologic Resources Supply-Demand Model (GeRS-DeMo). The Low and Best Guess (BG) scenarios suggest that world fossil fuel production may peak before 2025 and decline rapidly thereafter. The High scenario indicates that fossil fuels may have a strong growth till 2025 followed by a plateau lasting approximately 50 years before declining. All three scenarios suggest that world coal production may peak before 2025 due to peaking Chinese production and that only natural gas could have strong growth in the future. In addition, by converting the fossil fuel projections to greenhouse gas emissions, the projections were compared to IPCC scenarios which indicated that based on current estimates of URR there are insufficient fossil fuels to deliver the higher emission IPCC scenarios A1Fl and RCP8.5. © 2014 Elsevier Ltd. All rights reserved.


Yang Y.,Jilin University | Zhang Y.,China University of Petroleum - Beijing | Hao S.,China University of Petroleum - Beijing | Kan Q.,Jilin University
Catalysis Communications | Year: 2010

A metal-template/metal-exchange method was used for the covalent attachment of a discrete bis(8-quinolinol)oxovanadium(IV) complex onto mesoporous silica SBA-15 to obtain a heterogeneous catalyst VOIVT. For comparison, its homogeneous counterpart VOIVN and the randomly ligand-grafted heterogeneous analogue VOIVG were also prepared. UV-vis spectra of the VOIV catalysts show VOIVT adopts a more solution-like bis(8-quinolinol) coordination environment than VOIVG. Correspondingly, olefin epoxidation with tert-butyl hydroperoxide shows VOIVT has improved reactivity, epoxide selectivity and recyclability than VOIVN or VOIVG. The homogeneity of the discrete bis(8-quinolinol)oxovanadium(IV) complex immobilized on SBA-15 should be responsible for the superior performances of the templated catalyst. © 2010 Elsevier B.V. All rights reserved.


Liao Y.,CAS Guangzhou Institute of Geochemistry | Shi Q.,China University of Petroleum - Beijing | Hsu C.S.,Florida State University | Pan Y.,CAS Guangzhou Institute of Geochemistry | Zhang Y.,China University of Petroleum - Beijing
Organic Geochemistry | Year: 2012

Seven reservoir core (tar sand) bitumens of identical source and similar maturity from the Liaohe Basin of northeast China possess a natural sequence of increasing severity of biodegradation. This set of samples provides us an opportunity to study the change in oil composition or compound class distributions with biodegradation severity by negative ion electrospray Fourier transform-ion cyclotron resonance mass spectrometry (FT ICR-MS). The bitumen extracts from two columns (Es3 and Es1) were separated into maltene and asphaltene fractions for analysis of heteroatomic species by ESI FT-ICR MS. The maltene fractions were found to mainly contain N1, N1O1, N1O2, N1O3, O1, O2, O3 and O4 classes, while the asphaltene fractions mainly contain N1, N2O1, N1O1, N1O2, N1O3, N1O4, O2, O3, O4 and O5 classes. These species identified by FT-ICR MS in asphaltene fractions are likely to be chemisorbed/coprecipitated compounds, or the species precipitated due to high polarity during deasphaltene process. The susceptibility of compound classes and homologous series to biodegradation was studied based on the relative abundances. The results indicate that microorganisms alter the distribution of acids and nitrogen-containing compounds by selective removal and preservation of certain classes of compounds according to their susceptibility to biodegradation. For example, O2 and N1O2 classes increase significantly while N1 and N1O1 classes decrease with biodegradation. The differences in the susceptibility to microbial alteration within acyclic acids, 4-5 ring acids and 1-2 ring acids are discussed and the differences in the susceptibility of homologous series of heteroatom-containing polycyclic aromatic hydrocarbons are also discussed in this work. © 2012 Elsevier Ltd.


Xiao H.,Tsinghua University | Guo D.,Tsinghua University | Liu S.,China University of Petroleum - Beijing | Pan G.,Tsinghua University | Lu X.,Tsinghua University
Tribology Letters | Year: 2011

Ionic liquids are generally considered as environmentally friendly material. The film thicknesses of ionic liquids and silicone oils at high pressures up to 3 GPa are measured employing the relative optical interference intensity method. The results show that for the three ionic liquids the relative order of film thickness is 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM]PF 6) > 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF 6) > 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6). In elastohydrodynamic lubrication the order of viscosity can simply account for this fact. In thin film lubrication condition the length of alkyl side chain and arrangement manner of cation are used to explain the experimental results. Another remarkable phenomenon is that even though the viscosities of silicone oils are close to those of ionic liquids, the measured film thicknesses of silicone oils are quite less than those of the ionic liquids. The results show that long alkyl chain ionic liquid can form rather thick films at high pressure. © 2010 Springer Science+Business Media, LLC.


Qian S.,Tsinghua University | Guo D.,Tsinghua University | Liu S.,Tsinghua University | Lu X.,China University of Petroleum - Beijing
Tribology Letters | Year: 2011

Lubrication failure of polyalphaolefin (PAO) oil film at high slide/roll ratios of more than 1.9 has been experimentally investigated based on a ball-on-disc configuration. The central film thickness and the oil pool shape in the contact were determined by optical interferometry and fluorescence microscopy, respectively, and the traction coefficient and surface profiles of the tribopairs were measured using a tension-compression sensor and light surface profilometer, respectively. The results demonstrate that the central film in the contact was in the elastohydrodynamic lubrication regime at the initial stage under high slide/roll ratios. Variation in the traction coefficient and the presence of wear scars on the disc surface shows that the sliding speed played an important role in lubrication failure. We propose that a thermal effect explains the obtained results at high slide/roll ratios. The fluorescence technique combined with optical interferometry was also used to gain more understanding of lubrication properties under mixed slide/roll conditions. © Springer Science+Business Media LLC 2011.


Zhang C.,Tsinghua University | Dong X.,Tsinghua University | Dong X.,China University of Petroleum - Beijing | Feng X.,Tsinghua University | Hwang K.-C.,Tsinghua University
Optics Letters | Year: 2013

Multiwavelength shearing interferometry, a full-field, real-time, and vibration-insensitive method with enhanced accuracy, is proposed. Theoretically, the more wavelengths that are used for shearing interferometers, the higher the precision that can be achieved in the measurement of slopes, curvatures, and the shapes of reflective surfaces. A spherical mirror with specified curvature radius is used to calibrate this method, and then the nonuniform deformation and shape of the TiNi film/Si substrate system are obtained experimentally. © 2013 Optical Society of America.


Qin F.,China University of Petroleum - Beijing | Qin F.,Wayne State University | Zhao Y.,Wayne State University
Optics Express | Year: 2011

Needle beam is a guided beam with nanoscale beam size and significant power propagating in core area of a three-layer dielectric waveguide. Systematical numerical analyses of properties of the needle beam are presented. Properties of the fundamental mode of the needle beam, including field distribution, power distribution, and power concentration, are calculated for different waveguide parameters. It is shown that there is an optimum value of normalized frequency for maximum power concentration. Concentrated power is higher if the refractive index difference between the core and the middle layer is higher. © 2011 Optical Society of America.


Fan Z.,Harbin Engineering University | Yan J.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | Wei T.,Harbin Engineering University | And 2 more authors.
Carbon | Year: 2013

Porous graphene obtained by chemical vapor deposition (CVD) using porous MgO sheets as template is demonstrated to exhibit a high reversible capacity (1723 mAh g-1), excellent high-rate capability and cycling stability for Li-ion batteries. The simple CVD approach offers a new way for large-scale production of porous graphene materials for energy storage. © 2013 Elsevier Ltd. All rights reserved.


Zhang Z.-C.,China University of Petroleum - Beijing | Zhang Z.-C.,Tsinghua University | Hui J.-F.,Tsinghua University | Liu Z.-C.,China University of Petroleum - Beijing | And 3 more authors.
Langmuir | Year: 2012

Metal nanocrystals with high-index facets (HIFs) have drawn significant attention for their superior catalysis activity compared to that of low-index faces. However, because of the high surface energy of HIFs, it is still challenging to preserve HIFs during the growth of nanocrystals. In this study, highly selective Pt concave nanocubes (CNCs) with high-index {hk0} facets have been successfully prepared in a simple aqueous solution. The vital role of glycine as the surface controller in the formation of CNCs was demonstrated. These Pt CNCs exhibited enhanced specific activities toward the electro-oxidation of methanol and formic acid in comparison to commercial Pt black and Pt/C catalysts. © 2012 American Chemical Society.


Zhao Y.,China University of Petroleum - Beijing | Wang M.,University of Leeds | Yao J.,Xiamen University
Procedia Engineering | Year: 2015

The colloidal particles have an electrical double layer associated with their surfaces when suspended in an aqueous medium. Under the influence of an alternating electric field, an induced electrical dipole moment can be formed due to the polarization of the electrical double layer. The electrical impedance spectroscopy (EIS) measurement can record the complex impedance, conductivity, relaxation frequency and phase angle caused by the polarization of the electrical double layer. These impedance parameters are in relation to particle characteristics, for example, the particle size. The research about particle size effect on electrical impedance spectra was carried out in a four-electrode system and the result indicated that impedance parameters shows a capability for characterizing the particle size. This paper reports the experimental results from electrical impedance spectroscopy measurements on silica suspensions in a two-electrode system with carbon probe. The main aim is to study the particle size effect on impedance parameters, especially the relaxation frequency and phase angle, to compare the data with those obtained from a four-electrode system with stainless steel electrodes and verify the capability for characterizing colloidal particles in different electrode systems. The particle size effect on the relaxation frequency and impedance phase angle was studied in two different electrode systems and a similar tendency can be observed. It indicates that the capability of impedance parameters for particle characterization is not limited in a four-electrode system, but commonly applicable in different electrode systems. © 2015 The Authors.


Yang Y.,Jilin University | Zhang Y.,China University of Petroleum - Beijing | Hao S.,China University of Petroleum - Beijing | Kan Q.,Jilin University
Journal of Colloid and Interface Science | Year: 2011

Novel periodic mesostructured organometallic silicas of MCM-41 type bearing homogeneously distributed bis(8-quinolinolato)dioxomolybdenum(VI) inside the channel walls (denoted as MoO2Q2@PMO-x) are synthesized via a convenient one-pot method and examined as catalysts in the epoxidation of cyclooctene. The ordered mesoporous structures as well as the organometallic groups incorporated into the framework are fully determined by comprehensive characterization techniques such as XRD, TEM, N2 adsorption/desorption, SEM, FT-IR, UV-vis spectroscopy, solid-state NMR, ICP-AES, XPS and TG/DSC. MoO2Q2@PMO-6% catalyst exhibits higher activity for the epoxidation of cyclooctene with tert-butyl hydroperoxide than other MoO2Q2@PMO materials and its homogeneous or randomly grafted analogue. © 2011 Elsevier Inc.


Xu C.,Tsinghua University | Yu H.,China University of Petroleum - Beijing | Meng X.,China University of Petroleum - Beijing
Asia-Pacific Journal of Chemical Engineering | Year: 2013

A reverse flow diverter (RFD) is a key fluidic component in RFD pumps, which are air-powered, low-maintenance devices used for transferring hazardous liquids. Despite several decades of practical application, no clear characteristic numbers exist for the suction ratio q = 1.0 and for the peak value of q, nor are there clear dimensionless performance curves for the reverse-flow portion of the pumping cycle. We experimentally investigated the effects of suction gap length and nozzle exit diameter on RFD flow and pressure under the condition of diffuser entrance to nozzle exit area ratio of m = 1.0. The results were used to derive two dimensionless performance curves (q = A · exp[-δ/B] + C · exp[-δ/D] + E and q = k · α + F) and characteristic numbers at q = 1.0 and the peak value of q. These curves and numbers are useful to simplify the design program and ease the selection of operation parameters for RFD pumping systems. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.


Wang J.,China University of Petroleum - Beijing | Feng L.,China University of Petroleum - Beijing | Tverberg G.E.,The Oil Drum
Energy Policy | Year: 2013

Many people believe that China's economic growth can continue almost indefinitely. For a manufacturing-based economy such as China's to continue to grow, it needs an adequate supply of inexpensive energy. To date, this energy growth has primarily come from coal, but China's indigenous coal supplies are now falling short of the amount needed to support this growth. In this situation, the status of China's future coal supply will be very important for China's future economic development. Our analysis shows that China's ultimate recoverable coal reserves equal 223.6×109MT, and its production will peak between 2025 and 2030, with peak production of approximately 3.9×109MT. The extent to which China can import coal in the future is uncertain. With rising coal demand, this combination is likely to create a significant challenge to China's future economic development. © 2013 Elsevier Ltd.


Zhu X.,China University of Petroleum - Beijing | Ning G.,China University of Petroleum - Beijing | Ma X.,China University of Petroleum - Beijing | Fan Z.,Harbin Engineering University | And 3 more authors.
Journal of Materials Chemistry A | Year: 2013

Here, we report a novel Co3O4-graphene hybrid electrode material with high density Co3O4 nanoparticles (NPs) in a size range of 2-3 nm confined in a few-layered porous graphene nanomesh (PGN) framework driven by an electrochemical process. Raman spectra indicate that Co species preferentially anchor on the defective sites of the PGN, which results in markedly reduced irreversible Li storage and therefore significantly enhanced coulombic efficiency. The ultra-small Co 3O4 NPs provide a large surface area and a short solid-state diffusion length, which is propitious to achieving a high Li ion capacity at high rate. Also, the few-layered graphene network with high electronic conductivity not only permits easy access to the high surface area of the Co3O4 NPs for the electrolyte ions, but also serves as a reservoir for high capacity Li storage. As a result, the Co 3O4-PGN composite layers deliver an ultra-high capacity (1543 mA h g-1 at 150 mA g-1) and excellent rate capability (1075 mA h g-1 at 1000 mA g-1) with good cycling stability. This journal is © The Royal Society of Chemistry.


Xu C.,Tsinghua University | Yu H.,China University of Petroleum - Beijing
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2014

A compact retrieval system without moving parts was designed to lift and transport residuals in storage tanks to a higher elevation. The key component of the retrieval system, a curve reverse flow diverter (CRFD) with a vortex diode, was machined into a stainless steel disk to enable the entire system to be compact. The compact retrieval system can be installed in storage tanks through an existing narrow mounting hole. The pumping performance of the retrieval system was examined in terms of the effects of curve reverse flow diverter configurations, lift height, compression pressure, and suction pressure. Results reveal that the vortex diode with higher swirl resistance does not enhance thepumpingcapacity of the retrieval system. The pumping capacity of the retrieval system increased with increasingcompression pressure and decreased with increasing lift height and suction pressure. During the compression phase of the retrieval system, the empty factor qc was found to be linear with the Euler number Eu. The compact retrieval system can resolve the difficulty to retrieve high-Level radioactive residuals in storage tanks without radioactive leak and frequent maintenance. © IMechE 2014.


Jia X.,China University of Petroleum - Beijing | Lu Y.,University of California at Los Angeles | Wei F.,Tsinghua University
Nano Research | Year: 2016

Nanomaterials with electrochemical activity are always suffering from aggregations, particularly during the high-temperature synthesis processes, which will lead to decreased energy-storage performance. Here, hierarchically structured lithium titanate/nitrogen-doped porous graphene fiber nanocomposites were synthesized by using confined growth of Li4Ti5O12 (LTO) nanoparticles in nitrogen-doped mesoporous graphene fibers (NPGF). NPGFs with uniform pore structure are used as templates for hosting LTO precursors, followed by high-temperature treatment at 800 °C under argon (Ar). LTO nanoparticles with size of several nanometers are successfully synthesized in the mesopores of NPGFs, forming nanostructured LTO/NPGF composite fibers. As an anode material for lithium-ion batteries, such nanocomposite architecture offers effective electron and ion transport, and robust structure. Such nanocomposites in the electrodes delivered a high reversible capacity (164 mAh·g–1 at 0.3 C), excellent rate capability (102 mAh·g–1 at 10 C), and long cycling stability. © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


Ning G.,China University of Petroleum - Beijing | Xu C.,China University of Petroleum - Beijing | Cao Y.,China University of Petroleum - Beijing | Zhu X.,China University of Petroleum - Beijing | And 5 more authors.
Journal of Materials Chemistry A | Year: 2013

We present a novel approach to fabricate flexible graphene papers using chemical vapor deposition (CVD) derived graphene. Expanded vermiculite was used as a layered template in the CVD process to produce bulk materials containing graphene sheets of the order of hundreds of microns at a gram scale. Meshes or carbon nanotubes can be introduced into the graphene sheets by template pretreating. Owing to the large sheet size, the as-obtained graphene sheets were easily fabricated into flexible graphene papers with low surface density and good conductivity, which exhibited greatly enhanced reversible capacity (1350 mA h g-1 at 50 mA g-1) and cycling performance as anodes for lithium rechargeable batteries as compared to the graphene papers fabricated using reduced graphene oxide. © 2013 The Royal Society of Chemistry.


Liu Q.,China University of Petroleum - Beijing | Shang L.,China University of Petroleum - Beijing | Duan Y.,Tsinghua University
Applied Energy | Year: 2016

Low-enthalpy geothermal heat can be efficiently utilized for feedwater preheating in coal-fired power plants by replacing some of the high-grade steam that can then be used to generate more power. This study analyzes a hybrid geothermal-fossil power generation system including a supercritical 1000. MW power unit and a geothermal feedwater preheating system. This study models for parallel and serial geothermal preheating schemes and analyzes the thermodynamic performance of the hybrid geothermal-fossil power generation system for various geothermal resource temperatures. The models are used to analyze the effects of the temperature matching between the geothermal water and the feedwater, the heat losses and pumping power during the geothermal water transport and the resource distance and temperature on the power increase to improve the power generation. The serial geothermal preheating (SGP) scheme generally generates more additional power than the parallel geothermal preheating (PGP) scheme for geothermal resource temperatures of 100-130. °C, but the SGP scheme generates slightly less additional power than the PGP scheme when the feedwater is preheated to as high a temperature as possible before entering the deaerator for geothermal resource temperatures higher than 140. °C. The additional power decreases as the geothermal source distance increases since the pipeline pumping power increases and the geothermal water temperature decreases due to heat losses. More than 50% of the power decrease is due to geothermal water temperature decreases along the pipeline since less higher pressure extracted steam is replaced by the geothermal water. For geothermal resource temperatures of 140-160. °C, the additional power generated by the hybrid geothermal-coal power generation system is about 90% (at a geothermal source distance of 0. km) or 39-49% (at a distance of 20. km) greater than the power generated by an optimized organic Rankine cycle system using isopentane (R601a), the hybrid power generation system has little benefit over the ORC system when the distance increases to 40. km. However, the additional power generated by the hybrid power generation system is less than the power generated by the ORC system at distances over 20. km for geothermal resource temperatures of 100. °C. © 2015 Elsevier Ltd.


Ruan L.,University of California at Los Angeles | Ramezani-Dakhel H.,University of Akron | Chiu C.-Y.,University of California at Los Angeles | Zhu E.,University of California at Los Angeles | And 4 more authors.
Nano Letters | Year: 2013

Surfactants with preferential adsorption to certain crystal facets have been widely employed to manipulate morphologies of colloidal nanocrystals, while mechanisms regarding the origin of facet selectivity remain an enigma. Similar questions exist in biomimetic syntheses concerning biomolecular recognition to materials and crystal surfaces. Here we present mechanistic studies on the molecular origin of the recognition toward platinum {111} facet. By manipulating the conformations and chemical compositions of a platinum {111} facet specific peptide, phenylalanine is identified as the dominant motif to differentiate {111} from other facets. The discovered recognition motif is extended to convert nonspecific peptides into {111} specific peptides. Further extension of this mechanism allows the rational design of small organic molecules that demonstrate preferential adsorption to the {111} facets of both platinum and rhodium nanocrystals. This work represents an advance in understanding the organic-inorganic interfacial interactions in colloidal systems and paves the way to rational and predictable nanostructure modulations for many applications. © 2013 American Chemical Society.


Qiao W.,China University of Petroleum - Beijing | Peng C.,China University of Petroleum - Beijing | Wang W.,Tsinghua University | Zhang Z.,China University of Petroleum - Beijing
Bioresource Technology | Year: 2011

The supernatant of hydrothermally treated sludge was treated by an upflow anaerobic sludge blanket (UASB) reactor for a 550-days running test. The hydrothermal parameter was 170°C for 60min. An mesophilic 8.6L UASB reactor was seeded with floc sludge. The final organic loading rate (OLR) could reach 18kg COD/m 3d. At the initial stage running for 189days, the feed supernatant was diluted, and the OLR reached 11kg COD/m 3d. After 218days, the reactor achieved a high OLR, and the supernatant was pumped into the reactor without dilution. The influent COD fluctuated from 20,000 to 30,000mg/L and the COD removal rate remained at approximately 70%. After 150days, granular sludge was observed. The energy balance calculation show that heating 1.0kg sludge needs 0.34MJ of energy, whereas biogas energy from the supernatant of the heated sludge is 0.43MJ. © 2011 Elsevier Ltd.


Xu X.,China University of Petroleum - Beijing | Sun H.,China University of Petroleum - Beijing | Yang Y.,China University of Petroleum - Beijing | Dai X.,China University of Petroleum - Beijing | And 6 more authors.
Angewandte Chemie - International Edition | Year: 2014

The shape-controlled synthesis of multicomponent metal nanocrystals (NCs) bounded by high-index facets (HIFs) is of significant importance in the design and synthesis of high-activity catalysts. We report herein the preparation of Pt-Ni alloy NCs by tuning their shape from concave-nanocubic (CNC) to nanocubic and hexoctahedral (HOH). Owing to the synergy of the HIFs and the electronic effect of the Pt-Ni alloy, the as-prepared CNC and HOH Pt-Ni alloy NCs exhibited excellent catalytic properties for the electrooxidation of methanol and formic acid, as well as for the oxygen reduction reaction (ORR). © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ning G.,China University of Petroleum - Beijing | Xu C.,China University of Petroleum - Beijing | Zhu X.,China University of Petroleum - Beijing | Zhang R.,Tsinghua University | And 4 more authors.
Carbon | Year: 2013

We report a MgO-catalyzed growth of N-doped carbon nanotubes (N-CNTs) that are constructed by graphene layers with wrinkles. Introducing NH3 to a chemical vapor deposition process and keeping a high reaction temperature (∼900 °C) are key factors to the N-CNT growth from MgO. Without N-doping or at a lower temperature, only graphene sheets deposited on MgO surfaces were obtained. Compared to the Fe-catalyzed N-CNTs, the MgO-catalyzed N-CNTs have larger diameters, thinner walls, more surface wrinkles and open ends with polygonal graphene edges. Because carbon dissolves into MgO in a very limited amount, the structural defects and broken sites formed in the graphene layers due to N-doping might have contributed to the formation of new graphene layers and thus lead to the growth of the wrinkled tubes. © 2013 Elsevier Ltd. All rights reserved.


Zhang Z.-C.,China University of Petroleum - Beijing | Zhang Z.-C.,Tsinghua University | Hui J.-F.,Tsinghua University | Guo Z.-G.,China University of Petroleum - Beijing | And 7 more authors.
Nanoscale | Year: 2012

Pt-Pd bimetallic alloy nanostructures with highly selective morphologies such as cube, bar, flower, concave cube, and dendrite have been achieved through a facile one-pot solvothermal synthesis. The effects of shape-controllers (sodium dodecyl sulfate (SDS), ethylenediamine-tetraacetic acid disodium salt (EDTA-2Na), NaI) and solvents (water/DMF) on the morphologies were systematically investigated. The electrocatalytic activities of these Pt-Pd alloy nanostructures toward formic acid oxidation were tested. The results indicated that these alloy nanocrystals exhibited enhanced and shape-dependent electrocatalytic activity toward formic acid oxidation compared to commercial Pt black and Pt/C catalysts. © 2012 The Royal Society of Chemistry.


Ye H.-M.,Tsinghua University | Ye H.-M.,China University of Petroleum - Beijing | Tang Y.-R.,Tsinghua University | Xu J.,Tsinghua University | Guo B.-H.,Tsinghua University
Industrial and Engineering Chemistry Research | Year: 2013

The details of poly(butylene fumarate) (PBF) as highly effective nucleating agent for poly(butylene succinate) (PBS) were systematically studied via X-ray diffraction, differential scanning calorimeter, polarized optical microscopy, and atom force microscopy. All results show that PBF can significantly improve the melt-crystallization temperature and the degree of crystallinity of PBS during the nonisothermal crystallization process. Both crystallization time span and spherulitic size of PBS decrease drastically with the addition of a small amount of PBF, which shows that PBF not only enhances the primary nucleation of PBS by epitaxial mechanism, but also greatly accelerates the secondary nucleation during spherulite growth. The secondary nucleation parameters of PBS, Kg and G0, are notably improved just with a small amount of PBF. Furthermore, the appearance of wrinkles on PBF-nucleated PBS ultrathin film visually suggests that PBF indeed affects the subsequent growth behavior, besides the primary nucleation. © 2013 American Chemical Society.


Huang W.,China University of Petroleum - Beijing | Gao D.,China University of Petroleum - Beijing | Liu F.,Tsinghua University
SPE Journal | Year: 2015

A new buckling equation in horizontal wells is derived on the basis of the general bending and twisting theory of rods. The boundary conditions of a long tubular string are divided into two categories: the sum of the virtual work of bending moment and shear force at the ends of tubular strings is equal to zero, and the sum of the virtual work of bending moment and shear force at the ends is not equal to zero. Buckling solutions under different boundary conditions are obtained by solving the new buckling model. For the boundary conditions of the first category, the buckling solutions are identical with previous results. For the boundary conditions of the second category, the buckling solutions are different from the results under the boundary conditions of the first category. The results indicate that buckling behaviors depend on both the axial force and the boundary conditions. Compared with previous results, buckling solutions of the new model provide a more comprehensive description of tubular-buckling behaviors. © 2015 Society of Petroleum Engineers.


Stevens D.,Waters Corporation | Shi Q.,China University of Petroleum - Beijing | Shi Q.,Florida State University | Hsu C.S.,China University of Petroleum - Beijing | Hsu C.S.,Florida State University
Energy and Fuels | Year: 2013

We report a novel analytical technique using gas chromatography/atmospheric pressure chemical ionization-mass spectrometry (GC/APCI-MS) or atmospheric pressure gas chromatography-mass spectrometry (APGC-MS), using corona discharge for analyzing nonpolar hydrocarbons, specifically for petroleum biomarkers that are important in geochemical studies of source rocks and crude oils. The advantages of applying MSE for both high-and low-energy collision simultaneously were demonstrated. The enhancement of molecular ions at low-energy MSE would facilitate the linkage with characteristic fragment ions for tandem mass spectrometry (MS-MS) experiments. The combination of quadrupole and time-of-flight (QTOF) mass analyzers renders sufficient and adequate resolution for accurate mass measurement, with measurement errors less than 1 mDa or 5 ppm for all ionic species in the hopane and sterane analyses. © 2012 American Chemical Society.


Lu H.,CAS Guangzhou Institute of Geochemistry | Peng P.,CAS Guangzhou Institute of Geochemistry | Hsu C.S.,China University of Petroleum - Beijing | Hsu C.S.,Florida State University
Energy and Fuels | Year: 2013

For the sulfur-rich heavy oils in Jinxian Sag, Bohai Bay Basin, northern China, high abundances of organic sulfur compounds (OSCs), including benzothiophenes and dibenzothiophenes, were detected in aromatic hydrocarbon fractions. Short-chain (such as 20-thienylpregnanes and thienylandrostanes) and regular carbon-numbered S-containing steroids are also present in the saturate hydrocarbon fractions. In addition, a series of short-chain steranes (C 21-26), unusual short-chain lanostanes (C24-25), 4-methyl steranes (C22-23), 4,4-dimethyl steranes (C22-24), and androstanes (C19-20) were found, accompanied with high-molecular-weight analogues, C27-30 regular steranes, C 27-30 4-methyl steranes, and C28-30 4,4-dimethyl steranes. The distinctive distribution characteristics and dominance of the short-chain steroids in these oils are believed to be derived from the cleavage of the weak C-S bond at C-17 and C-20 positions of extensively sulfurized steroids with subsequent microbial attack or bacterial reworking. To overcome the limitations of routine gas chromatography mass spectrometric analysis, which are only suitable for analyzing volatile and nonpolar saturate and aromatic hydrocarbon fractions, and to obtain more information and overall cognition on macromolecular OSCs in highly complicated petroleum substrates, such as polar NSO and asphaltene fractions, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was employed for the analysis of Jinxian heavy oils after methylation pretreatment. The results revealed that very complicated sulfur (S1, S2, and S3) and oxidized sulfur (OS and OS2) compounds were present in the Jinxian heavy oils, with the absence of nitrogen-containing compounds. In addition, the distribution of the most abundant S1-type OSCs was featured by a series of compounds with a wide range of double bond equivalent (DBE) values of 1-14 and carbon numbers of 10-44. On the basis of the reported carbon number distributions of steroid biomarkers in these oils, the most abundant OSCs in Jinxian oils with DBE = 5-7 in the vicinity of C19-22 and C 28-30 might come from the short-chain and regular S-containing steroids. The occurrence of abundant S-containing steroids was the results of extensive sulfurization during early diagenetic stages because much more double bonds, hydroxyl groups, and carbonyl groups exist in sterols and sterenes, which are prone to attack by inorganic sulfur. © 2013 American Chemical Society.


Wang J.,China University of Petroleum - Beijing | Wang J.,Tsinghua University | Xu C.,Tsinghua University
Chemical Engineering and Technology | Year: 2014

A mini liquid-liquid extractor was designed based on a feedback fluidic oscillator. According to the Coanda effect, the designed oscillator with two feedback channels enables good mixing of the aqueous and organic phases. Co-current liquid-liquid extraction was performed in the mini extractor, and it was visually observed that the aqueous phase was dispersed into small droplets because of fluidic oscillation and vortex formation. The aqueous phase was more effectively dispersed at the stage near the outlet and with increasing flow. Several tests were performed for evaluating the extraction performance of the extractor using 30% tributyl phosphate-kerosene and 3M HNO3 solutions as the organic and aqueous phases, respectively. The obtained extraction efficiency was close to the equilibrium efficiency, indicating that this extractor has the potential for liquid-liquid extraction of hazardous liquids. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Guo Y.-B.,Tsinghua University | Guo Y.-B.,China University of Petroleum - Beijing | Wang D.-G.,China University of Petroleum - Beijing | Liu S.-H.,China University of Petroleum - Beijing | Zhang S.-W.,China University of Petroleum - Beijing
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2013

Gold and silver nanoparticles in polyelectrolyte multilayers film can be prepared by alternate immersion of a substrate in poly(diallyldimethylammonium) chloride (PDDA)-AuCl4 - complexes solution and poly(acrylic acid) (PAA)-Ag+ complexes solution followed by reduction of the metal cations (Au3+, Ag+) through immersion of NaBH4 solution. UV-vis spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectra (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to confirm the successful construction of the polyelectrolyte multilayers film and the formation of gold and silver nanoparticles. The coefficient of friction as a function of sliding velocity and normal load also has been studied. The nanoparticles composite polyelectrolyte multilayers exhibited increased wear resistance compared with the pure polyelectrolyte multilayers. © 2012 Elsevier B.V.


Liu J.,China University of Petroleum - Beijing | Li S.C.,Beijing Aerospace Propulsion Institute | Luo X.,China University of Petroleum - Beijing
Computational and Mathematical Methods in Medicine | Year: 2013

Support vector machine is an effective classification and regression method that uses machine learning theory to maximize the predictive accuracy while avoiding overfitting of data. L2 regularization has been commonly used. If the training dataset contains many noise variables, L1 regularization SVM will provide a better performance. However, both L1 and L2 are not the optimal regularization method when handing a large number of redundant values and only a small amount of data points is useful for machine learning. We have therefore proposed an adaptive learning algorithm using the iterative reweighted p-norm regularization support vector machine for 0 < p ≤ 2. A simulated data set was created to evaluate the algorithm. It was shown that a p value of 0.8 was able to produce better feature selection rate with high accuracy. Four cancer data sets from public data banks were used also for the evaluation. All four evaluations show that the new adaptive algorithm was able to achieve the optimal prediction error using a p value less than L1 norm. Moreover, we observe that the proposed Lp penalty is more robust to noise variables than the L1 and L2 penalties. © 2013 Jianwei Liu et al.


Xu C.,Tsinghua University | Yu H.,Tsinghua University | Yu H.,China University of Petroleum - Beijing
Chemical Engineering Research and Design | Year: 2014

Reverse-flow diverter pumps have no moving parts that are in direct contact with the fluid; as a result, they are applicable for the transport of hazardous liquids or liquid-solid mixtures. To date, there is no method available for predicting the pumping capacity of reverse-flow diverter pumps. In this study, we experimentally investigated the pumping performance of reverse-flow diverters in the reverse-flow mode. Two dimensionless performance equations, expressed as q=0.9597exp(-Eur/0.9237)+0.4946exp(-Eur/7.360)+0.1765 and q=kα+I, were determined from the experimental data. Based on these two equations, a method for predicting the pumping capacity of reverse-flow diverter pumps was proposed. © 2013 The Institution of Chemical Engineers.


Hu J.,China University of Petroleum - Beijing | Zhang L.,China University of Petroleum - Beijing | Ma L.,Queensland University of Technology | Liang W.,China University of Petroleum - Beijing
Expert Systems with Applications | Year: 2011

In complex industrial system, most of single faults have multiple propagation paths, so any local slight deviation is able to propagate, spread, accumulate and increase through system fault causal chains. It will finally result in unplanned outages and even catastrophic accidents, which lead to huge economic losses, environmental contamination, or human injuries. In order to ensure system intrinsic safety and increase operational performance and reliability in a long period, this study proposes an integrated safety prognosis model (ISPM) considering the randomness, complexity and uncertainty of fault propagation. ISPM is developed based on dynamic Bayesian networks to model the propagation of faults in a complex system, integrating the priori knowledge of the interactions and dependencies among subsystems, components, and the environment of the system, as well as the relationships between fault causes and effects. So the current safety state and potential risk of system can be assessed by locating potential hazard origins and deducing corresponding possible consequences. Furthermore, ISPM is also developed to predict the future degradation trend in terms of future reliability or performance of system, and provide proper proactive maintenance plans. Ant colony algorithm is introduced in ISPM by comprehensively considering two factors as probability and severity of faults, to perform the quantitative risk estimation of the underlining system. The feasibility and benefits of ISPM are investigated with a field case study of gas turbine compressor system. According to the outputs given by ISPM in the application, proactive maintenance, safety-related actions and contingency plans are further discussed and then made to keep the system in a high reliability and safety level in the long term. © 2010 Elsevier Ltd. All rights reserved.


Ma J.,Rice University | Ma J.,China University of Petroleum - Beijing | Rixey W.G.,University of Houston | Alvarez P.J.J.,Rice University
Water Research | Year: 2015

The increased probability of groundwater contamination by ethanol-blended fuel calls for improved understanding of how remediation efforts affect the fate and transport of constituents of concern, including the generation and fate of fermentation byproducts. A pilot-scale (8m3) model aquifer was used to investigate changes in the concentrations of ethanol and its metabolites (methane and volatile fatty acids) after removal of the contamination source. Following the shut-off of a continuous release of a dissolved ethanol blend (10% v:v ethanol, 50mg/L benzene, and 50mg/L toluene), fermentation activity was surprisingly stimulated and the concentrations of ethanol metabolites increased. A microcosm experiment showed that this result was due to a decrease in the dissolved ethanol concentration below its toxicity threshold (~2000mg/L for this system). Methane generation (1.5mg/L of dissolved methane) persisted for more than 100days after the disappearance of ethanol, despite clean air-saturated water flowing continuously through the tank at a relative high seepage velocity (0.76m/day). Quantitative real-time PCR showed that functional genes associated with methane metabolism (mcrA for methanogenesis and pmoA for methanotrophy) also persisted in the aquifer material. Persistent methanogenesis was apparently due to the anaerobic degradation of soil-bound organic carbon (e.g., biomass grown on ethanol and other substrates). Overall, this study reflects the complex plume dynamics following source removal, and suggests that monitoring for increases in the concentration of ethanol metabolites that impact groundwater quality should be considered. © 2014 Elsevier Ltd.


Chen Y.,University of Texas at Austin | Yuan J.,China University of Petroleum - Beijing | Jin Z.,University of Edinburgh | Chen K.,University of Houston | Zhang L.,CAS Institute of Geology and Geophysics
Journal of Geophysics and Engineering | Year: 2014

The benefits of simultaneous source acquisition are compromised by the challenges of dealing with intense blending noise. In this paper, we propose a processing workflow for blended data. The incoherent property of blending noise in the common-midpoint gathers is utilized for applying median filtering along the spatial direction after normal moveout (NMO) correction. The key step in the proposed workflow is that we need to obtain a precise velocity estimation which is required by the subsequent NMO correction. Because of the intense blending noise, the velocity scan cannot be obtained in one step. We can recursively polish both the deblended result and the velocity estimation by deblending using the updated velocity estimation and velocity scanning using the updated deblended result. We use synthetic and field data examples to demonstrate the performance of the proposed approach. The migrated image of deblended data is cleaner than that of blended data and is similar to that of unblended data. © 2014 Sinopec Geophysical Research Institute.


Liu Q.,China University of Petroleum - Beijing | Shen A.,Tsinghua University | Duan Y.,Tsinghua University
Applied Energy | Year: 2015

Organic Rankine cycles (ORCs) are preferred to convert low temperature geothermal energy (<150. °C) to electricity. The working fluid selection and system parameters optimization are the main approaches to improve geothermal ORC systems performance. Zeotropic mixtures are showing promise as ORC working fluids due to the better match between the working fluid and the heat source/sink temperatures. This study optimizes the cooling water temperature rise as well as the evaporation and condensation pressures of isobutane/isopentane (R600a/R601a) mixtures for various mole fractions to maximize the net power output of a geothermal ORC for geothermal water temperatures of 110. °C, 130. °C and 150. °C and reinjection temperatures not less than 70. °C. Two mole fractions maximize the turbine power generation, while the maximum net power output occurs for R600a mole fractions from 0.7 to 0.9 due to the variation of the parasitic power consumed by the working fluid feed pump and the cooling water circulating pump. A geothermal ORC using R600a/R601 can generate 11%, 7% and 4% more power than an ORC using pure R600a for geothermal water inlet temperatures of 110. °C, 130. °C and 150. °C, respectively. Both the evaporator and condenser area per unit power output using R600a/R601a are higher than that using pure R600a or R601a due to the reduction in the heat transfer coefficient and the temperature difference between the mixture working fluid and the heat source/sink. The total heat transfer area per unit power output increases to a maximum at an R600a mole fraction of 0.5 and then decreases with increasing R600a mole fraction. The total heat transfer area can be reduced for the same power output with higher geothermal source temperatures. The turbine using R600a/R601a with higher R600a mole fractions is nearly the same size as a turbine using pure R600a. © 2015 Elsevier Ltd.


Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University
Earth and Planetary Science Letters | Year: 2014

We observe a clear seismic arrival at ~35-45. s after the direct P wave in USArray recordings of two deep earthquakes occurring beneath northeast China. Velocity-spectrum and beam-forming analyses reveal that this arrival has a lower slowness value than the direct P wave and a back azimuth slightly different from the great-circle direction. The measured slowness and arrival time indicate that it is a transmitted S to P conversion from structures below the sources. We employ the common-conversion-point (CCP) stacking and diffraction migration methods to determine the location and geometric features of the seismic structures. The CCP stacking image indicates that the structure is a localized discontinuity at ~1000. km with a dimension at ~200. km by ~50. km along the E-W and N-S directions, respectively. It is located at ~150. km northeast to the two events. The 2D migrated images, on the other hand, indicate that the sources structure are reflectors dipping northeastwards by ~17° at a slightly shallower depths. The reflectors have a length scale of ~100. km ant their centers are ~50. km away from the epicenters of the two earthquakes. Forward waveform modeling suggests that the dipping reflectors may be thin layers with a thickness of few kilometers. The layers have a lower shear velocity and a higher density than that of the surrounding mantle, which matches well with those predicted for mid-ocean-ridge basalt (MORB) at mid-mantle depths, according to a recent ab initio study. Combined with the results from previous studies, our observations here suggest that the former oceanic crust may be ubiquitously present in the lower mantle beneath subduction zones. © 2013 Elsevier B.V.


Niu Q.,Tohoku University | Qiao W.,Tohoku University | Qiao W.,China University of Petroleum - Beijing | Qiang H.,Northwest University, China | And 2 more authors.
Bioresource Technology | Year: 2013

The thermophilic methane fermentation of chicken manure (10% TS) was investigated within a wide range of ammonia. Microbiological analysis showed significant shifts in Archaeal and Bacterial proportions with VFA accmulation and CH4 formation before and after inhibition. VFA accumulated sharply with lower methane production, 0.29 L/g VS, than during the steady stage, 0.32L/g VS. Biogas production almost ceased with the synergy inhibition of TAN (8000mg/L) and VFA (25,000mg/L). Hydrogenotrophic Methanothermobacter thermautotrophicus str. was the dominate archaea with 95% in the inhibition stage and 100% after 40days recovery compared to 9.3% in the steady stage. Aceticlastic Methanosarcina was not encountered with coincided phenomenal of high VFA in the inhibition stage as well as recovery stage. Evaluation of the microbial diversity and functional bacteria indicated the dominate phylum of Firmicutes were 94.74% and 84.4% with and without inhibition. The microbial community shifted significantly with elevated ammonia concentration affecting the performance. © 2013 .


Liu H.,Rice University | Dai N.,BGP Inc. | Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University | Wu W.,BGP Inc.
Geophysics | Year: 2014

Cost-effective waveform modeling is the key to practical reverse time migration (RTM) and full-waveform inversion (FWI) implementations. We evaluated an explicit time evolution (ETE) method to efficiently simulate wave propagation in acoustic media with high temporal accuracy. We started from the constant-density acoustic wave equation and obtained an analytical time-marching scheme in the wavenumber domain. We then formulated an ETE scheme in the time-space domain by introducing a cosine function approximation. Although the ETE operator appears to be similar to the second-order temporal finite-difference (FD) operator, the exact nature of the ETE formula ensures high accuracy in time. We further introduced a set of optimum stencils and coefficients by minimizing evolution errors in a least-squares sense. Our numerical tests indicated that ETE can achieve similar waveform accuracy as FD with four times larger time steps. Meanwhile, the compact ETE operator keeps the computation efficient. The efficiency and capability to handle complex velocity field make ETE an attractive engine in acoustic RTM and FWI. © 2014 Society of Exploration Geophysicists.


Yang Y.,Jilin University | Zhang Y.,China University of Petroleum - Beijing | Hao S.,China University of Petroleum - Beijing | Kan Q.,Jilin University
Chemical Engineering Journal | Year: 2011

A variety of transition metal tetrahydro-salen complexes M-[H4]Salen (M=Cu, Co and Fe) and the corresponding metal salen complexes M-Salen were firstly tethered onto amino-functionalized mesoporous SBA-15 and screened as heterogeneous catalysts for aerobic epoxidation of styrene. The mesoporous structural integrity throughout the tethering procedure, the successful tethering of the organometallic complexes, the loadings of metal ions and organic ligands as well as the catalyst surface constitution and location of active organometallic species on the SBA-15 support were determined by comprehensive characterization techniques such as XRD, N2 adsorption/desorption, TEM, FT-IR, UV-vis spectroscopy, ICP-AES, XPS and TG/DSC. The tethered catalyst M-[H4]Salen-SBA (M=Cu or Co) exhibits improved reactivity than the corresponding M-Salen-SBA catalyst due to the incorporation of a modified coordination environment of the central metal cations by CN bond hydrogenation. However, Fe-[H4]Salen-SBA shows lower reactivity as compared to Fe-Salen-SBA possibly due to the easy formation of relatively inactive dinuclear iron(III) tetrahydro-salen complexes, verified by XPS and ESR. The recycling results of these heterogeneous catalysts exemplified by Co-Salen-SBA, Co-[H4]Salen-SBA and Fe-Salen-SBA, show good recoverability without significant loss of activity and selectivity within successive runs. Heterogeneity tests of three sample catalysts confirm the high stability of cobalt catalysts against leaching of active species into solution. © 2011 Elsevier B.V.


Liu X.,Tsinghua University | Wang W.,Tsinghua University | Shi Y.,Tsinghua University | Zheng L.,Tsinghua University | And 3 more authors.
Waste Management | Year: 2012

The effects of organic loading rate on the performance and stability of anaerobic co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) were investigated on a pilot-scale reactor. The results showed that stable operation was achieved with organic loading rates (OLR) of 1.2-8.0kgvolatile solid (VS)(m3d)-1, with VS reduction rates of 61.7-69.9%, and volumetric biogas production of 0.89-5.28m3(m3d)-1. A maximum methane production rate of 2.94m3(m3d)-1 was achieved at OLR of 8.0kgVS(m3d)-1 and hydraulic retention time of 15days. With increasing OLRs, the anaerobic reactor showed a decrease in VS removal rate, average pH value and methane concentration, and a increase of volatile fatty acid concentration. By monitoring the biogas production rate (BPR), the anaerobic digestion system has a higher acidification risk under an OLR of 8.0kgVS(m3d)-1. This result remarks the possibility of relating bioreactor performance with BPR in order to better understand and monitor anaerobic digestion process. © 2012 Elsevier Ltd.


Zheng K.,Queensland University of Technology | Zheng Y.,Microsoft | Yuan N.J.,Microsoft | Shang S.,China University of Petroleum - Beijing | And 2 more authors.
IEEE Transactions on Knowledge and Data Engineering | Year: 2014

The increasing pervasiveness of location-acquisition technologies has enabled collection of huge amount of trajectories for almost any kind of moving objects. Discovering useful patterns from their movement behaviors can convey valuable knowledge to a variety of critical applications. In this light, we propose a novel concept, called gathering, which is a trajectory pattern modeling various group incidents such as celebrations, parades, protests, traffic jams and so on. A key observation is that these incidents typically involve large congregations of individuals, which form durable and stable areas with high density. In this work, we first develop a set of novel techniques to tackle the challenge of efficient discovery of gathering patterns on archived trajectory dataset. Afterwards, since trajectory databases are inherently dynamic in many real-world scenarios such as traffic monitoring, fleet management and battlefield surveillance, we further propose an online discovery solution by applying a series of optimization schemes, which can keep track of gathering patterns while new trajectory data arrive. Finally, the effectiveness of the proposed concepts and the efficiency of the approaches are validated by extensive experiments based on a real taxicab trajectory dataset. © 2013 IEEE.


Chen M.,Massachusetts Institute of Technology | Chen M.,Rice University | Huang H.,Massachusetts Institute of Technology | Yao H.,Massachusetts Institute of Technology | And 4 more authors.
Geophysical Research Letters | Year: 2014

We present a refined 3D crustal model beneath SE Tibet from ambient noise adjoint tomography. Different from ray-theory-based tomography, adjoint tomography in this study incorporates a spectral-element method (SEM) and takes empirical Green's functions (EGFs) of Rayleigh waves from ambient noise interferometry as the direct observation. The frequency-dependent traveltime misfits between SEM synthetic Green's functions and EGFs are minimized with a preconditioned conjugate gradient method, meanwhile the 3D model gets improved iteratively utilizing 3D finite-frequency kernels. The new model shows 3 - 6% shear wave speed increasing beneath the western Sichuan Basin (SCB) (depth > 15 km) and the central Chuan-Dian Block (CDB), and 6 - 12% shear wave speed reduction in the mid-lower crust beneath the northern and the southern CDB. The inferred spatial pattern of low wave speed zones, consistent with possible partial melt, suggests more complex and disconnected geometry than the pervasive narrow zone from the channel flow models. ©2013. American Geophysical Union. All Rights Reserved.


Niu Q.,Tohoku University | Qiao W.,Tohoku University | Qiao W.,China University of Petroleum - Beijing | Qiang H.,Northwest University, China | And 3 more authors.
Bioresource Technology | Year: 2013

A 12L mesophilic CSTR of chicken manure fermentation was operated for 400days to evaluate process stability, inhibition occurrence and the recovery behavior suffering TAN concentrations from 2000mg/L to 16,000mg/L. A biogas production of 0.35-0.4L/gVSin and a COD conversion of 68% were achieved when TAN concentration was lower than 5000mg/L. Ammonia inhibition occurred due to the addition of NH4HCO3 to the substrate. The biogas and COD conversion decreased to 0.3L/gVSin and 20% at TAN 10,000mg/L and was totally suppressed at TAN 16,000mg/L. Carbohydrate and protein conversion decreased by 33% and 77% after inhibition. After extreme inhibition, the reactor was diluted and washed, reducing TAN and FA to 4000mg/L and 300mg/L respectively, and the recovered biogas production was 0.5L/gVSin. The extended Monod model manifested the different sensitivities of hydrolysis, acidogenesis and methanogenesis to inhibition. VFA accumulation accompanied an increase in ammonia and exerted a toxic on microorganism. © 2013 Elsevier Ltd.


Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Key Laboratory for Environmental Pollution Control | Zhang X.,CAS Zhengzhou Research Institute | Xie G.,Henan Institute of Science and Technology
Analytical Methods | Year: 2011

This paper developed a new method with temperature controlled ionic liquid dispersive liquid-phase microextraction for the determination of pyrethroid insecticides such as fenpropathrin, fenvalerate and bifenthrin in water samples. The effect of alkyl chain length of ionic liquid 1-alkyl-3-methylimidazolium hexafluorophosphate and other parameters such as sample pH, temperature, salting-out effect and sample volume on the extraction efficiency were investigated in detail. Four different alkyl chain length ionic liquids ([C nMIM][PF6], n = 4, 6, 7, 8) were tested. The experimental results demonstrated that the alkyl chain length of ionic liquids (ILs) did have an important role on the extraction efficiency. The experimental results indicated that the longer alkyl chain length of ILs resulted in better extraction efficiency. Among the four ILs, 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM] [PF6] was the best one for extraction of the target analytes. Under the optimized conditions, three pyrethroid insecticides had limits of detection (LOD, S/N = 3) in the range of 0.34∼0.48 μg L-1. The precisions of the proposed method (RSDs, n = 6) with a spiked concentration of 20 μg L-1 were in the range of 2.0∼3.4%. The proposed method was evaluated with real water samples spiked at a concentration of 10 ng mL-1 and good spiked recoveries over the range of 89.2∼102.7% were obtained. © 2011 The Royal Society of Chemistry.


Li Y.F.,China University of Petroleum - Beijing | Yang W.,China University of Petroleum - Beijing | Tu Z.Q.,China University of Petroleum - Beijing | Liu Z.C.,China University of Petroleum - Beijing | And 3 more authors.
Applied Physics Letters | Year: 2014

We have investigated the performance of Schottky junction solar cells based on silicon and graphene with 1-6 layers. The open-circuit voltage of solar cells shows an increase when increasing the number of graphene layers. However, the power conversion efficiency and short-circuit current density increase monotonically when the number of graphene layers is less than 4 and reduces as the number of graphene layers further increases. Our results demonstrate that the number of layers related to the work function and transmission of graphene plays a critical role in determining the performance of solar cells. © 2014 AIP Publishing LLC.


Ning G.,China University of Petroleum - Beijing | Fan Z.,Harbin Engineering University | Wang G.,China University of Petroleum - Beijing | Gao J.,China University of Petroleum - Beijing | And 2 more authors.
Chemical Communications | Year: 2011

Graphene that had nanomeshes, only one to two graphene layers, and specific surface areas of up to 1654 m 2 g -1 was produced on gram-scale by template growth on porous MgO layers. Its unique porous structure gave excellent electrochemical capacitance (up to 255 F g -1), cycle stability and rate performance. © 2011 The Royal Society of Chemistry.


Wei L.-H.,China University of Petroleum - Beijing | Yan W.-C.,Xiamen University | Luo Z.-H.,Xiamen University
Powder Technology | Year: 2011

A Eulerian-Eulerian model incorporating the kinetic theory of granular flow is adopted to describe the gas-solid two-phase flows in a multizone circulating propylene polymerization reactor. Corresponding simulations are carried out in a commercial computational fluid dynamics (CFD) code Fluent. First, the model is validated by comparing simulation results with the experimental data. Entire fields in the reactor composed of a riser and a downer are also obtained numerically. Furthermore, the model is used to distinguish the flow behaviors in the riser and the downer. The effects of riser-outlet configuration and operation gas velocity on the flow behaviors in the reactor are also investigated numerically. The simulated results show that the flow behaviors in the riser of MZCR are different from those in the downer of MZCR. In addition, the simulation results also show that both the exit configuration of the riser and the operation gas velocity can significantly affect the flow behaviors in the MZCR. © 2011 Elsevier B.V.


Zhang L.,CAS Institute of Geology and Geophysics | Bai G.,China University of Petroleum - Beijing | Zhao Y.,CAS Institute of Geology and Geophysics
Mathematical Geosciences | Year: 2012

All petroliferous basins exhibit near-surface anomalous signals. The successful use of these signals must lead to great development in petroleum exploration. However, oil/gas fields cannot be effectively predicted in the case of intensive influence of caprock thickness on intensities of anomalies in a geochemical survey for hydrocarbons. In this paper, we first study the features of the influence of caprock thickness and then establish digital conceptual models for the influence in one and two dimensions. Finally, we develop techniques for eliminating this influence with wavelet analysis, based on the digital conceptual models. The newly developed techniques are applied to the actual data of acid-extractable hydrocarbons of soils in the southern slope of the Dongying Depression, East China where the anomaly intensities are considerably influenced by caprock thickness. The results illustrate that this new approach enables us to satisfactorily eliminate the influence of caprock thickness on anomaly intensities and thus can greatly improve the predictive capability of the existing geochemical data. © 2012 International Association for Mathematical Geosciences.


Zhang D.,Tsinghua University | Jiang C.,Tsinghua University | Yang C.,China University of Petroleum - Beijing | Yang Y.,Tsinghua University
International Journal for Numerical Methods in Fluids | Year: 2014

SUMMARY: Three new far-upwind reconstruction techniques, New-Technique 1, 2, and 3, are proposed in this paper, which localize the normalized variable and space formulation (NVSF) schemes and facilitate the implementation of standard bounded high-resolution differencing schemes on arbitrary unstructured meshes. By theoretical analysis, it is concluded that the three new techniques overcome two inherent drawbacks of the original technique found in the literature. Eleven classic high-resolution NVSF schemes developed in the past decades are selected to evaluate performances of the three new techniques relative to the original technique. Under the circumstances of arbitrary unstructured meshes, stretched meshes, and uniform triangular meshes, for each NVSF scheme, the accuracies and convergence properties, when implementing the four aforementioned far-upwind reconstruction techniques respectively, are assessed by the pure convection of several scalar profiles. The numerical results clearly show that New-Technique-2 leads to a better performance in terms of overall accuracy and convergence behavior for the 11 NVSF schemes. © 2013 John Wiley & Sons, Ltd.


Zhang Z.-C.,Tsinghua University | Zhang Z.-C.,China University of Petroleum - Beijing | Zhang X.,China University of Petroleum - Beijing | Yu Q.-Y.,Tsinghua University | And 5 more authors.
Chemistry - A European Journal | Year: 2012

Palladium is a key catalyst invaluable to many industrial processes and fine-chemical synthesis. Although recent progress has allowed the synthesis of Pd nanoparticles with various shapes by using different techniques, the facile synthesis of Pd nanocrystals and turning them into a highly active, selective, and stable catalyst systems still remain challenging. Herein, we report the highly selective one-pot synthesis of monodisperse Pd cluster nanowires in aqueous solution; these consist of interconnected nanoparticles and may serve as highly active catalysts because of the enrichment of high index facets on the surface, including {443}, {331}, and {221} steps. For the first time, carbon nanotube and Î3-Al 2O 3 immobilized Pd cluster nanowires showed highly enhanced catalytic performance in the liquid-phase selective hydrogenation of cinnamaldehyde and gas-phase hydrogenation of 1,3butadiene relative to immobilized Pd icosahedra and nanocubes, as well as commercial Pd catalysts. Power in the cluster: Monodisperse Pd cluster nanowires, which consist of interconnected nanoparticles (see figure), have been synthesized in aqueous solution and may serve as highly active catalysts due to the enrichment of high index facets on the surface. Carbon nanotube and Î3-Al 2O 3 immobilized Pd cluster nanowires showed enhanced catalytic performance in hydrogenations reactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lan W.,China University of Petroleum - Beijing | Li S.,Tsinghua University | Wang Y.,Tsinghua University | Luo G.,Tsinghua University
Industrial and Engineering Chemistry Research | Year: 2014

A level set method embedded in a Computational Fluidic Dynamics (CFD) simulation is a useful approach in the study of microfluidic two-phase flow. In this work, we established a new governing equation for the level set function to overcome the "mass loss" problem. The feasibility of the modified method was proved by the simulation of a droplet formation in a co-tube microchannel. The modified method was then used to simulate the droplet flow in a focusing shape microchannel. The simulation results showed that the droplet size would decrease with an increase in the continuous phase flow rate. In the early stage of the droplet formation process, there was strong inner circulation flow that enhanced the mass transfer between the two phases and generated a concentration notch at the head of the droplet. In the later stage of the droplet formation process, the droplet moving velocity became higher, and there was no longer inner circulation flow in the droplet. The mass transfer speed slowed, and there was an enrichment of the material at the head of the droplet. The total mass transfer ratio in the droplet formation process reached 50%. The simulation results were consistent with both our previous experiment results and the results reported in the literature, which further proved the feasibility of the modified method. © 2014 American Chemical Society.


Zhu W.,Tsinghua University | Li W.,Tsinghua University | Yang H.,Tsinghua University | Jiang Y.,Tsinghua University | And 3 more authors.
Chemistry - A European Journal | Year: 2013

Based on the simple counterion exchange of ionic liquids, a rapid, facile, and efficient strategy to create a cross-reactive sensor array with a dynamic tunable feature was developed, and exemplified by the construction of a sensor array for the identification and classification of nitroaromatics and explosives mimics. To achieve a good sensing system with fast response, good sensitivity, and low detection limit, the synthesized ionic liquid receptors were tethered onto a silica matrix with a macro-mesoporous hierarchical structure. Through the facile anion exchange approach, abundant ionic-liquid-based individual receptors with diversiform properties, such as different micro-environments, diverse molecular interactions, and distinctive physico-chemical properties, were easily and quickly synthesized to generate a distinct fingerprint of explosives for pattern recognition. The reversible anion exchange ability further endowed the sensor array with a dynamic tunable feature as well as good controllability and practicality for real-world application. With the assistance of statistical analysis, such as principal component analysis (PCA) and linear discrimination analysis (LDA), an optimized-size array with a good resolution was rationally established from a large number of IL-based receptors. The performed experiments suggested that the ionic-liquid-based sensing protocol is a general and powerful strategy for creating a cross-reactive sensor array that could find a wide range of applications for sensing various analytes or complex mixtures. Chemical track hound: A cross-reactive sensor array based on an ionic liquid (IL) was developed for nitroaromatics and explosives mimics. Based on the simple counterion exchange, abundant IL-based individual receptors with diverse properties are easily and quickly synthesized. The reversible anion exchange ability further endowed the sensor array with a dynamic tunable feature as well as good controllability and practicality for real-world applications (see figure). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Guo T.,China University of Petroleum - East China | Guo T.,China University of Petroleum - Beijing | Zhang S.,China University of Petroleum - Beijing | Qu Z.,China University of Petroleum - East China | And 3 more authors.
Fuel | Year: 2014

"Stimulated reservoir volume" (SRV) makes it possible for commercial production of shale gas by means of multistage fracturing of horizontal wells. However, the formation mechanism of effective fracture network has not been well understood. The mechanism of fracture propagation in shale with hydraulic fracturing needs to be further explored, in order to realize the control on morphology of fracture network with SRV and increase the single well production of shale gas. In this article, the true triaxial test system was deployed for horizontal well hydraulic fracturing simulation experiments of shale outcrops for the first time. The effects of multiple factors on propagating rules of fractures of horizontal well in shale with SRV were studied, and the fracture morphology of post-fracturing rock cores was observed for the first time by high-energy CT scanning using the large-scale non-destructive testing system based on linear accelerator. The results show that the influence of flow rate (for SRV) on fracture complexity differs when its value falls in different intervals. When the horizontal in situ stress difference is less than 9 MPa, the hydraulic fracture easily propagates along the natural fractures, forming a fracture network. In this range, when the stress difference is increased, the appearance of the main hydraulic fracture contributes to interconnecting more natural fractures, forming a relatively more complex fracture system. Under the condition of the same horizontal stress difference, if the coefficient of stress difference Kh > 0.25, there is an obvious trend to form single main fracture. The effects of viscosity of fracturing fluid and flow rate on the fracture propagation can be expressed by the parameter q·μ. When the order of magnitude of q·μ-value is 10-9 N m, it is favorable to the generation of fracture network, but too small or too large values are both harmful. The development and cementing strength of depositional beddings seriously affect the propagating complexity of fracture network with hydraulic fracturing. Refracturing helps to produce some new fractures which are different from the initial ones, and better fracturing effect is achieved. The fracture initiation morphology in perforation fracturing is closely related to the distribution of natural fractures (depositional bedding) around the perforations. If the pressure curve fluctuates significantly, it is indicated that the shale core contains a large number of opened natural fractures or depositional beddings before fracturing, which causes the serious loss of fracturing fluid in the propagation process. © 2014 Elsevier Ltd. All rights reserved.


Hu J.,China University of Petroleum - Beijing | Zhang L.,China University of Petroleum - Beijing | Ma L.,Queensland University of Technology | Liang W.,China University of Petroleum - Beijing
Safety Science | Year: 2010

In large-scale and complex industrial systems, unplanned outages and hazardous accidents cause huge economic losses, environmental contamination, and human injuries, due to component degradation, exogenous changes, and operational mistakes. In order to ensure safety and increase operational performance and reliability of complex system, this study proposes an integrated method for safety pre-warning to analyze the current safety state of each component and the whole system indicating hidden hazards and potential consequence, and furthermore predict future degradation trends in the long term.The work presented here describes the rationale and implementation of the integrated method incorporating HAZOP study, degradation process modeling, dynamic Bayesian network construction, condition monitoring, safety assessment and prognosis steps, taking advantage of the priori knowledge of the interactions and dependencies among components and the environment, the relationships between hazard causes and effects, and the use of historical failure data and online real-time data from condition monitoring.The application of the integrated safety pre-warning approach described here to the specific example of the gas turbine compressor system demonstrates how each phase of the presented method contributes to completion of the safety pre-warning system development in a systematic way. © 2010 Elsevier Ltd.


Tong H.,China University of Petroleum - Beijing | Yin A.,University of California at Los Angeles | Yin A.,China University of Geosciences
Tectonophysics | Year: 2011

Understanding the mechanical controls on reactivation of preexisting weakness is a fundamental problem in tectonic studies. In this study, we develop a theoretical framework for evaluating the likelihood of seismicity on active faults and the sequence of reactivation of multiple sets of preexisting weakness. Our analysis overcomes the restrictions of the early work that assumes uniform coefficient of friction across all preexisting planes with negligible cohesive strength and vertical or horizontal orientations of principal stresses. Using a coordinate-system transformation, we developed a new graphical technique that can express the reactivation problem in the Mohr space with the principal stresses oriented neither vertically nor horizontally. We verified the predicted sequence of reactivation on preexisting weakness and initiation of new fractures, according to the Byerlee law and the Coulomb fracture criterion, by conducting a simple sandbox experiment. Our proposed reactivation-tendency analysis can be expanded to evaluate the likelihood of seismicity on a single fault with curvi-planar geometry (e.g., listric normal faults, ramp-flat thrusts, and strike-slip faults with restraining- and releasing-bend geometry). Our analysis also provides a new insight into the mechanical cause of temporal evolution of pre-existing weakness in geologic records. Finally, our work implies that the sequence of faulting reactivated from preexisting weakness provides critical information on the mechanical properties of the deforming lithosphere. © 2011 Elsevier B.V.


Yang X.,China University of Petroleum - Beijing | Teng F.,Tsinghua University
Resources, Conservation and Recycling | Year: 2016

Coal keeps dominating the primary energy consumption in China, and is highly-related to the carbon emission and air quality challenge. Recently, China has submitted its Intended Nationally Determined Contribution (INDC) and committed to peak the carbon emission around 2030, and reduce the emission intensity by 60%-65% in 2030 compared to the 2005 level. Moreover, severe haze problem blanketed China in recent years and tends to getting worse, which is directly related to fossil fuel combustion, especially coal consumption in China. To address these challenges, this study carried out an analysis on effect of coal control strategy to energy system and local pollutant reduction. A bottom-up model of China-MAPLE is developed, linking the carbon emission and local pollutant emissions to the coal control policy scenarios. Four scenarios are designed for the energy system and co-benefit study. Three main conclusions can be drawn based on the study: first, the deep energy conservation measures including coal control has apparent effect on the energy system optimization, and the coal peaking year is near 2020 which is highly related and consistent with the carbon peaking. Second, the end-of-pipe control measures will significantly reduce the local pollutant emission, however the reduction is not sufficient enough to achieve the air quality standard. Energy conservation measures, especially coal control strategy, are essential for the source control side. Third, for the co-control from both source control and end-of-pipe control, emission of SO2, NOX and PM2.5 in 2030 will be reduced by 78.85%, 77.56% and 83.32% compared to the level of 2010, which fits the air quality targets, together with carbon peaking target achieved. In electricity generation sector, the source control measures will contribute 10%-35% in future and coal control measures contributes 17%-40% to the local pollutant reduction. The strategy of coal control is of high importance for carbon mitigation and also local pollutant control. © 2016 Elsevier B.V.


Chen Q.,Xiamen University | Li J.,Lanzhou University | Li Y.,China University of Petroleum - Beijing
Journal of Physics D: Applied Physics | Year: 2015

Over the past few decades, a new branch of plasma research, nanomaterial (NM) synthesis through plasma-liquid interactions (PLIs), has been developing rapidly, mainly due to the various, recently developed plasma sources operating at low and atmospheric pressures. PLIs provide novel plasma-liquid interfaces where many physical and chemical processes take place. By exploiting these physical and chemical processes, various NMs ranging from noble metal nanoparticles to graphene nanosheets can easily be synthesized. The currently rapid development and increasingly wide utilization of the PLI method has naturally lead to an urgent need for the presentation of a general review. This paper reviews the current status of research on PLIs for NM synthesis. The focus is on a comprehensive understanding of the synthesis process and perceptive opinions on current issues and future challenges in this field. © 2015 IOP Publishing Ltd.


Xu Q.,China University of Petroleum - Beijing | Pu P.,China University of Petroleum - Beijing | Zhao J.,China University of Petroleum - Beijing | Dong C.,Rice University | And 5 more authors.
Journal of Materials Chemistry A | Year: 2015

Sulfur-doped carbon dots (S-doped C-dots)were synthesized using a simple and straightforward hydrothermal method. The as-prepared S-doped C-dots exhibit significant fluorescence quantum yield (67%) and unique emission behavior. The spherical S-doped C-dots have an average diameter of 4.6 nm and the fluorescence of S-doped C-dots can be effectively and selectively quenched by Fe3+ ions. Thus, S-doped C-dots were applied as probes toward Fe3+ detection, exhibiting a limit of detection of 0.1 μM. This journal is © The Royal Society of Chemistry 2015.


Ning G.,China University of Petroleum - Beijing | Xu C.,China University of Petroleum - Beijing | Mu L.,China University of Petroleum - Beijing | Chen G.,China University of Petroleum - Beijing | And 5 more authors.
Chemical Communications | Year: 2012

We report for the first time an experimental investigation of gas storage in porous graphene with nanomeshes. High capacity methane storage (236 v(STP)/v) and a high selectivity to carbon dioxide adsorption were obtained in the nanomesh graphene with a high specific surface area (SSA) and a SSA-lossless tightly stacking manner. © The Royal Society of Chemistry 2012.


Miller M.S.,University of Southern California | Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University | Vanacore E.A.,University of Leeds
Physics of the Earth and Planetary Interiors | Year: 2013

Lateral heterogeneities at the top of the inner core are investigated using earthquakes that occurred in Indonesia and southeast Asia and were recorded in the southeastern Caribbean. Using seismic observations of attenuation and seismic velocity, we were able to constrain the characteristics of the boundary between the inner and outer core to further investigate the dynamics and evolution of the Earth's core. Our seismic observations from core phases confirm that the outermost inner core is asymmetrically heterogeneous and we are able to further constrain the morphology and physical properties of this layer. Comparison of data from earthquakes with ray paths traversing from east to the west versus those with ray paths from west to east allow us to map the aspherical heterogeneity of the boundary layer and specifically image the boundary between the proposed quasi-eastern and western hemispheres of the inner core. The variation of differential travel times between PKPdf and PKPbc, attenuation in terms of Q factor, and latitudinal changes for both of these observations, can be attributed to localized heterogeneity at the quasi-hemispherical boundaries of the inner core. We constrain the change in the thickness of outermost core boundary layer from 100 to 250km within a distance of a few 10s of kilometers at 45°E±2°, for the western boundary, with an overall P-wave velocity decrease in the western hemisphere of 0.5% and increase of 0.5% in the eastern hemisphere. We constrain the eastern boundary at latitudes greater than 45°N to 173°E±4° with an overall P-wave velocity decrease in the western hemisphere of 1.0% in the uppermost 200km of the inner core. The eastern boundary at equatorial latitudes is constrained to a region <170°E with a western hemisphere with a 0.5% drop in P-wave velocity in the uppermost 250km. © 2013 Elsevier B.V.


Liu Y.,Jilin University | Fomel S.,University of Texas at Austin | Liu G.,China University of Petroleum - Beijing
Geophysical Prospecting | Year: 2010

Attenuation of random noise and enhancement of structural continuity can significantly improve the quality of seismic interpretation. We present a new technique, which aims at reducing random noise while protecting structural information. The technique is based on combining structure prediction with either similarity-mean filtering or lower-upper-middle filtering. We use structure prediction to form a structural prediction of seismic traces from neighbouring traces. We apply a non-linear similarity-mean filter or an lower-upper-middle filter to select best samples from different predictions. In comparison with other common filters, such as mean or median, the additional parameters of the non-linear filters allow us to better control the balance between eliminating random noise and protecting structural information. Numerical tests using synthetic and field data show the effectiveness of the proposed structure-enhancing filters. © 2009 European Association of Geoscientists & Engineers.


Wang F.,Jilin University | Xu W.-L.,Jilin University | Xu W.-L.,Wuhan University | Gao F.-H.,Jilin University | And 5 more authors.
Gondwana Research | Year: 2014

The Central Asian Orogenic Belt (CAOB) is a natural laboratory of the Phanerozoic accretionary orogen. The eastern section of the CAOB contains several microcontinental massifs, and it is unknown whether these massifs carry Precambrian basement. Here we present the results of U-Pb dating of detrital zircons from the Dongfengshan and Tadong groups in the eastern margin of the Songnen-Zhangguangcai Range Massif. The Dongfengshan and Tadong groups are subdivided, from bottom to top, into the Liangzihe, Huapigou, and Honglin formations, and the Lalagou and Zhudundian formations, respectively. Zircons from a two-mica quartz schist (sample HCM4-2) in the Liangzihe Formation yielded eight age populations, from 821 to 1802. Ma, whereas zircons from a two-mica quartz schist (sample 12HCM3-2) in the Huapigou Formation yielded four age populations (752, 803, 821, and 851. Ma). Zircons from a two-mica schist in the Lalagou Formation of the Tadong Group yielded two age populations (450 and 485. Ma), and zircons from a biotite-bearing plagioclase gneiss in the lower part of the Zhudundian Formation yielded five main age populations, from 551 to 1815. Ma. Samples 11NNA5-1 and 11HNA10-1 from the upper layer of the Zhudundian Formation yielded six main age groups, from 749 to 948. Ma. These data, together with the ages of zircons within a tonalite that intrudes the Tadong Group and the overlying Chenming Formation, indicate the presence of a Precambrian terrane associated with sedimentation at various times during the Neoproterozoic, including at ~. 821-752, ~. 752-560, and ~. 750-516. Ma, on the eastern margin of the Songnen-Zhangguangcai Range Massif. The Dongfengshan and Tadong groups were previously thought to be Proterozoic, but our study reveals that they constitute a Neoproterozoic-Late Paleozoic tectonic mélange. In addition, the widespread occurrence of detrital zircons with ages of 0.75-0.95, 1.5-1.6, 1.8, and 2.4-2.5. Ga provides evidence of a Neoproterozoic magmatic event and the presence of remnant ancient basement material within the Songnen-Zhangguangcai Range Massif. © 2013 International Association for Gondwana Research.


Xu Q.,China University of Petroleum - Beijing | Xu H.,China University of Petroleum - Beijing | Chen J.,Xi'an Jiaotong University | Lv Y.,China University of Petroleum - Beijing | And 2 more authors.
Inorganic Chemistry Frontiers | Year: 2015

Advanced membrane systems with excellent permeance are important for controllable separation processes, such as gas separation and water purification. The ideal candidate materials should be very thin to provide high permeance, be stiff enough to withstand working under high applied pressure, with a large surface area and micro- or nano-pore structure for excellent selectivity. Graphene oxide (GO) nanosheets are graphene with oxygen-containing functional groups, obtained by treating graphite with strong oxidizers. Graphene-based materials, by virtue of their high mechanical strength, large surface area, single-atom-thick unique two-dimensional honeycomb lattice structure, and narrow pore distribution, provide exciting opportunities to assemble novel types of advanced, ultra-thin, high-efficiency membrane devices. In this contribution, we discuss the progress made in the direction of using graphene oxide as high-efficiency membranes for gas separation and water purification. The primary focus will be on introducing the fabrication processes, exceptional properties, and innovative membrane applications of two-dimensional graphene oxide materials for controllable separation processes. This state-of-the-art review will provide a platform for understanding the intricate details of gas and water molecular transport through laminar graphene oxide membranes, as well as a summary of the latest process in the field. This journal is © the Partner Organisations 2015.


Wang W.,Tsinghua University | Luo Y.,Tsinghua University | Qiao W.,China University of Petroleum - Beijing
Frontiers of Environmental Science and Engineering in China | Year: 2010

In China, over 1. 43×107 tons of dewatered sewage sludge, with 80% water content, were generated from wastewater treatment plants in 2007. About 60% of the COD removed during the wastewater treatment process becomes concentrated as sludge. Traditional disposal methods used by municipal solid waste treatment facilities, such as landfills, composting, or incineration, are unsuitable for sludge disposal because of its high water content. Disposal of sludge has therefore become a major focus of current environmental protection policies. The present status of sludge treatment and disposal methodology is introduced in this paper. Decreasing the energy consumption of sludge dewatering from 80% to 50% has been a key issue for safe and economic sludge disposal. In an analysis of sludge water distribution, thermal drying and hydrothermal conditioning processes are compared. Although thermal drying could result in an almost dry sludge, the energy consumption needed for this process is extremely high. In comparison, hydrothermal technology could achieve dewatered sewage sludge with a 50%-60% water content, which is suitable for composting, incineration, or landfill. The energy consumption of hydrothermal technology is lower than that required for thermal drying. © Higher Education Press and Springer Berlin Heidelberg 2010.


Yang Y.,Jilin University | Ding H.,Jilin University | Hao S.,China University of Petroleum - Beijing | Zhang Y.,China University of Petroleum - Beijing | Kan Q.,Jilin University
Applied Organometallic Chemistry | Year: 2011

A series of Fe(III), Co(II) and Cu(II) complexes of 8-quinolinol were encapsulated into the supercages of zeolite-Y and characterized by X-ray diffraction, SEM, N2 adsorption/desorption, FT-IR, UV-vis spectroscopy, elemental analysis, ICP-AES and TG/DSC measurements. The encapsulation was achieved by a flexible ligand method in which the transition metal cations were first ion-exchanged into zeolite Y and then complexed with 8-quinolinol ligand. The metal-exchanged zeolites, metal complexes encapsulated in zeolite-Y plus non-encapsulated homogeneous counterparts were all screened as catalysts for the aerobic oxidation of styrene under mild conditions. It was found that the encapsulated complexes always showed better activity than their respective non-encapsulated counterparts. Moreover, the encapsulated iron complex showed good recoverability without significant loss of activity and selectivity within successive runs. Heterogeneity test for this catalyst confirmed its high stability against leaching of active complex species into solution. © 2011 John Wiley & Sons, Ltd.


Zhu X.,China University of Petroleum - Beijing | Ning G.,China University of Petroleum - Beijing | Fan Z.,Harbin Engineering University | Gao J.,China University of Petroleum - Beijing | And 3 more authors.
Carbon | Year: 2012

Graphene-carbon nanotube (G-CNT) hybrids were synthesized by a one-step chemical vapor deposition process using a mixed catalyst of MgO and Fe/MgO. MgO layers acted as templates for the growth of graphene, and Fe particles on the MgO layers catalyzed the growth of single or double-walled CNTs. The G-CNT hybrids had porous structures with hierarchical pore distributions due to the composition of graphene with CNT network. Superparamagnetism with a saturation magnetization of 2.7 emu/g was found in the G-CNT hybrids due to the existence of Fe 3C nanoparticles of size ∼3 nm. The graphene to CNT ratio was conveniently changed by varying the MgO to Fe/MgO ratio, as characterized by Raman analysis and specific surface area measurements. Furthermore, a simplified synthesis of G-CNT hybrids was demonstrated by using MgO supported Fe or Ni catalysts with a low metal concentration. © 2012 Elsevier Ltd. All rights reserved.


Hao S.,China University of Petroleum - Beijing | Cui L.,China University of Petroleum - Beijing | Chen Z.,Argonne National Laboratory | Jiang D.,China University of Petroleum - Beijing | And 6 more authors.
Advanced Materials | Year: 2013

A novel stretchable coaxial NiTi-sheath/Cu-core composite wire was fabricated by means of simple mechanical processing. This composite simultaneously possesses high electric conductivity, high strength and superelasticity. This set of properties renders this composite a unique position in the properties chart of all known electrical conductor materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Dong Z.-Y.,China University of Petroleum - Beijing | Dong Z.-Y.,China University of Geosciences | Huang W.-H.,China University of Geosciences | Xing D.-F.,Petrochina | Zhang H.-F.,China Shenhua Coal to Liquid and Chemical Yulin Chemical Company
Journal of Hazardous Materials | Year: 2013

Successful remediation of soil co-contaminated with high levels of organics and heavy metals is a challenging task, because that metal pollutants in soil can partially or completely suppress normal heterotrophic microbial activity and thus hamper biodegradation of organics. In this study, the benefits of integrating electrokinetic (EK) remediation with biodegradation for decontaminating soil co-contaminated with crude oil and Pb were evaluated in laboratory-scale experiments lasting for 30 days. The treated soil contained 12,500. mg/kg of total petroleum hydrocarbons (TPH) and 450. mg/kg Pb. The amendments of EDTA and Tween 80, together with a regular refreshing of electrolyte showed the best performance to remediate this contaminated soil. An important function of EDTA-enhanced EK treatment was to eliminate heavy metal toxicity from the soil, thus activating microbial degradation of oil. Although Tween 80 reduced current, it could serve as a second substrate for enhancing microbial growth and biodegradation. It was found that oil biodegradation degree and microbial numbers increased toward the anode and cathode. Microbial metabolism was found to be beneficial to metal release from the soil matrix. Under the optimum conditions, the soil Pb and TPH removal percentages after 30 days of running reached 81.7% and 88.3%, respectively. After treatment, both the residual soil Pb and TPH concentrations met the requirement of the Chinese soil environmental quality standards. © 2013 Elsevier B.V.


Nie H.,China University of Petroleum - Beijing | Nie H.,Deutsches Biomasseforschungszentrum gemeinnutzige GmbH | Jacobi H.F.,Deutsches Biomasseforschungszentrum gemeinnutzige GmbH | Strach K.,Deutsches Biomasseforschungszentrum gemeinnutzige GmbH | And 3 more authors.
Bioresource Technology | Year: 2015

The effects of ammonia concentration on the performance and stability of mono-fermentation of chicken manure were investigated in a lab-scale continuous stirred tank reactor at 40. °C. Technical stripping was performed to remove ammonia from the liquid fraction of digestate, and the entire product was recycled to the fermenter to control ammonia concentration in the fermenter. Organic loading rate (OLR) of 5.3 gVS/(L d) was achieved with an average free ammonia nitrogen (FAN) concentration of 0.77 g/L and a specific gas yield of 0.39 L/gVS. When OLR was increased to 6.0 gVS/(L d), stable operation could be obtained with an average FAN concentration of 0.86 g/L and a specific gas yield of 0.27 L/gVS. Mono-fermentation of chicken manure was successfully carried out at high ammonia concentrations. Controlled recirculation of treated liquid fraction of digestate could be a solution in large-scale application for both: to avoid ammonia inhibition and minimize digestate. © 2014 Elsevier Ltd.


Dong Z.,China University of Petroleum - Beijing | Lu M.,Jingdezhen Ceramic Institute | Huang W.,China University of Geosciences | Xu X.,China University of Geosciences
Journal of Hazardous Materials | Year: 2011

In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10. h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10. h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier. © 2011 Elsevier B.V.


Zhang Y.,University of Science and Technology Beijing | Pang X.,University of Science and Technology Beijing | Qu S.,University of Science and Technology Beijing | Li X.,China Petroleum Pipeline Engineering Corporation | And 2 more authors.
International Journal of Greenhouse Gas Control | Year: 2011

Corrosion experiments were performed with X65 pipeline steel under static supercritical carbon dioxide (SC CO2) conditions at 50, 80, 110 and 130°C. The morphology, structure, chemical composition and fracture toughness of CO2 corrosion scales formed on the surface of X65 pipeline steel at various temperatures were investigated by means of Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS). The corrosion rates were measured using weight-loss method. The fracture toughness of CO2 corrosion scale formed at different temperatures was investigated by means of nanoindentation and Vicker's indentation on a polished cross-section of the CO2 corrosion scale. The results showed that the corrosion rates increased from 50°C to 80°C and then decreased from 80°C to 130°C. As the temperature increased, the fracture toughness of CO2 corrosion scale first decreased and then increased, and the lowest fracture toughness was found at 80°C. The corrosion rate (CR) has a quantitative relationship with the fracture toughness (KIC)CR=(3.25/KIC3/2)-0.908. © 2011 Elsevier Ltd.


Zhang Y.,University of Science and Technology Beijing | Pang X.,University of Science and Technology Beijing | Qu S.,University of Science and Technology Beijing | Li X.,China Petroleum Pipeline Engineering Corporation | And 2 more authors.
Corrosion Science | Year: 2012

The corrosion behaviour of X65 pipeline steel at various temperatures for different immersion time under low CO 2 partial pressure and supercritical CO 2 condition were investigated by weight loss measurements and surface analysis techniques. By comparing the characteristics of CO 2 corrosion product scale formed under experimental conditions and the variation rule of corrosion rate with temperature, the CO 2 corrosion mechanism under low partial pressure and supercritical condition was studied. To explain the big difference of corrosion rate between low CO 2 partial pressure and supercritical CO 2 condition, thermodynamic calculation of the solubility of CO 2 in H 2O were discussed. © 2012 Elsevier Ltd.


Shi Q.,China University of Petroleum - Beijing | Hou D.,China University of Geosciences | Chung K.H.,Well Inc | Xu C.,China University of Petroleum - Beijing | And 2 more authors.
Energy and Fuels | Year: 2010

A Liaohe crude oil was separated as saturates, aromatics, resins, and asphaltenes (SARA) and neutral nitrogen fractions. The crude oil and its subfractions were analyzed by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results show that neutral nitrogen and acidic heteroatom compounds in the crude oil contain 15-55 carbon atoms with double-bond equivalent (DBE) values of 1-27, containing N 1, N 2, N 1O 1, N 1O 2, N 1O 3, N 1O 4, O 1, and O 2 heteroatom classes. No molecules in the saturate fraction can be ionized by ESI. The aromatic fraction contains N 1 and N 1O x compounds with high molecular weights but low DBE values. The resin and asphaltene fractions contain highly aromatic and acidic class species, which are enriched in oxygen- and nitrogen-containing compounds with lower molecular weights than those found in the aromatic fraction. The distribution patterns of N 1, N 1O 1, and O 1 class species in the resins and asphaltenes are similar. The mass spectrum of the neutral nitrogen fraction differs from those for the bulk crude oil and its SARA fractions; the neutral nitrogen fraction is enriched with N 1 and N 1O 1 class species. Neutral nitrogen compounds with molecular weights lower than 200 were discriminated in the FT-ICR MS spectrum under the chosen operating conditions. However, the nitrogen species detected by gas chromatography only accounted for a small amount of that found in the neutral nitrogen fractions. Some of the neutral nitrogen species were entrained in asphaltenes during the deasphalting step of sample fractionation. © 2010 American Chemical Society.


Li Y.,China University of Petroleum - Beijing | Li Y.,State Key Laboratory of Petroleum Resources and Prospecting | Wu S.,China University of Petroleum - Beijing | Wu S.,State Key Laboratory of Petroleum Resources and Prospecting
Petroleum Exploration and Development | Year: 2013

A hierarchal nested reservoir architecture simulation methodology is proposed to meet the current challenges in reservoir heterogeneity modeling. It matches the architecture geological research principle which is shortened as "hierarchical constraint, pattern fitting and multi-dimension proof". In this proposed methodology, different modeling approaches are adopted in different stages of architecture analysis, and the result from current architecture analysis is used as constraints and information for next level architecture analysis. The meandering river reservoir architecture modeling is used to illustrate the proposed methodology. The meandering river sand complex is the first modeling stage. The Fluvsim program is updated to characterize the bounding surface of single channel within the channel sand complex. In second stage, a new point bar simulation program, Barsim, is developed. The abandoned channel and the known point bars are assembled together according to the quantity fluvial reservoir architecture model. The spatial vector based program Ihssim is developed to characterize the inclined heterogeneity strata (IHS) inside the point bar sand at third level architecture study stage. Through such an integrated three modeling procedures, the heterogeneity characteristics of a reservoir which is represented by reservoir architecture elements in different scales and hierarchical levels are presented in the final reservoir model. © 2013 Research Institute of Petroleum Exploration & Development, PetroChina.


Ma D.-M.,China University of Petroleum - Beijing | Ma D.-M.,Xi'an University of Science and Technology | Zhang S.-A.,China University of Petroleum - Beijing | Lin Y.-B.,Xi'an University of Science and Technology
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

Facing the shortage of desorption mechanism of CBM industry, executed 6 groups coal samples isothermal adsorption and desorption experiments. The results show that desorption process is delay to adsorption, it exists a lack pressure point having residual adsorption volume between isothermal desorption curve and adsorption curve. Using the analysis results of experiment, framed accuracy fitting equation of CBM desorption when pressure reducing.


Han S.,China University of Petroleum - Beijing | Huang Z.,University of Michigan | Senra M.,University of Michigan | Hoffmann R.,Statoil | Fogler H.S.,University of Michigan
Energy and Fuels | Year: 2010

Wax precipitation and deposition are major flow assurance problem in crude oil production and transportation. Knowledge of the amount of wax that precipitates from the crude oil at different temperatures, delineated by the solubility curve, is necessary for accurate predictions of wax deposition in subsea pipelines. The solubility curve is obtained from the wax precipitation curve, which is determined using centrifugation and high temperature gas chromatography (HTGC). However, previous studies have overestimated the amount of precipitated wax by assuming that all heavy alkanes or heavy n-alkanes exist solely in the solid phase. This work addresses this issue by conducting mass balances on the noncrystallized carbon numbers in the centrifuged cake and in the crude oil. A new equation was developed to obtain the solid fraction of the centrifuged cake and crude oil. The wax precipitation curve developed by this new method was compared with the curves determined using the previous methods and differential scanning calorimetry (DSC). The curve determined by this new method was consistent with the results obtained by DSC, while previous methods overpredicted the amount of precipitated wax. © 2010 American Chemical Society.


Zhou Q.,China University of Petroleum - Beijing | Lin H.,Jilin Municipal Research Institute of Environmental science
Clean - Soil, Air, Water | Year: 2013

Nanoscale zerovalent iron (NZVI) has been proved to be effective in the degradation of environmental pollutants and exhibits advantages in the removal of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea (CCU), an analog of diflubenzuron. This present study focused on the influence of surfactants in the degradation procedure with NZVI in order to provide a simple and rapid removal method for CCU. Triton X-100, Tween 20, Tween 80, sodium dodecyl sulfonate (SDS), and cetyltrimethylammonium bromide (CTAB) were investigated under anaerobic conditions. The experimental results demonstrated that the degradation rate increased sharply with the presence of SD during the first 15min, up to 99.97% with addition of 0.01gL-1 SDS, whereas the presence of Triton X-100, Tween 80, and Tween 20 resulted in a slight enhancement of the degradation of CCU. The enhancement strength of them was in the order Tween 20, Triton X-100, and Tween 80. However, addition of the cationic surfactant CTAB resulted in a significant inhibitive effect. In contrast, the mixed surfactants did not result in the expected performance, and the performance was lower than that using some certain single surfactant among the mixed surfactants. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Gao J.,China University of Geosciences | Gao J.,China University of Petroleum - Beijing | Gao J.,University of Alberta | Sacchi M.D.,University of Alberta | Chen X.,China University of Petroleum - Beijing
Geophysics | Year: 2013

Rank reduction strategies can be employed to attenuate noise and for prestack seismic data regularization. We present a fast version of Cadzow reduced-rank reconstruction method. Cadzow reconstruction is implemented by embedding 4D spatial data into a level-four block Toeplitz matrix. Rank reduction of this matrix via the Lanczos bidiagonalization algorithm is used to recover missing observations and to attenuate random noise. The computational cost of the Lanczos bidiagonalization is dominated by the cost of multiplying a level-four block Toeplitz matrix by a vector. This is efficiently implemented via the 4D fast Fourier transform. The proposed algorithm significantly decreases the computational cost of rank-reduction methods for multidimensional seismic data denoising and reconstruction. Synthetic and field prestack data examples are used to examine the effectiveness of the proposed method. © 2013 Society of Exploration Geophysicists.


Zhu X.,China University of Petroleum - Beijing | Jia C.,University of Memphis
Journal of Environmental Monitoring | Year: 2012

Measurements of semi-volatile organic compounds (SVOCs) in air are subject to substantial variability and uncertainty. This study apportions total variance of polycyclic aromatic hydrocarbons (PAHs) and chlordanes to variability and uncertainty components. Concentrations of PAHs and chlordanes were measured inside and outside of 116 residences in three large cities in the U.S. during 1999-2000. Total variance was apportioned to between-city, between-tract, between-residence, and seasonal variation, as well as measurement uncertainty using variance component analysis and log-transformed data for frequently detected compounds. Outdoors, seasonal variation was the greatest portion (44-67%) of total variance, and city effects were significant (19-24%). Indoors, seasonality dominated variability of PAH measurements (>50%). Gas-phase PAHs varied more within city than between cities; particulate-phase PAHs varied significantly between cities but were largely homogeneous within cities. Gas-phase chlordanes showed larger intra-urban variation (63%) than seasonal variation (18%). Measurement uncertainty was generally below 10% with a few exceptions occurring at very low concentrations. Results indicate a need to collect multiple-season samples to account for the large temporal variation between seasons. Samples from centrally located monitoring stations could be representative of ambient SVOCs. Variance component analysis is useful to weigh influential factors in SVOC concentrations, identify and apportion sources, evaluate method performance, and design effective monitoring programs. © 2012 The Royal Society of Chemistry.


Hu X.F.,China University of Petroleum - Beijing | Long D.,Willow View | Jeans C.V.,University of Cambridge
Clay Minerals | Year: 2014

Detrital, volcanic and diagenetic origins have been used to explain the smectite clay assemblage that characterizes the Upper Cretaceous Chalk of Europe. To further the understanding of how clays of different origins may have converged to this characteristic clay mineral assemblage a new approach is put forward for their investigation. This is based upon (1) the correlation that exists between the trace element and stable isotope geochemistry of the calcite cements preserved within Chalk brachiopods and the various diagenetic phases of early lithification and cementation recognized in the Chalk, and (2) an understanding of the process of late diagenetic cementation that has caused regional differences in the hardness of the Chalk. It is suggested that each phase of lithification and associated calcite cementation may preserve the different clay assemblages at various stages in their convergence to the characteristic Chalk smectite assemblage. © 2014 The Mineralogical Society.


Hook M.,Uppsala University | Bardi U.,University of Florence | Feng L.,China University of Petroleum - Beijing | Pang X.,China University of Petroleum - Beijing
Marine and Petroleum Geology | Year: 2010

This paper reviews the historical development of both biogenic and non-biogenic petroleum formation. It also examines the recent claim that the so-called "abiotic" oil formation theory undermines the concept of "peak oil," i.e. the notion that world oil production is destined to reach a maximum that will be followed by an irreversible decline. We show that peak oil is first and foremost a matter of production flows. Consequently, the mechanism of oil formation does not strongly affect depletion. We would need to revise the theory beyond peak oil only for the extreme - and unlikely - hypothesis of abiotic petroleum formation. © 2010 Elsevier Ltd.


Pang Z.-X.,China University of Petroleum - Beijing | Pang Z.-X.,MOE Key Laboratory of Petroleum Engineering
Transport in Porous Media | Year: 2010

Foam flow experiments were carried out to study the influence factors such as surfactant concentration, foam quality, injection rate of liquid and gas, permeability of porous media, temperature, and oil saturation on blocking ability and flowing characteristics of steady foams in porous media. Foam blocking mechanisms and flowing characteristics were summarized according to the experimental results and foam migration behavior. The results showed that the pressure distribution of flowing foams was linearly descending in porous media at steady state. The results further showed that the foam size and quality in pores along the sand pack were almost uniform, that is, foam generation and destruction gradually reached dynamic equilibrium at steady state. In porous media, the blocking ability of steady foams increased with the concentration of the foaming agent and the increase in the permeability of porous media, but the blocking ability decreased with the increase in the temperature, the shearing rate, and the oil saturation of the porous media. Foam resistance factor reached maximal value at the foam quality of 85% in porous media. © 2010 Springer Science+Business Media B.V.


Xing X.,China University of Petroleum - Beijing | Dou D.,CNODC | Li Y.,China University of Petroleum - Beijing | Wu C.,China University of Petroleum - Beijing
Applied Thermal Engineering | Year: 2013

A mathematical model is proposed to study the heat transfer and flow of a buried hot oil pipeline in operation. Governing equations for thermal analyses are derived based on certain reasonable assumptions and solved by combining the finite volume method with the finite difference method. Our simulation for the preheating operation of the crude pipeline in Niger indicates that there is a good agreement between numerical simulations and field measurement. Our study thus answers four questions about the optimization of parameters for controlling the preheating process and reveals the general rules for their optimization. © 2012 Elsevier Ltd. All rights reserved.


Wu S.,Xi'an Jiaotong University | Yu Z.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Liu G.,Xi'an Jiaotong University | And 2 more authors.
Energy | Year: 2013

Growing hydrogen demands in oil refining are forcing many refiners to optimize their hydrogen distribution networks in order to address the demands without incurring excessive energy consumption, capital investment and operating costs. In addition to the use of hydrogen utility, the foremost consumption of energy is the compression power. In order to express hydrogen consumption and compression power on a common basis, this study uses the convention of "exergy standard" in the optimization of hydrogen distribution networks. Besides, the optimization of hydrogen networks should also minimize the number of hydrogen compressors, which are among the most expensive devices in a refinery. Consequently, two mathematical models are proposed for hydrogen distribution network synthesis. A sequential optimization strategy is utilized to determine the targets of total exergy consumption and number of compressors. In addition, several practical strategies for compressor combination are introduced which can further reduce the number of compressors. The proposed methodology can be applied to hydrogen networks with either the flowrate constraint or the pure hydrogen load constraint imposed on sink streams. The applicability and effectiveness of the proposed methodology are illustrated by two case studies. © 2013 Elsevier Ltd.


Ding Y.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Journal of Cleaner Production | Year: 2011

Hydrogenation units are often operated at high pressure, requiring the use of compressors which are one of the most expensive chemical processing equipment. Optimizing a hydrogen network should therefore take into consideration not only purity and flowrate constraints but also pressure requirements. In this paper, based on the hydrogen surplus diagram approach, the average pressure profiles of hydrogen sources and sinks are proposed through the introduction of a system's minimum pressure drop Δp. Combined with the traditional purity profiles, whether a source can meet a sink either for hydrogen concentration or for pressure requirements can be determined intuitively. In cases where the pressure of a source is not sufficient for a sink, installing a hydrogen compressor or using another source with higher purity and pressure could be potential solutions. A cost equation is established to determine which of the two solutions is economically more viable. For different matching situations between sources and sinks, strategies for optimum placement of compression equipment within a given hydrogen network are proposed. A case study is used to illustrate the application and effectiveness of the proposed method. © 2010 Elsevier Ltd. All rights reserved.


Pang M.,Xi'an Jiaotong University | Wei J.,Xi'an Jiaotong University | Yu B.,China University of Petroleum - Beijing
Chemical Engineering Science | Year: 2010

Bubbly flows exist extensively in industrial processes, so it is very meaningful to study hydrodynamic characteristics of them to improve efficiency of bubbly flow equipments. This paper introduces a numerical method of the Euler-Lagrange two-way model for the air-water bubbly flows in detail. The flow field is simulated by using direct numerical simulations (DNS) in Euler frame of reference, while the bubble dynamics are fully analyzed by integration of Newtonian equations of motion taking into account interphase interaction forces including drag force, lift force, wall lift force, pressure gradient force, virtual mass force, gravity force, buoyant force, and inertia force in Lagrange frame of reference. The coupling between phases is considered by regarding the interphase interaction forces as a momentum source term of the continuous phase. Bubbles distribution and turbulent statistics of the liquid phase are comprehensively analyzed. The results show that an overwhelming majority of bubbles cluster near the walls, and turbulent structures of the liquid phase are modified to some certain by addition of bubbles, namely, the mean streamwise velocity become increased at the core of the channel, the wall-normal and spanwise turbulent intensities and Reynolds stress are reduced. Redistribution of turbulent energy from the streamwise velocity components to wall-normal and spanwise velocity components is also suppressed due to the addition of bubbles. © 2010 Elsevier Ltd.


Wang G.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Journal of Cleaner Production | Year: 2013

Instability is a severe barrier to the successful development and evolution of industrial symbiosis systems. In this paper, a novel approach for stability analysis of industrial symbiosis systems is proposed. Two parameters (symbiosis profit and symbiosis cost) are defined on the basis of profit consideration. With the introduction of asymmetric distribution coefficient as a quantitative index, the distribution of symbiosis cost and symbiosis profit can be analyzed. An illustrative example demonstrates that the approach can be used to assess the stability of a hypothetical coal-based symbiosis system under different states. Specifically, the impact of changes in the system structure and external environment on the stability of the coal-based symbiosis system is investigated. The results confirm the practical applicability and effectiveness of the proposed approach. © 2012 Elsevier Ltd. All rights reserved.


Zhao Y.,China University of Petroleum - Beijing | Yu B.,China University of Petroleum - Beijing | Tao W.,Xi'an Jiaotong University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2013

This article describes an improved paving method of automatic quadrilateral mesh generation. Paving, which was first proposed by Blacker and Stephenson [1], is a kind of direct method for generating a quadrilateral mesh and has been widely used since it was presented. This article aims to improve some weaknesses of the traditional paving method by generating high-quality quadrilateral grids without employment of a background mesh. Through efficient intersection resolution and other optimization measures, the improved paving method can generate well-aligned rows of quadrilateral elements almost parallel to the boundary of the domain, automatically and quickly. © 2013 Copyright Taylor and Francis Group, LLC.


Wang Q.,Harbin Engineering University | Yan J.,Harbin Engineering University | Wang Y.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | And 5 more authors.
Carbon | Year: 2013

A carbon material consisting of hollow carbon spheres anchored on the surface of carbon nanotubes (CNT-HCS) has been synthesized by an easy chemical vapor deposition process using a CNT-MnO2 hybrid as template. An electrode made of this material exhibits a maximum specific capacitance of 201.5 F g-1 at 0.5 A g-1 and excellent rate performance (69% retention ratio at 20 A g-1). It has impressive cycling stability with 90% initial capacitance retained after 5000 cycles at 5 A g-1 in 6 mol L-1 KOH. Symmetric supercapacitors based on CNT-HCS achieve a maximum energy density of 11.3 W h kg-1 and power density of 11.8 kW kg-1 operated within a wide potential range of 0-1.6 V in 1.0 mol L-1 Na2SO4 solution. © 2012 Elsevier Ltd. All rights reserved.


Pang M.J.,Xi'an Jiaotong University | Pang M.J.,Changzhou University | Wei J.J.,Xi'an Jiaotong University | Yu B.,China University of Petroleum - Beijing
Ocean Engineering | Year: 2014

Although many investigations on the drag reduction by microbubbles have been conducted, a general mechanism guiding the design of the drag reduction system has not been achieved yet. The drag reduction by microbubbles was investigated in detail with the Euler-Lagrange two-way coupling method in order to understand the drag reduction mechanism by microbubbles in this paper. The liquid velocity field was solved with direct numerical simulations (DNS), and the bubble trajectory was calculated by Newtonian motion equation. The mutual momentum transfer between gas and liquid phases was bridged by interphase forces. The computational results show that a low drag-reduction rate is obtained, the liquid-phase velocity is slightly increased in the region away from the channel wall (i.e., the channel side containing microbubbles), and the turbulence intensity and Reynolds shear stress of the liquid phase are changed along the whole channel height. The present analysis shows that the drag reduction depends on mutual interactions between microbubbles and the liquid turbulence with the help of interphase forces. © 2014 Elsevier Ltd.


Chu K.H.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing
Process Safety and Environmental Protection | Year: 2013

Two types of waste paper materials, newspaper and office paper, were evaluated for their potential to be used as renewable feedstock for the production of fermentable sugars via the enzymatic hydrolysis of their cellulose fractions. The effects of four factors (hydrolysis time, enzyme loading, surfactant addition and phosphoric acid pretreatment) on the extent of sugar yield were assessed and quantified by using a methodical approach based on response surface methodology. The statistical experimental design used in this study requires fewer experimental runs compared to some commonly used experimental designs. In the newspaper hydrolysis case, response surface plots revealed that the degree of sugar release increased with an increase in hydrolysis time but it was hardly affected by the enzyme loading and acid pretreatment factors. The surfactant addition factor exhibited a positive effect when the enzyme loading level was relatively low. With office paper as the substrate, three of the four factors (hydrolysis time, enzyme loading and acid pretreatment) exhibited positive effects on the extent of sugar release. At local optimum conditions, the maximum sugar yield from office paper was found to be 0.82 g of reducing sugars per gram of paper, which was about 4.8 times higher than the maximum sugar release from the newspaper substrate. © 2011 The Institution of Chemical Engineers.


An C.,Federal University of Rio de Janeiro | An C.,China University of Petroleum - Beijing | Castello X.,Federal University of Rio de Janeiro | Duan M.,China University of Petroleum - Beijing | And 2 more authors.
Ocean Engineering | Year: 2012

Sandwich pipes (SP) can be an effective solution for the ultra-deepwater submarine pipeline, combining high structural resistance with thermal insulation capability. Besides polymer, steel fiber reinforced concrete (SFRC) can be an another choice for the annular material, based on the characteristics of high fracture toughness and good adhesion with metal. The purpose of this work was to investigate numerically the ultimate strength of SP filled with SFRC under external pressure and longitudinal bending. The mechanical behaviour of SFRC was simulated using a Concrete Damaged Plasticity (CDP) model whose parameters were estimated by uniaxial tension, compression and four-point bending tests. The applicability of the parameters obtained was verified by simulating the compression and four-point bending tests, where the results showed good correlation between measured and predicted numerical values. Pressure-curvature ultimate strength for SP with perfect adhesion and no adhesion interface condition was obtained. Besides, a parametric study was performed to investigate the effect of the thickness of each layer on the pressure-curvature collapse envelope of SP. It was found that the adhesion between layers and the lateral confinement effect on SFRC play a dominant role in the ultimate strength behaviour of SP, which lead to the non-monotonicity of the collapse envelope. © 2012 Elsevier Ltd.


Wang L.,North China Electrical Power University | Li M.,North China Electrical Power University | Qi F.-H.,Beijing Wuzi University | Xu T.,China University of Petroleum - Beijing
Physics of Plasmas | Year: 2015

Under investigation in this paper is a variable-coefficient derivative nonlinear Schrödinger (vc-DNLS) equation modeling the nonlinear Alfvén waves in the inhomogeneous plasmas. The modulation instability is examined for this inhomogeneous nonlinear model. The nonautonomous breather and rogue wave solutions of the vc-DNLS equation are obtained via the modified Darboux transformation. It is found that the velocity and amplitude of the breather can be controlled by the inhomogeneous magnetic field and nonuniform density. Such novel phenomena as breather amplification and nonlinear Talbot effect-like property are demonstrated with the proper choices of the inhomogeneous parameters. Furthermore, dynamics of the fundamental rogue wave, periodical rogue wave, and composite rogue wave are graphically discussed. The trajectories and amplitudes of the rogue waves can be manipulated by the inhomogeneous magnetic field and nonuniform density. In addition, the nonlinear tunneling of the rogue waves and breathers is studied. As an application, a sample model is treated with our results, and the graphical illustrations exhibit the compressing, expanding, and fluctuating phenomena of the Alfvén rogue waves. © 2015 AIP Publishing LLC.


Wang B.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Journal of Cleaner Production | Year: 2012

In the oil refining and petrochemical industry, hydrogen flows in so-called hydrogen networks are a common feature. A practical problem in hydrogen network analysis is to identify the minimum fresh hydrogen input flowrate to ensure that the hydrogen streams produced by combining the flows of internal sources satisfy certain concentration specifications of sinks for hydrogen and impurities such as H 2S. To tackle this problem, this paper presents a novel graphical procedure, much inspired by the pioneering work of Shelley and El-Halwagi (2000) that makes use of the unique features of ternary composition diagram for three-component systems. In addition, accounting for constraints on flowrates inside a ternary visualization diagram is another novel aspect of this graphical method. Two literature case studies based on hydrogen systems with multiple impurities are solved to illustrate the effectiveness and elegance of the proposed method. © 2012 Elsevier Ltd. All rights reserved.


Sun X.,China University of Petroleum - Beijing | Zhang J.-Z.,Xi'an Jiaotong University
Nonlinear Dynamics | Year: 2016

A finite element solution procedure is proposed, and the nonlinear vibrations of a flexible membrane under periodic load are investigated numerically. First, a simplified model is proposed for the flow-induced vibration of a membrane wing at higher angles of attack and the corresponding governing equation is derived briefly. Then, a solution procedure based on the Galerkin finite element method, Generalized-α method and Newton–Raphson method is developed to solve the governing equation and its accuracy and stability are examined by a steady problem with exact solution. Finally, using the numerical method proposed, the forced vibration of a flexible membrane under periodic load is simulated, and the effects of the membrane density, elastic modulus and pre-strain are investigated in detail. In addition, the change in the vibration state along the membrane is also analysed to examine whether the centre point can reflect correctly the vibration state of the whole structure. © 2016, Springer Science+Business Media Dordrecht.


An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Applied Mathematics and Mechanics (English Edition) | Year: 2014

The generalized integral transform technique (GITT) is used to find a semianalytical numerical solution for dynamic response of an axially moving Timoshenko beam with clamped-clamped and simply-supported boundary conditions, respectively. The implementation of GITT approach for analyzing the forced vibration equation eliminates the space variable and leads to systems of second-order ordinary differential equations (ODEs) in time. The MATHEMATICA built-in function, NDSolve, is used to numerically solve the resulting transformed ODE system. The good convergence behavior of the suggested eigenfunction expansions is demonstrated for calculating the transverse deflection and the angle of rotation of the beam cross-section. Moreover, parametric studies are performed to analyze the effects of the axially moving speed, the axial tension, and the amplitude of external distributed force on the vibration amplitude of axially moving Timoshenko beams. © 2014, Shanghai University and Springer-Verlag Berlin Heidelberg.


Li H.-Y.,CAS Guangzhou Institute of Geochemistry | Xu Y.-G.,CAS Guangzhou Institute of Geochemistry | Liu Y.-M.,China University of Petroleum - Beijing | Huang X.-L.,CAS Guangzhou Institute of Geochemistry | He B.,CAS Guangzhou Institute of Geochemistry
Gondwana Research | Year: 2013

U-Pb-Hf isotopic analyses have been carried out on detrital zircons from Late Permian-Jurassic strata in the Western Shandong-Bohai Bay (WSBB) basins with aims of constraining the paleogeography and evolution of the eastern North China Craton (NCC). Four major groups of U-Pb ages (namely, 3.0-2.3Ga, 2.2-1.4Ga, 1250-430Ma and 410-150Ma) are recognized for zircons from the fine-grained sandstones. The post-Paleoproterozoic zircons of the Late Permian sample show an age cluster of 344-255Ma with εHf(t) values of -18 to -8, being similar to those extracted from Late Paleozoic igneous rocks from the Yinshan-Yanshan Orogenic Belt (YYOB) on the northern margin of the NCC. However, the Devonian-Jurassic zircons (390-150Ma) from the Jurassic sediments have εHf(t) values from -45 to +14, very similar to the mixture of Phanerozoic zircons from the Xing-Meng Orogenic Belt (XMOB) and the YYOB, but significantly different from those of the Liaodong Peninsula, Jiaodong Peninsula and the Western Shandong Uplift. In addition, Cambrian-Silurian zircons (535-430Ma) of the Jurassic samples have εHf(t) values from -27 to +7, resembling the Early Paleozoic zircons extracted from the Northern Qinling Orogen (NQO). The U-Pb age spectra and Hf isotope of Devonian-Jurassic zircons as well as bulk Nd isotopes suggest that the central eastern NCC received some juvenile materials from the XMOB, the YYOB and the NQO during the Jurassic. This indicates widespread prototype basins and a low elevation during the Jurassic, arguing against the presence of a paleo-plateau in the eastern NCC at that time. The lack of evidence predicted by lithospheric delamination (e.g., large-scale elevation or doming after Late Triassic) makes the delamination unlikely to be a viable mechanism of lithospheric thinning of the NCC. The subsidence rather than elevation of the eastern NCC after Late Triassic might be related to thermo-chemical erosion of the lithosphere by underlying convective mantle in a back-arc setting. © 2012 International Association for Gondwana Research.


Fu G.,Federal University of Rio de Janeiro | Lourenco M.I.,Federal University of Rio de Janeiro | Duan M.,China University of Petroleum - Beijing | Estefen S.F.,Federal University of Rio de Janeiro
Journal of Constructional Steel Research | Year: 2014

This study investigates the welding residual stress and distortion in T-joint welds under various mechanical boundary conditions. An experimentally calibrated and sequentially coupled thermal and mechanical 3D finite element (FE) model is developed, and Goldak's double ellipsoidal heat source model is implemented into the numerical model. The results show that the transverse residual stress, vertical displacement, angular distortion and transverse shrinkage depend significantly on the mechanical boundary conditions, and the influence on the longitudinal residual stress is not significant. Applying the clamped condition along the edges during the welding process and releasing it after the T-joint cools down to ambient temperature can significantly reduce the welding-induced geometric imperfections. © 2014 Elsevier Ltd. All rights reserved.


Song C.,China University of Petroleum - Beijing | Zhuang J.,State University of New York at Buffalo
International Transactions in Operational Research | Year: 2016

In the food industry, manufacturers may add some chemical additives to augment the appearance or taste of food. This may increase the food demand and sales profits, but may also cause health problems to consumers. The government could use a punishment policy to regulate and deter such risky behavior but could also benefit from economic prosperity and tax income based on their revenues. This generates a tradeoff for the government to balance tax income, punishment income, and health risks. Adapting to government regulations, the manufacturers choose the level of chemical additives, which impacts the consumer demand. To our knowledge, no prior work has studied the strategic interactions of regulating the government and the manufacturers, faced with strategic customers. This paper fills this gap by (a) building a government-manufacturer model and comparing the corresponding decentralized and centralized models; and (b) applying the 2008 Sanlu food contamination data to validate and illustrate the models. © 2016 The Authors.


Pu J.,Xi'an Jiaotong University | Pu J.,Taiyuan Institute of Architecture Design and Research | Liu G.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing
Energy and Buildings | Year: 2010

The cumulative exergy approach is applied to evaluate two cases with different air conditioning systems. The first case includes three air conditioning systems, one is the gas direct fired air conditioning system, and the other two have air cooled heat-pump chiller and water chiller, respectively; the second case consists of four air conditioning systems, one is the gas direct fired air conditioning system, and the others have centrifugal water chiller, screw water chiller, air cooled water chiller, respectively. The results of the first case show that the air conditioning system with the air cooled heat-pump chiller maybe inferior to that with the water chiller, as the cumulative exergy efficiency of the former is 11.28%, which is less than that of the latter (11.92%). The second case shows that the gas direct fired air conditioning system, whose cumulative exergy efficiency is 14.86%, is better than the system with the air cooled water chiller, whose cumulative exergy efficiency is only 11.56%. The results are different from those of the exergy analysis, indicating that cumulative exergy analysis is an effective method to quantitatively evaluate different air conditioning systems according to resource utilization. © 2010 Elsevier B.V. All rights reserved.


Hao F.,Wuhan University | Hao F.,China University of Petroleum - Beijing | Zou H.,China University of Petroleum - Beijing | Lu Y.,Wuhan University
AAPG Bulletin | Year: 2013

This article reviews the mechanisms of shale gas storage and discusses the major risks or uncertainties for shale gas exploration in China. At a given temperature and pressure, the gas sorption capacities of organic-rich shales are primarily controlled by the organic matter richness but may be significantly influenced by the type and maturity of the organic matter, mineral composition (especially clay content), moisture content, pore volume and structure, resulting in different ratios of gas sorption capacity (GSC) to total organic carbon content for different shales. In laboratory experiments, the GSC of organicrich shales increases with increasing pressure and decreases with increasing temperature. Under geologic conditions (assuming hydrostatic pressure gradient and constant thermal gradient), the GSC increases initially with depth due to the predominating effect of pressure, passes through a maximum, and then decreases because of the influence of increasing temperature at greater depth. This pattern of variation is quite similar to that observed for coals and is of great significance for understanding the changes in GSC of organic-rich shales over geologic time as a function of burial history. At an elevated temperature and pressure and with the presence of moisture, the gas sorption capacities of organic-rich shales are quite low. As a result, adsorption alone cannot protect sufficient gas for highmaturity organic-rich shales to be commercial gas reservoirs. Two models are proposed to predict the variation of GSC and total gas content over geologic time as a function of burial history. High contents of free gas in organic-rich shales can be preserved in relatively closed systems. Loss of free gas during postgeneration uplift and erosion may result in undersaturation (the total gas contents lower than the sorption capacity) and is the major risk for gas exploration in marine organicrich shales in China. Copyright © 2013. The American Association of Petroleum Geologists. All rights reserved.


Hao F.,Wuhan University | Hao F.,China University of Petroleum - Beijing | Zou H.,China University of Petroleum - Beijing
Marine and Petroleum Geology | Year: 2013

This article reviews the abnormal characteristics of shale gases (natural gases produced from organic-rich shales) and discusses the cause of the anomalies and mechanisms for gas enrichment and depletion in high-maturity organic-rich shales. The reported shale gas geochemical anomalies include rollover of iso-alkane/normal alkane ratios, rollover of ethane and propane isotopic compositions, abnormally light ethane and propane δ13C values as well as isotope reversals among methane, ethane and propane. These anomalies reflect the complex histories of gas generation and associated isotopic fractionation as well as in-situ "mixing and accumulation" of gases generated from different precursors at different thermal maturities. A model was proposed to explain the observed geochemical anomalies. Gas generation from kerogen cracking at relatively low thermal maturity accounted for the increase of iso-alkane/normal alkane ratios and ethane and propane δ13C values (normal trend). Simultaneous cracking of kerogen, retained oil and wet gas and associated isotopic fractionation at higher maturity caused decreasing iso-alkane/normal alkane ratios, lighter ethane and propane δ13C and corresponding conversion of carbon isotopic distribution patterns from normal through partial reversal to complete reversal. Relatively low oil expulsion efficiency at peak oil generation, low expulsion efficiency at peak gas generation and little gas loss during post-generation evolution are necessary for organic-rich shales to display the observed geochemical anomalies. High organic matter richness, high thermal maturity (high degrees of kerogen-gas and oil-gas conversions) and late-stage (the stage of peak gas generation and post-generation evolution) closed system accounted for gas enrichment in shales. Loss of free gases during post-generation evolution may result in gas depletion or even undersaturation (total gas content lower than the gas sorption capacity) in high-maturity organic-rich shales. •Geochemical anomalies of shale gases were characterized in detail.•A model was proposed to explain the observed geochemical anomalies of shale gases.•High TOC contents, high thermal maturity and late-stage closed system account for gas enrichment in shales.•Loss of free gases during post-generation evolution may result in gas depletion or even undersaturation in high-maturity organic-rich shales. © 2013 Elsevier Ltd.


Hao F.,China University of Petroleum - Beijing | Hao F.,Wuhan University | Zhou X.,Zhejiang University | Zhu Y.,Tianjin Branch of China National Offshore Oil Co. | Yang Y.,China University of Petroleum - Beijing
Organic Geochemistry | Year: 2011

Three Paleogene syn-rift intervals from the Bohai Bay Basin, the most petroliferous basin in China, were analyzed with sedimentological and geochemical techniques to characterize the lateral source rock heterogeneities, to reveal the environmental and ecological changes through geologic time and to construct depositional models for lacustrine source rocks under different tectonic and climatic conditions. The third (Es3) and first (Es1) members of the Eocene Shahejie Formation and the Oligocene Dongying Formation (Ed) display widely variable total organic carbon contents, hydrogen indices and visual kerogen compositions, suggesting changes in organic facies from deep to marginal sediments. Carefully selected deep-lake facies samples from any interval, however, display fairly uniform biomarker composition. These three intervals have distinctly different biomarker assemblages, which indicate weakly alkaline, freshwater lakes with a moderately deep thermocline during Es3 deposition, alkaline-saline lakes with shallow chemocline during Es1 deposition and acidic, freshwater lakes with deep, unstable thermocline during the deposition of the Dongying Formation. Such environmental changes corresponded to changes in subsidence rate and paleoclimate, from rapid subsidence and wet climate during Es3 deposition, through slow subsidence and arid climate during Es1 deposition to rapid subsidence and wet climate during Ed deposition and resulted in synchronous changes in terrigenous organic matter input, phytoplankton community and primary productivity. The co-evolution of environments and organisms controlled by tectonic subsidence and climate accounted for the deposition and distribution of high quality lacustrine source rocks with distinctly different geochemical characteristics. Most rift basins experienced changes in subsidence rates and possibly changes in climates during their syn-rift evolutions. The models constructed in this paper may have important implications for source rock prediction in other lacustrine rift basins. © 2011 Elsevier Ltd.


An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Nuclear Engineering and Design | Year: 2015

In this paper, the dynamic behavior of pipes conveying gas-liquid two-phase flow was analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation lead to a coupled system of second order differential equations in the dimensionless temporal variable. The Mathematica's built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. The characteristics of gas-liquid two-phase flow were represented by a slip-ratio factor model that was devised and used for similar problems. Good convergence behavior of the proposed eigenfunction expansions is demonstrated for calculating the transverse displacement at various points of pipes conveying air-water two-phase flow. Parametric studies were performed to analyze the effects of the volumetric gas fraction and the volumetric flow rate on the dynamic behavior of pipes conveying air-water two-phase flow. Besides, the normalized volumetric-flow-rate stability envelope for the dynamic system was obtained. © 2015 Elsevier B.V. All rights reserved.


He C.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Applied Energy | Year: 2013

This paper presents a comprehensive steady state kinetic model of a commercial-scale pressurized Lurgi fixed-bed dry bottom coal gasifier. The model is developed using the simulator Aspen Plus. Five sequential modules: drying zone, pyrolysis zone, gasification zone, combustion zone and overall heat recovery unit, are considered in the main process model. A non-linear programming (NLP) model is employed to estimate the pyrolysis products, which include char, coal gas and high-weight hydrocarbons/distillable liquids (tar, phenol, naphtha and oil). To accelerate solution convergence, an external FORTRAN subroutine is used to simulate the kinetics of the combustion and gasification processes which are formulated in terms of a series of continuous stirred-tank reactors. The model is validated with industrial data. The effects of two key operating parameters, namely oxygen/coal mass ratio and steam/coal mass ratio, on the thermodynamic efficiencies of the Lurgi gasifier and the gasification system as a whole are investigated via extensive simulation studies. © 2013 Elsevier Ltd.


Gu J.,Federal University of Rio de Janeiro | An C.,Federal University of Rio de Janeiro | Duan M.,China University of Petroleum - Beijing | Levi C.,Federal University of Rio de Janeiro | Su J.,Federal University of Rio de Janeiro
Nuclear Engineering and Design | Year: 2015

Analysis of dynamic response of pipe conveying fluid is an important aspect in nuclear power plant design. In the present paper, dynamic response of a clamped-clamped pipe conveying fluid was solved by the generalized integral transform technique (GITT). The governing partial differential equation was transformed into a set of second-order ordinary differential equations which is then numerically solved by making use of the subroutine DIVPAG from IMSL Library. A thorough convergence analysis was performed to yield sets of reference results of the transverse deflection at different time and spanwise position. We found good agreement between the computed natural frequencies at mode 1-3 and those obtained by previous theoretical study. Besides, modal separation analysis was carried out and the influence of mass ratio on deflection and natural frequencies was qualitatively and quantitatively assessed. © 2012 Elsevier B.V. All rights reserved.


Hu N.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Deng C.,China University of Petroleum - Beijing
Chemical Engineering Journal | Year: 2011

Regeneration reuse water systems can obviously reduce freshwater usage and wastewater discharge, and avoid unexpected accumulation of contaminants. Appropriate process decomposition strategies can help to further reduce freshwater usage and avoid recycling. In this paper, the effect of different process decomposition strategies on saving freshwater usage is analyzed on the concentration-mass load diagram. For multiple-contaminant water systems, the approach for the determination of interim concentrations for concentration decomposition is explored. Three sequential mathematical models and related optimization procedure to optimize regeneration reuse water networks are proposed. The propose approach is general and can be utilized for the synthesis of single/multiple-contaminant regeneration reuse water networks. Three illustrated case studies demonstrate the applicability and effectiveness of the proposed approach. © 2011 Elsevier B.V.


Yan Q.,Mississippi State University | Wan C.,Mississippi State University | Liu J.,China University of Petroleum - Beijing | Gao J.,China University of Petroleum - Beijing | And 3 more authors.
Green Chemistry | Year: 2013

Biochar, a by-product from the fast pyrolysis of pine wood, was used as the support material for the synthesis of carbon-encapsulated iron nanoparticles. The nanoparticles were characterized for physicochemical properties by multiple morphological and structural methods (e.g., SEM, TEM, XRD, FTIR, and TPD). The Fischer-Tropsch synthesis (FTS) process was carried out to evaluate the catalytic activity of the nanoparticles on conversion of biomass-derived synthesis gas (bio-syngas) to liquid hydrocarbons. Characterization results revealed that the nanoparticles had core-shell structures with iron in situ encapsulated within a graphitic shell. Moreover, significant amounts of iron carbide (mainly Fe3C) were formed as an interface between the carbonaceous shell and the iron core. FTS tests indicated that such carbon-encapsulated iron nanoparticles possessed a high activity on conversion of bio-syngas and good selectivity towards liquid hydrocarbons (of which olefins were the dominant product). Over a 1500 h testing period, the nanoparticles showed striking stability against deactivation, with CO conversion maintained at about 95% and liquid hydrocarbon selectivity at about 68%. © 2013 The Royal Society of Chemistry.


An C.,China University of Petroleum - Beijing | An C.,Federal University of Rio de Janeiro | Su J.,Federal University of Rio de Janeiro
Applied Thermal Engineering | Year: 2013

In this study, a lumped parameter model was developed for one-dimensional heat conduction with melting of a phase change material (PCM) slab with volumetric heat generation. Two types of boundary conditions were considered: (a) adiabatic condition at the left side and isothermal condition at the right side and (b) isothermal condition at the left side and convective condition at the right side. The lumped model was obtained through two-point Hermite approximations for integrals. The two-side corrected trapezoidal rule (H 1,1 approximation) was employed in the averaged temperature integrals for both the liquid and solid phases during melting process of the slab, and the plain trapezoidal rule (H0,0 approximation) was used to estimate the heat fluxes. For the melting problem with the boundary conditions (a), the lumped model results were verified by the analytical solution of melting in half-plane without internal heat source. Case study was performed to investigate the effect of the volumetric energy generation and the Stefan number on the instantaneous interface position. For the melting problem with the boundary conditions (b), the lumped model results were verified by the enthalpy method solution. Transient heat condition of the PCM slab was analyzed to illustrate the applicability of the proposed lumped model, with respect to different values of the volumetric energy generation, the Stefan number, the Biot number, the liquid-to-solid thermal conductivity ratio and the boundary temperature at the left side. Excellent agreement with available analytical or numerical solutions was achieved. © 2013 Published by Elsevier Ltd.


Zhang Q.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Industrial and Engineering Chemistry Research | Year: 2013

Large consumption and soaring demand have led to huge deficiencies in the availability of fresh resources such as hydrogen and water in the chemical industries throughout the world, casting a long shadow over their operating margins. More than ever the efficient use and conservation of fresh resources plays a pivotal role in many large-scale chemical processing enterprises such as refinery operations. This paper addresses the target of minimum fresh resource demand and design of resource conservation networks with multiple contaminants. With a view to the allocation of a single sink, a triangle rule is deduced from an existing design technique. In order to describe the quality difference of sources and sinks according to different impurity concentrations, the nearest neighbor algorithm for resource conservation networks with single contaminant is generalized to the case of resource conservation networks with multiple contaminants. On the basis of the new nearest neighbor algorithm, a ranking rule is established to give a reasonable order of sources as well as sinks. With the ranked order, the material recovery pinch diagram for multiple contaminants is constructed. For each match, the proposed solution procedure can achieve the maximum direct reuse at sharp match status of at most two contaminants. The resulting group of matching polygons gives the target and the corresponding network as well as the restrictive contaminants in each match. Three cases are studied to illustrate the proposed methodology. © 2012 American Chemical Society.


Yang M.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Industrial and Engineering Chemistry Research | Year: 2013

Setting heat pumps correctly in a chemical process system can enhance the energy utilization ratio of the system, reduce the consumption of both the hot and cold utilities, and achieve utility savings and economic benefits. In this paper, for the case of introducing a single heat pump into a system, the dynamic changes of the grand composite curve and pinch temperature under different scenarios are analyzed using a graphical analysis method. The reasons and conditions for such changes are determined. It is shown that for cases that exhibit a change in pinch temperature more hot and cold utility savings may be obtained by using two heat pumps. Existing as well as new two-heat-pump arrangements that comply with the cross-pinch rule are presented. © 2013 American Chemical Society.


Mu H.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Ecological Engineering | Year: 2012

Calculating emergy flows within a typical chemical production system is challenging because it is made up of various interconnected reaction, separation, heating and cooling units with extensive recycle of material and energy. The complexity of the interior structure of a chemical production system, if not carefully considered, could pose problems in emergy calculation. The difficulty is further compounded by the fact that the rules of emergy algebra are somewhat opaque and incomplete. This article shows that complex chemical production systems may be decomposed into four basic structures: series, parallel, bypass and feedback, which can greatly facilitate the process of emergy calculation. Systematic procedures for calculating the emergy flows of the four basic structures without violating the basic rules of emergy algebra are given in detail. Special attention has been paid to the feedback structure, which is analyzed using a novel concept known as virtual emergy flow. An illustrative example based on a hypothetical system made up of the four basic structures and a case study based on an actual polypropylene production system are used to demonstrate the efficacy of the emergy calculation procedures presented in this study. © 2012 Elsevier B.V.


Zhang Q.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Liu G.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Chemical Engineering Science | Year: 2011

Increase in refining demand and tighter environmental regulations have led to sharp increases in hydrogen consumption of oil refineries. Hydrogen conservation and effective use are of interest to refineries whose operations and profitability are constrained by hydrogen. Purification is widely used in hydrogen networks of refineries to reduce hydrogen production load. To minimize hydrogen utility consumption, it is necessary to optimize the hydrogen network with purification as a whole. In this paper, for hydrogen purification process, a triangle rule (which can be generalized to polygon rule) is proposed for graphical representation of its mass balance. The proposed procedure treats the product concentration and recovery rate of the purification process as adjustable parameters. An ensuing graphical method is developed for targeting the pinch point and minimum utility consumption of the hydrogen system with purification reuse. This graphical method can be used for any purification devices and in systems with any utility concentration. A refinery case is studied to demonstrate the optimization method. © 2010 Elsevier Ltd.


Yan Q.,Mississippi State University | Yu F.,Mississippi State University | Liu J.,China University of Petroleum - Beijing | Street J.,Mississippi State University | And 3 more authors.
Bioresource Technology | Year: 2013

A continuous process involving gasification, syngas cleaning, and Fischer-Tropsch (FT) synthesis was developed to efficiently produce synthetic aviation turbine fuels (SATFs). Oak-tree wood chips were first gasified to syngas over a commercial pilot plant downdraft gasifier. The raw wood syngas contains about 47% N2, 21% CO, 18% H2, 12% CO2, 2% CH4 and trace amounts of impurities. A purification reaction system was designed to remove the impurities in the syngas such as moisture, oxygen, sulfur, ammonia, and tar. The purified syngas meets the requirements for catalytic conversion to liquid fuels. A multi-functional catalyst was developed and tested for the catalytic conversion of wood syngas to SATFs. It was demonstrated that liquid fuels similar to commercial aviation turbine fuels (Jet A) was successfully synthesized from bio-syngas. © 2012 Elsevier Ltd.


An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Applied Thermal Engineering | Year: 2015

In this study, improved lumped parameter models were proposed for transient thermal analysis of multilayered composite pipeline with active heating, which is essential for flow assurance design and operating strategies of deepwater subsea pipelines. Improved lumped models for transient heat conduction in multilayered composite pipelines were based on two-points Hermite approximations for integrals. The transient energy equation for the bulk temperature of the produced fluid was transformed into a set of ordinary differential equations in time by using a finite difference method. The coupled system of ordinary differential equations for average temperatures in the solids and bulk temperature of the fluid at each longitudinal discretization point along the pipeline was solved by using an ODE solver. With the proposed method, we analyzed the transient heat transfer in stainless steel-polypropylene-stainless steel sandwich pipes (SP) with active electrical heating. Convergence behaviors of the average temperature of each layer and the bulk temperature of the produced fluid calculated by using the improved lumped models (H0,0/H1,1 and H1,1/H1,1 approximations) against the number of grid points along the pipelines were presented. Case studies were performed to investigate the effect of the linear rate of power input and the average velocity on the bulk temperature distribution of the produced fluid. © 2015 Elsevier Ltd. All rights reserved.


Zhou Q.,China University of Petroleum - Beijing | Zhang X.,CAS Zhengzhou Research Institute | Xie G.,Henan Institute of Science and Technology
Analytical Methods | Year: 2011

A simple, rapid and efficient method is described for the simultaneous pre-concentration and determination of phthalate esters and pyrethroid insecticides in water samples by temperature controlled ionic liquid dispersive liquid phase microextraction in combination with high performance liquid chromatography. In this procedure, only ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM][PF6] was used for the enrichment. The proposed method successfully overcomes the disadvantages of conventional single drop liquid phase microextraction and dispersive liquid-liquid microextraction such as the instability of the suspending drop and the use of toxic solvents, and requires a smaller extraction volume. Factors such as volume of [C8MIM][PF6], sample pH, extraction time, centrifugation time, and temperature and salting-out effect were systematically investigated and optimized. The detection limits obtained for phthalate esters and pyrethroid insecticides were in the range of 0.23-0.47 μg L-1 and the precisions were in the range of 2.2-5.9% (n = 6). Real water samples were used for validating the proposed method and satisfactory results were achieved. © The Royal Society of Chemistry 2011.


Wang Y.,China University of Petroleum - Beijing | Wei Y.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Applied Energy | Year: 2014

A new method based on the heat duty-time (Q- t) diagram is proposed for heat integration of heat exchanger networks featuring batch streams. Using the Q-. t diagram method, the energy targets and the structure of the initial heat exchanger network can be easily obtained. The method can be used both for direct and indirect heat integration of batch streams. For indirect heat integration, the heat degradation of intermediate media is considered. A case study on optimizing the heat exchanger network of a hydrazine hydrate plant is used to illustrate the application of the method. The results show that integration of this heat exchanger network without considering its batch streams can limit the total energy savings. © 2013 Elsevier Ltd.


Gao X.F.,Xi'an Jiaotong University | Zhang C.W.,Xi'an Jiaotong University | Wei J.J.,Xi'an Jiaotong University | Yu B.,China University of Petroleum - Beijing
Applied Thermal Engineering | Year: 2010

For an air-cooled steam condenser (ACSC), environmental wind can cause a large flow rate reduction in the axial fans mainly near the windward side of the air-cooled platform due to cross-flow effects, resulting in a heat transfer reduction. This leads to an increase of turbine back pressure, and occasional turbine trips occur under extremely gusty conditions. A new method is proposed in this paper to remove the strong wind effect by adding deflecting plates under the air-cooled platform, which contributes to forming a uniform air mass flow rate in the axial fans by leading enough cooling air to the fans in the upwind region. Numerical simulation is made of the thermal-flow characteristics and heat transfer performance of the improved ACSC with deflectors. A heat exchanger model is used for simulating the flow and heat transfer in the ACSC, in which the heat exchanger is simplified to a porous medium and all flow losses are taken into account by a viscous and an inertial loss coefficient. A fan model is used for reaching the flow condition at the heat exchanger inlet with the actual performance curves of the fan. It is found that the improved ACSC with deflector shows a significant enhancement in both the cooling air mass flow rate and the heat rejection rate compared with the conventional ACSC. The higher the wind speed is, the larger the heat transfer enhancement of the improved ACSC is. The effect of the plate inclination is also investigated, and the inclination angle of 45° is found to be the optimum value for the arrangement of the deflector. © 2010 Elsevier Ltd. All rights reserved.


Feng X.,China University of Petroleum - Beijing | Shen R.,Xi'an Jiaotong University | Zheng X.,Xi'an Jiaotong University | Lu C.,China University of Petroleum - Beijing
Industrial and Engineering Chemistry Research | Year: 2011

Water system integration can effectively reduce freshwater consumption and minimize wastewater discharge of a water-using system, but integration makes the resultant water network structurally more integrated among process units. Therefore, to design a flexible water allocation network that is easy to control becomes highly desirable. In this Article, a methodology is presented for water allocation network design with process disturbance taken into account. For a new design, the synthesized network structure can guarantee that the water system consumes minimum freshwater under both normal and disturbance conditions and with minimum number of control streams under disturbance. At the same time, the information needed to adjust flow rate under disturbance will be obtained. For an existing water system, an adjustment scheme under disturbance with minimum freshwater consumption for the existing structure will be obtained. The water network designed by the new methodology has the feature of minimum freshwater consumption and high flexibility under disturbance. Some case studies are used to demonstrate the method. © 2010 American Chemical Society.


Goel S.,University of California at Berkeley | Wu Z.,University of California at Berkeley | Wu Z.,China University of Petroleum - Beijing | Zones S.I.,University of California at Berkeley | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

The synthesis protocols for encapsulation of metal clusters reported here expand the diversity in catalytic chemistries made possible by the ability of microporous solids to select reactants, transition states, and products on the basis of their molecular size. We report a synthesis strategy for the encapsulation of noble metals and their oxides within SOD (Sodalite, 0.28 nm × 0.28 nm), GIS (Gismondine, 0.45 nm × 0.31 nm), and ANA (Analcime, 0.42 nm × 0.16 nm) zeolites. Encapsulation was achieved via direct hydrothermal synthesis for SOD and GIS using metal precursors stabilized by ammonia or organic amine ligands, which prevent their decomposition or precipitation as colloidal hydroxides at the conditions of hydrothermal synthesis (<380 K) and favor interactions between metal precursors and incipient aluminosilicate nuclei during self-assembly of microporous frameworks. The synthesis of ANA requires higher crystallization temperatures (∼415 K) and high pH (>12), thereby causing precipitation of even ligand-stabilized metal precursors as hydroxides. As a result, encapsulation was achieved by the recrystallization of metal clusters containing GIS into ANA, which retained these metal clusters within voids throughout the GIS-ANA transformation. © 2012 American Chemical Society.


Chen S.-L.,China University of Petroleum - Beijing | Wang A.-J.,China University of Petroleum - Beijing | Hu C.-T.,China University of Petroleum - Beijing | Dai C.,China University of Petroleum - Beijing | Benziger J.B.,Princeton University
AIChE Journal | Year: 2012

An nc-TiO 2/SnO 2 inverse opal composite membrane was fabricated, the photo-activity of which was significantly enhanced by utilizing both slow photons and stop-band reflection of the photonic crystal layer. The materials of the photonic crystal layer must be transparent in the area of adsorption edge of the nc-TiO 2, so that SnO 2, having much greater electronic band gap than TiO 2, was used for the materials of the photonic crystal layer. The photonic band-gap of the SnO 2 photonic crystal was designed at the semiconductor band gap of TiO 2 to harvest slow photons in the interface between the SnO 2 layer and the TiO 2 layer. The two layer structure makes it possible to couple the stop-band reflectivity of the photonic layer to the photocatalyst. Composite membranes can improve solar energy harvesting and substantially improve photocatalysts for photolysis and photochemical degradation of environmental pollutants. © 2011 American Institute of Chemical Engineers (AIChE).


Sun C.,China University of Petroleum - Beijing | Yu B.,China University of Petroleum - Beijing | Oztop H.F.,Firat University | Oztop H.F.,King Saud University | And 2 more authors.
International Journal of Heat and Mass Transfer | Year: 2011

Control of mixed convection (combined forced and natural convection) in a lid-driven square cavity is performed using a short triangular conductive fin. A numerical technique is used to simulate the flow and temperature fields. The vertical walls of the cavity are differentially heated. Both the top lid and the bottom wall are adiabatic. The fin is located on one of the motionless walls of the cavity. Three different cases have been studied based on the location of the fin. In this context, Cases I, II and III refer to the fin on the left, bottom and right walls, respectively. Results are presented for +x and -x directions of the top lid in horizontal axis and different Richardson numbers as Ri = 0.1, 1.0 and 10.0. It is observed that the triangular fin is a good control parameter for heat transfer, temperature distribution and flow field. © 2010 Published by Elsevier Ltd. All rights reserved.


Deng C.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing
Industrial and Engineering Chemistry Research | Year: 2011

Water scarcity and stringent emission legislation have been motivating process industries to emphasize water conservation. Pinch analysis has been accepted as one of the powerful approaches to locate targets of wastewater minimization. In this paper, the improve problem table (IPT) is presented to target conventional and property-based water networks with multiple resources on the basis of the composite table algorithm (CTA) (Agrawal, V.; Shenoy, U. V. Unified conceptual approach to targeting and design of water and hydrogen networks. AIChE J.2006, 52, 1071-1082). The corresponding limiting composite curve and water supply line are plotted to facilitate the analyzing and understanding of basic physical insights. The minimum operating cost subject to availability of the water resources is also addressed. In addition, two strategies are proposed to handle flow rate constraints for certain resources, and the corresponding wastewater stream identification techniques are introduced successively. To illustrate the applicability of IPT, two conventional so-called concentration-based water networks with different scenarios, i.e., direct reuse/recycle and regeneration reuse/recycle, are synthesized. Moreover, the targets for a property-based water network with a pretreatment system are determined via the proposed IPT. © 2011 American Chemical Society.


Yu Z.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing
Huagong Xuebao/CIESC Journal | Year: 2011

The increment of hydrogen demand in oil refineries motivates the industries to optimize the hydrogen network and rationally use hydrogen resources for energy conservation and cost reduction. In the hydrogen distribution networks, in addition to the consumption of hydrogen, the foremost consumption of energy is compression power. In order to unify and optimize the consumption of hydrogen and compression power, "exergy standard" is proposed to design and optimize the hydrogen distribution network. The consumption of hydrogen utility and compression power are converted to exergy and the total exergy consumption is utilized to evaluate the hydrogen network. In addition, a network evolution strategy is also utilized to reduce the number of compressors effectively, which can guarantee the optimal energy performance and economical benefit. A literature case is solved to illustrate the applicability and effectiveness of the proposed methodology. © All Rights Reserved.


Wang Y.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University | Wang Z.,China University of Petroleum - Beijing
Industrial and Engineering Chemistry Research | Year: 2014

Conventional cooling water networks usually operate in a parallel configuration. Converting a parallel design to a series arrangement can yield a significant reduction in fresh cooling water consumption because of water reuse. This paper presents a two-step methodology for retrofit design of cooling water networks. The proposed methodology can convert a parallel configuration to a series arrangement without investment in a new heat-transfer area. The series arrangement is assumed to contain two heat exchangers. The first heat exchanger in the series arrangement is designated as the supplier because it supplies reuse water to the second heat exchanger, which is called the receiver. To retrofit a cooling water network with a parallel arrangement of several heat exchangers, the first step of the methodology uses the concept of flow rate difference curve to classify the heat exchangers into the two categories of supplier and receiver. In the second step, receiver sensitivity graphs provide guidelines for systematic matching of the suppliers and receivers. A case study is presented to illustrate the practical utility of the two-step methodology. © 2013 American Chemical Society.


Wang Y.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Applied Thermal Engineering | Year: 2014

Recent research efforts on total site heat integration have mainly focused on determining the energy target without considering the following two factors. The first factor is distances between separate plants. The required pipelines between plants in total site heat integration is much longer than heat integration within one plant, so more attentions must be paid on this distance factor as it incurs more expense. The other factor is the type of heat transfer medium. In most studies, steam is used as the heat transfer medium between plants but it cannot be applied in low temperature range. In this work, three connection patterns for individual plants within one site are presented. Both the locations of the plants and the use of water as the heat transfer medium are considered. A graphical methodology for determining the energy target for the three connection patterns in total site integration is proposed. The utility of the proposed methodology is illustrated using a case study based on three plants. © 2014 Elsevier Inc. All rights reserved.


Yu G.,China University of Petroleum - Beijing | Yu B.,China University of Petroleum - Beijing | Sun S.,King Abdullah University of Science and Technology | Tao W.-Q.,Xi'an Jiaotong University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2012

In this article, comparative studies on computational accuracies and convergence rates of triangular and quadrilateral meshes are carried out in the frame work of the finite-volume method. By theoretical analysis, we conclude that the number of triangular cells needs to be 4/3 times that of quadrilateral cells to obtain similar accuracy. The conclusion is verified by a number of numerical examples. In addition, the convergence rates of the triangular meshes are found to be slower than those of the quadrilateral meshes when the same accuracy is obtained with these two mesh types. © 2012 Taylor and Francis Group, LLC.


Mu H.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xi'an Jiaotong University
Ecological Engineering | Year: 2011

Emergy analysis is able to account for ecosystems' contribution to industrial activity. Accordingly, it is an ecologically conscious tool useful for assessing the environmental impact and sustainability of industrial systems. The emergy-based approach requires proper system boundary definitions and uses several standard indices. In this article some perspectives on the deficiencies of three standard emergy indicators - environmental loading ratio (ELR), emergy yield ratio (EYR) and emergy index of sustainability (EIS) - when applied to industrial systems involving waste management are put forward and suggestions for overcoming them given. In addition, in order to account for the impact of waste emissions on the environment, a simple impact amplification factor is proposed for inclusion in the improved emergy indicators. To demonstrate their usefulness and highlight their superiority over standard indices, the improved emergy indicators are used to evaluate the interaction between a commercial polyethylene production process incorporating waste management and its surrounding environment. © 2010 Elsevier B.V.


Li S.,China University of Petroleum - Beijing | Amrani A.,Hebrew University of Jerusalem | Pang X.,China University of Petroleum - Beijing | Yang H.,Petrochina | And 3 more authors.
Organic Geochemistry | Year: 2015

A large amount of deep oil has been discovered in the Tazhong Uplift, Tarim Basin whereas the oil source is still controversial. An integrated geochemical approach was utilized to unravel the characteristics, origin and alteration of the deep oils. This study showed that the Lower Cambrian oil from well ZS1C (1x) was featured by small or trace amounts of biomarkers, unusually high concentration of dibenzothiophenes (DBTs), high δ34S of DBTs and high δ13C value of n-alkanes. These suggest a close genetic relationship with the Cambrian source rocks and TSR alteration. On the contrary, the Middle Cambrian oils from well ZS1 (2a) were characterized by low δ13C of n-alkanes and relatively high δ34S of individual sulfur compounds and a general "V" shape of steranes, indicating a good genetic affinity with the Middle-Upper Ordovician source rocks. The middle Cambrian salt rock separating the oils was suggested to be one of the factors responsible for the differentiation. It was suggested that most of the deep oils in the Tazhong Uplift were mixed source based on biomarkers and carbon isotope, which contain TSR altered oil in varied degree. The percentage of the oils contributed by the Cambrian-Lower Ordovician was in the range of 19-100% (average 57%) controlled by several geological and geochemical events. Significant variations in the δ34S values for individual compounds in the oils were observed suggesting a combination of different extent of TSR and thermal maturation alterations. The unusually high DBTs concentrations in the Tazhong-4 oilfield suggested as a result of mixing with the ZS1C oil (1x) and Lower Ordovician oils based on δ34S values of DBT. This study will enhance our understanding of both deep and shallow oil sources in the Tazhong Uplift and clarify the formation mechanisms of the unusually high DBTs oils in the region. © 2014 Elsevier Ltd.


Li Y.,CAS Guangzhou Institute of Geochemistry | Xiong Y.,CAS Guangzhou Institute of Geochemistry | Liang Q.,CAS Guangzhou Institute of Geochemistry | Fang C.,CAS Guangzhou Institute of Geochemistry | Wang C.,China University of Petroleum - Beijing
Journal of Chromatography A | Year: 2010

In this study, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography-flame ionization detection (GC-FID), was employed to determine short-chain fatty acids (SCFAs) in ruthenium tetroxide (RuO4) oxidation products of asphaltenes. Several significant parameters, such as drop solvent type, drop volume, sample solution ionic strength, agitation speed, extraction time, and ratio of headspace volume to sample volume were optimized. Under optimum extraction conditions (i.e., a 3-μL drop of 1-butanol, 20min exposure to the headspace of a 6mL aqueous sample placed in a 10mL vial, stirring at 1000rpm at room temperature, and 30% (w/v) NaCl content), the reproducibility and accuracy of the method have been tested and found to be satisfactory. The analysis of a real asphaltene sample using this method proved that HS-SDME can be a promising tool for the determination of volatile SCFAs in complex matrices. © 2010 Elsevier B.V.


Liu G.,China University of Petroleum - Beijing | Tang M.,Xi'an Jiaotong University | Feng X.,China University of Petroleum - Beijing | Lu C.,China University of Petroleum - Beijing
Industrial and Engineering Chemistry Research | Year: 2011

An evolutionary method is proposed for designing resource allocation networks with multiple impurities. With every match possibility considered, the maximum match flow rate matrix (M matrix), potential match flow rate matrix (P matrix), and optimal match flow rate matrix (O matrix) can be determined in turn. Both the complementary advantage of source streams and the supplement possibilities are considered in the design procedure. Furthermore, the minimum flow rate rule and maximum flow rate rule are proposed to guide the design. The proposed method can be applied to resource networks with multiple impurities, no matter whether the utility contains impurities. The application of this method is illustrated by two case studies, and the results show that this method can successfully identify the minimum utility consumptions and optimal networks. © 2011 American Chemical Society.


Wang E.,China University of Petroleum - Beijing | Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Geophysical Journal International | Year: 2016

The 2-D acoustic wave equation is commonly solved numerically by finite-difference (FD) methods in which the accuracy of solution is significantly affected by the FD stencils. The commonly used cross stencil can reach either only second-order accuracy for space domain dispersion-relation-based FD method or (2M)th-order accuracy along eight specific propagation directions for time-space domain dispersion-relation-basedFDmethod, if the conventional (2M)th-order spatial FD and second-order temporal FD are used to discretize the equation. One other newly developed rhombus stencil can reach arbitrary even-order accuracy. However, this stencil adds significantly to computational cost when the operator length is large. To achieve a balance between the solution accuracy and efficiency, we develop a new FD stencil to solve the 2-D acoustic wave equation. This stencil is a combination of the cross stencil and rhombus stencil. A cross stencil with an operator length parameter M is used to approximate the spatial partial derivatives while a rhombus stencil with an operator length parameter N together with the conventional second-order temporal FD is employed in approximating the temporal partial derivatives. Using this stencil, a new FD scheme is developed; we demonstrate that this scheme can reach (2M)th-order accuracy in space and (2N)th-order accuracy in time when spatial FD coefficients and temporal FD coefficients are derived from respective dispersion relation using Taylor-series expansion (TE) method. To further increase the accuracy, we derive the FD coefficients by employing the time-space domain dispersion relation of this FD scheme using TE. We also use least-squares (LS) optimization method to reduce dispersion at high wavenumbers. Dispersion analysis, stability analysis and modelling examples demonstrate that our new scheme has greater accuracy and better stability than conventional FD schemes, and thus can adopt large time steps. To reduce the extra computational cost resulting from adopting the new stencil, we apply the variable spatial operator length schemes. Adopting our new FD scheme, characterized by new stencil, LS-based optimization, variable operator lengths and larger time step, modelling efficiency is significantly improved. © The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society.


Hou S.,Louisiana Tech University | Song P.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Wang L.,China University of Petroleum - Beijing | Zhao H.,University of California at Irvine
Journal of Computational Physics | Year: 2013

A typical elliptic interface problem is casted as piecewise defined elliptic partial differential equations (PDE) in different regions which are coupled together with interface conditions, such as jumps in solution and flux across the interface. In many situations, such as the interface is moving, the challenge is how to solve such a problem accurately, robustly and efficiently without generating a body fitted mesh. The key issue is how to capture complex geometry of the interface and jump conditions across the interface effectively on a fixed mesh while the interface is not aligned with the mesh and the PDE is not valid across the interface. In this work we present a systematic formulation and further study of a second order accurate numerical method proposed in Hou and Liu (2005) [16] for elliptic interface problem. The key idea is to decompose the solution into two parts, a singular part and a regular part. The singular part captures the interface conditions while the regular part belongs to an appropriate space in the whole domain, which can be solved by a standard finite element formulation. In a general setup the two parts are coupled together. We give an explicit study of the construction of the singular part and the discretized system for the regular part. One key advantage of using weak formulation is that one can avoid assuming/using more regularity than necessary of the solution and the interface. We present the numerical algorithm and numerical tests in 3D to demonstrate the accuracy and other properties of our method. © 2013.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin | Sen M.K.,CSIR - Central Electrochemical Research Institute
Journal of Computational Physics | Year: 2013

High-order finite-difference (FD) methods have been widely used for numerical solution of acoustic wave equations. It has been reported that the modeling accuracy is of 2nd-order when the conventional (2. M)th-order space domain FD and the 2nd-order time domain FD stencils are directly used to solve the acoustic wave equation. Under the same discretization, the present version of time-space domain dispersion-relation-based FD method can improve the accuracy from 2nd-order to (2. M)th-order along eight directions for the 2D acoustic wave equation. To increase the accuracy further, we propose a new FD stencil for 2D acoustic wave equation modeling. This new time-space domain dispersion-relation-based FD stencil can reach the same arbitrary even-order accuracy along all directions, and is more accurate and more stable than the conventional one for the same M. Dispersion analysis and modeling examples demonstrate its advantages. © 2012 Elsevier Inc.


Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Zhang X.,Henan Normal University
Journal of Separation Science | Year: 2010

This paper describes a new method for rapid and sensitive determination of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron in water samples by ultrasound-assisted ionic liquid dispersive liquid-phase microextraction in combination with HPLC. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as the extraction solvent for the enrichment of four benzoylurea (BU) pesticides. Factors such as volume of [C6MIM][PF6], sonication time, sample pH, extraction time, centrifuging time and salting-out effect were systematically investigated. Under the optimum conditions, an excellent linear relationship was achieved in the range of 1.0-100 μg/L. The detection limits varied from 0.21 to 0.45 μg/L and the precision of the method was below 6.9% (RSD, n=6). The proposed method was successfully applied for the determination of these BU pesticides in water samples and excellent spiked recoveries were achieved. All these results demonstrated that this procedure provided a new simple, rapid, easy to operate, efficient and sensitive method for the analysis of BU pesticides in aqueous samples. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tian J.,China University of Petroleum - Beijing | Wang Y.,China University of Petroleum - Beijing | Feng X.,China University of Technology
Energy | Year: 2016

Fouling is a crucial problem in refinery HEN (heat exchanger network) that reduces heat transfer and affects regular production. The conventional way to mitigate fouling is cleaning heat exchanger regularly or improving operation conditions, but simultaneous consideration of the two methods is rare. This paper presents a combined approach for mitigating fouling in HEN by optimizing operation condition and cleaning schedule simultaneously. For optimization of operation condition, flow velocity is selected as a key variable since it can correlate fouling, heat transfer and pressure drop. An overall optimization of network performance can be achieved through redistribution of velocity. In a refinery HEN, fouling cannot be completely prevented through optimization of operation conditions, so management of cleaning actions is optimized to deal with the remained fouling. SA (Simulated annealing) algorithm is used in this work to obtain a comprehensive strategy for mitigating fouling. The application of the proposed method is demonstrated using a case study. The results show higher energy saving and economic efficiency compared with existing methods. © 2016 Elsevier Ltd.


Wang X.,Henan Normal University | Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Zhai M.,Henan Normal University
Analytical Methods | Year: 2012

The present study focused on the investigation of the applicability of a new material, Zr doped TiO 2 nanotubes, used as the solid phase extraction adsorbent for the enrichment of bisphenol A. The possible impacting parameters on the extraction such as the kind and volume of eluent, sample pH, sample flow rate, and sample volume were investigated in detail. Under the optimal extraction conditions, the proposed method had excellent linear range of 1-80 μg L -1 and the LOD was 0.016 μg L -1. The relative standard deviation at the concentration of 20 μg L -1 (RSDs, n = 6) was 2.9%. Four different real water samples were used for validation, and the spiked recoveries were satisfactory in the range of 102.9-108.8%, and all these results indicated that Zr doped TiO 2 nanotubes had much better extraction performance and would be widely used in the future. © The Royal Society of Chemistry 2012.


Yu C.,China University of Petroleum - Beijing | Yu C.,University of Hong Kong | Wong T.N.,University of Hong Kong
International Journal of Production Research | Year: 2014

In practice, it is common for companies to purchase multiple products simultaneously. For the multiple required products, a large number of interested suppliers are involved. It is necessary for the purchasing company to shortlist a small number of qualified and competitive potential suppliers prior to finalising the suppliers for order fulfilment. In addition, synergy effect which is an effect arising between two or more products that produce an effect greater than the sum of their individual effects, could exist in the multi-product supplier selection environment. Since synergy effect between products can affect the choice of suppliers, it is also necessary to incorporate the synergy effect between products in the supplier selection for multiple products. However, few research efforts have been focused on the supplier pre-selection problem, let alone explicitly for multiple products with synergy effect. This paper presents a supplier pre-selection model for multiple products with synergy effect. The model is able to evaluate interested suppliers on the multiple pre-selection criteria, by the fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)-based supplier pre-selection algorithm, and shortlist a small number of potential suppliers. Illustrative examples are conducted to demonstrate the function and application of the supplier pre-selection model for multiple products with synergy effect. © 2014 Taylor & Francis.


Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Zhao N.,China University of Petroleum - Beijing | Xie G.,Henan Institute of Science and Technology
Journal of Hazardous Materials | Year: 2011

This paper established a new, rapid and sensitive method for the determination of lead in water samples preconcentrated by dispersive liquid-liquid microextraction (DLLME) prior to atomic fluorescence spectrometry. Dithizone was used as the chelating agent. In the DLLME procedure, lead formed lead-dithizone complex and migrated into the carbon tetrachloride micro-droplets. Important factors that would affect the extraction efficiency had been investigated including the kind and volume of extraction solvent and dispersive solvent, sample pH, the amount of chelating agent, extraction time and centrifugation time. The results showed that the coexisting ions containing in water samples had no obvious negative effect on the determination of lead. The experimental results indicated that the proposed method had a good linear range of 0.01-100ngmL-1 (r2=0.9990). The precision was 2.12% (RSD, n=7) and the detection limit was 0.95ngL-1. Proposed method was validated with four real environmental samples and the results indicated that the proposed method was excellent for the future use and satisfied spiked recoveries were in the range of 92.9-97.4%. © 2011 Elsevier B.V.


Liu K.,Renmin University of China | Li Y.,Renmin University of China | Zheng X.,Renmin University of China | Liu W.,Renmin University of China | And 2 more authors.
Tetrahedron | Year: 2012

A general and practical method for the synthesis of α-ester-β- keto peroxides has been achieved by iron-catalyzed three-component reactions of alkenes, aldehydes, and TBHP. A wide variety of functionalized organic peroxides were synthesized efficiently and selectively. © 2012 Elsevier Ltd. All rights reserved.


Wang J.,University of Texas at Austin | Wang J.,China University of Petroleum - Beijing | Liu H.,China University of Petroleum - Beijing | Ning Z.,China University of Petroleum - Beijing | And 2 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2014

Based on the theory of scaling criteria, a physical experimental model of fractured-vuggy cell which meets the geometric similarity, kinematic similarity, dynamic similarity and characteristic parameters similarity was designed. The factors affecting fluid flow and water flooding characteristics, and the EOR features of different displacing modes were studied by experiments. The experimental results show that: Oil and water displacement effect caused by the density difference between oil and water is the main mechanism of water flooding; Injection rate has no effect on the remaining oil and water-cut; Fracture-vuggy connection is the dominant factor controlling water-free recovery, ultimate limit of remaining oil and water-cut variation in the fractured-vuggy cell; Oil-water viscosity ratio has an important effect on oil production rate, oil replacement ratio and economic limit remaining oil; When the filling degree is low, it has no effect on remaining oil, but when the filling degree is high, the remaining oil contains both "attic oil" and the oil existing in porous media; Foam flooding after water flooding enhances oil recovery by starting the attic oil at the top of vugs, and the remaining oil is in the center of the vugs after foam flooding; Polymer flooding after water flooding enhances the economic limit recovery by increasing the oil production rate and oil draining ratio, but it has no effect on the limit remaining oil of water flooding.


Yu C.,China University of Petroleum - Beijing | Wong T.N.,University of Hong Kong
Journal of Intelligent Manufacturing | Year: 2015

Supplier selection an important problem in supply chain management (SCM), since the performances of suppliers determine the competitiveness of the SCM. It is practical for the purchasing company to procure multiple products simultaneously. Synergy effect may exist between products in multi-product supplier selection process, and affect the final choice of suppliers. It is advantageous for the purchasing company to take into account the synergy effect between products to reduce cost and improve efficiency. On the other hand, suppliers need to consider the synergy effect between products to increase the chance of winning bids. Nevertheless, supplier selection involves complex decision making processes regarding supplier evaluation, selection and order fulfillment, it is difficult to fully incorporate the synergy effect between products in the case of multi-product supplier selection. Most of existing research only deal with supplier selection involving the acquisition of one product, or they assume that the multiple required products are independent. They are not sufficient to incorporate the synergy effect between products for multi-product supplier selection. This paper presents a product bundle determination model which can determine the synergy effect between products, group products based on the synergy effect between products, and determine the preferred product bundles of the purchasing company. This model can help the decision maker to make right decision in multi-product supplier selection process. Illustrative examples are conducted to demonstrate the functioning of the proposed product bundle determination model and its application in multi-product supplier selection process. © 2013, Springer Science+Business Media New York.


Yu C.,China University of Petroleum - Beijing | Yu C.,University of Hong Kong | Wong T.N.,University of Hong Kong
Expert Systems with Applications | Year: 2015

Supplier selection is an important problem in supply chain management (SCM), and has attracted the attention of many researchers. Tremendous effort has been spent on the development of agent-based systems to automate supplier selection negotiation process in SCM applications. In this kind of multi-agent system (MAS), software agents are established to represent various parties and functions involving in the supplier selection negotiation process. Most of current systems only deal with relatively simple negotiations involving the acquisition of one product, they are not sufficient to support complex negotiations involving multiple products with synergy effect. However, in practice, it is common for a purchasing company to procure multiple products simultaneously, and the synergy effects that exist between products could affect the final choice of cooperative suppliers. This paper presents an agent-based negotiation model to automate the supplier selection process involving a bundle of products with synergy effect. A MAS is established to realize the proposed negotiation model for multi-product supplier selection. Furthermore, the negotiation proposal, negotiation protocol, negotiation strategies, and decision making methods involving in the negotiation model are elaborated for the multi-product supplier selection environment. Through the proposed negotiation model, the purchasing company and suppliers can reach agreements on the details of products simultaneously and exploit the synergy effect between products. Finally, illustrative examples are conducted to demonstrate the function and effectiveness of the negotiation model for multi-product supplier selection. © 2014 Elsevier Ltd. All rights reserved.


Zhu J.,TU Berlin | Wei Y.,China University of Petroleum - Beijing | Chen W.,Fuzhou University | Zhao Z.,China University of Petroleum - Beijing | Thomas A.,TU Berlin
Chemical Communications | Year: 2010

Polymeric carbon nitride is reported to be a promising candidate in environmental catalysis for NO decomposition carried out at elevated temperature. Theoretical calculations support a mechanism where Lewis basic site of g-C3N4 can donate electrons to the adsorbed NO, decreasing the bond order of N-O thus facilitating the reaction. © 2010 The Royal Society of Chemistry.


Zeng H.,University of Texas at Austin | Zhu X.,China University of Petroleum - Beijing | Zhu R.,Petrochina | Zhang Q.,Petrochina
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2013

Seismic diagenetic facies is an important control factor on reservoir quality. This study investigated the possibility and feasibility of predicting sandstone diagenetic facies with conventional 3D seismic data by seismic sedimentology, calibrated by lab core analysis data in the Qijia area of the Songliao Basin. There are three core issues related to seismic characterization of diagenetic facies, including how to correlate stratigraphic and diagenetic units from seismic data, how to evaluate relationship between core-based diagenetic facies and seismic attributes, and how to find an effective way to map seismic diagenetic facies. Well- and seismic-based high-resolution sequence analysis and seismic stratal slicing provided reservoir-scale (20 m) seismic representations of diagenetic units. Core-based analyses of sandstone diagenetic processes and diagenetic sequence revealed that the diagenesis has the most important influence on reservoir quality. An investigation of reservoir parameters and acoustic rock properties further disclosed link between diagenetic facies and impedance, leading to the recognition of calcite cementation as a process that can be detected by seismic data. Seismic-based lithology cube (e. g., 90°-phased seismic volume) provided amplitude (impedance) signal for detection of diagenetic facies. The stratal slices made from the seismic-based lithology cube were used to interpret depositional facies and systems. Eventually, a seismic diagenetic facies map was generated by analyzing relationships between depositional facies, impedance, and diagenetic facies. The case study of the clay-cemented sandstone and calcite-cemented sandstone in the Qijia area showed that although being in its infant stage with many difficulties, the seismic detection of sandstone diagenetic facies with conventional seismic data is not only possible, but also feasible.


Chen Y.,University of Texas at Austin | Ma J.,China University of Petroleum - Beijing
Geophysics | Year: 2014

Random noise attenuation always played an important role in seismic data processing. One of the most widely used methods for suppressing random noise was f-x predictive filtering. When the subsurface structure becomes complex, this method suffered from higher prediction errors owing to the large number of different dip components that need to be predicted. We developed a novel denoising method termed f-x empirical-mode decomposition (EMD) predictive filtering. This new scheme solved the problem that makes f-x EMD ineffective with complex seismic data. Also, by making the prediction more precise, the new scheme removed the limitation of conventional f-x predictive filtering when dealing with multidip seismic profiles. In this new method, we first applied EMD to each frequency slice in the f-x domain and obtained several intrinsic mode functions (IMFs). Then, an autoregressive model was applied to the sum of the first few IMFs, which contained the high-dip-angle components, to predict the useful steeper events. Finally, the predicted events were added to the sum of the remaining IMFs. This process improved the prediction precision by using an EMD-based dip filter to reduce the dip components before f-x predictive filtering. Synthetic and real data sets demonstrated the performance of our proposed method in preserving more useful energy. © 2014 Society of Exploration Geophysicists.


Tong H.,China University of Petroleum - Beijing | Koyi H.,Uppsala University | Huang S.,University of Alaska Fairbanks | Zhao H.,Tianjin Chengjian University
Tectonophysics | Year: 2014

High-resolution three-dimensional seismic data show that fault distribution and evolution in rift basins can be very complicated and inconsistent with the classic model of fault formation and propagation. Fault development in the presence of multiple pre-existing weaknesses is still not clearly studied. Trying to understand the role of multiple pre-existing weaknesses in sand models, two series of experiments were prepared. In the first series of models, the mechanical properties of pre-existing weaknesses were the same but their orientations were different, whereas in the second series of models, both mechanical properties and orientations were different. The basic characteristics of fault formation and evolution in a rift basin revealed by the models are as follows: 1) weakness-reactivated faults (faults that formed directly along and above the pre-existing weaknesses) and weakness-related faults (faultswhich are not located above the pre-existingweaknesses, but have similar orientation) form much earlier than weakness-unrelated faults. The order of formation of different weaknessreactivated faults is determined by the relative reactivation tendency factors (fa) of the weaknesses; 2) weakness-reactivated faults and weakness-related faults develop mainly along or parallel to pre-existing weaknesses. In contrast, weakness-unrelated faults develop nearly perpendicular to the extension direction; 3) a complicated fault system can form during a single extension phase in the presence of multiple preexistingweaknesses; and 4) themode of fault formation and propagation and the increase in length and number of faults have close ties to the nature of pre-existing weaknesses. Fault displacement and length do not have a power law relationship for the majority of faults, and there is no unique relationship for different kinds of faults. In addition to providing newinsights to the formation of complex fault systems, the experiment results presented here could be reasonably explained using the Reactivation Tendency Theory. They can also be applied to the complicated fault system in rift basin. © 2014 Elsevier B.V.


Li Y.,Renmin University of China | Ma L.,Renmin University of China | Jia F.,Renmin University of China | Li Z.,Renmin University of China | Li Z.,China University of Petroleum - Beijing
Journal of Organic Chemistry | Year: 2013

A general and efficient method for amide bond synthesis has been developed. The method allows for synthesis of tertiary amides from readily available tertiary amines and anhydrides in the presence of FeCl2 as catalyst and tert-butyl hydroperoxide in water (T-Hydro) as oxidant. Mechanistic studies indicated that the in situ-generated α-amino peroxide of tertiary amine and iminium ion act as key intermediates in this oxidative transformation. © 2013 American Chemical Society.


Chen Y.,University of Texas at Austin | Gan S.,China University of Petroleum - Beijing | Liu T.,China University of Petroleum - Beijing | Yuan J.,China University of Petroleum - Beijing | And 2 more authors.
Journal of Geophysics and Engineering | Year: 2015

Empirical mode decomposition (EMD) becomes attractive recently for random noise attenuation because of its convenient implementation and ability in dealing with non-stationary seismic data. In this paper, we summarize the existing use of EMD in seismic data denoising and introduce a general hybrid scheme which combines f - x EMD with a dipping-events retrieving operator. The novel hybrid scheme can achieve a better denoising performance compared with the conventional f - x EMD and selected dipping event retriever. We demonstrate the strong horizontal-preservation capability of f - x EMD that makes the EMD based hybrid approach attractive. When f - x EMD is applied to a seismic profile, all the horizontal events will be preserved, while leaving few dipping events and random noise in the noise section, which can be dealt with easily by applying a dipping-events retrieving operator to a specific region for preserving the useful dipping signal. This type of incomplete hybrid approach is termed a selective hybrid approach. Two synthetic and one post-stack field data examples demonstrate a better performance of the proposed approach. © 2015 Sinopec Geophysical Research Institute.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Geophysical Prospecting | Year: 2012

We recently proposed an efficient hybrid scheme to absorb boundary reflections for acoustic wave modelling that could attain nearly perfect absorptions. This scheme uses weighted averaging of wavefields in a transition area, between the inner area and the model boundaries. In this paper we report on the extension of this scheme to 2D elastic wave modelling with displacement-stress formulations on staggered grids using explicit finite-difference, pseudo-implicit finite-difference and pseudo-spectral methods. Numerical modelling results of elastic wave equations with hybrid absorbing boundary conditions show great improvement for modelling stability and significant absorption for boundary reflections, compared with the conventional Higdon absorbing boundary conditions, demonstrating the effectiveness of this scheme for elastic wave modelling. The modelling results also show that the hybrid scheme works well in 2D rotated staggered-grid modelling for isotropic medium, 2D staggered-grid modelling for vertically transversely isotropic medium and 2D rotated staggered-grid modelling for tilted transversely isotropic medium. © 2012 European Association of Geoscientists & Engineers.


Huang Y.,Henan Normal University | Huang Y.,Nanyang Normal University | Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Xiao J.,University of Science and Technology Beijing
Analyst | Year: 2011

This paper described a new method for the enrichment and determination of pyrethroid pesticides from environmental water samples with ordered TiO 2 nanotube array micro-solid phase equilibrium extraction (μ-SPEE) prior to gas chromatography (GC) with electron capture detection (ECD). Several factors such as the anodization voltage, the kind of organic solvents, sample pH, equilibrium extraction time, desorption time and salting-out effect were optimized. Under the optimal conditions, ordered TiO2 nanotube arrays demonstrated excellent merits on the preconcentration of pyrethroid pesticides and good detection limits were achieved as 0.018, 0.020, 0.031, 0.041, and 0.070 μg L-1 for bifenthrin, fenpropathrin, cyhalothrin, fenvalerate, and deltamethrin, respectively. Four real water samples were used to validate the proposed method and the spiked recoveries were over the range of 81.9-110.6%. Compared to conventional solid phase extraction (SPE), the present method showed better recoveries and good reproducibility. These results showed that this μ-SPEE technique could be an important alternative to multistep SPE for the extraction and determination of such analytes in complex samples and become a useful tool in monitoring such analytes in the environment. © 2011 The Royal Society of Chemistry.


Chen Y.,University of Texas at Austin | Liu T.,China University of Petroleum - Beijing | Liu T.,Sinopec | Chen X.,China University of Petroleum - Beijing
Geophysics | Year: 2014

Weighted semblance can be used for improving the performance of traditional semblance for specific data sets. We have developed a novel approach for prestack velocity analysis using weighted semblance. The novelty came from a different weighting criteria in which the local similarity between each trace and a reference trace is used. On the one hand, low similarity corresponded to a noise point or a point indicating incorrect moveout, which should be given a small weight. On the other hand, high similarity corresponded to a point indicating correct moveout that should be given a high weight. Our approach could also be effectively used for analyzing AVO anomalies with increased resolution compared with AB semblance. Synthetic and field common-midpoint gathers demonstrated higher resolution using the approach we developed. Applications of the proposed method on a prestack data set further confirmed that the stacked data using the similarity-weighted semblance could obtain better energy-focused events, which indicated a more precise velocity picking. © 2015 Society of Exploration Geophysicists.


Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Gao Y.,Henan Normal University
Analytical Methods | Year: 2014

The present study describes a simple and sensitive method for the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by temperature-controlled ionic liquid dispersive liquid-liquid microextraction prior to high performance liquid chromatography with an ultraviolet detector. Three ionic liquids including 1-hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6], 1-benzyl-3-methylimidazolium hexafluorophosphate [C7MIM][PF6] and 1-octyl-3- methylimidazolium hexafluorophosphate [C8MIM][PF6] were investigated for enrichment, and the experimental results indicated that the best extraction efficiencies were achieved when [C8MIM][PF 6] was used as the extraction solvent. Other factors affecting the extraction efficiency such as the volume of ionic liquid, heating temperature, extraction time, addition of 2-propanol, centrifugation time and ionic strength were also optimized. Under the optimal conditions, the detection limits of PAHs were in the range of 0.0005-0.88 μg L-1. The intra-day and inter-day precisions of the proposed method (RSDs, n = 6) were in the range of 2.7-7.4% and 5.5-11.4%, respectively. The proposed method was applied to the analysis of real environmental water samples and good spiked recoveries in the range of 83.5-118% were achieved. All these results indicate that the proposed method is a viable alternative to existing methods and would be very useful in the future. © 2014 the Partner Organisations.


Liu G.,China University of Petroleum - Beijing | Fomel S.,University of Texas at Austin | Chen X.,China University of Petroleum - Beijing
Geophysics | Year: 2011

Time-frequency analysis is an important technology in seismic data processing and interpretation. To localize frequency content in time, we have developed a novel method for computing a time-frequency map for nonstationary signals using an iterative inversion framework. We calculated time-varying Fourier coefficients by solving a least-squares problem that uses regularized nonstationary regression. We defined the time-frequency map as the norm of time-varying coefficients. Time-varying average frequency of the seismic data can also be estimated from the time-frequency map calculated by our method. We tested the method on benchmark synthetic signals and compared it with the well-known S-transform. Two field data examples showed applications of the proposed method for delineation of sand channels and for detection of low-frequency anomalies. © 2011 Society of Exploration Geophysicists.


Yang Y.,CAS Lanzhou Institute of Chemical Physics | Yang Y.,China University of Petroleum - Beijing | Gao G.,CAS Lanzhou Institute of Chemical Physics | Zhang X.,China University of Petroleum - Beijing | Li F.,CAS Lanzhou Institute of Chemical Physics
ACS Catalysis | Year: 2014

Bimetallic catalysts are of great importance due to their unique catalytic properties. However, their conventional synthesis requires tedious multistep procedures and prolonged synthetic time, and the resulting bimetallics usually disperse unevenly and show poor stability. It is challenging to develop a facile and step-economic synthetic methodology for highly efficient bimetallic catalysts. In this study, we report an elegant metal complex-involved multicomponent assembly route to highly efficient Ru-Ni bimetallics in ordered mesoporous carbons (OMC). The fabrication of composition-tuned Ru-Ni bimetallics in OMC (RuxNi1-x-OMC, x = 0.5-0.9) was facilely realized via in situ construction of CTAB-directed cubic Ia3d chitosan-ruthenium-nickel- silica mesophase before pyrolysis and silica removal. The resulting Ru xNi1-x-OMC materials are in-depth characterized with X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, infrared spectrum, and X-ray absorption fine structure. This facile fabrication method renders homogeneously dispersed Ru-Ni bimetallics embedded in the mesoporous carbonaceous framework and creates a highly active and stable Ru0.9Ni0.1-OMC catalyst for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL), a biomass-derived platform molecule with wide application in the preparation of renewable chemicals and liquid transportation fuels. A high TOF (>2000 h-1) was obtained, and the Ru0.9Ni0.1-OMC catalyst could be used at least 15 times without obvious loss of its catalytic performance. © 2014 American Chemical Society.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Exploration Geophysics | Year: 2011

Most conventional finite-difference methods adopt second-order temporal and (2M)th-order spatial finite-difference stencils to solve the 3D acoustic wave equation. When spatial finite-difference stencils devised from the time-space domain dispersion relation are used to replace these conventional spatial finite-difference stencils devised from the space domain dispersion relation, the accuracy of modelling can be increased from second-order along any directions to (2M)th-order along 48 directions. In addition, the conventional high-order spatial finite-difference modelling accuracy can be improved by using a truncated finite-difference scheme. In this paper, we combine the time-space domain dispersion-relation-based finite difference scheme and the truncated finite-difference scheme to obtain optimised spatial finite-difference coefficients and thus to significantly improve the modelling accuracy without increasing computational cost, compared with the conventional space domain dispersion-relation-based finite difference scheme. We developed absorbing boundary conditions for the 3D acoustic wave equation, based on predicting wavefield values in a transition area by weighing wavefield values from wave equations and one-way wave equations. Dispersion analyses demonstrate that high-order spatial finite-difference stencils have greater accuracy than low-order spatial finite-difference stencils for high frequency components of wavefields, and spatial finite-difference stencils devised in the time-space domain have greater precision than those devised in the space domain under the same discretisation. The modelling accuracy can be improved further by using the truncated spatial finite-difference stencils. Stability analyses show that spatial finite-difference stencils devised in the time-space domain have better stability condition. Numerical modelling experiments for homogeneous, horizontally layered and Society of Exploration Geophysicists/European Association of Geoscientists and Engineers salt models demonstrate that this modelling scheme has greater accuracy than a conventional scheme and has better absorbing effects than Clayton-Engquist absorbing boundary conditions. © 2011 ASEG.


Liu G.,China University of Petroleum - Beijing | Liu G.,University of Texas at Austin | Fomel S.,University of Texas at Austin | Chen X.,China University of Petroleum - Beijing
Geophysical Prospecting | Year: 2011

Unequal illumination of the subsurface highly impacts the quality of seismic imaging. Different image points receive different folds of reflection-angle illumination, which can be caused by irregular acquisition or by wave propagation in complex media. Illumination problems can deteriorate amplitudes in migrated images. To address this problem, we present a method of stacking angle-domain common-image gathers, in which we use local similarity with soft thresholding to determine the folds of local illumination. Normalization by local similarity regularizes local illumination of reflection angles for each image point of the subsurface model. This approach compensates for irregular illumination by selective stacking in the image space, regardless of the cause of acquisition or propagation irregularities. Additional migration is not required because the methodology is implemented in the reflection angle domain after migration. We use two synthetic examples to demonstrate that our method can normalize migration amplitudes and effectively suppress migration artefacts. © 2010 European Association of Geoscientists & Engineers.


Li Y.,Renmin University of China | Jia F.,Renmin University of China | Li Z.,Renmin University of China | Li Z.,China University of Petroleum - Beijing
Chemistry - A European Journal | Year: 2013

Unconventional couple: A new oxidative coupling protocol for amide bond formation has been developed (see scheme). The method provides an efficient and practical route for the synthesis of tertiary amides from readily available tertiary amines and aldehydes in the presence of a simple FeCl2 catalyst. Mechanistic studies indicated that a peroxide and an iminium ion act as the reactive intermediates in this oxidative amidation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Bulletin of the Seismological Society of America | Year: 2011

The staggered-grid finite-difference (SFD) method is widely used in numerical modeling of wave equations. Conventional SFD stencils for spatial derivatives are usually designed in the space domain. However, when they are used to solve wave equations, it becomes difficult to satisfy the dispersion relations exactly. Liu and Sen (2009c) proposed a newSFDscheme for one-dimensional (1D) scalarwave equation based on the time-space domain dispersion relation and plane wave theory, which is made to satisfy the exact dispersion relation. This newSFD scheme has greater accuracy and better stability than a conventional scheme under the same discretizations. In this paper, we develop this new SFD scheme further for numerical solution of 2D and 3D scalar wave equations.We demonstrate that the modeling accuracy is second order when the conventional 2M-th-order space-domain SFD and the second order time-domain finite-difference stencils are directly used to solve the scalar wave equation. However, under the same discretization, our 1D scheme can reach 2M-th-order accuracy and is always stable; 2D and 3D schemes can reach 2M-th-order accuracy along 8 and 48 directions, respectively, and have better stability. The advantages of the new schemes are also demonstrated with dispersion analysis, stability analysis, and numerical modeling.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Geophysics | Year: 2011

Most finite-difference simulation algorithms use fixed-length spatial operators to compute spatial derivatives. The choice of length is dictated by computing cost, stability, and dispersion criteria that are satisfied globally. We propose finite-difference schemes with adaptive variable-length spatial operators to decrease computing costs significantly without reducing accuracy. These schemes adopt long operators in regions of low velocity and short operators in regions of high velocity. Two methods automatically determine variable operator lengths. Dispersion analysis, along with 1D and 2D modeling, demonstrates the validity and efficiency of our schemes. In addition, a hybrid absorbing boundary condition helps reduce unwanted reflections from model boundaries. Our scheme is more efficient than those based on variable-grid methods for modeling, migration, and inversion of models with complex velocity structures because the latter require local grid refinement, which usually increases memory requirements and computing costs. © 2011 Society of Exploration Geophysicists.


Liu K.,Renmin University of China | Jia F.,Renmin University of China | Xi H.,Renmin University of China | Li Y.,Renmin University of China | And 5 more authors.
Organic Letters | Year: 2013

An intermolecular oxidative cyclization between thiophenols and alkynes for benzothiophene formation has been established. A variety of multifunctional benzothiophenes are synthesized. In addition, we demonstrated that the obtained benzothiophenes can be used for further transformation to give diverse benzothiophene derivatives efficiently and selectively. © 2013 American Chemical Society.


Lv L.,Renmin University of China | Shen B.,China University of Petroleum - Beijing | Li Z.,Renmin University of China | Li Z.,China University of Petroleum - Beijing
Angewandte Chemie - International Edition | Year: 2014

Biologically significant clavilactones A, B, and the previously proposed D have been synthesized through iron-catalyzed carbonylation-peroxidation of a 1,5-diene. Three steps from aldehydes, alkenes, and tert-butylhydroperoxide build up α,β-epoxy-γ-butyrolactone skeleton as a key building block for synthesis of clavilactone family and its derivatives. Based on our results, the structure of the proposed clavilactone D is not correct and requires revision. A general, concise, and efficient approach for synthesis of clavilactones A, B, and D has been established. Three steps from aldehydes, 1,5-dienes, and tBuOOH build up α,β-epoxy-γ-butyrolactones (see scheme, left) as the key building blocks for synthesis of clavilactone family and its derivatives. From these results, the previously proposed clavilactone D structure requires revision. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Gao Y.,China University of Petroleum - Beijing | Xie G.,Henan Institute of Science and Technology
Talanta | Year: 2011

Present study described a simple, sensitive, and viable method for the determination of bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol in water samples using temperature-controlled ionic liquid dispersive liquid-phase microextraction coupled to high performance liquid chromatography-fluorescence detector. In this experiment, 1-octyl-3-methylimidazolium hexafluorophosphate ([C 8MIM][PF 6]) was used as the extraction solvent, and bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol were selected as the model analytes. Parameters affecting the extraction efficiency such as the volume of [C 8MIM][PF 6], dissolving temperature, extraction time, sample pH, centrifuging time and salting-out effect have been investigated in detail. Under the optimized conditions, good linear relationship was found in the concentration range of 1.0-100 μg L -1 for BPA, 1.5-150 μg L -1 for 4-NP, and 3-300 μg L -1 for 4-OP, respectively. Limits of detection (LOD, S/N = 3) were in the range of 0.23-0.48 μg L -1. Intra day and inter day precisions (RSDs, n = 6) were in the range of 4.6-5.5% and 8.5-13.3%, respectively. This method has been also successfully applied to analyze the real water samples at two different spiked concentrations and excellent results were obtained. © 2011 Elsevier B.V. All rights reserved.


Jia F.,Renmin University of China | Liu K.,Renmin University of China | Xi H.,Renmin University of China | Lu S.,Renmin University of China | And 2 more authors.
Tetrahedron Letters | Year: 2013

An efficient method for oxindole synthesis is established by iron-catalyzed carbonylation-arylation of N-arylacrylamides with aldehydes. 3-Functionalized oxindoles are synthesized smoothly using FeCl3 as catalyst and TBHP as oxidant. The obtained oxindoles can be used for further transformations to give diverse indole alkaloid structure motifs. © 2013 Elsevier Ltd. All rights reserved.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Geophysics | Year: 2010

The finite-difference (FD) method is widely used in numerical modeling of wave equations. Conventional FD stencils for space derivatives are usually designed in the space domain. When they are used to solve wave equations, it is difficult to satisfy the dispersion relations exactly. We have designed a spatial FD stencil based on a time-space domain dispersion relation to simulate wave propagation in an acoustic vertically transversely isotropic (VTI) medium. Two-dimensional dispersion analysis and numerical modeling demonstrate that this stencil has greater precision than one used in a conventional FD, when the same number of grid points is used in the calculation of the spatial derivatives. Thus, the spatial FD stencil based on time-space domain dispersion relation can be used to replace a conventional one such that we can achieve greater accuracy with almost no increase in computational cost. © 2010 Society of Exploration Geophysicists.


Liu Y.,China University of Petroleum - Beijing | Sen M.K.,University of Texas at Austin
Geophysics | Year: 2010

We propose an efficient scheme to absorb reflections from the model boundaries in numerical solutions of wave equations. This scheme divides the computational domain into boundary, transition, and inner areas. The wavefields within the inner and boundary areas are computed by the wave equation and the one-way wave equation, respectively. The wavefields within the transition area are determined by a weighted combination of the wavefields computed by the wave equation and the one-way wave equation to obtain a smooth variation from the inner area to the boundary via the transition zone. The results from our finite-difference numerical modeling tests of the 2D acoustic wave equation show that the absorption enforced by this scheme gradually increases with increasing width of the transition area. We obtain equally good performance using pseudospectral and finite-element modeling with the same scheme. Our numerical experiments demonstrate that use of 10 grid points for absorbing edge reflections attains nearly perfect absorption. © 2010 Society of Exploration Geophysicists.


Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Huang Y.,Henan Normal University | Huang Y.,Nanyang Normal University | Xie G.,Henan Institute of Science and Technology
Journal of Chromatography A | Year: 2012

Present study investigated the applicability of ordered TiO 2 nanotube arrays for the enrichment and determination of polychlorinated biphenyls (PCBs) in water samples. A new and reliable method was developed for the preconcentration and determination of PCBs by micro-solid phase equilibrium extraction in combination with gas chromatography and electron capture detection (GC-ECD), which exploited the special physical and chemical properties of ordered TiO 2 nanotube arrays. The experimental results indicated that low LODs were easily achieved in the range of 0.02-0.10μgL -1 for PCB-28, PCB-52, PCB-101, PCB-153, PCB-138, and PCB-180. The proposed method was validated with several real water samples, and good spiked recoveries have been obtained in the range of 95.8-110.5%. The experimental results demonstrated that TiO 2 nanotube arrays could be reused for over 200 times without the lost of the extraction efficiency. All these showed that TiO 2 nanotube arrays would be very useful in the enrichment and determination of trace pollutants. © 2012 Elsevier B.V..


Li Q.,China University of Petroleum - Beijing | Li Q.,University of Texas at Austin | Chen M.,China University of Petroleum - Beijing | Jin Y.,China University of Petroleum - Beijing | Wang F.P.,University of Texas at Austin
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Testing system MTS 815 is used to carry out triaxial compression tests for specimens from Barnett, Haynesville, Eagle Ford in North American, and Longmaxi shale in South China. Their failure modes and mechanical behaviors under different confining pressures are obtained correspondingly. The similarities and differences between them are analyzed in detail. Splitting failure and splitting-shear mixed failure modes are the main failure modes for shale samples under low confining pressures, while shear failure modes predominate under higher pressures. The types of shale, burial depth, coring direction and confining pressures are all factors affecting the mechanical behavior of specimens. More quartz and carbonate contained specimen tends to be more brittle. In addition, the peak strength and Young's modulus of shale are proportional with confining pressure, especially when the confining pressure is higher than 30 MPa. The peak strength of Barnett shale is higher than Haynesville, but lower than Eagle Ford. Shale samples from South China, compared with that from North America, have higher strength and Young's modulus, while lower Poisson's ratio. The brittleness characteristics of shale samples from China is similar to that from America.


Huang Y.,Henan Normal University | Huang Y.,Nan Yang Normal University | Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Xie G.,Henan Institute of Science and Technology
Journal of Hazardous Materials | Year: 2011

This paper described a simple and novel analytical technique for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. A micro-solid phase extraction (μ-SPE) was developed utilizing cetyltrimethylammonium bromide modified ordered TiO 2 nanotube array. The experimental results indicated that modified TiO 2 nanotube arrays demonstrated an excellent merit on the preconcentration of PAHs, and there were excellent linear relationships between peak area and the concentration of PAHs in the range of 0.2-100μgL -1 and 1.0-100μgL -1, respectively. The detection limits of proposed method for the targeted PAHs were in the range of 0.026-0.82μgL -1 (S/N=3). The real-world environmental water samples were used to validate the applicability of the proposed method and good spiked recoveries were in the range of 75.0-114%. All these results demonstrated that this new μ-SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples. © 2011 Elsevier B.V.


Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Gao Y.,Henan Normal University | Bai H.,Henan Normal University | Xie G.,Henan Institute of Science and Technology
Journal of Chromatography A | Year: 2010

Present study developed a new method for the sensitive determination of pyrethroid insecticides with solid phase extraction in combination with high performance liquid chromatography and UV detector. SiO2 microspheres, a new SiO2 based material, was investigated for the enrichment ability and applicability as the solid phase extraction sorbent. Four pyrethroid pesticides such as fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were used as the target analytes. Parameters that maybe influence the extraction efficiency such as the eluent type and its volume, sample flow rate, sample pH, and the sample volume were optimized in detail, and the optimal conditions were as followed: sample volume, 100mL; concentration of methanol, 30%; acetone volume, 5mL; sample flow rate, 4.2mLmin-1; sample pH, 7. The experimental results indicated that there was good linearity in the concentration range of 0.1-50μgL-1 except biphenthrin in the range of 0.05-25μgL-1. The detection limits for fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were in the range of 0.02-0.08μgL-1. The intra-day and day to day precisions (RSDs, n=6) were in the ranges of 2.6-4.4% and 5.3-7.2%, respectively. The method was validated with five real environmental water samples, and all these results proved that proposed method could be used as a good alternative for the routine analysis for such pollutants in environmental samples. © 2010 Elsevier B.V.


Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Pang L.,Henan Normal University | Xiao J.,University of Science and Technology Beijing
Microchimica Acta | Year: 2011

A simple and sensitive method was developed for the determination of three carbamate pesticides in water samples. It is based on temperature controlled ionic liquid dispersive liquid phase microextraction combined with high-performance liquid chromatography. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate was used as the extractant, and the factors affecting the extraction were investigated in detail. The detection limits obtained for isoprocarb, diethofencarb and fenothiocarb are 0. 91, 0. 45, and 1. 40 μgL-1, respectively, and the precisions are in the range between 1. 0 and 1. 8% (n = 6). The method was validated with environmental water samples and the results indicate that it represents a viable alternative to existing methods. © 2011 Springer-Verlag.


Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Huang Y.,Henan Normal University | Xiao J.,University of Science and Technology Beijing | Xie G.,Henan Institute of Science and Technology
Analytical and Bioanalytical Chemistry | Year: 2011

Ordered TiO2 nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and catalysis. This present study exploited a new functional application of the ordered TiO2 nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO2 nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron capture detection. Ordered TiO2 nanotube arrays exhibited excellent merits on the pre-concentration of organochlorine pesticides and lower detection limits of 0.10, 0.10, 0.10, 0.098, 0.0076, 0.0097, 0.016, and 0.023 μg L-1 for α-HCH, β-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT, respectively, were achieved. Four real water samples were used for validation, and the spiked recoveries were in the range of 78-102.8%. These results demonstrated that the developed micro-solid phase equilibrium extraction using ordered TiO2 nanotube arrays would be very constructive and have a great beginning with a brand new prospect in the analysis of environmental pollutants. [Figure not available: see fulltext.] © 2011 Springer-Verlag.


Zhao H.,China University of Petroleum - Beijing | Chen M.,China University of Petroleum - Beijing | Jin Y.,China University of Petroleum - Beijing | Ding Y.,Petrochina | Wang Y.,Petrochina
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012

The formation mechanism of fracture mesh and the mechanism of activating natural closed fractures during shale fracturing are studied based on rock fracture kinetics. It is found that steering conditions should be satisfied at both left and right ends of a natural fracture to form intensive fracture mesh after the hydraulic fracture reaches the natural fracture; there exists a minimum critical pump rate (critical pump rate) to form intensive fracture mesh. The critical pump rate increases as the inclination of natural fracture increases and reaches a maximum value (constant) when the inclination of natural fracture is 90°. When the inclination of natural fracture is less than 90°, the critical pump rate first decreases and then increases as the angle between horizontal wellbore and natural fracture increases; the critical pump rate reaches a minimum value for the natural fractures perpendicular to the wellbore. The critical pump rate increases as natural fracture length increases and rock elastic modulus decreases. It is also found that natural fracture surface is rough and not fitting, so when hydraulic fractures reopen existing natural fractures, the release of the original shear stress in the fracture surface would lead to the fracture surface slippage, which would greatly enhance the flow conductivity of the natural fracture. Very small or very large inclination of natural fracture is not conducive to fracture activation, best activating result can be reached at 30°-60° inclination. Rise in elastic modulus inhibits fracture surface slippage and Poisson's ratio has little effect on fracture surface slippage.


Guo Y.,Petrochina | Liu J.,Petrochina | Yang H.,Petrochina | Liu Z.,China University of Petroleum - Beijing | And 4 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012

By analyzing the hydrocarbon accumulation conditions under the guideline of sequence stratigraphy, the hydrocarbon accumulation mechanism in the low permeability, tight reservoirs of the Yanchang Formation in the Ordos Basin is studied from the perspective of pore evolution, and the hydrocarbon accumulation evolution models are concluded. The low permeability, tight reservoirs of the Yanchang Formation are distributed within the range of good hydrocarbon source rocks. The reservoir sand-bodies are dominated by lacustrine gravity flow deposits and delta front deposits. In the early period when hydrocarbons are accumulated in the Yanchang Formation, the reservoirs are characterized by high porosity and high permeability. The oil and gas generated in the period are accumulated normally under the effect of buoyancy. In the middle-late period, the reservoirs have experienced continuous compression. The petroleum generated in the late period, the major hydrocarbon generation period, migrates and accumulates by infiltration along the previously remained paths under the effect of buoyancy and pressure difference between the source rocks and the reservoirs. When the reservoirs become tight, oil and gas stop migration. From the Late Jurassic to the middle period of the Early Cretaceous, oil and gas widely charge the high porosity sandstones near the source rocks when they migrate from the center of the lacustrine basin to the borders. In the late period of the Early Cretaceous, the diagenesis of sandstone reservoirs is enhanced, making the reservoirs tight. After the Late Cretaceous, the present low permeability tight lithologic reservoirs are formed due to the compressing and uplifing movement of the structure which dips down in the west and tilts up in the east.


Dai J.,China University of Petroleum - Beijing | Li J.,Petrochina | Wang B.,China University of Petroleum - Beijing | Pan R.,China University of Petroleum - Beijing
Petroleum Exploration and Development | Year: 2012

Serious water production and the confusion about the distribution regularity and formation mechanism of gas and water affect the progressive development in the western area of Sulige gas field. Making use of drilling, logging, and testing data, this comprehensive study determines the gas-water distribution regularity and formation mechanism, and establishes the evolution modes of gas-water distribution. The results show that, (1) the gas-water distribution appears complementarily, and relatively water-rich area is located in the northwest; (2) source rock, reservoir physical property and structure are the key controlling factors of gas-water distribution, and formation water is distributed in areas with less developed source rocks, areas of poor properties, and structural lows within connecting bodies; (3) source rocks play a key role in controlling the distribution of gas and water, source area of low maturity is rich in formation water, while source area of high maturity is rich in gas. This research gives direction for favorable areas and well site selection in the progressive development of the gas field. © 2012 Research Institute of Petroleum Exploration & Development, PetroChina.


Zeng L.,China University of Petroleum - Beijing | Tang X.,China University of Petroleum - Beijing | Wang T.,Petrochina | Gong L.,Petrochina
AAPG Bulletin | Year: 2012

Paleogene saline lacustrine carbonate rocks are important fractured reservoirs in the western Qaidam Basin. Core data show that most fractures are small, steeply dipping faults; beddingplane slip faults; and subvertical opening-mode fractures. Other fractures are diagenetic in origin. Fracture occurrence and abundance patterns are controlled by lithology, bed thickness, and proximity to larger faults. Fractures are generally filled with calcite, gypsum, or glauberite (Na2Ca[SO4]2); the degree of fracture filling determines the effectiveness of fractures as fluid conduits and the distribution of high-quality reservoirs. Open fractures not only provide the main pathways for fluid flow, but also enhance the free fluid index and the free fluid saturation measured by nuclear magnetic resonance and determine the potential production rates of tight carbonate reservoirs. The open fractures are parallel to and occur near faults, and many do not coincide with the present-day direction of the maximum horizontal compressive stress. Copyright ©2012. The American Association of Petroleum Geologists. All rights reserved.


Pang Z.,China University of Petroleum - Beijing | Liu H.,China University of Petroleum - Beijing | Ge P.,Sinopec | Han L.,Petrochina
Petroleum Exploration and Development | Year: 2012

According to the similarity criterion of 3D physical simulation of thermal recovery, experimental parameters of 3D physical simulation of steam flooding and thermal foam compound flooding in extra-heavy oil reservoirs of the Gudao Oilfield were calculated, and relevant experiments were carried out. Based on the experimental results, 3D fine numerical simulation was carried out to analyze the steam flooding and thermal foam compound flooding in heavy oil reservoirs. The results show that thermal foam compound flooding could effectively inhibit steam channeling and improve sweep efficiency, and thus enhance the oil recovery in heavy oil reservoirs after steam flooding. Technological parameters of thermal foam compound flooding were optimized according to the results of fine numerical simulation. The optimum injection method is foam-slug injection, the optimal steam injection rate is 25 mL/min, nitrogen injection rate is 1 000 mL/min (standard conditions), the time of foam-slug injection is 1.0 min and the interval between foam-slugs is about 10-20 min during thermal foam-slug injection. At last, the similarity criterion was employed for inversion calculation of the optimization results. Based on the results, optimal field injection and production parameters can be confirmed. The ultimate recovery ratio of thermal foam compound flooding in super-heavy oil reservoirs could reach 42.15%, which is 12.50% higher than steam flooding. © 2012 Research Institute of Petroleum Exploration & Development, PetroChina.


Wei Y.,China University of Petroleum - Beijing | Liu J.,China University of Petroleum - Beijing | Zhao Z.,China University of Petroleum - Beijing | Duan A.,China University of Petroleum - Beijing | And 5 more authors.
Energy and Environmental Science | Year: 2011

A series of catalysts of three-dimensionally ordered macroporous (3DOM) Ce 0.8Zr 0.2O 2-supported gold nanoparticles with controllable sizes were successfully synthesized by the facile method of gas bubbling-assisted membrane reduction (GBMR). All the catalysts possess well-defined 3DOM structures, which consist of interconnected networks of spherical voids, and the Au nanoparticles are well dispersed and supported on the inner wall of the uniform macropore. The relationship between Au particle sizes and the ability to adsorb and activate oxygen was characterized by means of O 2-TPD and XPS. The results show that the active oxygen species (O -) and gold ions with oxidation state of Au + are essential for soot oxidation reaction. 3DOM Au 0.04/Ce 0.8Zr 0.2O 2 catalyst with Au particle size of 2-3 nm has the strong capability of adsorption and activation of oxygen. Thus, it exhibits super-catalytic activity for diesel soot oxidation, especially at low temperature. The reaction pathways of catalytic soot oxidation in the presence or absence of NO can be outlined as follows: at low temperature (<250 °C), the catalytic performance of supported Au catalyst is dependent on the Au particle sizes. At relatively high temperature (>250 °C), the catalytic activity is strongly related to the NO gas, because NO 2 derived from NO oxidation is used as intermediate to catalyze soot oxidation. © 2011 The Royal Society of Chemistry.


Jin Y.,Tianjin University | Liu W.,China University of Petroleum - Beijing | Liu Q.,University of Alberta | Yeung A.,University of Alberta
Fuel | Year: 2011

The aggregation of micron-sized silica particles in non-aqueous (i.e. hydrocarbon) media was examined on both the macroscopic and microscopic scales. The silica surfaces were either "clean" or "treated" (i.e. with irreversibly adsorbed materials from Athabasca bitumen); the hydrocarbons were mixtures of toluene and heptane at various ratios (to allow for different degrees of "aromaticity" in the solvent). On the macroscopic scale, gravity settling of the silica beads in non-aqueous media was monitored, and particle-particle interactions were characterized semi-empirically by the initial rates of sedimentation. On the microscopic scale, adhesive forces between individual glass spheres were directly measured using the microcantilever technique (again, in non-aqueous liquids). It was found that, for clean silica spheres, the settling rates of the suspensions were relatively insensitive to the interparticle adhesive forces. This is in contrast to the case for treated silica beads, where strong correlation was observed between the settling rate and particle-particle adhesion. These findings may have important relevance to the commercial "paraffinic froth treatment" process. © 2011 Elsevier Ltd. All rights reserved.


Liu W.,China University of Petroleum - Beijing | Jin Y.,Tianjin University | Tan X.,University of Alberta | Yeung A.,University of Alberta
Fuel | Year: 2011

The abilities of three ionic surfactants - sodium methylnaphthalene sulfonate (SMNS), sodium dodecyl sulfate (SDS), and cetyl trimethylammonium bromide (CTAB) - to alter the wettability of bitumen-treated glass surfaces was examined. Surface wettability was characterized by contact angles, and all measurements were carried out under alkaline conditions by having sodium carbonate (Na2CO3) dissolved in the aqueous phase. It was found that Na2CO3 alone could slightly increase the hydrophilcity of bitumen-treated glass surfaces. With surfactants added to the system, it was demonstrated that SMNS and SDS (both anionic surfactants) were much more effective in enhancing the water wettability of bitumen-treated glass in comparison to CTAB (a cationic surfactant). X-ray photoelectron spectroscopy (XPS) analyses were also conducted to determine the functional groups and relative mass concentrations of various elements on the glass substrates. Based on these results, we speculate that most or all of the adsorbed hydrocarbon material could be removed from a glass substrate through synergistic effects between sodium carbonate, which provides the alkaline condition, and anionic surfactants, which likely interacted with adsorbed cationic materials. This resulted in dramatic alteration in the wettability of bitumen-treated glass surfaces - from oil-wet to water-wet. © 2011 Elsevier Ltd. All rights reserved.


Zhibo L.,China University of Petroleum - Beijing | Linsong C.,China University of Petroleum - Beijing | Youjun J.,Southwest Petroleum University | Qicheng L.,Petrochina
Petroleum Exploration and Development | Year: 2011

Using the numerical simulation method and the drafting software of Surfer, we charted the temperature fields and remaining oil saturation fields of steam assisted gravity drainage (SAGD) and steam and gas push (SAGP) in oil drainage periods, including beginning, peak stage and last stage of oil drainage. An intuitive and reliable comparative research was done about the formation and expanding process of steam chambers, the shape of steam chambers and flow features in different oil drainage periods. The recovery effectiveness of the two production methods was compared. The results show that: in the SAGP production process, the lateral expansion of the steam chamber is faster than that in SAGD and the vertical expansion slower than that in SAGD. By adding non-condensate gas in the steam of SAGD, it can reduce the amount of steam injection, increase thermal efficiency, improve the ratio of oil to steam, and ultimately improve the development effectiveness of SAGD. The case study indicates that SAGP can slow the decline of oil rate and extend the development time of heavy oil reservoir and improve the development effectiveness. © 2011 Research Institute of Petroleum Exploration & Development, PetroChina.


Qi J.F.,China University of Petroleum - Beijing | Li X.G.,Petrochina | Yu F.S.,China University of Petroleum - Beijing | Yu T.C.,Petrochina
Science China Earth Sciences | Year: 2013

Based on the interpretation of 3D seismic data and structural mapping we analyzed the geometry and kinematics of the fault system and validated the expression of the "Tan-Lu Fracture Zone" in the West Sag of Liaohe Depression, Bohaiwan basin province. The Cenozoic structural deformation within the West Sag of Liaohe Depression can be divided into extensional structure system and dextral structure system. The extensional system is constituted by numerous NNE-NE trending Paleogene normal faults, where the Taian-Dawa fault (F1) is the master boundary fault (MBF) dominating the deposition during Paleogene so that the sag shows a complex half-graben with "boundary fault in the east and overlap in the west". The dextral system is constituted by 2-3 dextral basement faults in NNE-NE trending (F2, F3, F4) and associated structure, and the time of structural action started in Oligocene and continued to Quarternary so that some associated secondary faults of the dextral system cut off the Neogene and Quaternary. Under the influence of the position and attitude of NNE-NE trending basement strike-slip faults, the central north part and the south part of the West Sag show obviously different structural features. The former appears to be a complex "graben" structure limited by the reversed strike-slip fault in the west and bounded by the inverted normal fault in the east, the latter remains the complex half-graben structure with "boundary fault in the east and overlap in the west", and the graben was mildly reconstructed by one or two normal strike-slip faults. The dextral system within the West Sag is the element of the west branch fault of the Tan-Lu Fracture Zone, which is a deep fracture zone extending along the east of the Liaodongwan Gulf. The deep fracture zone branches off into two separate faults within the Liaohe Depression. The east branch goes through from northern part of the Liaodongwan Gulf to the East Sag of Liaohe Depression and links with the Denghua-Mishan Fault near Shenyang, and the west branch passes from northern part of the Liaodongwan Gulf to the West Sag and Damintun Sag of Liaohe Depression and links with the Yilan-Yitong Fault. The principal displacement zone of the west branch of the Tan-Lu Fracture Zone cuts off the master extensional fault (F1) within the West Sag of Liaohe Depression and induces many cover faults in EW trending within the Neogene and Quaternary. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.


Bai D.,Beijing University of Chemical Technology | Chen G.,China University of Petroleum - Beijing | Zhang X.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Langmuir | Year: 2012

Using molecular dynamics simulations on the microsecond time scale, we investigate the nucleation and growth mechanisms of CO 2 hydrates in a water/CO 2/silica three-phase system. Our simulation results indicate that the CO 2 hydrate nucleates near the three-phase contact line rather than at the two-phase interfaces and then grows along the contact line to form an amorphous crystal. In the nucleation stage, the hydroxylated silica surface can be understand as a stabilizer to prolong the lifetime of adsorbed hydrate cages that interact with the silica surface by hydrogen bonding, and the adsorbed cages behave as the nucleation sites for the formation of an amorphous CO 2 hydrate. After nucleation, the nucleus grows along the three-phase contact line and prefers to develop toward the CO 2 phase as a result of the hydrophilic nature of the modified solid surface and the easy availability of CO 2 molecules. During the growth process, the population of sI cages in the formed amorphous crystal is found to increase much faster than that of sII cages, being in agreement with the fact that only the sI hydrate can be formed in nature for CO 2 molecules. © 2012 American Chemical Society.


Meng Q.,China University of Petroleum - Beijing | Liu B.,China University of Petroleum - Beijing | Piao J.,Petrochina | Liu Q.,Petrochina
Journal of Catalysis | Year: 2012

Y/ASA composite was successfully prepared by wrapping NaY zeolite with small-crystal size in amorphous silica-alumina (ASA) gel. Characterization results show that bonding action between zeolite Y and ASA contributes new acid sites in HY/ASA, which are responsible for its higher activity in the catalytic cracking of n-decane and light diesel, comparing with the mixture-derived catalysts. HY/ASA catalyst possesses larger surface area and mesoporous volume and uniform slit-shaped mesopores, which are beneficial to the diffusion of the products and responsible for higher yield of the middle distillates. The smaller zeolite Y crystallites in Y/ASA lead to more contact points between Y crystallites and ASA and thus provide more new acid sites for the HY/ASA catalyst. The high conversion of n-decane and yield of middle distillates over the HY/ASA catalyst can be ascribed to its acid quantity and super pore structure. © 2012 Elsevier Inc. All rights reserved.


Shi Y.,Dalian University of Technology | Li S.,China University of Petroleum - Beijing | Hu H.,Dalian University of Technology
Journal of Analytical and Applied Pyrolysis | Year: 2012

The resources of lignite in Dongsheng, Inner Mongolia Autonomous Region, China are abundant. Because of its low energy density and typically high moisture content, lignite is not utilized extensively compared to higher coal grades. This paper focused on pyrolysis characteristic of lignite and the properties of its pyrolysates. The result demonstrated that comprehensive utilization of Dongsheng lignite can be achieved with in-depth knowledge of property of Dongsheng lignite. The pyrolysis experiments on lignite were carried out using a thermogravimetric analyzer (TGA) at four different heating rates of 10, 15, 20 and 25°C/min and with a final temperature of 600°C. The kinetics model has been developed and the kinetic parameters are determined from TGA data. © 2012 Elsevier B.V. All rights reserved.