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Xu C.,Southwest Petroleum University | Kang Y.,Southwest Petroleum University | Chen F.,China Central Depository & Clearing Co., Ltd. | You Z.,University of Adelaide
Journal of Natural Gas Science and Engineering | Year: 2016

Well-developed natural fractures are beneficial for the economic and efficient development of tight reservoirs. However, they also lead to drill-in fluid loss and induced severe formation damage. Fracture plugging with loss control material (LCM) is the most common way to control lost circulation. Fracture plugging effect largely depends on the fracture propagation pressure, because plugging failure is mainly caused by fracture propagation in fractured formation. Nevertheless, the effects of the plugging parameters on the fracture propagation pressure are still unclear. The current paper develops a mathematical model for fracture propagation pressure accounting for fracture plugging. Key indexes are proposed for fracture plugging optimization based on parameter analysis. Laboratory experiments are conducted to select reasonable LCM type and concentration. The application procedure of the proposed model to drill-in fluid loss control is presented and successfully applied to field case study. The modelling results show that the plugging zone length, width and permeability are the major plugging parameters that affect the fracture propagation pressure. The larger the plugging zone width and the smaller the plugging zone length and permeability, the higher the fracture propagation pressure. Maximum plugging pressure, total loss volume before sealing and D90 degradation rate are proposed as the three indexes for LCM selection. Experimental results show that the combination of rigid granule, fiber and elastic particle can create a synergistic effect to optimize the fracture plugging effect. For the 500 μm width fracture, the optimal concentrations for rigid granule, fiber and elastic particle are 5.0%, 1.5% and 2.5%, respectively. © 2016 Elsevier B.V.

Swinburn B.,University of Auckland | Swinburn B.,Deakin University | Sacks G.,Deakin University | Vandevijvere S.,University of Auckland | And 19 more authors.
Obesity Reviews | Year: 2013

Summary: Non-communicable diseases (NCDs) dominate disease burdens globally and poor nutrition increasingly contributes to this global burden. Comprehensive monitoring of food environments, and evaluation of the impact of public and private sector policies on food environments is needed to strengthen accountability systems to reduce NCDs. The International Network for Food and Obesity/NCDs Research, Monitoring and Action Support (INFORMAS) is a global network of public-interest organizations and researchers that aims to monitor, benchmark and support public and private sector actions to create healthy food environments and reduce obesity, NCDs and their related inequalities. The INFORMAS framework includes two 'process' modules, that monitor the policies and actions of the public and private sectors, seven 'impact' modules that monitor the key characteristics of food environments and three 'outcome' modules that monitor dietary quality, risk factors and NCD morbidity and mortality. Monitoring frameworks and indicators have been developed for 10 modules to provide consistency, but allowing for stepwise approaches ('minimal', 'expanded', 'optimal') to data collection and analysis. INFORMAS data will enable benchmarking of food environments between countries, and monitoring of progress over time within countries. Through monitoring and benchmarking, INFORMAS will strengthen the accountability systems needed to help reduce the burden of obesity, NCDs and their related inequalities. © 2013 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of the International Association for the Study of Obesity.

Xu Z.,Shanghai JiaoTong University | Wang M.,China Central Depository & Clearing Co., Ltd. | Zhao C.,Shanghai JiaoTong University
ICOPE 2015 - International Conference on Power Engineering | Year: 2015

Pool boiling heat transfer performances of metal foams with gradient pore densities have been experimentally investigated in saturated deionized water at atmospheric pressure. Foam materials are copper and nickel, foam porosity is fixed as 0.98, and foam thickness are from 4 mm to 14 mm. The experimental results show that, compared to uniform metal foams, metal foams with gradient pore densities significantly enhance pool boiling heat transfer, but the enhancement degree is affected by foam thickness and material; pool boiling heat transfer performance of metal foam with gradient pore densities decreases with increasing SDS concentration, and adding the surfactant SDS into water makes the CHF reach earlier. Adding Al2O3 nanoparticles severely weakens the pool boiling heat transfer of copper foam with gradient pore densities. © 2015 The Japan Society of Mechanical Engineers.

Aaron G.J.,Global Alliance for Improved Nutrition GAIN | Dror D.K.,U.S. Department of Agriculture | Yang Z.,China Central Depository & Clearing Co., Ltd.
Nutrients | Year: 2015

Multiple-micronutrient (MMN) fortification of beverages may be an effective option to deliver micronutrients to vulnerable populations. The aim of the present systematic review and meta-analysis is to evaluate the nutritional impacts of MMN fortified beverages in the context of low-middle income countries. A systematic search of published literature yielded 1022 citations, of which 10 randomized controlled trials (nine in school-aged children and one in pregnant women) met inclusion criteria. Results of school-aged children were included in the meta-analysis. Compared to iso-caloric controls, children who received MMN fortified beverages for 8 weeks to 6 months showed significant improvements in hemoglobin (+2.76 g/L, 95% CI [1.19, 4.33], p = 0.004; 8 studies) and serum ferritin (+15.42 pmol/L, [5.73, 25.12], p = 0.007; 8 studies); and reduced risk of anemia (RR 0.58 [0.29, 0.88], p = 0.005; 6 studies), iron deficiency (RR 0.34 [0.21, 0.55], p = 0.002; 7 studies), and iron deficiency anemia (RR 0.17 [0.06, 0.53], p = 0.02; 3 studies). MMN fortified beverage interventions could have major programmatic implications for reducing the burden of anemia and iron deficiency in school-aged children in low-middle income countries. Additional research is needed to investigate effects on other biochemical outcomes and population subgroups. © 2015 by the authors; licensee MDPI, Basel, Switzerland.

Mei M.,China Central Depository & Clearing Co., Ltd. | Jiang W.,Shelfoil Petroleum Equipment & Services Co. | Wei Z.,China Central Depository & Clearing Co., Ltd.
Drilling Fluid and Completion Fluid | Year: 2016

An eccentric mechanical vibration cementing technique was used in Changqing oilfield in an effort to improve the cementing job quality of the injector wells. Cementing slurry was evaluated after vibration on a ZD-34 model electric vibrator as to its compressive strength, bond strength, thickening time, initial setting transition time, final setting transition time, and permeability. The evaluated cement slurry was then used in filed operations. The laboratory study showed that the thickening time of the cement slurry after vibration was reduced by 25%-30%, the initial and the final setting transition time reduced by 30%-50%, the 24 h strength of the set cement increased by 10%-14%, the bond strength increased by 11%-16%, and the permeability reduced by 33.3%-43.9%. This technique has been used in 5 wells in the block Wupu in Changqing oilfield, and the oil zones and water zones in these wells are well separated, with the rate of excellent well cement jobs increased by more than 20%. The laboratory experiments and the field applications all demonstrate that the eccentric mechanical vibration cementing technique can effectively enhance the quality of well cementing, and is prospective in future cementing operations. © 2016, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.

Qin Y.,China Central Depository & Clearing Co., Ltd. | Ma K.,China University of Petroleum - Beijing | Jiang G.,China University of Petroleum - Beijing
Drilling Fluid and Completion Fluid | Year: 2016

Hectorite can be used as a high temperature viscosifier in water base drilling fluids, and it is a rare mineral found in nature. A hectorite has been successfully synthesized in laboratory using microwave irradiation method and characterized with XRD, FTIR and particle size distribution analysis. The performance of the synthesized hectorite in water base drilling fluid has been evaluated. The particle sizes of the synthesized hectorite falls in the range between 18.17 nm and 58.77 nm, averaged at 29.72 nm. 4% bentonite slurry treated with 0.3% - 1.5% synthesized hectorite, has viscosity, gel strength and YP/PV ratio remarkably increased, and filter loss reduced. When the concentration of hectorite is 1.2%, the viscosity of the slurry is increased by 2.64 times, while the gel strength and YP/PV ratio still remains moderate. The bentonite slurry treated with 1.5% hectorite can resist the contamination of calcium (2.5%) and salt (15%). With temperatures increased from 80℃ to 220℃, the apparent viscosity of the 4% bentonite slurry + 1.5% hectorite decreases followed by an increase, and finally remains at above 20 mPa · s. The gel strength and YP/PV ratio changes at a same pattern as that of apparent viscosity, but with remarkable decreases at first. At 200℃, almost all conventional polymers lose their efficiency as viscosifiers in water base drilling fluid, while hectorite is still functioning. Thus the synthesized hectorite is an ideal viscosifier for use in high temperature water base drilling fluid, and is well compatible with other additives. © 2016, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.

Zhang H.,China National Petroleum Corporation | Wang D.,China Central Depository & Clearing Co., Ltd. | Hu L.,Petrochina
Drilling Fluid and Completion Fluid | Year: 2016

In running the φ177.8 mm liner string in well Moxi009-4-x2, many difficulties have been expected to be encountered, such as high bottom hole temperature, long cementing section, long and active oil and gas shows, drilling fluid of high density that are severely contaminated, and decreased mud density in the next interval, etc. To deal with these difficulties, a high strength high density anti-gas-migration cement slurry and a high performance contamination-resistant spacer fluid have been developed based on the choice of weighting materials and studies on these issues such as the mechanisms of enhancing the toughness of set cement through expansion, the mechanism of cement slurry contamination, and the optimization of cementing techniques. With the cement slurry, the spacer, and the corresponding techniques, the development of the strength of the top cement slurry has been accelerated, and the toughness of the high density set cement has been improved. The contamination of cement slurry and drilling fluid has been minimized, and the bond strengths of set cement with casing string and borehole wall have been enhanced. 94.5% of the liner string cemented has been up to the standard, and the merit factor of cementing job has reached 74.8%. This cementing technology provides a support for the improvement of the quality of well cementing in the area, and a guarantee for the safe and efficient development of the deep high pressure wells in Anyue gas field. © 2016, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.

Luo M.,China University of Petroleum - East China | Jia Z.,China University of Petroleum - East China | Sun H.,China University of Petroleum - East China | Liao L.,China Central Depository & Clearing Co., Ltd. | Wen Q.,China University of Petroleum - East China
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012

The rheological behavior and microstructure of anionic fatty acid methyl ester sulfonate sodium (MES) surfactant micelle solution with pyroelectric nanoparticle were investigated by dynamic light scattering (DLS), freeze-fracture transmission electron microscopy (FF-TEM) and rheological measurement. The formation of wormlike micelle due to salt addition was observed and the nanoparticle can accelerate the micelle growth and entanglement with each other. The effect of concentration of surfactant, added salt and pyroelectric barium titanate (BaTiO 3) nanoparticle were investigated, respectively. The viscosity of MES micelle solution increases with the temperature rise within a certain range because of the pyroelectric effect of nanoparticles. At low temperature (∼25°C), the sample with 0.6wt.% nanoparticle behaves like an elastic gel with an infinite relaxation time and viscosity. The change of microstructure and rheological properties for MES viscoelastic micelle solutions may be attributed to the electrostatic interaction and pseudo-crosslinking between micelles and nanoparticles. MES viscoelastic micelle solution can retain high viscosity at elevated temperature due to nanoparticle addition and has very attractive for reservoir stimulation and enhanced-oil-recovery in higher temperature reservoirs. © 2011 Elsevier B.V.

LIN Y.,Southwest Petroleum University | DENG K.,Southwest Petroleum University | SUN Y.,Southwest Petroleum University | ZENG D.,China Central Depository & Clearing Co., Ltd. | XIA T.,China National Petroleum Corporation
Petroleum Exploration and Development | Year: 2016

The unified algorithm of through-wall yield collapse pressure for casing with due consideration of strength differential (SD), yield-to-tensile strength ratio, material hardening and intermediate principal stress, which is suitable to calculate collapse strength of all casing has been obtained based on unified strength theory, and four classical through-wall yield collapse formulas of casing have been presented based on the L. Von Mises, TRESCA, GM and twin yield strength criterion. The calculated value is maximum based on the twin yield strength criterion, which can be used as upper limit of through-wall yield collapse pressure, and the calculated value is minimum based on the TRESCA strength criterion, which can be used as lower limit of through-wall yield collapse pressure in the design process. Numerical and experimental comparisons show that the equation proposed by this paper is much closer to the collapse testing values than that of other equations. © 2016 Research Institute of Petroleum Exploration & Development, PetroChina

Wensheng W.,China University of Petroleum - Beijing | Wei N.,China University of Petroleum - Beijing | Li L.,China Central Depository & Clearing Co., Ltd.
Geophysics | Year: 2013

Because of the effects of background and measurement environment and multiplet effects of different elements, high-precision analysis of mixed capture γ-ray energy spectra of complicated formations remains challenging for geochemical elemental logging. The direct demodulation (DD) method makes full use of the measured data information, enabling physical constraints to be rationally applied to the spectral analysis process, and can yield high-precision elemental content from poor-statistics, low signal-to-noise ratio, and disturbed data. We construct mixed formations of different sandstones and limestones, mixed formations of sandstone and anhydrite, and more complicated mixed formations of multiple lithologies and employ Monte Carlo numerical simulations to obtain the neutron-capture γ-ray energy spectra of these mixed formations. We then employ the DD method and the weighted-least-squares (WLS) method to analyze quantitatively such mixed spectra, respectively, and compare the results with the actual contents of formation elements. The results indicate that the DD method offers higher precision spectral analysis compared with the results of the WLS method. The results for the capture γ-ray energy spectra of the formation for two actual wells also indicate that the DD method can be useful for spectral analysis in actual application. © 2014 Society of Exploration Geophysicists.

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