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Liao W.-Z.,National Central University | Lin A.T.,National Central University | Liu C.-S.,National Taiwan University | Oung J.-N.,CPC Corporation Taiwan | Wang Y.,Central Geological Survey
Journal of Asian Earth Sciences | Year: 2014

Temperature measurements carried out on 9 hydrocarbon exploration boreholes together with Bottom Simulating Reflectors (BSRs) from reflection seismic images are used in this study to derive geothermal gradients and heat flows in the northern margin of the South China Sea near Taiwan. The method of Horner plot is applied to obtain true formation temperatures from measured borehole temperatures, which are disturbed by drilling processes. Sub-seafloor depths of BSRs are used to calculate sub-bottom temperatures using theoretical pressure/temperature phase boundary that marks the base of gas hydrate stability zone. Our results show that the geothermal gradients and heat flows in the study area range from 28 to 128°C/km and 40 to 159mW/m2, respectively. There is a marked difference in geothermal gradients and heat flow beneath the shelf and slope regions. It is cooler beneath the shelf with an average geothermal gradient of 34.5°C/km, and 62.7mW/m2 heat flow. The continental slope shows a higher average geothermal gradient of 56.4°C/km, and 70.9mW/m2 heat flow. Lower heat flow on the shelf is most likely caused by thicker sediments that have accumulated there compared to the sediment thickness beneath the slope. In addition, the continental crust is highly extended beneath the continental slope, yielding higher heat flow in this region. A half graben exists beneath the continental slope with a north-dipping graben-bounding fault. A high heat-flow anomaly coincides at the location of this graben-bounding fault at the Jiulong Ridge, indicating vigorous vertical fluid convection which may take place along this fault. © 2014 Elsevier Ltd.

Su W.-B.,CPC Corporation Taiwan | Chang T.-K.,CPC Corporation Taiwan | Hwang J.-H.,CPC Corporation Taiwan | Huang H.-Y.,CPC Corporation Taiwan
Journal of the Taiwan Institute of Chemical Engineers | Year: 2015

The trickle-bed reactor model proposed by Mostoufi et al. was rebuilt for use in commercial software, Aspen Plus®. Coupling with thirty hydrogenation rate equations, the process model could simulate a pyrolysis gasoline hydrogenation unit. With an optimization procedure, the thirty rate constants were obtained after minimizing the relative-concentration-based objective function. In this work, the hydrodynamic parameters including physical properties were simultaneously calculated from the software platform according to the reactor conditions, such as temperature, concentration, etc. Therefore, the effect of parameter variation can be avoided not only along the catalyst bed, but also at the start of run and end of run. This semi-empirical method can be applied to highly exothermic hydrogenation reactor models, and then used it to estimate residue catalyst activity much more theoretically than the weighted average bed temperature method and interpret plant data more in practice, for example, bed temperature profile and its deviation, the relationship between the throughput and pressure drop. © 2015 Taiwan Institute of Chemical Engineers.

Cheng T.-W.,National Taiwan University | Chang Y.-H.,National Taiwan University | Tang S.-L.,Academia Sinica, Taiwan | Tseng C.-H.,Academia Sinica, Taiwan | And 10 more authors.
ISME Journal | Year: 2012

Terrestrial mud volcanism represents the prominent surface geological feature, where fluids and hydrocarbons are discharged along deeply rooted structures in tectonically active regimes. Terrestrial mud volcanoes (MVs) directly emit the major gas phase, methane, into the atmosphere, making them important sources of greenhouse gases over geological time. Quantification of methane emission would require detailed insights into the capacity and efficiency of microbial metabolisms either consuming or producing methane in the subsurface, and establishment of the linkage between these methane-related metabolisms and other microbial or abiotic processes. Here we conducted geochemical, microbiological and genetic analyses of sediments, gases, and pore and surface fluids to characterize fluid processes, community assemblages, functions and activities in a methane-emitting MV of southwestern Taiwan. Multiple lines of evidence suggest that aerobicanaerobic methane oxidation, sulfate reduction and methanogenesis are active and compartmentalized into discrete, stratified niches, resembling those in marine settings. Surface evaporation and oxidation of sulfide minerals are required to account for the enhanced levels of sulfate that fuels subsurface sulfate reduction and anaerobic methanotrophy. Methane flux generated by in situ methanogenesis appears to alter the isotopic compositions and abundances of thermogenic methane migrating from deep sources, and to exceed the capacity of microbial consumption. This metabolic stratification is sustained by chemical disequilibria induced by the mixing between upward, anoxic, methane-rich fluids and downward, oxic, sulfate-rich fluids. © 2012 International Society for Microbial Ecology All rights reserved.

Sun C.-H.,CPC Corporation Taiwan | Chang S.-C.,CPC Corporation Taiwan | Kuo C.-L.,CPC Corporation Taiwan | Wu J.-C.,CPC Corporation Taiwan | And 2 more authors.
Journal of Asian Earth Sciences | Year: 2010

The supply of natural gas from mud volcanoes is commonly attributed to the migration of gas-bearing fluids from a deeper source area. However, the relative importance of these gas sources is not well known. Onshore mud volcanoes in Taiwan are mainly located in the Foothills of southwestern Taiwan and in the Coastal Range of eastern Taiwan, generally along structurally weak zones. Geochemical analyses of gases and sediments from 17 mud volcanoes were undertaken in this study. Using molecular and stable isotopic compositions, hydrocarbon gases were characterized by type and source maturity. Source rock assessments and nanofossil analyses were carried out to evaluate the potential, and to infer the origin of sediments. A particular effort was directed towards determining the genetic relationships between mud volcanic gas and associated sediments. Gases from Taiwan's mud volcanoes are predominantly CH4-enriched, with the exception of a few mud volcanoes where CO2 predominates. The origins of hydrocarbon gases in these systems range from microbial to thermally over-mature sources; while, excess CO2 may be derived from an inorganic origin as indicated by measured δ13CCO2 values. The integration of geochemistry and local geology has yielded models with which to evaluate possible mechanisms for the formation of mud volcanoes. © 2009 Elsevier Ltd. All rights reserved.

Kung S.-L.,National Cheng Kung University | Lewis C.,National Cheng Kung University | Wu J.-C.,CPC Corporation Taiwan
Journal of Geophysics and Engineering | Year: 2013

In clastic and carbonate rock sequences, the neutron and sonic log curves usually deflect in a similar fashion. Moreover, in some cases the two curves can be overlain and they generally appear to mimic each other, with variations between them only in the amplitudes of the two curves. This descriptive correlation is the basis of direct cross-plot techniques used to convert a neutron log into a pseudo-sonic log, which can then be combined with a density log to create a pseudo-synthetic seismogram. Unfortunately, the seismograms produced in this way may not match the standard synthetic seismograms produced from the sonic and density logs if the 'gas effect' is not taken into account. In order to correct for the gas effect, the inter-log correlations between the compensated neutron log (CNL) and the borehole-compensated (BHC) sonic log curves from a well in Taiwan were carefully examined. Then, we developed a technique for transforming the CNL log into a pseudo-BHC log by splicing together several continuous sandstone intervals in which the gas effect could be identified from the scattered data on the cross-plot of neutron porosity versus sonic interval transit time. Based upon our results, application of the new composite transform method yields a pseudo-synthetic seismogram that better matches the standard synthetic seismogram (made from the sonic and density logs) according to frequency, amplitude and polarity. This gas correction technique may be particularly useful in oil and gas exploratory and development areas where neutron logs are more prevalent than sonic logs or where sonic logs are scarce. © 2013 Sinopec Geophysical Research Institute.

Shen C.-H.,National Cheng Kung University | Hsieh B.-Z.,National Cheng Kung University | Tseng C.-C.,CPC Corporation Taiwan | Chen T.-L.,CPC Corporation Taiwan
Energy Procedia | Year: 2014

The purpose of this modelling study is to investigate the combined contributions of CO2-IGR and CO2 storage in a nearly depleted gas-condensate reservoir, Taiwan. The estimation of the storage potential of a depleted gas condensate reservoir, the evaluation of the economic benefits from the CO2-improved gas recover (IGR), and the determination of the best operating strategy for maximizing economic benefits were studied. After the CO2 mixed with the natural gas, the two-phase envelope shrinkage was noticed in the Pressure-Temperature (P-T) diagram for CO2-IGR phase in the reservoir. The mechanisms of CO2 displacement and condensate revaporization contributed to the gas recovery. Due to the gravity, the stored CO2 sank to the bottom of the gas cap; consequently, and the injected CO2 can be stored permanently. The best economic scenario for this case study, which had the highest net present value (NPV) of US $18.7 million, was to use one down-dip injection well with an injection rate of 30,000 standard cubic meters (SCM)/day and a discount rate of 10%. The analysis of the principal components of the economic assessment showed that the benefit of CO2-IGR was highly sensitive to the cost of CO2 capture, and that the carbon tax incentive had a positive effect on the economic benefit of the Carbon Capture, Utilization, and Storage (CCUS) method. © 2014 The Authors. Published by Elsevier Ltd.

Chang Y.-H.,National Taiwan University | Cheng T.-W.,National Taiwan University | Lai W.-J.,National Taiwan University | Tsai W.-Y.,National Taiwan University | And 3 more authors.
Environmental Microbiology | Year: 2012

Microbial communities responsible for methane cycling in mud volcanoes onshore are poorly characterized. This study analysed bubbling fluids and cored sediments retrieved from a mud volcano in eastern Taiwan. The pore water profiles revealed that methane concentrations generally increased with depth and changed dramatically at different depth intervals at different sites. The methane concentrations were inversely correlated with Fe 2+/Mn 2+ concentrations and δ 13C values of methane, marking iron/manganese-methane transition zones in the sediment cores. Archaeal communities were dominated by ANME-2a members and methylotrophic methanogens, whereas bacterial communities consisted primarily of Proteobacteria, Firmicutes and Bacteroidetes. The 16S rRNA gene copy numbers of ANME-2a and Desulfuromonas/Pelobacter populations varied by two to three orders of magnitude along the profile and exhibited a pattern comparable with those of Fe 2+ and δ 13C values of methane. These lines of evidence suggest a coupling between anaerobic methanotrophy and metal reduction in the metal-methane transition zones under sulfate-deficient conditions, a metabolic scheme contrasting with that observed in marine cold seeps. Anaerobic methanotrophs proliferate by removing methane produced from in situ methanogenesis and originating from the deep source. Methane finally emitted into the atmosphere is quantitatively and isotopically altered by various microbial processes compartmentalized at different depth intervals. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

CPC Corporation Taiwan and AMT International Inc. | Date: 2010-04-24

A highly effective liquid-liquid extraction process to remove nitrogen compounds and especially basic nitrogen compounds from aromatic light petroleum oils with excellent recovery employs de-ionized water, which can be acidified, as the extractive solvent. The product is an aromatic hydrocarbon with ultra-low amounts of nitrogen poisons that can deactivate acidic catalysts. The extracted oils are suitable feedstock for the subsequent catalytic processes that are promoted with the high performance solid catalysts, which are extremely sensitive to nitrogen poison.

CPC Corporation Taiwan | Date: 2011-01-14

Deasphalted residual oil (DAO) and the aromatics-rich extract that is derived from DAO have low polycyclic aromatics contents, relatively low aniline points, and high flash points. They form blending stocks that improve properties of mixed feedstocks to consistently produce environmentally qualified rubber processing oil (RPO) by extraction under low solvent-to-oil ratios and moderate extraction temperatures. Distilling a petroleum crude oil under atmospheric pressure generates a bottom residual oil which is then subject to vacuum distillation to yield a bottom residual oil. DAO is produced by removing the asphalt from the vacuum bottom residual oil through extraction with light paraffinic solvent. The extract of DAO is a co-product in the production of the bright stock of the lubricating oil through extraction. The feedstock is mixed with the extract from a petroleum fraction boiling in lube oil range. Liquid-liquid counter-current extraction yields a raffinate stream; removal of solvent therefrom produces the RPO.

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