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Distribution and fractionation mechanism of stable carbon isotope of coalbed methane

Science china Earth Sciences 2006年第12期49卷 1252-1258页

作者： QIN Shengfei1, TANG Xiuyi2, SONG Yan1 & WANG Hongyan3.1. research institute of petroleum {3. and Development, petrochina, Beijing 100083. china 2. Anhui Science and Technology College, Huainan 23.000, china 3. langfang branch, research institute of petroleum {3. and Development, petrochina, langfang 065007, china 1. research institute of petroleum {3. and Development PetroChina Beijing 100083 China 2. Anhui Science and Technology College Huainan 232000 China 3. langfang branch Research Institute of Petroleum Exploration and Development PetroChina Langfang 065007 China

The stable carbon isotope values of coalbed methane range widely, and also are gener- ally lighter than that of gases in normal coal-formed gas fields with similar coal rank. There exists strong carbon isotope fractionation in coalbed methane and it makes the carbon isotope value lighter. The correlation between the carbon isotope value and Ro in coalbed methane is less obvious. The coaly source rock maturity cannot be judged by coalbed methane carbon isotope value. The carbon isotopes of coalbed methane become lighter in much different degree due to the hydrodynamics. The stronger the hydrodynamics is, the lighter the CBM carbon isotopic value becomes. Many previous investigations indicated that the desorption-diffusion effects make the carbon isotope value of coalbed methane lighter. However, the explanation has encountered many problems. The authors of this arti- cle suggest that the flowing groundwater dissolution to free methane in coal seams and the free methane exchange with absorbed one is the carbon isotope fractionation mechanism in coalbed methane. The flowing groundwater in coal can easily take more 13.H4 away from free gas and com- paratively leave more 12CH4. This will make 12CH4 density in free gas comparatively higher than that in absorbed gas. The remaining 12CH4 in free gas then exchanges with the adsorbed methane in coal matrix. Some absorbed 13.H4 can be replaced and become free gas. Some free 12CH4 can be ab- sorbed again into coal matrix and become absorbed gas. Part of the newly replaced 13.H4 in free gas will also be taken away by water, leaving preferentially more 12CH4. The remaining 12CH4 in free gas will exchange again with adsorbed methane in the coal matrix. These processes occur all the time. Through accumulative effect, the 12CH4 will be greatly concentrated in coal. Thus, the stable carbon isotope of coalbed methane becomes dramatically lighter. Through simulation experiment on wa- ter-dissolved methane, it had been proved that the f

关键词： coalbed methane,methane stable carbon isotope,fractionation mechanism,accumulative effect.

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Structural characteristics and petroliferous features of Tarim Basin

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Chinese Science Bulletin 2002年第S1期47卷 1-11页

作者： JIA Chengzao~1 & WEI Guoqi~2 1. petrochina Company Limited, Beijing 100011, china 2. langfang {3. of research institute of petroleum exploration & Development, petrochina, langfang 065007, china 1. petrochina Company Limited 100011 Beijing China 2. langfang branch of research {3. of petroleum exploration & Development PetroChina 065007 Langfang China

Using the modern tectonic geology theories andmethods such as the plate tectonic analysis, the paleo-struc-ture analysis, the structural-Iithofacies analysis, and the faultrelated fold and petroleum system, and combining with theseismic data, well drilling data and the circumferential fieldgeology, study on the structural characteristics and petro-leum prospect in the Tarim Basin has been carried out. Re-sults show that the Tarim Basin is a large superimpositionand combination basin with continental crustal basement,composed of a Paleozoic craton and Meso-Cenozoic forelandbasins. The characteristics of the basin are: the kernel partof the basin is the marine facies Paleozoic craton, superim-posed 4 continental facies foreland basins. Though the scaleof the paleozoic craton of the Tarim Basin is relatively small,the structure is steady. The petroleum prospect of the Paleo-zoic craton is: multiphase pool-generation and accumulationcontrolled by ancient uplift. The Meso-Cenozoic forelandbasins in the Tarim Basin, which are distributed on the era-tonic circumference and are a long-term subsidence, turnedinto rejuvenated foreland basins after the Meso-Cenozoicperiod. The petroleum prospects are: coal-bed generatinghydrocarbon, abundant natural gas, pool-generation in laterand recent periods, the oil and gas distribution controlled bythe foreland thrust belt. The structural characteristics ofTarim provide it with a superimposition and combinationpetroleum system of multiple resources, multiple reservoirsand multiphase pool-generation. The oil and gas explorationprospect covers two large fields: the Paleozoic craton and theMeso-Cenozoic foreland thrust belt.

关键词： Tarim superimposition and combination basin craton foreland basin superimposition and combination petroleum system.

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Natural gas geochemistry and its origins in Kuqa depression

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Science china Earth Sciences 2008年第S1期51卷 174-182页

作者： LIU QuanYou 1 ,QIN ShengFei 1 ,LI Jian 2 ,LIU WenHui 3.,ZHANG DianWei 3.,ZHOU QingHua 1 &HU AnPing 1 1 research institute of petroleum {3. and Development,petrochina,Beijing 100083.china 2 langfang branch of research institute of petroleum {3. and Development,petrochina,{13.,china 3.{3. and Production research institute,SINOPEC,Beijing 100083.china petrochina Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China petrochina Langfang Branch Res Inst Petr Explorat & Dev Langfang 065007 Peoples R China SINOPEC Explorat & Prod Res Inst Beijing 100083 Peoples R China

According to gas compositional and carbon isotopic measurement of 114 gas samples from the Kuqa depression,accumulation of the natural gases in the depression is dominated by hydrocarbon gases, with high gas dryness(C1/C1-4)at the middle and northern parts of the depression and low one towards east and west sides and southern *** carbon isotopes of methane and its homologues are relatively enriched in 13.C,and the distributive range ofδ13. 1 ,δ13. 2 andδ13. 3.is-3.‰―-3.‰,-22‰―-24‰and-20‰―-22‰,*** general,the carbon isotopes of gaseous alkanes become less negative with the increase of carbon ***δ13. CO2 value is less than-10‰in the Kuqa depression,indicating its organogenic *** distributive range of 3.He/ 4 He ratio is within n×10-8 and a decrease in 3.He/ 4 He ratio from north to south in the depression is *** on the geochemical parameters of natural gas above,natural gas in the Kuqa depression is of characteristics of coal-type gas *** possible reasons for the partial reversal of stable carbon isotopes of gaseous alkanes involve the mixing of gases from one common source rock with different thermal maturity or from two separated source rock intervals of similar kerogen type,multistages accumulation of natural gas under high-temperature and over-pressure conditions,and sufficiency and diffusion of natural gas.

关键词： Kuqa depression natural gas stable carbon isotope gas origin

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Geochemical characteristics and origin of gases from the Upper,Lower Paleozoic and the Mesozoic reservoirs in the Ordos Basin,china

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Science china Earth Sciences 2008年第S1期51卷 183-194页

作者： HU AnPing 1 ,Li Jian 2 ,ZHANG WenZheng 3.,LI ZhiSheng 2 ,HOU Lu 4 &LIU QuanYou 5 1 Department of Earth Sciences,Zhejiang University,Hangzhou 3.0027,china 2 langfang branch,Reasearch {3. of petroleum exploration and Development,petrochina,langfang 065007,china 3.{3. of exploration and Development,petrochina Changqing Oilfield Company,Xi’an 710021,china 4 University of petroleum,Beijing102249,china 5 petrochina research {3. of petroleum exploration and Development,Beijing 100083.china 1. Department of Earth Sciences Zhejiang University Hangzhou 310027 China2. Langfang Branch Reasearch Institute of Petroleum Exploration and Development PetroChina Langfang 065007 China3. Institute of Exploration and Development PetroChina Changqing Oilfield Company Xi’an 710021 China4. University of Petroleum Beijing 102249 China5. PetroChina Research Institute of Petroleum Exploration and Development Beijing 100083 China

The Ordos Basin,the second largest sedimentary basin in china,contains the broad distribution of natural gas *** far,several giant gas fields have been discovered in the Upper and Lower Paleozoic in this basin,each having over 1000×10 8 m 3.of proven gas reserves,and several gas pools have also been discovered in the *** paper collected the data of natural gases and elucidated the geochemical characteristics of gases from different reservoirs,and then discussed their *** hydrocarbons preserved in the Upper Paleozoic,the elevatedδ13. values of methane,ethane and propane indicate that the gases would be mainly coal-formed gases;the singular reversal in the stable carbon isotopes of gaseous alkanes suggests the mixed gases from humic sources with different *** the Lower Paleozoic,theδ13. 1 values are mostly similar with those in the Upper Paleozoic,but theδ13. 2 andδ13. 3.values are slightly lighter,suggesting that the gases would be mixing of coal-type gases as a main member and oil-type *** are multiple reversals in carbon isotopes for gaseous alkanes,especially abnormal reversal for methane and ethane(i.e.δ13. 1 >δ13. 2 ),inferring that gases would be mixed between high-mature coal-formed gases and oil-type *** the Mesozoic,the δ13.values for gaseous alkanes are enriched in 12C,indicating that the gases are mainly derived from sapropelic sources;the carbon isotopic reversal for propane and butane in the Mesozoic is caused by microbial oxidation and mixing of gases from sapropelic sources with different *** contrast to the Upper Paleozoic gases,the Mesozoic gases are characterized by heavier carbon isotopes of iso-butane than normal butane,which may be caused by gases generated from different kerogen types. Finally,according toδ13. 1 -Ro relationship and extremely low total organic carbon contents,the Low Paleozoic gases would not be generated from the Ordovician source as a main gas source,bycontrast, the Upper Pale

关键词： Ordos Basin natural gas chemical composition carbon isotope genesis

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Preliminary study on the origin identification of natural gas by the parameters of light hydrocarbon

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Science china Earth Sciences 2008年第S1期51卷 131-139页

作者： HU GuoYi 1,2,3.,LI Jian 1,2 ,LI Jin 1,2 ,LI ZhiSheng 1,2 ,LUO Xia 1,2 ,SUN QingWu 1,2 &MA ChengHua 1,2 1 research institute of petroleum {3. and Development(langfang branch),petrochina,langfang 065007,china 2 The Key Laboratory of Gas Formation and Development,petrochina,langfang 065007,china 3.College of Geo-Resources and Information,china University of petroleum,Beijing 102200,china petrochina Res Inst Petr Explorat & Dev Langfang Branch Langfang 065007 Peoples R China petrochina Key Lab Gas Format & Dev Langfang 065007 Peoples R China china Univ Petr Coll Georesources & Informat Beijing 102200 Peoples R China

The light hydrocarbon composition of 209 natural gas samples and individual light hydrocarbon carbon isotopes of 53.natural gas samples from typical humic-sourced gas and sapropelic-sourced gas in the four basins of china have been determined and *** identification parameters for humic-sourced gas and sapropelic-sourced gas are proposed or *** differences of compound-specificδ13. value of individual light hydrocarbon between humic-sourced gas and sapropelic-sourced gas have been *** humic-sourced gas has the distribution ofδ13. benzene > -24‰,δ13. toluene >-23.,δ13. cyclohexane >-24‰andδ13. methyl cyclohexane >-24‰,while the sapropelicsourced gas has the distribution ofδ13. benzene 24‰,δ13. toluene 24‰,δ13. cyclohexane 24‰and δ13. methyl cyclohexane 24‰.Among the components of C7 light hydrocarbon compound,such as normal heptane(nC7),methyl cyclohexane(MCH)and dimethyl cyclopentane(ΣDMCP),etc,relative contents of nC7 and MCH are influenced mainly by the source organic matter type of natural ***,it is suggested that the gas with relative content of nC7 of more than 3.%and relative content of MCH of less than 70%is sapropelic-sourced gas,while gas with relative content of nC7 of less than 3.%and relative content of MCH of more than 50%is humic-sourced *** components of C5-7 aliphatics, the gas with relative content of C5-7 normal alkane of more than 3.%is sapropelic-sourced gas,while the gas with relative content of C5-7 normal alkane of less than 3.%is humic-sourced *** paremeters have been suggested to identify humic-sourced gas and sapropelic-sourced gas.

关键词： natural gas humic-sourced gas sapropelic-sourced gas carbon isotope light hydrocarbon parameters

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The special sealing mechanism of caprock for Quaternary biogenetic gas in Sanhu area,Qaidam Basin,china

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Science china Earth Sciences 2008年第S1期51卷 45-52页

作者： LI Jian 1 ,YAN QiTuan 1 ,ZHANG Ying 1 ,LIU GuangDi 2 &WANG XiaoBo 1 1 research institute of petroleum {3. and Development-langfang,langfang 065007,china 2 University of petroleum,Beijing 102249,china Res Inst Petr Explorat & Dev Langfan Langfang 065007 Peoples R China Univ Petr Beijing 102249 Peoples R China

The Quaternary biogenetic gas reservoirs in the east of Qaidam Basin have many characteristics such as late forming time,shallow burial depth,low diagenetic grade,high porosity and high permeability and so *** cannot be considered as caprock according to the traditional evaluation ***, the large scale and high efficient biogenetic gas reservoirs of the Qaidam Basin are really formed under these kinds of caprocks,so it does have some specialty in its sealing *** at the special sealing mechanism,some simulating experiments have been *** research results show that the sealing ability of biogenetic gas caprock is related with water saturation,the caprock that is saturated with salt water can effectively block seepage and ***,the multiple reservoir-caprock groups have accumulated sealing effect,causing the formation of big gas *** evaluation method with traditional caprock parameters cannot be adopted in evaluating the study area.

关键词： Qaidam Basin biogenetic gas caprock sealing mechanism diffusion water saturation accumulated sealing

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Geochemical characteristics of pyrolysis gas from epimetamorphic rocks in the northern basement of Songliao Basin,Northeast china

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Science china Earth Sciences 2008年第S1期51卷 140-147页

作者： YANG Chun 1 ,LUO Xia 2 ,LI Jian 2 ,LI ZhiSheng 2 ,LIU QuanYou 3.&Wang YuLin 4 1 Department of Earth Sciences,Zhejiang University,Hangzhou 3.0027,china 2 research institute of {3. exploration and Development(langfang branch),langfang 065007,china 3.research institute of {3. exploration and Development,Beijing 100083.china 4 Department of Source and Environment,Liaoning Technical University,Fuxin 123.00,china Zhejiang Univ Dept Earth Sci Hangzhou 310027 Peoples R China Res Inst Petr Explorat & Dev Langfang Branch Langfang 065007 Peoples R China Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China Liaoning Tech Univ Dept Source & Environm Fuxing 123000 Peoples R China

The Xushen gas field,located in the north of Songliao Basin,is a potential giant gas area for china in the *** proved reserves have exceeded 1000×10 8 m 3.by the end of ***,the origin of natural gases from the deep strata is still in *** rocks as a potential gas source are widely spreading in the northern basement of Songliao *** to pyrolysis experiments for these rocks in the semi-confined system,gas production and geochemistry of alkane gases are discussed in this *** Carboniferous-Permian epimetamorphic rocks were heated from 3.0℃to 550℃,with temperature interval of 50℃.The gas production was quantified and measured for chemical and carbon isotopic *** show thatδ13. 1 is less than?20‰,carbon isotope trend of alkane gas isδ13. 1 3. 2 3. 3.orδ13. 1 3. 2 >δ13. 3.,these features suggest that the gas would be coal-type gas at high-over maturity,not be inorganic gas with reversal trend of gaseous alkanes (δ13. 1 >δ13. 2 >δ13. 3.).These characteristics of carbon isotopes are similar with the natural gas from the basin basement,but disagree with gas from the Xingcheng ***,the mixing gases from the pyrolysis gas with coal-typed gases at high-over maturity or oil-typed gases do not cause the reversal trend of carbon *** gas generation intensity for epimetamorphic rocks is 3.0×10 8 ―23.8×10 8 m 3./km 2 ,corresponding to Ro from 2.0%to 3.5%for organic matter.

关键词： Northern Songliao Basin epimetamorphic rock pyrolysis experiment gas generation potential carbon isotope

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Timing and history of marine hydrocarbon accumulation in Tarim craton

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Chinese Science Bulletin 2002年第S1期47卷 120-127页

作者： ZHAO Jingzhou~(1,2) & LI Qiming~3.1. Department of petroleum Geology, Xi’an petroleum institute, Xi’an 710065, {3. 2. research institute of petroleum exploration and Development, petrochina, Beijing 100083. {3. 3. Tarim Oilfield Company, Kuerle, Xinjiang 841000, {3. Xian Petr Inst Dept Petr Geol Xian 710065 Peoples R China petrochina Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China Tarim Oilfield Co Xinjiang 841000 Peoples R China

Based on the analyses of hydrocarbon inclu-sions, K-Ar dating of authigenic illites and oil/gas-watercontact retrospection as well as other methods, the marineprimary reservoirs in the cratonic region of the Tarim Basinare found to have been formed in the late Caledonian toearly Hercynian, late Hercynian, and Himalayan, and oil andgas adjusted and redistributed in the Yanshanian (Jurassic toCretaceous) and Himalayan (Tertiary). The analyses alsoshow that the remaining primary oil accumulations aremostly formed in the late Hercynian, and the secondary oilreservoirs resulted from the adjustment and redistribution ofthe earlier accumulations during the Yanshanian and Hima-layan (especially late Himalayan), of which the Himalayan isalso the major stage of gas accumulation. The primary oilreservoirs formed in the late Hercynian mostly occur withinthe Paleozoic formation, whereas the secondary reservoirsformed in the Himalayan in the Mesozoic. The late adjust-ment and redistribution of reservoirs in the craton region ofthe Tarim Basin is ubiquitous because of the intensified tec-tonic movements since the Mesozoic, especially Cenozoic andintrusion of the high- to over-mature gas. Furthermore, thelower amplitude of reservoirs in the craton region also makesthem easier to be adjusted and redistributed. Therefore, theremaining paleo-uplift and palaeo-slope developed in rela-tively stable tectonic regions are the main potential areas forthe middle-large marine reservoirs in the Tarim Basin.

关键词： Tarim Basin craton geochronology of hydrocarbon accumulation history of hydrocarbon accumulation marine reservoir primary reservoir secondary reservoir.

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Sequence stratigraphic framework and distribution of depositional systems for the Paleogene in Liaodong Bay area

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Science china Earth Sciences 2008年第S2期51卷 1-10页

作者： ZHU XiaoMin1,DONG YanLei1,YANG JunSheng1,ZHANG Qin1,LI DeJiang2,XU ChangGui3.& YU Shui3.1 National Key Laboratory of petroleum Resources and Prospecting,china University of petroleum,Beijing 102249,china 2 research institute of petroleum exploration and Development——langfang,petrochina,langfang 065007,china 3.Technology Department of CNOOC Tianjin Company,Tianjin 3.0452,china china Univ Petr Natl Key Lab Petr Resources & Prospecting Beijing 102249 Peoples R China petrochina Res Inst Petr Explorat & Dev Langfang Langfang 065007 Peoples R China CNOOC Tianjin Co Dept Technol Tianjin 300452 Peoples R China

With a comprehensive geological and geophysical data base,the Paleogene in the Liaodong Bay area,which consists of the Kongdian,Shahejie and Donghying Formations from the base to top,was divided into 4 second-order sequences and 8 third-order sequences based on the characteristics of the se-quence boundaries. Each third-order sequence is subdivided into the lowstand,lake transgressive and highstand systems tracts. The Lowstand systems tract (LST) is mainly composed of progradational parasequence sets,while the lake transgressive systems tract (TST) largely consists of the retrograda-tional parasequence sets and the highstand systems tract (HST) is dominated by the progradational parasequence sets. The main types of depositional systems include the shallow lake,semi-deep lake,deep lake,delta,fan delta,braided fluvial delta and nearshore subaqueous fan. The braided fluvial delta and fan delta depositional systems are mainly confined to the sequences of the lower SEs4-Ek,SEs3.and SEs1+2,while the sequences of SEd3.SEd2 and SEd1 are dominated by the delta and nearshore subaqueous fan depositional systems with the latter being developed at the downthrown side of the basin-bounding fault in each sequence. The evolution of the depositional systems is always con-trolled by the paleo-tectonic setting and the ancient landform in the space and geological time. It is concluded that the most favorable reservoirs are distributed in the Liaoxi low uplift and the central Liaozhong sag.

关键词： Liaodong Bay area Paleogene sequence stratigraphy sequence boundary depositional system

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Geological characteristics of large gas provinces and large gas fields in china

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Science china Earth Sciences 2008年第S1期51卷 14-35页

作者： ZOU CaiNeng &TAO ShiZhen research institute of petroleum {3. and Development,petrochina,Beijing 100083.china petrochina Res Inst Petr Explorat & Dev Beijing 100083 Peoples R China

Based on the examination of the global researches on oil and gas provinces and large gas fields and the analysis of the features,attributes and distribution of large gas provinces and gas fields,this paper puts forward three indicators of determining large oil and gas provinces:spatial indicator,reservoir-forming indicator and resource *** classifies the gas accumulated areas and large gas provinces in china and analyzes the controlling factors on the distribution of large gas provinces and large gas fields:the lateral distribution is mainly controlled by high-energy sedimentary facies and constructive diagenetic facies,palaeo-highs and their periclinal zones,deep faults,etc,and the vertical distribution is mainly controlled by unconformities,series of evaporates and deep low-velocity highly-conductive beds,*** also reveals the main geological characteristics of large gas provinces and large gas fields in *** gas fields in four-type basins have their own characteristics and onland large gas fields are dominantly developed in foreland basins and craton basins;there are three types of gas sources,of which,coal is the main source with high gas generating intensity and varying origins;reservoir rocks of the large gas fields(provinces)are of various types and dominated generally by low-middle permeability and porosity pore-type reservoirs;structural traps and litho-stratigraphic traps coexist in Chinese large gas fields and form dense high abundance and large-area low and middle-abundance large gas fields;most of the large gas fields have late hydrocarbon-generation peaks and reservoir formation,and experienced the process of multiple-stage charging and late finalization; large gas provinces(fields)have good sealing and preservation conditions,and evaporates seals are largely developed in large and extra-large gas *** paper intends to shed light on the exploration and development of large gas fields(provinces)through analyzing their geological

关键词： large gas province large gas field indicator of large oil and gas provinces forming condition distribution characteristics geological feature

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