收稿日期: 2015-12-15
修回日期: 2015-01-05
网络出版日期: 2016-01-10
基金资助
中国石油天然气股份有限公司油气勘探重大科技项目“中国煤成气地球化学与成藏机制规律研究”(编号:2014B-0608)资助.
Origins of secondary negative carbon isotopic series in natural gas
Received date: 2015-12-15
Revised date: 2015-01-05
Online published: 2016-01-10
烷烃气碳同位素系列类型有3种：随烷烃气分子碳数递增，δ13C值依次递增称为正碳同位素系列，是有机成因原生烷烃气的一个特征；随烷烃气分子碳数递增，δ13C值依次递减称为负碳同位素系列；不按以上2种规律而出现不规则增减则称为碳同位素倒转。负碳同位素系列又分为原生型和次生型2种。原生型负碳同位素系列是无机成因的；次生型负碳同位素系列是正碳同位素系列经次生改造来的，出现在过成熟的页岩气和煤成气中。关于次生型负碳同位素系列成因的观点繁多，包括：二次裂解、扩散、过渡金属和水介质在250~300℃范围内发生氧化还原作用导致乙烷和丙烷瑞利分馏等。详细研究对比后发现不论页岩气或者煤成气，次生型负碳同位素系列仅出现在过成熟页岩或源岩区，在成熟和高成熟页岩或者源岩区未见次生型负碳同位素系列，由此得出过成熟或者高温（＞200℃）是次生型负碳同位素系列的主要控制因素，在此主控因素下可由二次裂解、扩散或者乙烷和丙烷瑞利分馏的一种或几种方式促使次生型负碳同位素系列的形成。
关键词： 碳同位素系列; 次生型负碳同位素系列; 页岩气; 煤成气; 成因
戴金星，倪云燕，黄士鹏，龚德瑜，刘丹，冯子齐，彭威龙，韩文学 . 次生型负碳同位素系列成因[J]. 天然气地球科学, 2016 , 27(1) : 1 -7 . DOI: 10.11764/j.issn.1672-1926.2016.01.0001
The carbon isotopic series of alkane gases could be divided into three types:(1)positive carbon isotopic series:δ13C values increase with increasing carbon numbers among the C1-C4 alkanes,which is a typical characteristic for primary alkane gases;(2)negative carbon isotopic series:δ13C values decrease with increasing carbon numbers among the C1-C4 alkanes;(3)partial carbon isotopic reversal,which has no increasing or decreasing relationship between the δ13C values and carbon numbers.Negative carbon isotopic series could be further subdivided into primary and secondary origins.The former is a typical characteristic of abiogenic gases while the later is resulted from the secondary alteration imposed on biogenic gases,which is commonly observed in over-mature shale gas or coal-derived gas.Previous works have proposed several possible explanations for negative carbon isotopic series of secondary origins such as secondary cracking,diffusion,the Rayleigh fractionation of ethane and propane through redox reaction with the participation of transition metal and water at 250-300℃.After a comparative study,the authors found that negative carbon isotopic series of secondary origin for both shale gas and coal-derived gas appeared in the area where source rocks(shales)are at over-mature stage while it was not observed in the area where source rocks(shales)are only at mature-high mature stage.As a result,extremely high maturity(＞200℃)is the main controlling factor for negative carbon isotopic series of secondary origin.Within this maturity interval,secondary cracking,diffusion and Rayleigh fractionation of ethane and propane could happen separately or together.
[1]Dai Jinxing,Xia Xinyu,Qin Shengfei,et al.Causation of partly reversed orders of δ13C in biogenic alkane gas in China[J].Oil & Gas Geology,2003,24(1):1-6.[戴金星,夏新宇,秦胜飞,等.中国有机烷烃气碳同位素系列倒转的成因[J].石油与天然气地质,2003,24(1):1-6.]
[2]Dai J,Xia X,Qin S,et al.Origins of partially reversed alkane δ13C values for biogenic gases in China[J].Organic Geochemistry,2004,35(4):405-411.
[3]Zorikin L M,Starobinets I S,Stadnik E V.Natural Gas Geochemistry of Oil-gas Bearing Basin[M].Moscow:Mineral Press,1984.
[4]MaraisD J D,Donchin J H,Nehring N L,et al.Molecular carbon isotopic evidence for the origin of geothermal hydrocarbons[J].Nature,1981,292(5826):826-828.
[5]Hosgrmez H.Origin of the natural gas seep of Cirali(Chimera),Turkey:Site of the first Olympic fire[J].Journal of Asian Earth Sciences,2007,30(1):131-141.
[6]Proskurowski G,Lilley M D,Seewald J S,et al.Abiogenic hydrocarbon production at Lost City Hydrothermal Field[J].Science,2008,319(5863):604-607.
[7]Yuen G,Blair N,Marais D J D,et al.Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite[J].Nature,1984,307(5948):252-254.
[8]Liu Ruobing.Typical features of the first giant shale gasfield in China[J].Natural Gas Geoscience,2015,26(8):1488-1498.[刘若冰.中国首个大型页岩气田典型特征[J].天然气地球科学,2015,26(8):1488-1498.]
[9]Dai J,Zou C,Liao S,et al.Geochemistry of the extremely high thermal maturity Longmaxi shale gas,southern Sichuan Basin[J].Organic Geochemistry,2014,74:3-12.
[10]Zumberge J,Ferworn K,Brown S.Isotopic reversal(‘rollover’)in shale gases produced from the Mississippian Barnett and Fayetteville formations[J].Marine & Petroleum Geology,2012,31(1):43-52.
[11][KG*4/5]Tilley B,Muehlenbachs K.Isotope reversals and universal stages and trends of gas maturation in sealed,self-contained petroleum systems[J].Chemical Geology,2013,339(339):194-204.
[12]Guo T,Zeng P.The structural and preservation conditions for shale gas enrichment and high productivity in the Wufeng-Longmaxi Formation,Southeastern Sichuan Basin[J].Energy Exploration & Exploitation,2015,33(3):259-276.
[13]Zhang Xiaoming,Shi Wanzhong,Xu Qinghai,et al.Reservoir 〖JP2〗characteristics and controlling factors of shale gas in Jiaoshiba area,Sichuan Basin[J].Acta Petrolei Sinica,2015,36(8):926-939.[张晓明,石万忠,徐清海,等.四川盆地焦石坝地区页岩气储层特征及控制因素[J].石油学报,2015,36(8):926-939.]〖JP〗
[14]Dai Jinxing,Zou Caineng,Li Wei,et al.Large Coal-formed Gas Field and Sources in China[M].Beijing:Science Press,2014:28-91.[戴金星,邹才能,李伟,等.中国煤成大气田及气源[M].北京:科学出版社,2014:28-91.]
[15]Rodriguez N D,Philp R P.Geochemical characterization of gases from the Mississippian Barnett Shale,Fort Worth Basin,Texas[J].AAPG Bulletin,2010,94(11):1641-1656.
[16]Jenden P D,Drazan D J,Kaplan I R.Mixing of thermogenic natural gases in northern Appalachian Basin[J].AAPG Bulletin,1993,77(6):980-998.
[17]Xia X,Chen J,Braun R,et al.Isotopic reversals with respect to maturity trends due to mixing of primary and secondary products in source rocks[J].Chemical Geology,2013,339(2):205-212.
[18]Burruss R C,Laughrey C D.Carbon and hydrogen isotopic reversals in deep basin gas:Evidence of limits to the stability of hydrocarbons[J].Organic Geochemistry,2009,41(12):1285-1296.
[19]Li Mingcheng.Petroleum Migration[M].4th edition.Beijing:Petroleum Industry Press,2013:93-94.[李明诚.石油与天然气运移[M].第四版.北京：石油工业出版社,2013:93-94.]
[20]Vinogradov A P,Galimor E M.Isotopism of carbon and the problem of oil origin[J].Geochemistry,1970,3:275-296.
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