天然气地球化学

柴达木盆地三湖地区生物气地球化学特征及重烃组分成因分析

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  • (1.中国科学院地质与地球物理研究所气体地球化学重点实验室,甘肃 兰州 730000;2.中国科学院研究生院,北京 100049)
第一作者 Email:dengjh@cnooc.com.cn.

网络出版日期: 2008-04-20

基金资助

国家“十五”重大科技攻关项目(编号:2003BA613A05)资助.

Geochemical Characteristics of Biogenic Gas and Heavy Hydrocarbon Origin in Sanhu Region of Qaidam Basin

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  • (Key Laboratory of Exploration Technologies for Oil and Gas Resources, Ministry of Education, 
    Department of Geochemistry, Yangtze University, Jingzhou 434023, China)

Online published: 2008-04-20

摘要

柴达木盆地三湖地区的天然气区是目前我国发现的最大生物气区。系统采集了该区涩北一号气田、涩北二号气田和台南气田不同气层组的35个天然气样和11个地层水样,进行了天然气组分和碳、氢同位素分析,同时对地层水的氢、氧同位素也进行了分析。结果表明:天然气组分以甲烷为主,CH4>99%,C2+<0.15%,干燥系数为0.999;气体同位素组成特征为-68.6‰<δ13, C1<-63.9‰, -50.6‰<δ13,C2<-40.7‰, -36.2‰<δ13,C3<-31.9‰,-234.7‰<δD1<-214‰;δ13 C1与δD1关系图和δD H 2O与δD1关系式都显示出三湖地区生物甲烷形成途径以CO2还原为主。认为三湖地区生物气中重烃与该盆地热成因重烃地球化学特征明显不同,其重烃成因复杂,可能为生物成因和低温热成因共同作用的结果。

本文引用格式

贾星亮, 周世新, 宋振响, 王保忠 . 柴达木盆地三湖地区生物气地球化学特征及重烃组分成因分析[J]. 天然气地球科学, 2008 , 19(4) : 524 -529 . DOI: 10.11764/j.issn.1672-1926.2008.04.524

Abstract

The quantitative evaluation of hydrocarbon\|generating potential of source rocks in the basin is the key problem which should be solved in the oil and gas exploration. Tiancao sag develops many sets of source rocks, but the main source rock is still unclear, and the report about the evaluation of source rock has not been seen. This research takes the dark color mudstone of the Tian 2 well as the dissection object, and takes advantage of many parameters such as organic matter abundance, the type and maturity of organic matter to describe quantitively or qualitatively the hydrocarbon\|generating potential characteristics of the dark color mudstone. Results indicate that the source rock's organic matter abundance of the lower segment in Lower Crataceous Bayingebi Formation is the highest and the thermal evolution is at the mature stage, the organic matter type isⅡ2—Ⅲ, so it should be the main hydrocarbon source rock of Tiancao sag; The organic matter abundance of Lower Crataceous Suhongtu Formation is higher, whose organic matter type isⅡ 2, while its hydrocarbon source rock maturity is not high, therefore, it is the secondary hydrocarbon source rock of Tiancao sag. Although the total organic carbon content of Carboniferous and Jurassic is high, the hydrocarbon generating potential is low and the organic matter type is only Ⅲ, nowadays R O>3.0%, so it is at the overmature stage and belongs to the depletive source rock.

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