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  

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

作　　者：贾星亮[1] 周世新[1] 宋振响[1] 王保忠[1] 

机构地区：[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

出　　处：《天然气地球科学》2008年第4期524-529,547,共7页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:40572088);中国科学院知识创新工程重要方向项目(编号:KZCX3-SW-147);中国科学院院长基金联合资助

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‰<δ13C1<-63.9‰,-50.6‰<δ13C2<-40.7‰,-36.2‰<δ13C3<-31.9‰,-234.7‰<δD1<-214‰;δ13C1与δD1关系图和δDH2O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。The Sanhu region in Qaidam basin is the biggest biogenic gas field in China. Thirty five gas samples and eleven formation water samples were collected from Sebei 1, Sebei 2 and Tainan gas fields. The compositions, carbon and hydrogen isotopes of the gas samples were analyzed. Oxygen and hydrogen isotopes of the water samples were also analyzed. The main composition of the natural gas is methane, which accounts for more than 99%, C2^＋ is less than 0. 15% and the dryness coefficient about 0. 999. The isotopic values of carbon and hydrogen are： δ^13C1 ranging from -68. 6‰ to -61.8‰, δ^13C2 from-50. 6%0 to -40. 7‰, δ^13C3 from -36.2‰ to --31.9‰, and δDl from --234.7‰ to 214‰. The graph of δ^13C1 and δD1 and the relation formula of δDH2O and δD1 show that the reduction of carbon dioxide is the main way of forming biogenic methane in the area. Research shows that the biogenic gas of the Sanhu region is obviously different from the thermogenic gas in the Qaidam basin. The origin of heavy hydrocarbon in the biogenic gas of the Sanhu region is complex. It may be derived from both biogenic and low temperature thermal generations.

关 键 词：柴达木盆地 生物气 地层水 CO2 还原 重烃成因 

分 类 号：TE122.113[石油与天然气工程—油气勘探]