川中-川南地区须家河组天然气同位素组成特征  

Isotopic characteristics of natural gas of Xujiahe Formation in southern and middle of Sichuan Basin

作　　者：肖芝华[1] 谢增业[2] 李志生[2] 马成华[2] 

机构地区：[1]中国石油大学资源与信息学院,石油天然气成藏机理教育部重点实验室,北京102249 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《地球化学》2008年第3期245-250,共6页Geochimica

基　　金：国家重点基础研究发展计划项目(2001CB209103)

摘　　要：川中-川南地区须家河组天然气烃类组成以甲烷为主,主要分布在80%～96%之间;天然气干燥系数(C1/C1-5)以小于0.95为主,为典型的湿气。天然气同位素组成包括C1—C4碳、氢同位素等。总体特征是碳、氢同位素值主要受成熟度的影响,均表现出较轻的特点,δ13C1值介于-43‰～-37‰之间,δ13C2值介于-30‰～-24‰之间;δDCH4值介于-190‰～-150‰之间,δDC2H6值介于-150‰～-110‰之间,δD2与δD1的差值大于15‰,明显轻于海相层系的天然气,具有煤型气特征,表明须家河组天然气主要来源于上三叠统煤系烃源岩。天然气甲烷碳同位素值与干燥系数之间有很好的正相关关系,同时,甲、乙烷氢同位素值也呈正相关关系。The natural gas of Xujiahe Formation in southern and middle Sichuan Basin was studied. The results show that the hydrocarbon of the natural gas consists mainly of CH4 from 80% to 96%. The ratio of C1/（C1-5） （arid factor） of the gas is principally lower than 0. 95, and it is a typical wet gas. The isotope compositions of the natural gas consist of δ13C1-4, δDCH4 and δDC2H6, etc. The general characteristic is that the isotope values of hydrogen and carbon are light and chiefly affected by the maturity. δ13C1 value ranges from - 43‰ to - 37‰, while δ13C2 from -30‰ to -24‰, δDCH4 from - 190‰ to - 150‰, and δDC2H6 from - 150‰ to - 110‰. The difference between δD2 and δD1is greater than 15‰. The isotope value of natural gas of Xujiahe Formation is obviously lighter than that of in the marine strata. It has the coal related gas feature which shows that the natural gas derived from the Upper Triassic coal-measure source rocks. There is a fairly well positive correlation between the δ13C1 and the arid factor. At the same time, there is also a fairly positive correlation between the δDCH4 and δDC2H6 values.

关 键 词：天然气 同位素特征 须家河组 四川盆地 

分 类 号：P593[天文地球—地球化学] P597[天文地球—地质学]