东海盆地西湖凹陷天然气来源探讨  

Source of Natural Gas in Xihu Depression of the East China Sea Basin

作　　者：苏奥[1,2] 陈红汉[1,2] 王存武[3] 李培军[1,2] 马丽娜[1,2] 刘洪平[1,2] 

机构地区：[1]中国地质大学资源学院,武汉430074 [2]中国地质大学构造与油气资源教育部重点实验室,武汉430074 [3]中国海洋石油有限公司勘探开发研究中心,北京100027

出　　处：《地质科技情报》2014年第1期157-162,共6页Geological Science and Technology Information

基　　金："十二五"国家重大油气专项(2011ZX05023-004-010)

摘　　要：关于西湖凹陷天然气的来源是很多学者争论的问题,主要原因在于计算出来的西湖凹陷部分天然气的成熟度与源岩的热演化程度不一致,因此准确确定天然气成熟度是关键。利用甲烷碳同位素演化二阶段分馏模式,计算出的天然气成熟度则明显分为两类:一类与西湖凹陷已钻遇渐新统花港组和中上始新统平湖组煤系烃源岩演化程度一致;另一类高于其演化程度,可能来自古新统-下始新统烃源岩。同时从天然气的地球化学参数:iC4/nC4、碳同位素分布、碳同位素系列倒转、煤型气δ13C—R o关系、热模拟实验5方面论证了西湖凹陷天然气存在2种不同来源的天然气。同时分析了天然气的运移特征,认为西湖凹陷的天然气具有垂向运移特征,垂向运移为西湖凹陷下部深凹部位和上部煤系烃源岩产生的天然气混源提供了前提。Many scholars argue about the source of natural gas in Xihu Depression. The main reason is that part of the calculated natural gas maturity is inconsistent with thermal evaluation level of source rocks. Therefore, determine the accurate gas maturity is the key issue. The ＂two-segments of methane stable car bon isotopic fractionation model＂ has been used to calculate the hydrocarbon gas maturities, and it is sug- gested that there are two mature stages of gas. one is consistent with thermal evaluation level of Huagang coal measures of Oligocene and Pinghu coal measures of Upper-Middle Eocene; another is in high evolution level, which may be from source rocks of Paleocene and Below Eocene. This work demonstrates that there are two kinds of different source of natural gas in Xihu Depression from five aspects of natural gas geo chemical parameters, e.g. iC4/nC4, carbon isotope distribution, carbon isotope series reversal, coal type gas 13C--Ro relations, the thermal simulation experiment. Meanwhile, the characteristics of the natural gas migration is also analyzed, and it is considered that natural gas has the characteristics of vertical migra tion, which provides the condition for a mixture source of lower deep depression and the upper coal meas ures.

关 键 词：西湖凹陷 天然气来源 混源 运移特征 

分 类 号：P618.130.2[天文地球—矿床学]