东海盆地西湖凹陷油气成因及成熟度判别  

Genesis and maturity identification of oil and gas in the Xihu Sag, East China Sea Basin

作　　者：苏奥[1] 陈红汉[1] 王存武[2] 李培军[1] 张晖[1] 熊万林[1] 雷明珠[1] 

机构地区：[1]中国地质大学(武汉)资源学院"构造与油气资源"教育部重点实验室 [2]中国海洋石油总公司研究总院

出　　处：《石油勘探与开发》2013年第5期521-527,共7页Petroleum Exploration and Development

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

摘　　要：基于东海盆地西湖凹陷天然气及凝析油样品组分和稳定碳同位素组成分析成果,运用多种方法对天然气中烃类气、CO2、N2和凝析油的成因和成熟度进行了综合判别。研究结果表明,西湖凹陷天然气中烃类气体主要为煤型气,CO2和低含量的N2主要为有机质热降解成因,高含量的N2由有机质热降解、运移分异作用及微生物降解作用共同形成;凝析油来源于腐殖型母质。在考虑"蒸发分馏"作用的基础上,利用修正的正庚烷值和异庚烷值计算凝析油成熟度,结果与Mango法获得的成熟度吻合,即凝析油来源于成熟烃源岩。采用甲烷稳定碳同位素组成二段分馏法,分析认为烃类气成熟度明显分为两个区域:①成熟阶段天然气,与凝析油成熟度相当;②高成熟度阶段天然气。Based on the composition and stable carbon isotope ratios of condensate and natural gas in the Xihu Sag, East China Sea Basin, origin and maturity of the hydrocarbon gas, CO2, N2 and condensate are determined using multiple methods. The CO2, low content of N2, condensate and hydrocarbon gas are mainly derived from thermal pyrolysis of coal-bearing measures, The relatively high content of N2 is collectively controlled by the thermal degradation of kerogen, vertical migration of gas and microbiological deterioration. Considering ＂evaporation fractionation＂ effect, a modified relationship between heptane and isoheptane has been used to calculate maturity of the condensate, which is in consistence with the results of the Mango method, i.e., the condensate is from mature source rock. The ＂two-segments of methane stable carbon isotopic fractionation model＂ has been used to calculate the hydrocarbon gas maturities. There are two mature stages of gas： one is mature gas which is equivalent to the condensate in maturity; the other is high maturity gas.

关 键 词：西湖凹陷 天然气 凝析油 油气成因 成熟度 

分 类 号：TE122.2[石油与天然气工程—油气勘探]