摘要
根据四川盆地上三叠统须家河组天然气甲烷同位素分布特征以及和同系物的系列碳同位素值关系,可判断其天然气为有机成因;四川盆地上三叠统须家河组天然气碳同位素富集系数,明显高于下伏层系天然气碳同位素富集系数,与部分侏罗系天然气碳同位素富集系数较为相近。利用天然气碳同位素富集系数与甲烷和乙烷碳同位素值间的相互关系,判断四川盆地上三叠统须家河组天然气成因类型以成熟的煤型气为主,部分气藏为成熟的油系—煤系的混合气,少数构造的须家河天然气为高成熟的油系—煤系混合气。
For the Upper Triassic Xujiahe formations in Sichuan Basin, the natural gas should be of organic origin based on the relationship between methane isotopic distribution and homologue carbon isotope ratio. The coefficient of concentration in carbon isotope of Upper Triassic Xujiahe formations is obviously higher than that of the underlying formation. Moreover, this coefficient in Xuejiahe formations is very close to that of partial Jurassic formations. We study the relationships between the concentration coefficient of carbon isotope in gas and the carbon isotopic ratio in both methane and ethane, showing that the natural gas of Upper Triassic Xujiahe formations in Sichuan Basin is dominantly mature coal-related gas, partly mature oil- and coal-related mixed gas, rarely high-mature oil- and coal-related mixed gas.
出处
《天然气勘探与开发》
2007年第2期26-29,共4页
Natural Gas Exploration and Development
关键词
四川盆地
上三叠统
地球化学特征
成因类型
Sichuan Basin, upper Triassic, geochemical characteristics, genetic type
