川中地区侏罗系天然气成因类型及气源

Genetic type and gas source of Jurassic natural gas in central Sichuan Basin,China

针对川中地区侏罗系天然气成因类型及气源的认识存在不同的观点,作者综合天然气组分特征、碳同位素特征、轻烃特征对该问题进行了探讨。组分分析结果表明,侏罗系天然气主要为干酪根裂解气;碳同位素分析结果表明,侏罗系天然气主要为油型气,部分为煤型气;轻烃分析结果表明,侏罗系天然气以油型气为主。综合上述成因类型分析结果认为:川中地区侏罗系天然气以干酪根裂解成因油型气为主,同时存在少量的煤型气。川中地区侏罗系油型气来自侏罗系烃源岩,煤型气来自上三叠统烃源岩。

There are different views on the genetic type of natural gas and gas source in Jurassic of the central Sichuan Basin.This paper uses three characteristics of the natural gas,that is,the characteristics of component,carbon isotope and light hydrocarbon,to recognize these problems again.An analysis of the components shows that the natural gas in Jurassic is mainly oil-type gas from kerogen cracking;Carbon isotope analysis indicates that the natural gas in Jurassic is mainly oil-type gas,but a part of it is coal-related gas.The light hydrocarbon analysis shows that the natural gas in Jurassic is mainly oil-type gas.Based on these results,it can be concluded that the natural gas in Jurassic of the central Sichuan Basin is mainly oil-type gas from kerogen cracking and only a small amount of it is coal-related gas.The oil-type gas in Jurassic reservoir derives from the Jurassic source rocks,but the coal-related gas derives from the upper Triassic source rocks.