川西坳陷侏罗系天然气气源对比研究

川西坳陷侏罗系天然气具有δ13C1<δ13C2<δ13C3 的正常系列分布特征，为典型的热催化成因的煤型气，天然气母质类型主要为腐殖型。通过岩石组合特征分析，认为侏罗系天然气大部分来源于上三叠统须五段源岩，须四段和侏罗系本身源岩（如自流井组暗色泥岩）可能也有一定贡献；轻烃特征研究也说明了须五段源岩对侏罗系天然气有较大的贡献；δ13C1-Ro关系更进一步说明了侏罗系天然气主要来源于须五段烃源岩，而孝-新-合地区须四段和自流井组源岩可能有一定程度的贡献。

A Comparison Study on the Gas Source of Jurassic Natural Gas in the Western Sichuan Depression

The Jurassic natural gas in the western Sichuan depression has the normal series distribution characteristics (δ13C1<δ13C2<δ13C3), which is typical of coal type gas oginated by thermal catalysis. The Kerogen of the natural gas is mainly of the humic type. Through analysis on the rock association characteristics it is suggested that most of the Jurassic natural gas was sourced from the 5th member of Xujiahe Formation of the Upper Triassic. The 4th member of Xujiahe Formation and the Jurassic (such as dark mudstone of the Ziliujing Formation) might also have some contribution for its source. The study on characteristics of light hydrocarbons also indicates important contribution of the 5th member of Xujiahe Formation source rocks. The relationship between δ13C1 and Ro further evidences the same conclusion.