四川中江气田沙溪庙组天然气成因类型及气源对比

探讨四川盆地中江气田侏罗系沙溪庙组天然气的成因和气源,为找气提供理论依据。利用天然气组分特征、碳同位素特征、轻烃特征等地球化学资料对该区天然气成因类型进行了分析,根据轻烃的气、源配对参数和碳同位素参数对天然气的来源进行了追踪。沙溪庙组天然气以烃类气体为主,含少量的非烃类气体,为腐植型干酪根裂解成因的煤型气;对碳同位素和轻烃的研究均表明,天然气为有机成因的煤型气。气源对比结果表明,须五段烃源岩为沙溪庙组煤型气的主要来源。中江气田侏罗系沙溪庙组气藏为次生气藏。

Correlation of gas sources and genetic types of natural gas in Jurassic Shaximiao Formation of Zhongjiang gas field,Sichuan, China

The genesis of natural gas and the source of natural gas in Jurassic Shaximiao Formation of Zhongjiang gas field are discussed so as to provide theoretical basis for gas exploration.Based on the geochemical data of natural gas compositions,carbon isotopes and light hydrocarbon,the genetic types of natural gas in this area are analyzed and the sources of natural gas are tracked on the basis of gas,source pairing parameters and carbon isotopic parameters of light hydrocarbons.It shows that the natural gas in the Shaximiao Formation is mainly natural gas and hydrocarbon gas,containing a small amount of non-hydrocarbon gas,and belonging to humic type kerogen cracking coal-type gas.Study of carbon isotope and light hydrocarbon indicates that natural gas in the area is organic genesis of coal-type gas.Gas sources correlation show that the coal-type gas in Shaximiao Formation is originated from the Member 5 of Upper Triassic Xujiahe Formation.It is considered that the gas reservoir of the Jurassic Shaximiao Formation in the Zhongjiang gas field is a secondary gas reservoir.