渝西永川地区DB1井茅一段灰质源岩气地球化学特征及意义OA

Well DB1 in Yongchuan area of western Chongqing obtained industrial gas flow in the limestone source rock of the first member of Maokou Formation(P1m1).On the basis of systematic sampling of limestone source rock and natural gas in the P1m1 of well DB1.Firstly,organic carbon analysis,pyrolysis,vitrinite reflectance analysis and gas content determination were carried out for the samples;Then,the identification of organic macerals,natural gas composition and carbon isotope analysis were further carried out.The geochemical analysis results of limestone source rocks show that the organic matter abundance of limestone source rocks in the P1m1 of well DB1 is high,the organic matter type is good,and they are in the over-mature stage;At the same time,the intensity of hydrocarbon generation of limestone source rocks in the P1m1 is large,which has the material basis for the formation of large-scale gas reservoirs.The gas content analysis results show that the gas loss in the natural gas in the P1m1 of well DB1 is relatively high,and limestone source gas is mainly free gas.The results of geochemical analysis of natural gas show that,on the one hand,the natural gas components of the P1m1 in well DB1 are characterized by oil-type gas;On the other hand,the carbon isotope composition of the gas collected from the gas test is consistent with that of the gas analyzed from the core,showing normal sequence characteristics.In addition,the maturity of natural gas in P1m1 is consistent with that of limestone source rock in P1m1.According to comprehensive analysis,the limestone source rock gas in the P1m1 of well DB1 in West Chongqing is self-generated and self-stored unconventional gas.