四川盆地页岩气储层特征综述

Characteristics of Shale Gas Reservoir in Sichuan Basin

四川盆地页岩气资源量十分丰富。通过对四川盆地页岩的有机地球化学特征、矿物组成、孔隙类型三个方面的文献收集以及资料整理表明:四川盆地发育了海相、海陆过渡相和陆相多套页岩气地层,海相页岩中有机质类型以Ⅰ型和Ⅱ1型为主,海陆过渡相有机质类型以Ⅲ型为主,部分区域含有Ⅱ2型,陆相页岩主要为Ⅱ型和Ⅲ型;四川盆地页岩TOC含量普遍较高,烃源岩质量好,生烃能力强,成烃阶段整体以生气为主,部分陆相页岩为成油期以及部分海相页岩生烃终止;矿物主要有石英、黏土矿物、碳酸盐岩,海相页岩中石英含量最多,以有机孔为主,孔隙度平均值在5%左右,海陆过渡相页岩黏土含量最多,以无机孔为主,孔隙度平均值在6.3%左右,陆相页岩的石英和黏土含量相当,不同层位孔隙类型有少许差异,总体以无机孔为主,孔隙度平均值差异较大,整体较低。

Sichuan Basin is rich in shale gas resources.Through reference collection and data collation of the organic geochemical characteristics,mineral composition,and pore type of the shale in the Sichuan Basin,it can be concluded that marine,marino-continental transitional and continental shale strata are developed in Sichuan Basin.The organic matter types of marine shale are mainlyⅠtype andⅡ1 type,the organic matter types of marino-continental transitional shale are mainlyⅢtype,and some areas containⅡ2 type.The continental shale is mainlyⅡtype andⅢtype.The TOC content of shale in Sichuan Basin is generally high,the quality of source rock is good,and the hydrocarbon generation ability is strong.The hydrocarbon generation stage is dominated by gas generation.Part of the continental shale hydrocarbon generation stage is oil generation stage,and part of the marine shale hydrocarbon generation stage is the end of hydrocarbon generation.The minerals mainly include quartz,clay minerals and carbonate rocks.Marine shale mainly contains quarz,in which organic pores are the main type,and the average porosity is about 5%.The marine-continent transition facies shale mainly contains the clay,in which inorganic pores are the main type,and the average porosity is about 6.3%.The contents of quarz and clay in terrestrial shale are equivalent.There are slight differences in the types of pores in different layers.In general,they are mainly inorganic pores.The average value of porosity varies greatly,and the overall level is low.