川西坳陷中江气田沙溪庙组致密砂岩次生孔隙形成机制  

Formation Mechanism of Secondary Pores in Middle Jurassic Shaximiao Formation Reservoir inZhongjiang Gas Field of Western Sichuan Depression

作　　者：蔡李梅[1] 阎丽妮 南红丽 CAI Limei;YAN Lini;NAN Hongi(Exploration and Production Research Institute,Southwest Oil&Gas Company of SINOPEC,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石化西南油气分公司勘探开发研究院,四川成都610041

出　　处：《宜宾学院学报》2023年第12期26-32,共7页Journal of Yibin University

基　　金：国家科技重大专项项目(2016ZX05002-004)。

摘　　要：利用铸体薄片、电子探针、扫描电镜、阴极发光、X射线衍射等分析测试手段,对中江气田上、下沙溪庙组储层的岩石学特征、孔隙结构特征、成岩作用类型进行研究,分析次生孔隙的形成机制及分布规律.结果表明:上、下沙溪庙组均以富长石类砂岩为主,储层中溶蚀孔隙的比例以及自生高岭石的含量较高.相较于上沙溪庙组,下沙溪庙组次生孔隙更为发育.次生孔隙的形成主要与有机酸对钠长石的溶解有关.下伏须五段烃源岩在晚侏罗世末期—早白垩世早期进入低熟—成熟阶段,有机质热解脱羧作用形成大量具有较强溶蚀能力的有机酸和碳酸溶液.这些高温酸性流体沿着燕山中晚期形成的断层向上运移至侏罗系储层中,造成大量易溶组分的溶解以及次生孔隙的形成.By means of casting thin section,electron microprobe,scanning electron microscope,cathodoluminescence and X-ray diffraction,the petrological characteristics,pore structure characteristics and diagenesis types of the upper and lower Shaximiao for-mation in Zhongjiang gas field were deeply studied,and the formation mechanism and distribution of secondary pores were sum-marized.The results show that the upper and lower Shaximiao formations sandstones are mainly enriched in feldspar particles,and the proportion of dissolution pores and the content of authigenic kaolinite in the reservoir are high.Compared with the upper Shaximiao formation,the secondary pores in the lower Shaximiao formation are more developed.The formation of secondary pores is mainly related to the dissolution of albite by organic acids.The underlying source rocks of the fifth member of Xujiahe formation entered the low maturity-maturity stage from late Jurassic to early Cretaceous,and a large number of organic acids and carbonic acid solutions with strong dissolution ability were formed by thermal decarboxylation of organic matter.These high-temperature acidic fluids migrated upward to Jurassic reservoirs along the faults formed in the middle and late Yanshanian,result-ing in the dissolution of soluble components and the formation of secondary pores.

关 键 词：川西坳陷 中江气田 沙溪庙组 次生孔隙 形成机制 

分 类 号：P618.13[天文地球—矿床学]