四川盆地天府气田中侏罗统沙溪庙组砂岩储层致密化机理及其与油气充注的耦合关系  

Coupling relationship between tight sand reservoir formation mechanism and hydrocarbon charge in Shaximiao Formation of Tianfu gas field in the Sichuan Basin

作　　者：王小娟[1] 张少敏[1] 庞小婷 杨曦冉 李晓芳 葛新锐 蔡来星 杨田[2,3] WANG Xiaojuan;ZHANG Shaomin;PANG Xiaoting;YANG Xiran;LI Xiaofang;GE Xinrui;CAI Laixing;YANG Tian(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan 610059,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院 [2]油气藏地质及开发工程全国重点实验室•成都理工大学 [3]成都理工大学沉积地质研究院

出　　处：《天然气工业》2024年第6期33-43,共11页Natural Gas Industry

基　　金：自然资源部沉积盆地与油气资源重点实验室开放基金项目“川中侏罗系沙溪庙组致密储层演化过程与天然气富集规律研究”(编号:cdcgs2020003)。

摘　　要：近年来,四川盆地中侏罗统沙溪庙组致密砂岩气勘探开发取得持续突破,展示出了良好的天然气勘探开发前景,但是砂岩储层致密导致“甜点区”分布复杂,特别是对储层致密化机理及其与油气充注的耦合关系认识不清,严重制约了沙溪庙组致密砂岩气藏的规模效益开发。为此,以四川盆地天府气田沙溪庙组一段(以下简称沙一段)致密砂岩储层为研究对象,综合岩心物性测试、薄片鉴定、扫描电镜、地球化学测试等多种资料,系统表征了致密砂岩储层的物质组成、储集物性、成岩作用等特征,并探讨了储层致密化机理,最后结合油气成藏期次,明确了储层致密化过程与油气充注耦合关系。研究结果表明:(1)沙一段储层以岩屑长石砂岩为主,发育少量长石岩屑砂岩,储层孔隙度为0.82%~17.48%,平均孔隙度为10.09%,渗透率为0.0001~632.4200 mD,平均渗透率为5.4200 mD,储层储集空间以原生孔隙为主,局部发育长石溶孔和浊沸石胶结物溶孔;(2)沙一段压实作用以弱—中等为主,绿泥石包壳广泛发育,浊沸石呈基底式、孔隙式和颗粒交代状等多种形式胶结,方解石呈基底式和孔隙式胶结,溶蚀作用以长石溶蚀和浊沸石溶蚀为主;(3)沙一段发育3种类型的致密储层,第一种致密储层是在压实作用基础上早期强胶结作用下形成的;第二种致密储层是在压实作用基础上晚期胶结作用下形成的;第三种储层现今并未致密,但是早期的压实胶结作用导致储层曾经致密,后期溶蚀作用改善储层物性。结论认为:(1)该区沙一段储层具有一期成藏特征,发生在距今88~68 Ma,第一种和第三种致密储层不能发生有效的油气充注,第二种致密储层可以发生有效的油气充注;(2)该区储层致密化过程与油气充注的耦合关系控制了天府气田简阳区块的天然气相对富集程度。Continuous breakthroughs have been made in the exploration and development of tight sand gas in the Middle Jurassic Shaximiao Formation of the Sichuan Basin over recent years,which shows a good prospect for natural gas exploration and development.However,the tightness of sandstone reservoir leads to a complex distribution of"sweet spots",especially the unclear understanding on the mechanism of reservoir densification and its coupling with hydrocarbon charge seriously restricts the scale and benefit development of tight sand gas reservoirs in the Shaximiao Formation.In this paper,taking the tight sand reservoir in the first member of Shahejie Formation(Sha-1 Member)of Tianfu gas field in the Sichuan Basin as an example,and based on various data of cores such as physical property test,thin section analysis,scanning electron microscope and geochemical test,the characteristics of tight sand reservoirs such material composition,reservoir property and diagenesis are systematically characterized,and the mechanism of reservoir densification is explored.Finally,combined with hydrocarbon accumulation stages,the coupling relationship between the reservoir densification process and the hydrocarbon charge is clarified.The results show that the reservoir of the Sha-1 Member is dominated by lithic arkose,with a small amount of feldspathic litharenite.The reservoir has a porosity of 0.82%–17.48%(avg.10.09%)and a permeability of 0.0001–632.4200 mD(avg.5.4200 mD).The reservoir space is dominated by primary pores,with feldspathic dissolved pores and laumontite cement dissolved pores developed locally.The compaction of the Sha-1 Member is mainly weak to moderate,with chlorite incrust widely developed.The laumontite exhibits basal,porous and particle replacement cementation,the calcite exhibits basal and porous cementation,and the denudation is mainly composed of feldspar denudation and laumontite denudation.Three types of tight reservoir are developed in the Sha-1 Member:(1)tight reservoir formed under early strong cementation o

关 键 词：四川盆地 中侏罗统 沙溪庙组 致密砂岩 储层致密化 形成机理 成岩作用 油气充注 

分 类 号：TE122.2[石油与天然气工程—油气勘探]