摘要
根据野外剖面、钻井和岩心等资料,采用岩心观察、常规及铸体薄片鉴定、扫描电镜、阴极发光、压汞实验、孔渗测试等方法,分析南羌塘坳陷中侏罗统布曲组碳酸盐岩储层特征及控制因素.结果表明:南羌塘坳陷布曲组碳酸盐岩储层岩性主要为亮晶鲕粒灰岩、生屑灰岩、晶粒白云岩和(残余)颗粒白云岩;储集空间主要为粒内溶孔、铸模孔、晶间孔、晶间溶孔、非组构选择性溶孔和裂缝.不同岩性的储层物性差别明显,白云岩储层物性优于过渡性岩类及灰岩的,主要为Ⅱ-Ⅲ类储层.沉积相和成岩作用为有利储层的控制因素,碳酸盐岩台缘浅滩及台内浅滩相沉积构成有利储层发育的物质基础,白云石化、压溶及溶蚀作用是有利储层形成的关键;较彻底的白云石化对储层孔隙度增加具有明显的促进作用,细晶自形白云岩物性最优,构造破裂作用产生的各种裂缝有利于溶蚀流体的运移,有效改善储层物性.该结果为研究区下一步油气勘探提供地质依据.
Abstract
Based on field profiles,drilling,and core data,this study explores the characteristics and con-trolling factors of the Middle Jurassic Buqu Formation carbonate reservoir using methods such as core observation,conventional and cast thin section identification,scanning electron microscopy,cathodolu-minescence,mercury intrusion,and porosity and permeability testing.The results indicate that the car-bonate reservoir rocks of the Middle Jurassic Buqu Formation in the South Qiangtang Depression are mainly composed of bright crystal oolitic limestone,grain dolomite,(residual)grain dolomite,and bio-clastic limestone.The storage space mainly consists of intragranular dissolution pores,mold pores,in-tergranular pores,intergranular dissolution pores,non fabric selective dissolution pores,and cracks.The physical properties of reservoirs with different rock types vary significantly,with dolomite reser-voirs having better physical properties than transitional rocks and limestone,mainly belonging to classⅡ-Ⅲ reservoirs.Sedimentary facies and diagenesis are the controlling factors for favorable reservoirs.The material basis for the development of favorable reservoirs is formed by the sedimentation of carbon-ate platform margin shoals and intra platform shoals.Dolomitization,dissolution,and pressure dissolu-tion are key factors for the formation of favorable reservoirs.Thorough dolomitization has a significant promoting effect on the increase of reservoir porosity.Fine crystalline self formed dolomite has the best physical properties.The various fractures generated by tectonic fracturing are beneficial for the migra-tion of dissolution fluids and effectively improve reservoir properties.This result provides geological ba-sis for the next step of oil and gas exploration in the study area.
基金项目
中国石油化工股份有限公司科技部项目(P22197)
中国石油化工股份有限公司科技部项目(P22198)
国家科技期刊平台
NSTL
万方数据