靖边气田马家沟组碳酸盐岩储层特征及主控因素

Characteristics of carbonate reservoir and its main controlling factors of Majiagou Formation in Jingbian Gas Field

为优选靖边气田马家沟组碳酸盐岩储层有利区域,以靖边南部马家沟组五段4亚段为例,基于岩心观察、铸体薄片鉴定、物性资料统计及压汞测试等方法,分析研究区碳酸盐岩储层特征,从古构造、岩相古地理环境、成岩作用及岩溶古地貌等方面研究主控因素与储层分布的关系。结果表明:马家沟组碳酸盐岩储集层岩石类型包括膏盐溶蚀泥粉晶白云岩、岩溶角砾泥粉晶白云岩及砂砾屑泥晶白云岩;储集空间类型包括铸模孔隙、晶间孔和晶间溶孔;储层孔隙结构划分为高饱和型、中饱和型、低饱和型及微饱和型4类,储层分布受古构造、岩相古地理、成岩作用和岩溶古地貌等因素控制,其中古构造中的高部位、古地理环境中的云坪沉积微相、成岩作用中的早期淡水溶蚀、白云石化和表生期岩溶作用,以及古地貌中的岩溶斜坡带是储层发育的有利因素。该结果为靖边气田碳酸盐岩储层天然气勘探有利区优选提供依据。

In order to optimize effectively the favorable area of Majiagou Formation carbonate reservoir in Jingbian Gas Field,taking the Ma 54 Sub-member of Majiagou Formation in the south of Jingbian as an example,the characteristics of carbonate reservoir in the target area were studied based on core observation,cast thin section identification,statistical analysis of physical property data and mercury injection test.The results show that the main rock types of carbonate reservoir in Ma 54 Sub-member include breccia dolomite with gypsum and salt dissolution,karst breccia micritic dolomite and sand-gravel micritic dolomite.The reservoir space types include moldic pore,intergranular pore and intergranular dissolution pore.Reservoir distribution is controlled by many factors,such as paleotectonics,lithofacies palaeogeography,diagenesis and karst palaeogeomorphology,among which the high position of paleotectonics,dolomitic flat sedimentary microfacies,early freshwater dissolution,dolomitization and epigenetic and karst,and karst slope zone are all favorable factors for reservoir development,and areas with these elements are favorable for carbonate reservoir development.The results provide a theoretical basis for the optimization of favorable areas for natural gas exploration in carbonate reservoirs of Jingbian Gas Field.