鄂尔多斯盆地胡尖山地区长7_(2)储层特征研究

Characteristics of Chang 7_(2) Reservoir in Hujianshan Area of Ordos Basin

根据鄂尔多斯盆地胡尖山地区延长组长7_(2)储层的砂岩薄片、铸体薄片、扫描电镜、高压压汞及常规物性等测试资料,对其储层特征进行分析。研究结果表明:储层岩石类型以细粒长石砂岩为主,石英砂岩和岩屑砂岩相对较少;储层岩石胶结物类型以铁方解石为主;储层孔隙类型以长石类溶孔为主,残余粒间孔次之,晶间孔和微裂隙很少见。储层物性总体较差,喉道较细,属于低孔—超低渗致密储层。储层成岩作用主要有压实作用、胶结作用和溶蚀作用;储层物性的影响因素主要有岩屑、长石、石英的含量,碳酸盐胶结物的含量以及沉积微相和成岩作用(压实、胶结和溶蚀)等。其中,压实作用是破坏其储层物性的主要因素,胶结作用会使储集层致密化,而溶蚀作用对储层物性有一定改善。

Based on the analysis and test data of sandstone thin section,casting thin section,scanning electron microscope,high pressure mercury injection and conventional physical properties of Yanchang 7_(2) reservoir in Hujianshan area of Ordos Basin,the reservoir characteristics are analyzed.The results show that the main rock types of Chang 7_(2) sandstone reservoir are fine-grained arkose,while quartz sandstone and lithic sandstone are relatively few.The main type of reservoir rock cement is ferruginous calcite.The pore types of the reservoir are mainly feldspar dissolved pores,followed by residual intergranular pores,and intergranular pores and microcracks are rare in the study area.The physical properties of Chang 7_(2) reservoir in the study area are generally poor,throat is thin and belongs to low porosity ultra-low permeability tight reservoir.The diagenesis types of Chang 7_(2) reservoir mainly include compaction,cementation and dissolution;the influencing factors of reservoir physical properties mainly include quartz content,carbonate cement content,sedimentary microfacies and diagenesis(compaction,cementation and dissolution).Among them,compaction is the first factor to destroy the physical properties of the reservoir,cementation will make the reservoir compact,and dissolution will improve the physical properties of the reservoir.