【摘要】 针对鄂尔多斯盆地延安地区马五段上组合（马五₄至马五₁亚段）细粒致密白云岩储层天然气勘探取得新突破,展开对低孔低渗白云岩储层特征及孔隙的成因研究。通过岩心观察、薄片分析及阴极发光等测试,结合岩石物性分析,明确了细粒白云岩储层的储渗特征、有利储层的演化过程及控制因素。结合地球化学及地球物理数据分析认为,研究区马五段上组合储层岩性主要包括含膏模白云岩、细晶白云岩和岩溶角砾岩等,储集空间以膏模溶孔、晶间（溶）孔、非选择性角砾间溶蚀孔洞为主,局部裂缝发育,属低孔低渗孔隙型储集层;位于高古地势、经多期岩溶（准同生期、表生期和埋藏期岩溶）叠加改造的膏晶模云坪是研究区细粒白云岩有利储层的主要分布区。更多还原

【Abstract】 A new natural gas exploration breakthrough has been gained in the fine-grained tight dolostone reservoirs of the Upper Assemblage of the Ma-5 Member in the Yan’an area of the Ordos Basin. This paper presents a detailed research on the characteristics of low-porosity and low-permeability dolostone reservoirs and the genesis of porosities. Through core observation, thin section analysis and cathodoluminescence testing, combined with rock physical property analysis, the porosity-permeability characteristics of the fine-grained dolostone reservoirs and the favorable reservoirs′evolution process and controlling factors are clarified. Results show that the lithology of fine-grained dolostone reservoirs is mainly composed of gypsum pseudocrystal dolomite, fine-grained dolomite and karst breccia dolomite. The porosity types contain gypsum pseudocrystal dissolved pores, intercrystalline dissolved pores and non-selective breccia dissolved pores, with local fractures developing. Thus, it is a pore type reservoir with low porosity and permeability. The mould-pore-contained gypsodolomite flat, which is located at the high position and transformed by multi-stage karsts(penecontemporaneous, epigenetic and burial), is the main distribution area of favorable reservoirs of the fine-grained dolomite in the study area.更多还原