鄂尔多斯盆地板桥–合水地区长8储层特征及主控因素

鄂尔多斯盆地板桥–合水地区长8储层物性差,油水关系复杂,开采难度大;应用常规物性、铸体薄片、扫描电镜和高压压汞等实验手段,结合岩石学、沉积学研究表明:板桥–合水地区长8储层岩性主要为细粒岩屑长石砂岩,残余粒间孔和长石溶孔较为发育,孔隙结构复杂,微观非均质性较强;该区主要发育三角洲前缘亚相,水下分流河道砂体是最有利的储集相带。强烈的压实作用是储层原生孔隙降低的主要因素;胶结作用对储层的物性以破坏性为主,但早期绿泥石薄膜胶结对储层孔隙保存有积极性作用;溶蚀作用所形成的溶蚀孔隙,对储层物性的改善起到了关键作用。

Reservoir characteristics and main controlling factors of Chang-8 formation in Banqiao-Heshui area,Ordos Basin

The reservoirs from Chang-8 formation in BanqiaoHeshui area, Ordos basin were characterized by poor reservoir property and complicated oil-water relations, and there existed great difficulty in exploration. By use of the techniques of physical properties, casting thin slices, scanning electron microscopy and high-pressure mercury,in combination with the theoretical knowledge of petrology and sedimentology, the research on reservoir characteristics of Chang-8 reservoir and its main controlling factors were carried out. Results indicated the rocks of Chang-8 reservoir were mainly fine lithic-arkoses. The residual intergranular pores and solution pore developed well.The complex pore structure led to strong microheterogeneity. The study area mainly developed the delta-front facies, and the physical properties of reservoir are determined by the facies. Underwater distributary channel sand body were the most favorable reservoir facies. Through the study of diagenesis, it was considered the study area had undergone strong compaction, which greatly reduced the primary pores of the reservoir. Cementation had both destructive and constructive effects on the physical properties of the reservoir. The results indicated there were many dissolution pores formed because of the dissolution, which played a key role in improving the physical properties of the reservoirs.