延安东部地区山2段储层评价

通过各类常规实验分析资料,开展储层的岩石学特征、成岩作用、孔隙类型、储层物性和孔喉结构特征的研究。依据薄片分析、扫描电镜等资料判定延安东部地区山西组山2段发育石英砂岩,含岩屑石英砂岩,砂岩储层经历了复杂的成岩作用,常见压实、压溶作用,发育石英次生加大,高岭石、绿泥石胶结,长石、岩屑的溶蚀等。由此造成石英砂岩储层内发育残余粒间孔,及溶蚀粒内孔隙,其他岩类以溶蚀孔隙为主,偶见各种成岩的裂缝(隙)。压汞实验分析显示山2段储层非均质性强,储集空间小,分选中等,物性差异较大,山23亚段物性最好,并依据毛细管曲线将山2段储层划分为四类。最终,综合研究成果,评价研究区主要发育物性较差,孔喉中等,分选一般,属特低孔特低渗的Ⅱ、Ⅲ类储层,仅山23亚段发育Ⅰ类储层。

Reservoir Evaluation of Shah 2 Member in Eastern Area of Yanan

This paper aim to study the petrology character, diagenesis, porosity style, reservoir quality based on the test and its analysis reference. First of all, according to the studies of casting thin section, scanning electron micros- copy, it is judged that the reservoir sandstone of the second member of shanxi formation in eastern area of Yanan was mainly made of quartzy sandstone. Meanwhile, the reservoir sandstone experienced complex diagenesis, likely com- paction, pressolution, developing quartz secondary enlargement, kaolinite and chlorite cementation, and dissolution of feldspar, fragment. When it comes to the pore spaces of reservoirs, it is mainly composed of residual intergranular pores, intragranular dissolution pores, such as fragment dissolution pores, feldspar dissolution pores, and occasional- ly few cracks because of diagenesis. Ultimately, all these factors have created the pore structure types were fine pore - small throat. The reservoir of shanxi formation showed stronger unhomogeneity through the research of capillary pressure curves, the reservoir physical differ widely in each submember,with Shan23 submember best. To sum up, the reservoir divided onto four types, and Ⅱ and Ⅲ type with extremely low porosity and permeability, medium pore throat, generally - sorted, were the primary reservoir in the study area, type was developed in shan23 submember only.