鄂尔多斯盆地西南部山1、盒8段孔隙特征及物性研究

Research on Pore Characteristics and Petrophysical Properties of P1s1 and P1h8 Members in the Southwest of Ordos Basin

近年来,鄂尔多斯盆地西南部逐渐成为致密气勘探开发的重点区块。然而,对该地区主力产气层山1段和盒8段的储集空间以及物性特征的研究还十分不足。利用偏光显微镜、扫描电镜观察,结合压汞实验数据,对研究区山1、盒8段砂岩的孔隙微观特征及类型、孔隙结构及物性关系进行了详细的分析。结果表明:研究区主要发育的孔隙类型为残余粒间孔、岩屑溶孔、杂基溶孔和晶间孔;孔喉大小、分选性以及连通性的分析显示,盒8上亚段的孔隙结构最好,其次为盒8下亚段,山1段的孔隙结构相对较差;山1段和盒8段均为低渗透储层,孔隙度与渗透率呈指数相关,其中盒8上亚段的孔渗高于下亚段,盒8段的孔渗性明显优于山1段。综合来看,储层物性以盒8上亚段最好,其次为盒8下亚段,山1段的物性最差。

In recent years,area in the southwest of Ordos Basin has become the key blocks of exploration and development. Nevertheless,there are still insufficient studies on reservoir space and petrophysical properties of P1s1 and P1h8 Members in this area. According to the observation of polarizing microscope and scanning electron microscopy with mercury injection t data,detailed analysis has been made on the pore microscopic features and types,pore structure and petrophysical properties. Results indicate that the major pore types in the research area are residual intergranular pore,lithic dissolved pore,matrix dissolved pore and intercrystalline pore. Pore structure of the upper P1h8 Member is the best,followed by the lower P1h8 Member,and the pore structure of P1s1 Member is relatively poor,on the basis of pore-throat size,sorting and connectivity. Both P1s1 and P1h8 Members are lowpermeability reservoirs. Porosity and permeability are in exponential correlation. The value of porosity and permeability of upper P1h8 Member is bigger than lower P1h8 Member. Obviously,porosity and permeability of P1h8 Member is superior to P1s1 Member. In general,petrophysical properties of the upper P1h8 Member is the best,followed by the lower P1h8 Member,but petrophysical properties of P1s1 Member is the worst.