安塞油田H区长6油层组储层微观孔隙结构特征

摘要

Pore structure has an important effect on reservoir properties.By thin section analysis,SEM,mercury injection method,the microscopic pore structure characteristics of Chang 6 reservoir in H area of Ansai Oilfield are studied.The result shows that Chang 6 reservoir belongs to low porosity and ultra-low permeability reservoir in H area of Ansai Oilfield.The main pore types of the reservoir include intergranular dissolved pore,residual intergranular pore and intragranular dissolved pore.The pore and throat have good sorting and general communication.The capillary pressure curve is divided into Ⅰ,Ⅱ,Ⅲ,Ⅳ types according to the characteristic parameters of pore structure.The type Ⅱ and Ⅲ are the main types in the study area.With capillary pressure curve changing from Ⅰ type to Ⅳ type,the driving pressure and Pc50 increase gradually,and Rc50 and average pore throat radius decrease gradually,which reflects that pore structure and reservoir property change from good to poor.By comprehensive research of the relationship between characteristic parameters of pore structure and property parameters,it is shown that reservoir property is the result of driving pressure,Pc50,structural coefficient and so on.%孔隙结构是影响储层物性的重要因素。采用铸体薄片、扫描电镜、压汞分析等技术手段,对安塞油田H区长6油层组储层微观孔隙结构特征进行了深入的研究。结果表明,安塞油田H区长6储层属于低孔、特低渗储层,孔隙以溶蚀粒间孔、残余粒间孔和粒内溶孔为主,属中孔、微细喉道类型,孔喉分选性好,连通性一般。根据孔隙结构特征相关参数将毛管压力曲线分为4类,研究区主要以Ⅱ类和Ⅲ类为主。从Ⅰ类到Ⅳ类,排驱压力和中值压力逐渐增大,中值半径和平均喉道半径逐渐减小,反映出储层的孔隙结构和渗流能力由好变差。孔隙结构特征参数与物性的相关性研究表明,物性是排驱压力、中值压力、结构系数等多种因素综合作用的结果。