Study microscopic pore structure characteristics of chang 8 reservoir of Jiyuan oilfield by capillary curves

By thin section analysis, SEM, mercury injection method, the microscopic pore structure characteristics of Chang 8 reservoir of Jiyuan oilfield are studied. The result shows that Chang 8 reservoir belongs to low-porosity and ultra-lowpermeability reservoir of Jiyuan Oilfield. The pore and throat have general sorting and communication. The capillary pressure curve is divided into 4 types according to the characteristic parameters of pore structure. The type Ⅰ and Ⅱ 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.