Microscopic pore structure characteristics of Chang 6 reservoir in H area of Ansai Oilfield

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.