Microcosmic Pore Structure in Low-Moderate Permeability Reservoir of Fuyu Oil Layer in Sanzhao Sag

By cast slices,co-focused SEM,traditional mercury-injection method,and constant rate mercury-injection method,the microcosmic pore structure in low-moderate permeability reservoir of Fuyu oil layer in Sanzhao sag was determined.The pore structure is very complex.The secondary dissolution pore(i.e.intragranular pore,intergranular pore) is the main type of reservoir,with average diameter of 22.49-49.31 mm and various connectivity between pore and throat.According to permeability,associating with pore type,pore throat radium,ratio of pore throat radium,and connectivity of pore throat,the reservoir is divided into two groups: moderate permeability reservoir with moderate pore and small throat and low permeability reservoir.the latter is further classified into three types: moderate pore and small throat reservoir,small pore and unhomogeneous and subtle throat reservoir,and small pore and homogeneous and subtle throat reservoir.These classifications of reservoir will guide the future exploration for this area.