Analysis of Chang 8 Reservoir Characteristics in Xiasiwan Oil Field

Based on analysis of casting thin sections, SEM observation, mercury injection and physical property data, characteristics of Chang 8 reservoir in Xiasiwan oil field were studied. The results show that Chang 8 reservoir in this area is characterized by fine-grained feldspar sandstone; residual intergranular pore and solution pore developed well. The pore structures can be divided into two types, including small pore-throat type and microscopic pore-throat type. Dissolution and fractures have improved the extra secondary porosity. Compaction and granular cementation have decreased the porosity, and made the permeability worse.