Characteristics of Xujiahe Fm sandstone reservoir in Northeast region of Sichuan basin

The characterists of Xujiahe Fm sandstone reservoir in Northeast region of Sichuan basin were investigated by the data of core analysis,scanning electron microscope,porosity and permeability analysis and acoustic emission test.The pore space of reservoir mainly includes the secondary pores.The microfractures can limitedly improve the petrophysical property of reservoir of Xujiahe Fm sandstone reservoir with low permeability and porosity,not high displacement and saturation median point pressure,small pore throat radius,poor pores throat sorting and fine skewness.The quality of reservoir was affected by sedimentary microfacies and dia-genesis.Distributary channel mesograin sandstone of delta plain was the best microfacies for the reservoir development.The agglutination of authigenic chlorite in the early stage of diagenesis were favorable for protection of primary pores and throats,but the dissolution only limitedly improve the connectivity of pore throat of Xujiahe Fm sandstone reser-voir.According to the pet rophysical properties of reservoir and pore structure parameters,Xujiahe Fm sandstone reservoir was classified into four types.The type I and type Ⅱ reservoirs are the available reservoirs under the current process conditions and can be taken as the major target zones for increasing reserves.