Based on comprehensive analysis of various data such as core observation

casting thin sections

scanning electron microscope

physical property analysis

mercury penetration and production test

we studied the characteristics and the main controlling factors of the sandstone reservoirs in the Pinghu Formation of Pinghu tectonic belt in Xihu depression.The results show that the reservoir rocks are dominated by feldspathic quartz sandstone with good sorting and roundness

moderate compositional maturity and high texture maturity.The reservoir is characterized by low porosity and low permeability or moderate porosity and moderate permeability

as well as a good correlation between porosity and permeability.The pores are dominated by intergmular dissolution pores and relic primary intergmular pores

the pore throats are mainly of necking throat

laminated throat and curved lamellar throat

and the pore-throat assemblages are dominated by moderate pore-coarse throat.The main controlling factors of reservoir development in the research region were studied in respects of sedimentary facies

diagenesis and abnormal high pressure.Sedimentary facies is one of the main factors controlling the reservoir quality.The sandstone reservoirs of delta plain distributary channel facies are the best in physical properties

followed by delta front underwater distributary channel facies.Compaction and cementation are destructive to reservoir physical property

while dissolution is constructive to reservoir physical property as it can generate secondary porosity.The existence of abnormal high pressure is also constructive to reservoir physical property

for it is helpful to the preservation of the original intergranular pores and to the improvement of dissolution of the early carbonate cement

resulting in intergranular dissolution pores and improving the reservoir physical properties.