Characteristics and evaluation of Chang 6 sandstone reservoir of Upper Triassic in Fuxian area,Ordos Basin

Based on core observation and the data of cast thin section,scanning electron microscope,physical pro-perty,porosity and permeability analysis,Chang 6 sandstone reservoir of Upper Triassic in Fuxian area is analyzed.The result shows that the reservoir is delta front deposit.The lithologies of the reservoirs are mainly arkose and lithic arkose and the reservoir space mainly includes primary residual intergranular pores and secondary intergranular dissolved pores with poor physical property,high displacement pressure and high saturation median point pressure,small pore throat radius,poor pores throat sorting and fine skewness.The quality of reservoir is affected by sedimentary microfacies and diagenesis.Subaqueous distributary channel and mouth bar sand bodies are the best microfacies for reservoir development.Strong compaction and pressolution is the another factor which results in low porosity and low permeability.According to the physical properties of reservoir and pore structure parameters,Chang 6 sandstone reservoir is classified into four types.The type Ⅰand type Ⅱ reservoirs can be taken as the major target zones for further exploitation.