Reservoir characteristics of lower sandstone member of Kumugeliemu Group in Quele area

Reservoir from lower sandstone member of Kumugeliemu Group in Quele area is a mainly of feldspathic lithic sandstone and lithic sandstone formation.Through rock analysis,thin section observation and physical property analysis,the study finds the lower sandstone reservoir space is mainly residual original intergranular pore,intergranular dissolved pore,intragranular dissolved pore,and a few cracks.The reservoir belongs to middle-low porosity,middle-low permeability type,and it experienced three evolution stages,namely syngenetic-supergene period,early A period and early B period,characterized by strong inside layer,interlayer and plane heterogeneity.High quality reservoir is affected by sedimentary microfacies,reservoir diagenesis,crack development and the influence of the overlying cream gypsum layers.Fan delta front bar is the best reservoir,followed by underwater distributary channel sand body.The cementation destroyed the development of pore,and the dissolution is the main cause of secondary porosity.Pore fracture communication can improve the reservoir permeability,and the cream gypsum layers protect the pore fracture,enhancing the dissolution pore growth at the same time.