Reservoir Characteristics And Sedimentary Microfacies On Chang 6 Of Tiebiancheng Region,Wuqi Oilfield

This paper take the sedimentary petrology,structural geology,petroleum geology as guide.Using the date of core analysis,well logging and oil testing to study the Sub-layer correlation,sand body distribution,structure characteristics,sedimentary microfacies and reservoir characteristics of Triassic in Tiebiancheng oil province.Analysis shows that the Chang 6 oil layer in study area can be divided into Chang 6₁,Chang 6₂ and Chang 6₃ three subgroups oil layer.The average thickness of Chang6₁ is 47 meters,Chang6₂ is 38 meters and Chang 6₃ is 46 meters.Structure in the study area inherited the large tectonic background,small layers show high east and low west large monoclinic,local development has a few little nose shaped uplift.Sedimentary environment is stable,belogs to delta front deposition,can be divided into underwater distributary channel,mouth bar,distribution bay between three sedimentary microfacies.The main channel plane from the NE to SW,Sand develop well,thickness of sandstone is great,transverse stretching far,provide well storage space for oil accumulation,sand body of Chang 6₁ develop best,Chang 6₂ is the second,Chang 6₃ is worst.The reservoir is mainly dominated by fine sandstone and silty sandstone,overall shows the characteristics of low compositional maturity and high structural maturity.Chang 6 oil layer group's pore throat combination is holes micro-fine throat,average of core porosity is 7.5%,average of permeability is 0.43x10^-3um²,which is a set of low porosity and permeability reservoirs.Infuence facors analysis of reservoir show that sedimentation and diagenesis are the main factors,it is affected by sedimentary facies belt on transverse,and by diagenesis in the longitudinal direction.It made poor by compaction.However,improved by secondary pores caused by dissolution.The chlorite is the main clay minerals in the study area,content is more than 43%,but sensitivity is not strong,water sensitivity and acid sensitivity damage is the main.Through the calculation and comprehensive evaluation,Chang 6 reservoir in the study area is strongly heterogeneous reservoir,reservoir classification is especially low to superly low permeability reservoir.