The Study Of Sedimentary Characteristics And Reservoir Evaluation Method For Carboniferous Oil Reservoir In North Truva Oilfield

North Truva oilfield is a large carbonate reservoir in carboniferous period,which has high oil well production,large lateral variation,strong heterogeneity,complex pore structure.Therefore,it is difficult to be developed.In this paper,the KT-1 oil reservoir group is the research object.Based on the data of oil field geology,well logging and chemical analysis,the study of the sedimentary characteristics,logging interpretation and reservoir classification is carried out.There are open platform,restricted platform and evaporation platform subfacies at target layer.Dolomite flat and miscellaneous debris beach micro facies are favorable reservoir facies belt.Beach depression is medium bad reservoir.The lithology is mainly limestone,followed by dolostone.The reservoir space are mainly intragranular pore and intercrystalline pore.The degree of cave and fracture development is low.Based on the study of lithology and electric property,the crossplot is established by using the synthetic curves U,IMP and well logs GR,CNL to determine the classification criteria for lithology.Through the study of physical property and electric property,the method for identifying reservoir is proposed.And the interpretation models for total porosity,matrix porosity,cave porosity,fracture porosity,total permeability,matrix permeability and fracture permeability are established.Based on the study of oil bearing and electric property,the standard for effective thickness lower limit of oil reservoir is established by using the crossplot of effective porosity and oil saturation.And the oil-gas layer,oil-water layer,poor oil layer,water layer and dry layer are divided.Although the invasion in high porosity and permeability layer and the calcite minerals in reservoir have an impact on identification of fluid properties by deep resistivity log,this method will eliminate the influence.Accordingly,the method has a higher accuracy on the identification of carbonate reservoir.