Sedimentary Facies And Reservoir Evaluation Of Permian Upper Wuerhe Formation In JR Well Block Of Karamay Oilfield

JR Well Block,is located in the south of the fifth area of the Karamay Oilfield.Multiple fault systems,structural and lithologic traps widely occur in this region.The favorable reservoir accumulation conditions make it the most preferred area for further hydrocarbon reserve discovery.Among which,the Permian Upper Wuerhe Formation is one of the main targets.However,following problems and limitations still existed in this area.The relationships among strata are very complicated without evident maker bed.The spatial distribution of sandstone bodies and the main controlling factors of reservoir physical properties are not clear.Based on the combination of geological,logging and seismic data,this paper evaluates the sedimentary facies and reservoir.The results show that the Permian Upper Wuerhe Formation in the JR Well Block can be divided into three members.The thickness gradually decreases from east to West.The particle size gradually becomes finer from bottom to top.The lateral distribution of sand bodies,the classification of sedimentary microfacies and processes are analyzed on the basis of the description of cores,facies characteristics of individual wells and well-connecting profiles,and the identification of seismic facies and chronostratigraphic correlation.The sedimentary facies of the Permian Upper Wuerhe Formation are alluvial fan,with several sedimentary fans of different scales are developed,and,the sedimentary microfacies of target layer is main flume of the watercourse.It is the main facies belt of high quality reservoir development.The source of sediment is from northwest direction.The lithology of the reservoir rock is dominated by sandy conglomerate,followed by lithic sandstone.They are characterized by low component maturity and low structural maturity.The numbers of P₃w₁and P₃w₂are target intervals in the study area.The reservoir is affected by compaction,cementation and dissolution.The reservoir space is mainly intergranular pores.The reservoir rock in the study area is characterized by poor physical properties,low porosity and poor permeability.It is reservoir with low porosity and low permeability.The main controlling factor of reservoir physical properties is shale content.P₃w₃is a set of mudstone with continuous occurrence.It is a set of regional caprock,forming a good reservoir cap combination vertically.