Research On Middle-Upper Jurassic Sedimentation And Reservoir Characteristics Of Fukang Sag In Junggar Basin

Based on the comprehensive application of core,logging,seismic and physical data,the sedimentary systems and reservoir characteristics of the Middle-Upper Jurassic strata in the Fukang Sag,the Boer Basin are studied.Emphasis was placed on the fine division and comparison of the top and bottom interfaces and the internal intervals of the Toutunhe Formation and Qigu Formation in the study area.The stratigraphic framework of the Toutunhe Formation and the Qigu Formation was established.Based on the establishment of phase markers,combined with lithology data,well logging data and seismic data,using sedimentary,sequence stratigraphy,geophysical and other theories to determine the sedimentary system developed in the study area is the shore shallow lake beach dam – song Flow River Delta-meandering river.The main types of sandstone are lithic sandstone and a small amount of feldspar lithic sandstone,which have low quartz content,low compositional maturity,and moderate rounding.The reservoir space is mainly secondary dissolved pores and a small amount of residual primary intergranular pores.The secondary dissolved pores are mainly intergranular dissolution pores,followed by intragranular dissolved pores and casting pores,and occasionally micro-cracks.The main controlling factors of sedimentary microfacies,burial depth and reservoir diagenesis are defined: reservoir evaluation and analysis are carried out for key well sections in the study area,and reservoir prediction and evaluation criteria are established.The favorable reservoirs mainly include three types: I,II and III: among them,the reservoirs of type II and III are relatively poor,and the layers of the study area are the most developed;I is the most favorable reservoir with the best physical properties,mainly developed in Qigu Formation.