Study on Sedimentary Facies of Shahezi Formation(Cretaceous) in Binxian Fault Subsidence in the Northern Songliao Basin

Three sedimentary layers including Shahezi Formation,Yingcheng Formation,Denglouku Formation and four fault-depressed blocks developed in lower Cretaceous layers of Binxian-Suihua area in the north of Songliao Basin.Six seismic facies developed in the area through the characteristic analysis on the amplitude,continuance,inner structure and formalness of the seismic reflection stratum.Through the data of multidisciplinary analysis with the outcrop,core observation and description,drilling-well logging,laboratory test and especially the seismic facies interpretation,six styles of sedimentary facies formed in lower Cretaceous layers are alluvial fan facies,fluvial facies,fan-delta facies,braided stream-delta facies,lacustrine facies,and volcanite facies,respectively.Through analyzed the plane distributed and developed character of the sedimentary facies in different layers,it was concluded that the lower Cretaceous layers were made up of coarse sediments mainly in the fault subsidence period.The sedimentary provenance which was controlled by the major fault came from the arctic region near the major fault in each fault depression.The fine grained sediments were favorable for the source rock and the coarse sediments of the overlying were favorable reservoir.The result was that Binxian and Beian fault depression maybe the priority area for the oil and gas exploration in the future.