Sedimentary Microfacies Of The Third Member Of Shahejie Formation In Gubei Area Of Jiyang Depression

The Gubei area is located in the the eastern part of Zhanhua sags in the Jiyang Depression of the Bohai Bay Basin.The sedimentary period of the Shahejie Formation in the Paleogene of the Bohai Bay Basin is due to the deepening of the lake.The fan delta,underwater fan and turbidite are deposited in the Gubei area,forming the potential high quality reservoirs in the area,so as to form the favorable combination of the reservoir Lay the material foundation.Based on the theory of sedimentology,tectonics and sequence stratigraphy,this study is based on the research results of the predecessors,based on the core,logging and logging data,combined with the analysis and test data,The sedimentary microfacies are identified and divided,and the distribution zones of favorable reservoirs are predicted.The main conclusions are as follows:(1)Based on the identification of core facies and logging facies,three types of sedimentary faciesare identified,they include fan delta facies,lacustrine facies and turbidite fan facies,.The fan delta is mainly developed fan delta plain and fan delta front The fan delta plain is mainly divided into three types:the underwater distributary channel,the underwater diversion bay,the beach bar and the frontal sand.The lake facies are divided intotwo subfamilies,thatis semi-deep Lake and shore shallow lake(2)The fan-delta facies lithology in the study area is mainly composed of purple mudstone,gray fine conglomerate,gray coarse sandstone,gray fine sandstone and dark gray mudstone.The sub-lithology of deep lake-semi-deep lake is mainly composed of black mudstone and The dark gray mudstone is mainly dominated by the gray mudstone in the subfacial lithology of the shallow lake.The turbidite is mainly composed of fine gray sandstone and mudstone.(3)During the depositional period of the third member of Shahejie Formation in the study area,the lake surface is relatively high,and the northern part of the study area is mainly composed of semi-deep lake sediments,and the southern part of the study area is reduced in the northern part of the study area.Which is mainly dominated by the south,and the main body of the fan delta is the main favorable reservoir distribution area,followed by the estuary sand and turbidite Fan sand body.