CHARACTERISTICS OF SEDIMENTARY FACIES FOR THE UPPER SUBMEMBER OF THE THIRD MEMBER OF THE SHAHEJIE FORMATION IN DAPINGFANG AREA OF EASTERN DEPRESSION

The upper submember of the third Member of the Shahejie Formation in the Dapingfang area of eastern depression is a major exploration target of deep sag zone,and has fundamental geological conditions of hydrocarbon accumulation.In order to provide basis for further disposition of exploration work,the predictive work for favorable reservoir facies was carried out.Drilling data,seismic and logging data were used to study the sedimentary structures and their combined features.It was recognized that there were 7 kinds of deep-water sediments developed at the upper submember of the third Member of the Shahejie Formation in this area.In fact,the formation at mainly developed braided river delta(braided river delta plain subfacies,braided river delta front subfacies) and the nearshore subaqueous fans.Braided river delta front subfacies mainly occurred in the west of studied area.The vertical evolution feature and the plan distribution of sedimentary facies of the formation were studied and outlined,which provided basis for favorable exploration areas in the future.