Analyses of Sandbody Formation and Oil/gas Reservoir-forming Mechanism of H₅ Horizon in Chunxiao Field Group of Xihu Trough,the East China Sea

H₅ reservoir of Huagang Formation stored up plentiful oil/gas resources in Xihu Trough. Discussed reservoir depositional sequence contrasting, distribution,genetic mechanism,caprock character and reservoir forming mechanism of H₅,This paper tries to find out some geologic conditions for outbalancing optimal oil/gas enrich layer,and puts forward particular viewpoint for deciding optimal exporting target in Xihu Trough.