Structural Characteristics and Its Conditions for Hydrocarbon Accumulation at the Wanggu 1 Buried Hill in the Wangjiagang Structural Belt,Dongying Sag

This paper mainly analyzes 3D seismic profiles and logging data for the Wangjiagang structural belt in the Dongying sag of the Jiyang depression,the Bohai Gulf basin.Combined with regional tectonic setting and reservoir-forming conditions,we propose that the Wanggu 1 buried hill developed initially during the Indosinian period.Then,the faulted block formed and uplifted during the Yanshanian extension and depression.The present-day geometry was produced in the Yanshanian period.The Wanggu 1 buried hill is a typical basindipping residual-hill in the gentle southern slope of the Dongying sag.The buried hill was cut by two fault sets,one NW-striking and the other NE-striking. Fractures,solution cavities and pores developed well in the structural culmination.The Shahejie Formation is the hydrocarbon source rock and the Kongdian Formation is the regional cap rock.The oil and gas migrated along the fault and unconformity surfaces into the crest of the buried hill and accumulated to form the erosional residual-hill reservoir.