Abstract:

Abstract:The Kongdian Formation in the Bamianhe area has necessary conditions for oil and gas accumulation,such as reservoirs,traps and sealing conditions,but it lacks hydrocarbon generation conditions.Oil in the Kongdian Formation of the Bamianhe area is characterized by low density,low viscosity,low sulfate content,high wax content and high freezing point and can correlate with that in the Kongdian Formation of the Wangjiagang area in the Dongying depression.According to the contrast of geochemical indicators,such as the nature of crude oil,the constitution of component and the biomarker between the Kongdian Formation and Shahejie Formation of the Bamianhe area,we believe that crude oil sourced from the lower 4^th member of Shahejie Formation ( Es⁴) and the 2^nd member of the Kongdian Formation (Ek²) of the Dongying depression migrated to the Bamianhe area along unconformities and favorable passageways which consisted of the Northwest palaeostructure crest and channel sand body.Therefore,a variety of reservoir types were formed with the majority of overlapping unconformity stratigraphic reservoirs and structural reservoirs.Controlled by structural setting,carrier system,reservoir distribution,trap distribution and fault activities,oil/gas in the Kongdian Formation are mainly distributed in the southwestern part of the nose structure zone horizontally and in the lower part of the Kongdian Formation vertically which are within 80 m of distance from the unconformity.These oil pools are featured by insufficient charging and small scale.