Hydrocarbon accumulation analysis of heavy oil reservoir in complex fault block of Xinzhuang oilfield

Xinzhuang oilfield is a typical complex small fault block reservoir and has the characteristics of a fractured structure, narrow oil- bearing width and small area,high viscosity of crude oil and big water - oil volume ratio.Based on matching relation among time,space and hydrocarbon accumulation, the process and pattern of hydrocarbon accumulation have been analyzed.The analysis shows that reservoir bodies entered oil source area and capping layers in fan or finger shaped feature from depression margin,with a large contact area to oil source area and capping layers,which provides a favorable condition for hydrocarbon accumulation and migration. The hydrocarbon was found to mainly come from He -Ⅲformation in the south of deep depression area and reached the generation and expulsion peak of hydrocarbon at late Liaozhuang period.The formation time of the trap caused by nose - like structure was no later than the main hydrocarbon generation period.Because of fault activity,hydrocarbon migrated vertically along the fault,continued to migrate laterally along the sandstone with high porosity and high permeability,if there was,and finally sealed hydrocarbon at a structural high position.