The Relationship between Fault-activity and Hydrocarbon Accumulation of Neogene in Zhanhua Depression,Bohai Bay Basin

Based on the study of the plannar and profile styles of faults and their activity,the pool forming stage and the hydrocarbon distribution of Neogene,the relationship between fault activity and Neogene reservoir formation in Zhanhua Depression was discussed.The results show that the intensity of fault activity in the study area has a prominent feature ofstrong in the west but weak in the eastbefore the deposition of Es3,while it has a contrary feature after the deposition of Es3,and the active phase of the NE trending and nearly EW trending faults matches well with the hydrocarbon filling periods.The periods when fault controls hydrocarbon and when fault controls migration are the two key stages which demonstrate the influence of fault activity on hydrocarbon accumulation.When fault controls hydrocarbon,fault activity provides good material basis for oil and gas accumulation while when fault controls migration,fault activity provides efficient migration pathways for the transportation of hydrocarbon.According to the activity velocity of fault during the two stages,the faults controlling the distribution of petroleum were divided into three degrees namedⅠ,ⅡandⅢ.The degreeⅠand degreeⅡfaults lead to richer accumulation of Neogene hydrocarbon in drape structural belt,and the degree of the control of fault on oil determines the petroleum richness of Neogene.