Fault-caprock Dual Control Hydrocarbon Accumulation Regularity in Volcanic Rocks in Xujiaweizi Fault Depression

To recognize the gas forming rule of Xujiaweizi depression under the fault-cap rock dual control, this paper is base on the material of Xujiaweizi which includes threedimensional seismic processing results interpretation of logging curves outcrop core observation and analytical test in laboratory, Analysis of the lithology, distribution and brittle ductile characteristics of ductile -brittle of Xujiaweizi depression, evaluating sealing property of cap rock, studying deformation mechanism of the fracture in patch of cap rock, analyzing the top sealing ability and vertical adjustment of gas.Study on the internal structure of the fracture zone, analyzing sealing mechanism of different types of fault, establishing quantitative sealing evaluation method on corresponding fault, and quantitatively evaluating fault sealing in gas reservoir controlled by fault, research on the correlativity between fault sealing and gas distribution, systematically summarize the forming models of gas controlled by different fault-cap rock passage system.There are three main types of deep gas cap rock in Xujiaweizi fault depression, and they are mud stone, volcanic rock and clayey breccia.Mudstone is mainly distributed in the 1st and 2nd Member of Quantou Formation, the 4th,3rd and 2nd Member of Denglouku Formation, it is primarily regional cap rock of deep gas in Xujiaweizi fault depression.Volcanic rock is mainly distributed in the 1st and 3rd Member of Yingcheng Formation and clayey breccia is mainly distributed in the 4th Member of Yingcheng, both of them constitute Yingcheng group's gas top locality cap rock in Xujiaweizi fault depression.Volcani crock and clayey breccia are intercalary strata at the 1st and 3rd Member of Yingcheng.Taking into account the formation and evolution of the sealing capacity of cap rock.During Quantou group's late