Controlling factors of tight sandstone gas enrichment and high yield in the fourth member of the Xujiahe Formation in Jianyang area,Sichuan Basin
Recently,significant breakthroughs have been made in the exploration and development of tight sandstone gas in the section 4(S4)member of the Jianyang area in Sichuan Basin.However,during the exploration and development process,it was found that there is differential enrichment of natural gas in the Xujiahe Formation in the Jianyang area,with a cross distribution of high and low production wells.The lack of understanding of the controlling factors related to natural gas enrichment severely restricts the next exploration deployment in this block.Aimed at addressing the key scientific problems of large-area,gas-bearing,local differential enrichment and the complex gas-water relationship in the Xujiahe Formation,the hydrocarbon source conditions,reservoir characteristics,and structural characteristics of the study area are comprehensively studied.The methods used in this study including studying thin rock sections,mercury injection,carbon isotopes,and pyrolysis gas of hydrocarbon source rocks.The controlling factors of tight sandstone gas accumulation in the study area are clarified,and a high-yield model of natural gas enrichment is established.The research results show that:(4)The natural gas in the S4 member of the Jianyang area is of coal-type,mainly supplied by local section 3,upper sub-member,hydrocarbon source rocks;(2)The development of hydrocarbon source rocks controls the gas-water distribution pattern of the S4 member,with thick hydrocarbon source rocks on the lower slope having high gas saturation,and thin hydrocarbon source rocks on the upper slope having high water saturation;(3)The tight gas enrichment and high yield are controlled by a combination of the physical properties of the fault and reservoir,including the development of a fault-fracture-reservoir superposition.A tight sandstone gas accumulation model of"near source hydrocarbon supply,fault channeling,reservoir fracture control production"is established.The research results provide theoretical guidance for the geological exploration of tight sandstone gas in the slope belt of Sichuan Basin.
tight sandstone gascontrol factorsaccumulation modethe fourth member of the Xujiahe FormationJianyang areaSichuan Basin
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