Control Factors Of Shale Gas Enrichment In Weiyuan Area,Sichuan Basin

Shale gas is a natural gas resource that exists in the source rock in the form of free and adsorbed state in mud shale.As a typical unconventional natural gas,shale gas is still in its infancy in China.In different regions,the shale gas enrichment control factors have great differences.It is of great practical significance for shale gas exploration and later development fracturing.This paper studies the marine shale in the Weiyuan area of the Sichuan Basin,uses logging indicators,combined with core,field profiles and geochemical data to analyze the redox environment and biological productivity,and clarify the material basis of shale gas enrichment;select typical wells For the samples of different lithofacies types,the characteristics of shale reservoirs in the study area are comprehensively studied from the aspects of reservoir material composition,pore fracture structure and physical properties,and the influencing factors of each reservoir characteristics are identified for shale gas enrichment influences.By analyzing the conditions of the shale gas bed and the self-sealing property,the sedimentary burial history and tectonic transformation are restored,and the evolution process of the controlled conditions is analyzed.The influence of storage conditions on shale gas enrichment is clarified,and the preservation conditions are evaluated.The high-quality black shale at the bottom of the Wufeng-Longmaxi Formation controlled by deep-water sheds in Weiyuan area has high organic matter abundance?>2%?,good organic matter type?type I and type II₁?,and high organic maturity?high-over-mature?.It provides a rich material foundation for high-quality shale in Weiyuan area,and the shale reservoir has poor physical properties.The organic pore-biosilicon-microcrack matching determines the effectiveness of the reservoir.The Longmaxi Formation has excellent top and bottom conditions and self-sealing effect,effectively reducing the loss of shale gas.The structural transformation of Weiyuan area is relatively weak,and the fault is not developed,which is conducive to the enrichment and preservation of shale gas.The Weiyuan area as a whole has a negative structure with a moderate pattern.From west to east,the pressure coefficient gradually increases and the display preservation condition gradually becomes better.