Prediction And Evaluation Of Shale Gas Geological "Sweet Spot" In Longmaxi Formation Of Yunshanba In North Yunnan And Guizhou

In this paper,through the interpretation of the fine seismic data of the two wells A and B in the work area,Longmaxi Formation is the main one to find out the structural style of the work area,find out the stratum,fault spatial distribution and sedimentary details of the target strata,and find out the factors and laws that have influence on shale gas enrichment in Yunshanba area.Pre-stack inversion uses pre-stack seismic data and drilling data to obtain the elastic parameters of underground media.Then the lithology,physical property and gas bearing property of underground media can be predicted through the change of elastic parameters.Among them,geological "sweet spot" includes 6 indexes such as structure,fracture,TOC,total gas content,porosity and thickness.Based on(multi-dimensional)seismic data,this study predicts the distribution characteristics of geological "sweet spot" through fine structural interpretation,well-earthquake joint inversion,and in combination with regional geological characteristics.With the help of geological sweet spot,the foundation is laid for the development prospect of the whole work area.This is of great significance to the study of marine shale gas in the southern Paleozoic in the whole area of northern Yunnan and Guizhou.The favorable geological sweet spot area of Longmaxi Formation in Yunshanba area is predicted by mapping and superimposing geological sweet spot indexes.The following results have been obtained in the research process:(1)Yunshanba area is generally a structural pattern of one uplift and two depressions in the east-west direction,with high in the south and low in the north.Yunshanba syncline has fewer faults,smaller dip angle and favorable shale gas preservation conditions.(2)Yunshanba area has high reservoir evaluation indexes,such as total organic carbon content,total gas content,reservoir thickness,effective porosity,etc.It has stable horizontal development and favorable geological conditions for shale gas reservoirs.(3)Yunshanba syncline is moderately buried,with few large faults and cracks.(4)The "sweet spot" category I area,the "sweet spot" category II area and the "sweet spot" category III area have been found by synthesizing various indexes.