Research On The Influence Of Wujiang Fault Structure Evolution On Shale Gas Production

The Wujiang fault zone is located in the southwestern part of the Jiaoshiba block,and its tectonic characteristic and evolutionary deformation have a very important control effect on shale gas accumulation.Predecessors have obtained many knowledge and achievements in the Jiaoshiba anticline area,but they have less knowledge about the nature,style and tectonic evolution of the peripheral faults,and further research is needed.Based on the study of regional geological structure,this paper uses seismic data,logging data,and simulation software technology to finely interpret the seismic profile,restore the tectonic evolution process of each section of the Wujiang fault,and determine the tectonic deformation stage,evolution characteristics and genesis.This article also counts the shortening amount and shortening rate of the strata in each period,and finally comprehensively analyzes the control effect of tectonic evolution on the formation of shale gas and its influence on the exploitation effect.This article has mainly gained the following knowledge:1?There are differences in the denudation degree and thrust fold strength of the overlying strata in each section of the Wujiang fault zone.From south to north,the strength of structural deformation gradually weakened,from deep to shallow,and the extent and scope of the Jurassic denudation of the Upper Paleozoic and Mesozoic gradually decreased.2?The formation of the Wujiang fault zone was the result of the Yanshan movement,and the tectonic deformation was mainly formed in the early and middle Yanshan.It mainly experienced three phases and five stages of structural deformation and transformation process.The first phase is the North-East Jurassic-type folding stage;the second phase is the basement involved in imbricate thrust(first),cap rock slipping nappe(middle),left-handed compression and twisting(after);The third phase is the denudation setting period.Among them,the formation period of the Jurassic-type folds and the involvement of the basement in the imbricate thrust stage established the basic structural pattern of the research area.The five main stages are:(1)Yangtze quasi-platform stage;(2)Jurassic-type fold generation and formation stage;(3)Jurassic mountain barrier and trough fold formation stage.(4)The generation and formation stage of the base-entanglement and cap rock slipping structure.(5)Late Yanshan period-now is the stage of denudation and transformation.3?Each segment of the Wujiang fault zone has different evolution characteristics.The southern section is mainly manifested by the formation of Jurassic folds,basement involvement and thrust,slipping nappe and denudation.The middle section shows the basement thrust,left-handed twisting,and denudation;while the north section shows the thrust,shallow slippage and denudation..4?The important control effect of tectonic evolution on shale gas is embodied in:the denudation degree of each section of the Wujiang fault strata affects the regional capping of shale gas;the deformation strength and fault sealing of each section directly affect the production of shale gas;strike-slip faults The accumulation control effect is obvious,and combined with the degree of denudation,it affects the preservation conditions of shale gas.