Analy And Comprehensive Evaluation Of Shale Gas Preservation Condition In Wufeng-Longmaxi Formation,Northern Guizhou

The northern Guizhou area has undergone intense transformation of multi-stage tectonic activities,and the preservation conditions have become an important factor affecting the exploration and development potential of the northern Guizhou area.The investigation of the influence of preservation conditions on shale gas enrichment in the northern Guizhou area can provide a theoretical basis for the exploration and development of shale gas in the structure-complex areas outside the basin.This article through to suck in five mountains-the dragon stream group of shale gas material foundation,roof and floor conditions and evaluation and structure characteristics of the zone is analyzed,find out the preservation conditions of the shale gas preservation effect,finally set up five mountains-the dragon stream group of shale gas preservation conditions,a comprehensive evaluation system for typical tectonic units to suck area five mountains-the dragon stream set of comprehensive evaluation of shale gas preservation conditions The favorable preservation areas of typical tectonic units are divided.The results show that a good material basis of shale gas is the prerequisite for shale gas enrichment and the basis for discussing the preservation conditions of shale gas.The regional cap rock,roof and floor have dense lithology,large breakthrough pressure,large thickness and stable distribution,which are conducive to the preservation of shale gas.The physical property difference in wufeng-Longmaxi formation shale results in two-stage self-sealing,and the methane adsorption effect in gas-rich shale will form the third-stage self-sealing effect.The later the tectonic uplift time is,the lower the uplift rate is,the less the formation denudation is,and the better the preservation of shale gas is.By finding out the gas content difference of typical Wells with different burial depths and dip angles,it is concluded that the smaller the dip Angle is,the more favorable the shale gas preservation is.The formation burial depth is moderate,which is beneficial to the preservation of shale gas.By analyzing the influence of different types of faults on gas content,it can be concluded that the farther away from the second-stage fault,the more favorable it is to the preservation of shale gas,and the footwall preservation condition of reverse fault is better than the hanging wall.The greater the Angle between the direction of the maximum principal stress and the strike of the fault,the better the preservation of shale.Finally,the comprehensive evaluation system of shale preservation conditions of Wufeng-Longmaxi Formation in northern Guizhou was established,and favorable areas of shale gas preservation conditions in Anchang syncline,Daozhen-Luolong syncline and Yuyanbroad syncline were selected.