The Development Of Structural Fractures In Wuxiang Area And Its Influence On The Occurrence Of Shale Gas

In this paper,the tectonic fractures in Wuxiang area are studied,and the tectonic features and tectonic stress field are analyzed.It mainly experienced three stages of tectonic movement,in which the tectonic movement of Yanshan period laid the main framework for this area.Due to the control of tectonic action,the tectonic fractures in this area are relatively developed,and show some regularity.The fractures formed under the tectonic action have an important influence on the formation of shale gas.Through the collection of research area data,statistics on the data of field joints,thin section under the microscope and the experimental area of Wuxiang on the fracture characteristics of shale gas reservoir has done thorough research,summarizes the development law of Wuxiang area tectonic fissures,and combined with the regional geological condition for forming shale gas,study the influence on the development of shale gas accumulation in the Wuxiang area of fracture.The following conclusions are obtained:(1)The evolution of the main structure in the Wuxiang area can be divided into 3 structural layers which are 1(Indosinian),II(Yanshan period),III(Himalaya period);the main structural features in NS,NE,NW;Wuxiang area mainly experienced Indosinian period,Yanshan period and Himalaya period 3 stages of tectonic movement.SN mainly in Indosinian compressional stress,Yanshan period to NW-SE compressional stress,Himalaya in the early NW-SE to tensile stress,the late Himalaya-the present stress direction is NEE-SWW to the extrusion stress.(2)In the study area,the main revealed the T1 h formation,T1 l formation,Neogene and quaternary strata.The structure of the study area is relatively simple,which belongs to the monoclinic structure,and the dip angle is small,which mainly distributed in 5-35 degrees,with an average of 13 degrees.In the area of joint belongs to high angle joints,mainly distributed in the angle between 50 degrees to 90 degrees;drawing the trend rose diagram and the density figure,which reflected in the study area mainly developed two sets of joints,to respectively is 61 degrees and 320 degrees,61 degrees which belongs to the main joint direction;by drawing the joint density contour line,reflected in the study area from south to north,and the joint density first decreases and then increases again.(3)According to the above researching and Studying on shale gas geological condition for forming the research,mainly from the shale reservoir permeability two and gas analysis of tectonic fracture development regularity of accumulation effect on shale,the results of the study show that in the current tectonic stress field under the action of a development zone is more conducive to the enrichment of shale gas development zone,61 degrees of dominant fracture macro and micro fractures are more favorable for the enrichment and occurrence of shale gas.