Study On Distribution Characteristics Of Fault Damage Zone In Tight Sandstone Of Xujiahe Formation In The Northeastern Sichuan Basin

Fault zone have long been regarded as a key factor in many geological studies,especially in the field of crust fluid seepage.As a brittle structure,it is usually accompanied by a complex fracture system,which provides an important channel for underground fluid seepage,affecting the storage of oil and gas migration and reservoirs,deposits,groundwater,etc.So far,most of the relevant researches on fault zone are based on field outcrop observations,while the detailed study of the characteristics of underground fault is relatively rare.Based on 3D seismic data,this paper aims to quantitatively study the distribution characteristics of the top-level reverse faults system of the T3X2 in the Malubei area.The Malubei area is located at the intersection of the Micang Mountain and the Daba Mountain orogenic belt.It is affected by the multi-phase structure activity effect,and the folds and faults are developed,and the structural features are complex.We successfully identified six north-northwest reverse faults in the Malubei area by extracting the dip and azimuth seismic attributes,the maximum and minimum curvature seismic attributes,the root mean square amplitude and reflection intensity seismic attributes,the variance and the ant tracking seismic attributes along the target layer of the work area.Among them,there are three reverse faults extending farther in the work area,and the extension lengths are more than 10km;there are three reverse faults with shorter extensions,and the extension length ranges from 3km-6km.Based on the variance attribute value,the widths of the three main fault fracture zones are segmented and quantified.It is found that the width of the fault damage zone shows strong inhomogeneity.Not only the width difference between the fracture zones is large,but also the width of the individual fracture zone is on the strike.There have also been significant changes.Furthermore,through the study of the distribution of variance attribute values of fault fracture zone,the internal structural features of four typical fault fracture zones and their corresponding variance attribute distribution patterns are summarized:Pulse-shape and Rake-shape.,Box-shape,Ramp-shape.In addition,we also study the structural characteristics of the fault fracture zone and find that the difference under the ideal condition decreases exponentially with the increase of the distance from the core,until it is close to the background value of the surrounding rock.The reaction has the highest degree of fracture deformation in the core,and the degree of deformation.As the distance from the core increases,it decreases exponentially.