Natural Fracture Distribution And 3D Modeling Of Longmaxi Formation Shale Reservoir In Luobu Syncline In Zhaotong Demonstration Area

Luobu Syncline Block in Zhaotong Demonstration Area on the southern edge of Sichuan Basin is located in the alternate part of compression and compression torsion deformation areas,with complex crustal stress.The natural fractures in the Longmaxi Formation and Wufeng Formation are relatively developed,and the gas testing production is relatively low.Based on comprehensive analysis,the development of natural fractures is a key factor affecting production.Accurately characterizing the distribution of natural fractures in the shale of the Wufeng Longmaxi Formation of the Luobu Syncline is the key to breakthrough productivity.Starting from core and the interpretation results of imaging logging,the mechanical causes of fractures were analyzed,the occurrence of fractures was statistically analyzed,the density of fractures on the well was calculated,and the vertical distribution pattern of fractures was determined.Extracting multiple seismic attributes and manually interpreting faults based on the original seismic profile,analyzing the planar distribution characteristics of faults and fault zones.Using ant tracking attributes to extract large-scale fractures with certainty;A small-scale fractures model was randomly simulated using ant tracking attributes to display planar trends and dominant fractures directions,and a fractures network model was established in a hierarchical manner.The results show that the natural fractures in the Luobu Syncline are mainly high angle shear fractures,with significant differences in fracture density among wells.More than 70 fractures have been developed in YS115 well,and no more than 3 fractures have been observed in YS130 and YS131 wells.Four seismic attributes were extracted,and ant tracking can clearly identify faults and better reflect the morphology of secondary fault zones within the fault zones.Based on the ant tracking attribute as the core,a natural fracture model in the study area is established by combining certainty and randomness.This model is well matched with faults encountered during horizontal well drilling and well leakage.Establishing an accurate three-dimensional fracture model is of great significance for subsequent geomechanical modeling,well location optimization,pre drilling risk warning,horizontal well fracturing scheme design,and achieving ultimate productivity breakthroughs.