Study On The Fracture Characteristics Of Moxi-Gaoshiti Area In Sichuan Basin

With the depth of oil and gas exploration and development,local tectonic zone and low-level fault are the key research objects of increasing production and storage.Moxi-Gaoshiti area is located in the central sichuan basin,affected by multiphase tectonic evolution function,there are a large number of internal fractures,fracture played an important role in controling the oil and gas distribution.At present,the exploration stratigraphy of the Mossi-Gaositi area is the deep-seated Sinian Dengying group and the Cambrian Longwangmiao group.The fracture characteristics are not clear,lacking of system research have severely affects the deep understanding of the reservoir and restrict the development of favorable target area.On the basis of previous studies,combining with the seismic interpretation results,comprehensive utilization of geological data and the production data,we have carried out a systematic study of the fracture system,first,fracture geometric features were summarized,secondly by fault growth index method and the analysis of the structural evolution section,we analysed the kinematics characteristics of the fracture system,and then combined with numerical simulation and physical simulation to investigate the dynamics characteristics,finally achieve the purpose of analyzing fracture effect on oil and gas distribution control.Mainly achieved the following conclusions:(1)The results of the three-dimensional seismic fine interpretation show that there are five fault zones in the Moxi-Gaoshiti area,and the fault zone's directions are mainly in the N-S,NW-SE,NE-SW,E-W.And we identifed the following three types of strike-slip torsional fractures: large flower-like faults,parallel or oblique high-angle strike-slip faults and associated broom-like faults,which have significant characteristics in both plane and profile.(2)The results of fracture growth index show that the characteristics of the whole activity of the fault system are from south to north and from west to east,from the Sinian to Cambrian.Based on the results of structural restoration profile,it is concluded that the fracture is mainly high angle,the part is nearly erect and the skid shape is obvious.The main formation period is Sinian Dengying group and the Cambrian Longwangmiao group.(3)The results of numerical simulation and physical simulation show that the north-east faults are formed in the early left-lateral torsional torsion,and the north-east faults and associated faults are formed in the right-handed twisted torsion.The early formation of the near-north-south faults is controlled by the later faults.The role of the right is not obvious,while the late right-handed action not only produced new fractures,but also transformed the early fracture,the two superposition of the final formation of the Moxi-Gaoshiti area complex system.(4)The prediction results of fractures based on stress field simulation show that the main formation period of the crack in the Moxi-Gaozitan area is Early Caledonian,the degree of development of late Cary East is the second,and the fractal density of the Himalayan period is small.Fracture is the main controlling factor of fracture development.The relationship between the stress and the fracture connectivity of the main fault controlled the gas distribution characteristics in space,and influenced the process of the exploration and development of the low permeability carbonate reservoir.