Study On The Fracturing Optimum Design And Effect Evaluation Of Deep Shale Gas

The shale gas resources are abundant in the Sichuan Basin,and the deep shale gas resources(the depth more than 3500 meters)account for more than 80%.However,the production of deep shale gas wells is low,the stable production time is short and the wells can not form effective industrial gas flow.Therefore,the deep shale gas exploration and development technology needs a breakthrough.In this paper,based on the study of the geological characteristics of deep shale gas at domestic and international,For the anomalous high temperature and high pressure of the horizontal wel in Weiyuan,firstly establishes the compressible mathematical model,using the gray system theory,which obtain the compressibility index of deep shale gas.The numerical simulation method is used to analyze the productivity of the well.For the model of ellipsoid volume fracturing network,the geologic factors(the formation pressure coefficient,adsorbed gas,matrix permeability)and engineering factors(horizontal length,fracture number,fracture length,fracture conductivity)are studied respectively.Then analyze the influence of each parameter on the production.Finally,the optimal fracture parameter combination is determined by orthogonal test.Based on the combination of the fracture parameters,the treatment parameters(the percentage of pre-liquid,pump rate,sand ratio and fracturing scale)are optimized by the fracturing software.The influence of the treatment parameters on the fracturing effect is studied,then obtaining the treatment program.Using the fracturing software for effect evaluation,mainly study for G function analysis,matching pressure,fracturing curve.In this paper,the compressibility evaluation,fracture parameter optimization,optimization of treatment parameters and effect evaluation are carried out on the horizontal well in Weiyuan,which provides some guiding significance for future fracturing design and site construction of deep shale gas.