Study On The Effect Of Non-uniform Conductivity Of Deep Shale Gas Fracture On Productivity

Deep shale gas reserves are rich,which is China’s shale gas production capacity construction and breakthrough of the main object.The development of deep shale gas depends on volume fracturing technology,and the conductivity of fracture is non-uniform.Based on the reservoir parameters and experimental study of deep shale gas well D in wufeng-longmaxi formation,the basic model of deep shale gas dual porosity medium is established.The non-uniform conductivity model of fractures along the horizontal wellbore direction is established,and four kinds of simulation schemes are put forward to simulate and analyze the results of cumulative production and pressure distribution The overall contribution rate can reach up to 40%,and the best conductivity distribution scheme of each fracture section in horizontal well is determined by comparing different schemes.A model of non-uniform flow conductivity in deep shale gas fracture(fracture length/fracture height)is established to simulate overdisplacement,proppant backflow and proppant settlement.After over-displacement,the cumulative yield is 12%～15% of the balanced displacement cumulative yield.The backflow model of proppant shows that the influence rate of single fracture on cumulative production is about 20%,and that of complex fractures is about 10%.The cumulative yield of proppant subsidence model is 81.6% ～ 96.2% of equilibrium displacement,and the influence rate is about8%.The formation of effective complex fractures near wellbore can reduce the overdisplacement effect.The deep shale gas was conducted the experimental and simulation study on the decline of conductivity.The short-term diversion capacity experiment was carried out to analyze the diversion characteristics of different closure pressure,proppant type,particle size,sand concentration and slippage.Carry out proppant long-term diversionability experiment,determine the law of diversion decline.Combining the model with the decline law,the results show that the decline of fracture conductivity has a significant effect on the production of deep shale gas.The cumulative production of the constant flow conductivity model is 1.26～1.35 times that of the model considering the decline of flow conductivity.When the flow conductivity decreases to a certain degree,the re-fracturing process is carried out to reduce the effect of the flow conductivity decrease on the production.