The Research On Well Pattern And Optimization Of Parameters In Low Permeability Reservoir

Because of the low natural productivity,water flooding has become a common method to replenish energy in low permeability reservoirs.In the meantime,it's difficult to establish the effective driving system by water flooding for the existence of the actuating pressure in low-permeability reservoirs.Hydraulic fracturing is one of important stimulation methods for the low permeability reservoir.Therefore,the key to enhancing oil recovery is whether the fracture and the well pattern match up and whether the injection-production parameters and the well pattern match up.According to the above problems,this paper studied the following content:Firstly,based on the study of developing low permeability reservoir with the application of integrated fracturing technologies in domestic and abroad,this paper analyses the reservoir geological characteristics,predict the elastic recovery of the reservoir and demonstrates the feasibility of waterflooding.On the top of it,a reservoirs-fracture model is established.The reserves and production history matching have been studied.then according to the theory of potential superimposition principle,a formula of technical limit well spacing at arbitrary water saturation was deduced in this paper,which take into account the water-oil phase flow theory and starting pressure gradient in water-oil phase flow by introducing the definition of apparent viscosity and virtual potential field.In addition,this paper considers every factor affecting the well spacing density,uses future value to calculate economic rational well pattern density and economic limit well pattern density of X reservoir,Shengli oilfield,and then determine the reasonable well spacing and row spacing by combining with reservoir numerical simulation method.Finally,the actual reservoir numerical simulation model is set up,this paper analyzes the influence law of fracturing fracture parameters and Injection-production parameters on the water flooding development effect of low permeability reservoir.On the basis of the analysis,fracturing fracture parameters and injection-production parameters of five spot well pattern and nine spot well pattern is optimized by combining the orthogonal design method with the fuzzy general judgment method.The results indicate the condition of optimum parameters for five spot well pattern are below.Well spacing is 300m,row spacing is 170m,the angle between the fracture and well row is 0°,fracture conductivity of water injection well is 20?m~2·cm,fracture conductivity of oil well is 30?m~2·cm,fracture penetration ratio of water injection well is 0.3,fracture penetration ratio of oil well is 0.7,fracturing ratio of water injection well is 0.4,fracturing ratio of oil well is 1,liquid production capacity before the optimum time of water injection is14m~3/d,the optimum time of water injection is when the formation pressure to initial formation pressure ratio is 90%,bottom-hole injection pressure is 50MPa,liquid production capacity is 14m~3/d,water injection rate is 14m~3/d.The condition of optimum parameters for nine spot well pattern are below.Well spacing is 200m,row spacing is 180m,the angle between the fracture and well row is 30°,fracture conductivity of water injection well is15?m~2·cm,fracture conductivity of oil well is 30?m~2·cm,fracture penetration ratio of water injection well is 0.5,fracture penetration ratio of oil well on the edge is 0.4,fracture penetration ratio of oil well on the point is 0.52,fracturing ratio of water injection well is 0.8,fracturing ratio of oil well is 1,liquid production capacity before the optimum time of water injection is 15m~3/d,the optimum time of water injection is when the formation pressure to initial formation pressure ratio is 80%,bottom-hole injection pressure is 48MPa,liquid production capacity is 13m~3/d,injection-production ratio is 1:1.According to the Simulation results,five spot well pattern is better than nine spot well pattern.