Study On The Well Pattern Adapted To Chemical Flooding From Steam Huff And Puff In Heavy Oil Reservoir

After multiple rounds of steam huff and puff for heavy oil reservoirs,the cycle development effect and economic benefits have deteriorated,and the recovery rate is less than20%.It is urgent to change the development method.Viscosity-reducing chemical flooding can increase the viscosity of the displacement phase and reduce the viscosity of the crude oil.By improving the oil-water mobility ratio,the oil recovery can be further improved.However,the characteristics of heavy oil reservoirs after multiple rounds of huff and puff are quite different from those of water drive development reservoirs.The formation characteristics,pressure system,well pattern,and remaining oil distribution law are all different from the previous chemical flooding units.Therefore,the conversion of this type of reservoir to chemical flooding needs to solve the problem of matching injection-production well patterns and the corresponding technical and economic limits under different conditions.In this paper,numerical simulation technology is used to characterize the flow field parameters of heavy oil reservoirs after steam huff and puff;considering the dynamic characteristics of the reservoir physical parameters after steam huff and puff,the gradual approach method of well spacing is used to establish the limit of effective production of remaining oil.With the maximum net present value as the objective function,combined with numerical simulation technology,the economic and reasonable well spacing is optimized;considering the characteristics of well pattern and uneven distribution of remaining oil after steam huff and puff,and based on the time-varying characteristics of viscosity and oil saturation of crude oil in the process of chemical flooding after steam huff and puff,combined with the balanced displacement technology,a well location optimization method for infill wells is established.In order to maximize the control degree of chemical flooding and improve the development effect of steam huff and puff in heavy oil reservoir,the injection and production fluid volume of viscosity reducing chemical flooding system is optimized by using optimization method.The results show that the influence factors of huff and puff radius after steam huff and puff are studied.The formation thickness,permeability and injection temperature have great influence on the radius of huff and puff.The optimization model of injection well location is established,and the particle swarm optimization algorithm is used to solve the optimization model.Numerical simulation shows that the optimization method of injection well location can effectively realize the maximum balanced displacement of remaining oil.The results show that after well patterns optimization,the distribution of oil saturation is relatively uniform,the daily oil production is increased by 80%,and the oil displacement effect is good.