Flow Field Analysis And Integrated Optimization Design Of Separate Injection Tool For Polymer Surfactant Flooding

With the maturity of polymer/surfactant dual flooding technology,dual flooding technology has become the support to maintain the continuous and efficient development of major oilfields and to enhance the recovery level of oilfields in the later stage of development.As the main reservoir of H oilfield has been basically developed,the main object of displacement is transformed into two or three types of reservoirs with prominent contradictions in and between layers,which have strong heterogeneity and low permeability.If the traditional injection method is adopted,the reservoir production degree is low and the displacement effect is poor,which seriously affects the development effect of Polymer Surfactant Binary displacement.Due to the low permeability of thin and poor oil layers,the residual resistance coefficient increases gradually with the continuous increase of adsorption in the process of polymer surface binary flooding in each oil layer of H oilfield,which makes the percolation capacity of low permeability oil layer decrease greatly and the production degree is low,which affects the overall binary flooding effect.The integrated technology of polymer surfactant flooding and separate layer injection can effectively solve the existing problems.In this technology,high molecular weight polymer is injected into high permeability reservoir,and the injection pressure is reduced by pressure regulator to limit the injection amount;low molecular weight polymer is injected into low permeability reservoir by molecular weight regulator to increase the control degree of binary flooding.The combination of molecular weight regulator and pressure regulator can realize the injection of binary flooding with different quality and pressure.Therefore,it is particularly important to optimize the structure design of the separate injection tool,optimize the structure and size of the polymer molecular weight regulator,use the molecular weight regulator for the low-permeability zone,with large range of molecular weight regulation and small throttling pressure difference,and cut the polymer injected from the wellhead mechanically to reduce the molecular weight and improve the effective utilization of the low-permeability zone;optimize the design of the pressure regulator Structure,size,through the pressure regulator to reduce the injection pressure,throttle control,reduce the viscosity loss,injection into high permeability reservoir,make the layered injection more effective and convenient.The overall structure of separate injection string for polymer surface binary flooding is eccentric separate injection,which can meet the injection conditions of reservoirs with different injection rates and permeability,realize the control and fishing of any layer,and is not limited by the number of injection layers.In this paper,according to the key problems in the development process of Polymer Surfactant Binary flooding,combined with the existing separate injection technology,the integrated separate injection technology of binary flooding is designed and developed.Through the flow field analysis and experimental research of the regulating element,the structure of the regulating element is optimized,and the injection volume,injection pressure and viscosity loss rate of the integrated separate injection tool are verified,which is helpful to improve the comprehensive recovery of H oilfield It has very important guiding significance.The above research results provide theoretical support for the injection technology of polymer surface binary system composite flooding,and have certain guiding significance for field application.