Study On The Feasibility Of Well Pattern Adjusting Surfactant-Polymer Flooding After Polymer Flooding

Surfactant-polymer flooding is an important enhance oil recovery. technology afterpolymer flooding.However, after polymer flooding reservoir non-homogeneous is more serious, the distribution of remaining oil is more dispersed.The potential for enhanced oil recovery is limited by using surfactant-polymer flooding alone.Combined with wellpattern adjustment, surfactant-polymer flooding can further improve the Swept volume and displacement efficiency. Therefore,it is of great significance to study the well patt-ern adjusting surfactant-polymer flooding technology.In this paper,based on the In-depth study of surfactant-polymer flooding mechanic-sm,considering the increase of viscosity, inaccessible pore volume,adsorption interfacial tension, etc, a mathematical model of polymer flooding is established. Based on the comparation and verification ,using the model which is built, the well pattern and res-ervoir adaptability of surfactant-polymer flooding after polymer flooding is studied.Theeffects of chemical character parameters (the maximum permeability reduction factor , inaccessible pore volume, adsorption,interfacial tension, etc.)and development parameter-rs(injection timing, slug size, concentration, injection rate, etc) on the surfactant-polym-er flooding after polymer flooding are studied. By multivariate analysis, the affectting order of the factors and their interaction on development effectiveness are analyzed.Utilizing the treatment of relative permeability curves under low interfacial tensi- on,The formula for calculating the aqueous-phase relative permeability was derivated under low interfacial tension. Based on the basic idea of mobility designs and descrip-tions of polymer, a mobility design model for combination flooding was established.T-he factord that affect the minimum polymer concentration which meet the requirements of cont-roling the mobility are analyzed. With the help of orthogonal design, a injection capabi-lity model is fitted .Base on input-output principle, a evaluation model for feasibility of well pattern adjusting surfactant-polymer flooding is established. The factor that aff- ect the feasibility of well pattern adjusting surfactant-polymer flooding are analyzed.Based on the actual data of Ng3 unit of GuDao oilfield ,the circumscription of polymer concentration which control the mobility and recovery efficiency are calculated .Combined with the results of numerical simulation ,the development plan for well pattern adjusting surfactant-polymer flooding after polymer flooding is optimized, the feasibility of its development is analyzed.