Abstract: Polymer Flooding is one of the most economic attractive EOR techniques which are used to improve the sweep efficiency, and in turn extract large fraction of the residual oil after primary recovery. The selection of the optimum polymer concentration should be considered as a main step in designing a polymer flooding project since it affects both the technical and economic feasibility of the project. There are several factors such as shearing, temperature, salinity and adsorption influencing the polymer concentration and viscosity required for achieving favorable mobility ratio. Thus, the impact of these factors should be considered while selecting the optimum concentration. The objectives of this research are to investigate the effect of polymer types, concentration, and adsorption and slug sizes on oil recovery at low and extremely high salinity. Rheological behavior of two types of polymer: Xanthan gum and PAM were measured in high salinity high temperature (HSHT). The effect of polymer adsorption was measured to determine the optimum polymer concentration. Results showed that the optimum polymer concentration was 500 ppm based on the relative permeability data and shear rate of 10s^(-1).in porous media. In addition, the effects of polymer concentration and slug size on cumulative oil recovery were investigated showing that the recovery factor increases with increasing the polymer concentration with an optimum slug size 0.6 PV. These extensive laboratory tests conducted will help in selecting the optimum polymer slug, concentration at reservoir conditions that will provide the favorable mobility ratio. The economic evaluation of the project based on the simulation study and polymer properties measured in the lab showed that the polymer flooding is economically feasible, since the project earned much higher NPV than water flooding. . A new correlation will be developed to be used to calculate the resistance factor at different shear rates. Finally, The economic feasibility of the selected concentration and slug size are determined.

Keywords: Enhanced oil recovery, Polymer, Slug size, Cumulative oil recovery, Adsorption, concentration.