The effect of salinity on polymer selection and oil recovery by polymer flooding

Abstract

Polymer flooding is one of the most promising EOR methods and has frequently been applied in EOR operations. In this process, water-soluble polymers increase the viscosity of the flood water and thus improve the water / oil mobility ratio. The incremental oil production is a result of improved vertical and areal sweep efficiency. The effect salinity on polymer solution viscosity determination and selection of suitable and optimum polymer type and concentration for different brine concentration present in the reservoir is important for polymer flooding success. In this work, cores were designed ai^d developed and considered as pores medium. These cores were saturated with light and low-viscosity oil samples from Malaysian crude oil and then flooded by 0.4 PV polymer slug in low-pressure and lowtemperature conditions. In this study the effect of two polymer types, polyacrylamide and xanthan, were utilized to inspect the effects of polymer type, concentration and salinity on polymer solution viscosity. The result of the optimum polymer type and concentration was used to make the polymer flooding using core saturated with four different brine concentration of CaCh (5000, 15000, 25000, and 45000 ppm).The results of experiments illustrated that the salinity effects on polyacrylamide viscosity is more comparing to xanthan gum and concentration of 1500 ppm xanthan gum is most suitable for good polymer flooding with favourable mobility ratio. The study shows that polymer flooding with low salinity brine is more beneficial compare to high saline. Finally, compared with waterflooding, polymer flooding resulted in a considerable growth in ultimate oil recovery.