Enhancing Polymer Flooding Efficiency in a Sandstone Oilfield in Kazakhstan through Silica Nanoparticle-Based Control of Polymer Adsorption

Polymer flooding improves reservoir tertiary recovery, especially in highly heterogeneous formations containing viscous crude oils. Because polymer adsorption can result in a significant loss of the injection fluid viscosity, polymer adsorption should be controlled by modifying the properties of the system. Alkali is widely used to improve the repulsive forces between the polymer and sand grains by making the rock surface more negative. Nanoparticles may also be effective to control polymer adsorption as a result of their large surface area and ability to interact with polymeric chains. Despite the positive synergy between nanoparticles and polymers, the research on the utilization of nanoparticles in minimizing polymer adsorption is limited with very few studies conducted under real field conditions. To improve oil recovery from a Kazakhstani oilfield, field A, by utilizing a previously designed optimum polymer concentration, this study aimed at controlling polymer adsorption with application of silica nanoparticles (NPs) and NaOH alkali. For this purpose, static and dynamic adsorption tests were performed, followed by oil recovery tests utilizing the optimum combination. The stable chemical concentrations for polymer, alkali, and nanoparticles were determined on the basis of aqueous stability and zeta potential measurements. Static adsorption results showed a noticeable effect of both silica NPs and NaOH alkali on lowering polymer adsorption. However, alkali was less efficient for longer contact durations with the rock. Silica NPs also facilitated around 18% reduction in polymer dynamic adsorption. At the same time, alkali was ineffective, leading to a 5% increase in polymer dynamic adsorption. Polymer-nanoparticle (P-NP) flooding as an enhanced oil recovery technique was successful, achieving a total recovery factor of around 95%, where incremental recovery of the remaining oil was 5% higher than the standalone polymer flooding scenario. On the basis of the results, it is recommended that the polymer flooding plan for field A can be improved by incorporating the findings of this study.