Polymer Flooding Dynamics in Enhanced Oil Recovery: A Pore-Scale Study of the Influence of Shear-Thinning Rheology on Flow Dynamics and Recovery Efficiency

This study addresses the limited understanding of how shear-thinning polymer rheology influences enhanced oil recovery (EOR) at the pore scale. Using a pore network model and the Carreau rheological model, the impact of shear thinning under varying wettability, dilution, flow rates, and mobility ratios is examined. Results show that shear thinning strongly affects displacement patterns, with significant viscous fingering and reduced recovery efficiency at high shear rates, as viscosity declines within pore spaces. In contrast, minimal shear-thinning effects lead to stable displacement fronts, resembling a shear-independent flood with improved recovery. Higher oil viscosities exacerbate the impact of shear thinning, with reduced oil recovery in the presence of more severe shear-thinning polymers. In oil-wet systems, capillary forces counteract shear-thinning effects, promoting uniform displacement. The results also show that higher injection rates do not guarantee better recovery when shear thinning is present, as excessive shear may reduce polymer viscosity. Optimal recovery occurs at lower flow rates, where the polymer maintains higher viscosity and displacement fronts remain stable. This work highlights the importance of incorporating realistic shear-thinning behavior in polymer flooding models to enhance the predictive accuracy of EOR simulations and improve understanding of how polymer rheology influences pore-scale mechanisms in oil recovery.