Rheological behavior of terpolymer (PAM-ATBS-NVP) in polymer flooding for enhanced oil recovery: impact of concentration, salinity and nanoparticles

The application of polymer flooding for enhanced oil recovery has resulted in the retrieval of an additional 10%–20% from the original oil in place (OOIP). The main objective of this study was to investigate the rheological behavior of terpolymer (PAM-ATBS-NVP) in polymer flooding for enhanced oil recovery. The effect of concentration, temperature, salinity/hardness, and nanoparticle type/concentration was assessed under different reservoir conditions. The results showed that, as the shear rate increased, the viscosity of the polymer decreased which reflected shear thinning behavior and when the polymer concentration increased, the viscosity of the polymer increased. The polymer also provided good thermal stability. Despite this terpolymer being designed to tolerate harsh condition of temperature and salinity/hardness, the viscosity of the polymer decreased with higher salinity/hardness. Using three types of nanoparticles (NPs), the viscosity of the polymer did not change for two NPs which were alumina NP and titanium NP while the viscosity of the silica NP-polymer mixture decreased with respect to the silica NP concentration. This difference in the behavior between NPs was due to the adsorption of the polymer molecules to the silica NP surface.