A series of experiments have been conducted to characterize and quantify the effects of shear rate, salinity, and hardness on the viscosity of polymer solutions. A set of correlations were developed to predict the viscosity of polymer solutions. These correlations consider the individual and combined effects of shear rate, salinity, and hardness on the viscosity of polymer solutions. The power-law model for the viscosity behavior has been modified to accommodate the influence caused by these three factors. Nonlinear regression was performed on the experimental data to develop the proposed correlations. The proposed correlations can be integrated into any reservoir simulator for polymer injection and should prove useful for the initial screening for the selection of the polymer for enhanced oil recovery applications in oil reservoirs. © 2014 Copyright Taylor & Francis Group, LLC.