Estimation of the Concentration of Hpam Polymer Required to Achieve a Desired Viscosity in Eor Projects

Polymeric solutions are one of the most relevant and promising techniques for enhanced oil recovery. Significant advances have been made in developing models to evaluate the rheology of polymeric solutions in remote places, such as the injection plants’ locations. However, these solutions still challenge the injection control engineers with determining the polymer concentration needed to achieve the desired viscosity. This paper aims to provide a reliable tool to predict the polymer concentration as a function of viscosity. Procedures, Process: Consequently, in this work, a numerical model is presented to predict the polymer concentration of polymeric solutions as a function of the desired viscosity based on the PAMA method. Universal viscosity charts were developed that allow estimating the viscosity at zero shear rates (η0), the intrinsic viscosity ([η]), or the polymer concentration (C) knowing at least two of these three variables. In the development of this model, the universal viscosity equations that start from viscosity measurements at a shear rate of 7.3 s-1 were used as a basis. A coefficient of determination R2 equal to 0.9 and an average Mean Absolute Error (MAE) of 0.3 were obtained when contrasting the proposed model results against experimental data found in the literature. Hence, it was shown that the universal viscosity charts developed using the numerical method have reliability above 90%. It was also found that the proposed model used to estimate the viscosity at zero shear rates has a better fit for low polymer concentrations. Specifically, the R2 increases to 0.95 when the desired viscosity at zero shear rates is between 1 and 150 cP. Furthermore, these charts allow any operator in the field to modify the concentration of polymer solutions and know its modified viscosity at zero shear rates, regardless of the brine or the molecular weight of the polymer. The development of universal viscosity charts based on the PAMA method documented in the literature allows the determination of viscosity at zero shear rates for any combination of brine and polymer from the partially Hydrolyzed Polyacrylamide (HPAM) family. This method requires a single viscosity measurement at a shear rate equal to 7.3 s-1. This tool is convenient for field engineers who need to make quick decisions to control the viscosity of the injected polymer solution.