Empirical correlations for viscosity of partially hydrolyzed Polyacrylamide

During water flooding operations, polymer can be added to injected water to improve sweep efficiency and retard viscous fingering. This technique, namely polymer flooding has achieved successful large-scale field applications in China. Polymer flooding is also being tested in several heavy oil fields. For oil field applications, partially hydrolyzed polyacrylamide (HPAM) is the most widely-used polymer. HPAM solution must maintain high viscosity to effectively mobilize oil. In reality however, polymer is very sensitive to salinity and hardness of base water and underground water. This phenomenon is studied in this paper. The two HPAM test samples have molecular weight of 10 million and 20 million Dalton. The first group of tests was conducted to study the effect of salinity on HPAM viscosity. The second group of tests was carried out to evaluate the effect of hardness on HPAM viscosity. It was discovered that both sodium and calcium ions can severely damage polymer viscosity. Data analysis shows that the empirical non-Newtonian parameters are strong functions of water salinity and hardness. Based on test data, empirical formulas are proposed to calculate HPAM viscosity influenced by polymer concentration, temperature, water salinity and water hardness. These formulas are useful tools for predicting HPAM viscosity in field applications. © 2013, The Author(s).