Banca de DEFESA: TATYANE MEDEIROS GOMES DA SILVA

Study of the effect of electrolytes on the rheology of anionic polyacrylamide solutions.

Polyacrylamide, APAM, Viscosity, Rheology, salts

Currently, a third of global energy is still obtained through oil. In this context, anionic polyacrylamide is widely applied in polymer injection processes for advanced oil recovery. However, due to its molecular composition, it becomes sensitive to several factors such as pH, temperature and salinity. Therefore, it is necessary to understand how the presence of different concentrations and types of electrolytes, together with temperature changes, affect their viscosity and rheological behavior. Therefore, rheological tests were carried out using the APAM 3430S with a molar mass of 12 million daltons in triplicate solutions of NaCl, KCl, MgCl2 and CaCl2, varying the temperature at 20, 35, 50, 65 and 80°C. The experiments were carried out in a rheometer with concentric cylinder geometry. The results showed that the addition of electrolytes resulted in a loss of viscosity in the solution. In some solutions containing MgCl2 and CaCl2, the Newtonian plateau for high shear rates was reached. The temperature variation reduced the viscosity of solutions with monovalent salts by around 45% and 70% of divalent solutions. The viscous activation energy and cloud point of the solutions were also obtained. In the end, the Ostwald de Waele and Carreau-Yasuda rheological models were applied, where the Carreau-Yasuda model was considered the best for data adjustment as it presented better R2 and lower RMSE values.