Impact of polymer addition, electrolyte, clay and antioxidant on rheological properties of polymer fluid at high temperature and high pressure

Abstract

AbstractNowadays, the application of polymer in petroleum industries due to its feasibility with enhancing hole cleaning, less formation damage characteristics of drilling fluids has been particularly advantageous in deep well operation. However, figuring out the influence mechanism of temperature on the rheological behavior of polymer fluids and keeping the excellent rheological regulation at high temperature and high pressure (HTHP) are still serious issues for the mud designers. In this work, the rheological properties of a commonly used drilling fluid polymer treating agent named Driscal-D were tested under HTHP conditions by Fann 50SL rheometer. The effects of polymer addition, electrolyte, clay type and antioxidant on the rheological properties of Driscal-D solution were studied in high-temperature environments. Results showed that the viscosity of the solutions tends to increase with the polymer addition increases, making its pseudoplastic characteristics more noticeable. As the temperature rises, the fluid loses viscosity, causing the polymer solution to evolve from pseudoplastic fluid to Newtonian fluid. The presence of the electrolyte and the oxygen scavenger leads to a decrease in the viscosity of the solution, but in high-temperature environments, the solution adding formate or antioxidant has a higher viscosity retention rate than the pure solution at low shear rates (< 50 s−1). The incorporation of the clay in Driscal-D solution enhances the rheological properties, which is beneficial for cuttings transportation. And the dispersion is best described by Herschel–Bulkley model.