Impact of ZnO and CuO nanoparticles on the rheological and filtration properties of water-based drilling fluid

During the past decade, many researchers have reported on various improvements to water-based drilling fluid properties through the addition of different nanoparticles to improve the rheological properties, the thermal and electrical conductivity, and fluid loss control. Although various types of nanoparticles have been tested for their ability to improve the rheological and filtration properties of water-based drilling fluids at low pressure and temperature, some of them have not yet been tested at elevated pressure and temperature. In this study, the impact of different concentrations of ZnO and CuO nanoparticle additives on the rheological properties of a water-based drilling fluid at 25oC, 50oC and 80oC, and on the filtration properties at 500 psi and 100oC was studied. A range of ZnO and CuO nanoparticle concentrations, from 0.1 to 1 wt%, were prepared as nanofluids and introduced as additives (1 vol%) into prepared water-based base drilling fluids. The rheological properties for both nanoparticle-based drilling fluids showed a significant improvement over the base drilling fluid, with ZnO providing a better overall performance than CuO. Both nanoparticle-based drilling fluids were also observed to be more stable at elevated temperatures. For the filtration tests conducted under elevated pressure and temperature conditions (500 psi and 100oC), a greater reduction in filtration loss was obtained at 0.8 wt% CuO nanoparticles (30.2%), compared to 0.8 wt% ZnO nanoparticles (18.6%). Mud cake thickness was also reduced, compared to the base fluid, with the CuO (27.6%) and ZnO (24.6%) nanoparticle fluids. These results demonstrate the ability of ZnO and CuO nanoparticles to enhance the properties of water-based drilling fluids, and their potential to be used as a high-efficiency filtration loss additive.