Rheological and filtration property evaluations of the nano-based muds for drilling applications in low temperature environments

As the search of hydrocarbon has moved to the more remote and unconventional areas, including low temperature offshore and Arctic circle, new challenges have also emerged to the life of the industry. The biggest drilling fluid-related challenge in low temperature environments, is maintaining fluid properties under an extreme temperature difference between the bottom hole and the surface. The rapid change of temperature conditions can affect mud rheological properties and reduce drilling performance. The heat released from the mud circulation system can also cause thawing of the permafrost and gas hydrate-bearing formations impacting the wellbore integrity and releasing greenhouse gases to the environment. Creating a more thermally independent drilling mud becomes one of the solutions to reduce the potential problem that may arise. The aim of this study is to address the issue by designing nano-based drilling muds that will demonstrate more thermally stable characteristics. Silica (SiO2) and alumina (Al2O3) nanoparticles were used in the freshwater- and saltwater-based mud formulations at various concentrations. The mud rheological properties evaluation was conducted using a direct-reading viscometer at a temperature range from 0 to 80 °C, whilst mud filtration properties was evaluated using a low-pressure filter press under 700 kPa (100 psi) differential pressure. The concentration of 0.1 wt% of each type of nanoparticles showed the optimum profile in which rheological properties were most stable across the broad temperature conditions in both the freshwater- and saltwater-based systems. The sample containing 0.1 wt% of silica also gave the lowest filtration properties in which a reduction of 8.2% was observed in the filtration loss volume.