Assessment of the rheological properties of a novel drilling fluid based on babassu esters for oil well applications

Drilling fluids are essential in oil exploration, balancing technical performance and environmental safety. In line with Sustainable Development Goal 12 (responsible consumption and production), this study formulates an eco-friendly fluid using babassu ester (Orbignya oleifera) as the base oil. A 2 3 factorial design assessed the effects of oil-water ratio, emulsifier concentration, and salinity at 30°C, 60°C, and 90°C. All formulations exhibited pseudoplastic behavior described by the Herschel-Bulkley model. Salinity was the most influential factor, significantly enhancing yield limit, consistency index, and apparent viscosity. Unexpected viscosity increases at 90°C suggest possible thermal degradation, warranting further investigation. While yield stress modeling achieved strong statistical fit, lower R 2 values for thixotropy and viscosity suggest nonlinear behavior better represented by quadratic models. These findings support the use of babassu ester as a sustainable alternative in drilling fluid systems, with potential for environmentally responsible application under varied operational conditions.