Rheological characterization of sepiolite-vegetable oil suspensions at high pressures

Abstract Drilling operations performed on geothermal wells require the ongoing search for sustainable fluids that will offer maximum performance and minimum environmental impact. Therefore, studies on the replacement of traditional clay suspensions in mineral and synthetic oils with clay suspensions in vegetable oils have offered some promising results. These preliminary results suggest the need for more extensive studies, including those considering high-pressure/high-temperature (HPHT) conditions, to assess the real capacity of biodegradable oils as substitutes for mineral and synthetic oils in oil-based muds (OBM) formulations. This work analyses the structure and thermomechanical properties of commercial organo-sepiolites dispersed in vegetable oils, as a function of temperature and pressure. This serves as the principal criterion for the development of environmentally-friendly OBM for HPHT drilling applications. The results suggest that organo-sepiolites in vegetable oil suspensions have suitable thermal and mechanical properties to produce sustainable and environmentally-friendly drilling fluid for application at a wide range of temperatures and pressures.