The influence of alkyl ammonium modifiers on the microstructure and high-pressure rheology of sepiolite-vegetable oil dispersions

Abstract

In the context of environmental sustainability, the drilling industry faces new challenges resulting in the study and development of new drilling fluids based on eco-friendlier components to replace harmful mineral oils. Organic modified sepiolite dispersed in oil is an excellent additive to provide suitable rheological properties at low concentrations. The present study investigates the effect of alkyl ammonium modifiers on the microstructure and rheological properties of sepiolite-vegetable oil dispersions under high-temperature (up to 140ºC) and high-pressure (up to 2000 bar) conditions. Organo-sepiolite, prepared using a high-shear processing method and containing surfactant with alkyl chains longer than 12 carbon atoms, exhibited a high degree of surface adsorption and thermal resistance. All modifiers developed a stable fibrous structure in the dispersion. This structure maintained the pseudoplastic behavior in a wide range of shear rate, temperature and pressure without reaching an apparent yield stress. These dispersions showed suitable rheological and thermal properties to develop sustainable drilling fluids.