Improving the drilling fluid properties using nanoparticles and water-soluble polymers

Water-based drilling fluids are utilized to carry out efficient and smooth drilling operations of oil and gas wells. Bentonite is a basic constituent of water-based drilling fluids. It has excellent swelling properties, ability to make gel structure and acts as viscosifier to tailor the rheological properties of drilling fluids. Deep well drilling with bentonite drilling fluids at high temperature and pressure conditions will severely affect the performance of drilling fluid in term of degradation and flocculation due to thermal induce swelling of bentonite. High salts contamination during the drilling process reduces the hydration and dispersion of bentonite and results in flocculation. The aim of this study was to improve bentonite drilling fluid performance using novel water-soluble polymers and nanoparticles. Nanoparticles significantly improved the filtration properties by reducing the fluid loss into formations and by making a thin filter cake for smooth drilling operations. Novel water-soluble polymers such as acrylamide/2-Acrylamido-2-methylpropane sulfonic acid copolymer and acrylamide/2-Acrylamido-2-methylpropane sulfonic acid/ N-Vinylpyrrolidone terpolymer were used to improve the rheological properties and dispersion of bentonite. Rheological and filtration properties were evaluated using functionalized carbon nanotubes and graphitized nanotubes by varying the temperature from 25°C-85^oC. Herschel-Bulkley and Bingham model were used to calculate various parameters such as plastic viscosity and yield stress. It was observed that incorporation of 0.25 wt.% polymers and 0.25 wt.% nanoparticles improved the filtration and rheological properties such as yield stress and steady shear viscosity.