Cellulose nanocrystals (CNCs) are natural bio-based nanoparticles that can be used to modify the viscosity and improve the performance of various fluids. For this reason, they are of interest to the oil and gas industry, where they can replace other expensive and non-biodegradable polymers that are commonly used. CNCs must first be modified so that they do not degrade or settle at high temperatures and pressures. To accomplish this, CNCs will be extracted from cotton using a variety of methods or by post-modifying the nanoparticle surface to have new chemical groups and new functionality.