Nano-silica to reduce of surfactant adsorption in oil recovery: A review

Oil recovery in geological reservoirs can be enhanced by surfactant flooding, yet this technique is limited by surfactant adsorption on rocks.Here we review the use of nano-silica to decrease surfactant adsorption and to recover more oil, with a focus on surfactant flooding and adsorption, nano-silica properties and development, strategies to reduce surfactant adsorption, and the use of other nanoparticles such as zinc oxide, zirconium oxide, and titanium dioxide.During classical waterflooding, more than 60% of the oil remains trapped in reservoirs due to adsorption of surfactants onto reservoir rocks, which can reach up to 2.84 mg/g.The use of nano-silica reduces surfactant adsorption by 43%, lowers the adsorption density to 1.61 mg/g, and, in turn, improves oil recovery from 4.43 to 9.11%.