Synthesis and use of functionalized SiO2 nanoparticles for formulating heavy oil macroemulsions

There has been a growing interest in applying nanoparticles for enhanced oil recovery. Within this context, there is a need to understand the influence of the factors involved in the formulation of nanoparticle based emulsions over their properties. In this contribution, functionalized SiO2 nanoparticles of two different sizes were synthesized and used as surfactants for the formulation of emulsions with two model oils: squalane and vacuum gas oil. Factorial experiments were made to analyze effects of particle size, water content, emulsification energy, and of the non-additive (second and third order interactions) effects between these variables over droplet size distributions, polydispersity, and over the rheological profiles of the formulated emulsions. It was found that the functionalized SiO2 nanoparticles produced either water in oil (W/O) or oil in water (O/W) macroemulsions depending on the chemical nature of the oil phase; namely, squalane made W/O emulsions and vacuum gas oil made O/W emulsions. Additionally, it was demonstrated that non-additive factors play an important role over the properties of the emulsions, especially for the vacuum gas oil based emulsions. Therefore, this work demonstrates that simpler linear relationships do not suffice for finding the best conditions for formulating crude oil type emulsions aimed for applications such as enhanced oil recovery. (c) 2022 The Author(s). Published by Elsevier Ltd.