LAUSR

Abstract Emulsion application in Enhanced Oil Recovery (EOR) processes is a common and practical subject in petroleum industry. Considering the chemical usage limitations, quantitative understanding of the ability of chemicals to improve other chemical performance is very important. In the present article, the coincident impacts of nanoparticles, salts and surfactants on interfacial tension reduction as well as zeta potential for determining the best emulsion stability have been examined. Resultant findings have shown that cobalt oxide nanoparticle and aluminum ions lead to an improvement in emulsion stability than each individually. Resulted emulsion stability indexes for cobalt oxide nanoparticles and aluminum ions are 0.48 and 0.49 at 25 °C and 0.54 and 0.66 at 50 °C, respectively. Nonetheless, their simultaneous presence, i.e., dispersion of cobalt oxide optimum weight percent in crude oil and dissolving of optimum aluminum ions concentration in water, change the stability indexes to 0.64 and 0.75 at temperatures of 25 °C and 50 °C, respectively. Presence of dispersed silica nanoparticles with low weight percent resulted in stability indexes of 0.49 and 0.43 at temperatures of 25 °C and 50 °C, respectively, but at high concentration because of repulsive forces against the asphaltene molecules, emulsion stability drops eventually with indexes of 0.35 and 0.26 at temperatures of 25 °C and 50 °C, respectively. While presence of cationic surfactant in the phase that silica nanoparticle is dispersed in, rises emulsion stability and viscosity. In all cases, along with emulsion stability increasing, quantities of zeta potential became more negative. But results of silica nanoparticle show that descending negative zeta potential trend of media does not lead to stability necessarily. This paper, quantitatively demonstrated that the effect of chemical co-existence by stimulating the polar molecules of crude oil caused a significant difference in emulsion stability than using the chemicals individually.