Optimization of Microemulsion Formulations with Linker Molecules

Abstract

Abstract Applications of microemulsion technology in the drilling and production industry have increased in recent years. Some of these applications include oil-based drilling fluid displacement to water-based fluid, near-wellbore remediation, well stimulation, enhanced oil recovery, flow-back recovery in shale gas wells, and cement spacers. Microemulsion formulations for these applications need to have high oil solubilization and very low interfacial tension, which is achieved with relatively high concentration of surfactants. High-performance microemulsion systems with lower surfactant concentrations are desired in order to optimize the cost of microemulsion technology applications. The reduction of surfactant concentration and cost could be achieved by introducing linker additives in the formulations. The addition of linker molecules enhances the solubilization property of microemulsions, which increases the hydrophilicity and/or the lipophilicity behavior of surfactants. Previous studies indicate that addition of a proper linker molecule could significantly increase the solubilization of the oil. The lipophilic linker molecules (e.g. long chain amines, acids, alcohols, phenols) increase the interactions between the surfactant and oil, although with some disorder to avoid formation of highly-organized structures and to decrease the viscosity. This paper provides a comprehensive discussion of work carried out to determine the influence of lipophilic and hydrophilic linkers in microemulsions formulated with anionic/nonionic surfactant blends. The interfacial tension, fluids compatibility, and return permeability evaluation of microemulsion formulations containing lipophilic linkers prove that these additives bring a significant improvement in water injection or crude oil production.