Enhanced Oil Solubilization Using Microemulsions With Linkers

Abstract In recent years, applications of microemulsion technology have increased in the drilling and production industry. Some of these applications include oil-based drilling fluid displacement to water-based fluid, near-wellbore remediation, well stimulation, enhanced oil recovery and flow-back recovery in shale gas wells. 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 to optimize the cost of the technology application. The reduction of surfactant concentration could be achieved by introducing linker additives in the formulations. The addition of linker molecules enhances the microemulsion solubilization property, which increases the hydrophilicity and/or the lipophilicity behavior of surfactants. Previous studies indicate the addition of a linker substance could double the solubilization of the system by segregating at the interface. The linker molecules create chaos, avoid formation of organized structure and decrease the viscosity, which helps to pack surfactants more efficiently at the interface. Some examples of linker additives include amines, acids, alcohols and phenols. This paper presents systematic studies that have been carried out to determine the influence of lipophilic and hydrophilic linkers in an anionic/nonionic surfactant mixture when exposed to olefin-based oils that are used in synthetic-based drilling fluids. The results of the study include phase behavior of a microemulsion system, interfacial properties and kinetic diffusion under several temperatures, as well as evaluation of the system with and without the addition of linker molecules for cleanup of synthetic and oil-based drilling fluids.