Interfacial behaviors of ionic liquids in petroleum Production: A review

Due to superior surface activity and physicochemical properties, ionic liquids (ILs) have been applied in petroleum industry in different ways, such as ILs-assisted solvent extraction of unconventional oil ores (oil/tar sands, asphalt rocks, shale oil ores, etc.), enhanced oil recovery of conventional crude oil and tight oil reservoirs and oil-water emulsions separation. Basically, the ILs play their roles by different status (e.g., pure ionic liquids status and ionic status) in two steps for the enhancement of separation: oil-solid separation and oil-water separation. In this review, the applications of ILs in different petroleum production processes (ILs-assisted solvent extraction, enhanced oil recovery and demulsification) are systematically discussed. In particular, the oil-solid and oil-water interfacial behaviors of ILs in these processes are reviewed, where the effects of ILs molecular structure and operational parameters on ILs interfacial behaviors are summarized. Additionally, the open area in the interfacial behaviors of ILs and the challenges in the large-scale applications of ILs in petroleum industry are also proposed.