Recent Advances in the Utilization of Imidazolium-Based Ionic Liquids for Chemical-Enhanced Oil Recovery: A Comprehensive Review.

The increasing global energy demand and the declining efficiency of conventional oil recovery methods underscore the urgency for advanced enhanced oil recovery (EOR) techniques. While chemical EOR enhances recovery, traditional surfactants face limitations such as high retention, thermal instability, and poor performance in high-salinity environments. Imidazolium-based ionic liquids (ILs) have emerged as a promising alternative due to their superior thermal stability, tunable interfacial properties, and potential for recyclability. This review evaluates their role in EOR, focusing on interfacial tension (IFT) reduction, wettability alteration, emulsification, viscosity control, and crude oil interactions. Long-chain ILs like [C16mim][Br] achieve over 99.8% IFT reduction while improving rock wettability and dispersing asphaltenes-key for enhancing oil mobility and recovery. In addition to technical performance, the review addresses the economic feasibility and environmental sustainability of ILs. Despite higher initial costs, their advancement in synthesis, lower consumption rates, reusability, and reduced ecological impact offer long-term advantages over conventional surfactants. Future directions include hybrid IL formulations, large-scale applications, and AI-assisted molecular design to optimize EOR efficiency across varied reservoir conditions.