A Perspective on ionic liquids as multifunctional agents in enhanced oil recovery and CO₂ sequestration in carbonate formations

Enhanced Oil Recovery (EOR) combined with carbon dioxide (CO₂) sequestration offers a promising solution to address the dual challenge of meeting global energy demands while reducing greenhouse gas emissions that drive global warming. Carbonate reservoirs with a large portion of the world's remaining oil present challenges, including complex pore structure, low permeability, and oil-wet characters. Furthermore, operational challenges such as intricate phase behaviour, water–rock–gas interactions, reservoir integrity risks, high salinity, and the presence of impurities like H₂S, further complicate their exploitation. Recently, ionic liquids (ILs) have emerged as potential solutions to such challenges. ILs have unique properties, including tunable nature, thermal stability, and near-zero vapor pressure. ILs have EOR capacity by modifying wettability, reducing interfacial tension, and improving CO₂ adsorption and dissolution under harsh reservoir conditions. This paper identifies the challenges associated with carbonate reservoirs and suggests the possible role of ILs in addressing these issues. The major objectives of this work are to demonstrate the potential of ILs in the sustainable implementation of EOR and the development of an efficient carbon management approach.