Review on chemical enhanced oil recovery: Utilization of ionic liquids and deep eutectic solvents

Abstract

The increasing demand for oil production requires the extraction of oil obtained from not only primary and secondary stages, but also tertiary recovery methods in order to meet increasing global demand on the power requirement. Therefore, enhanced oil recovery (EOR) is expected to increase their relevance in the coming years. Physical gas injection and thermal methods have been used for EOR for a while; however, due to its limited applicability and high operating cost, chemical-based EOR processes have been considered a promising alternative considering higher efficiency, technical and economic feasibilities, and reasonable capital cost requirements. Therefore, the search and design of new chemical compounds are of pivotal relevance for the oil and gas industry to boost reservoir production. Among the new types of compounds considered for chemical EOR, ionic liquids (IL) and deep eutectic solvents (DES) have gained considerable attention over the last few years. The purpose of this review is to review the database of published work on these compounds and analyze ILs and DESs performance in the EOR process. The possible mechanisms of action of both types of fluids, their suitability, and problems, as well as economic factors, are studied. The details of experimental results on rock wettability, core flooding performance and interfacial tension data for both ILs and DESs have been examined. The pros and cons of these fluids compared to the available traditional chemical enhanced oil recovery methods have been discussed, and the marginal effect on EOR performance via ILs and DESs has been highlighted. Guidelines for designing and developing new ILs and DES for EOR have been provided to obtain more sustainable and environmentally friendly chemicals suitable for EOR operations.