Enhanced Heavy Oil Recovery Using [Bmim][ClO4] Ionic Liquid and Solvent Synergy: Mechanistic Insights and Experimental Validation

Separating heavy oil from solid matrices is still difficult, mainly because of the strong adhesion between oil and solids and the intrinsically high viscosity of heavy oil, both of which restrict efficient large-scale recovery. Ionic liquids have recently attracted attention as additives that may improve extraction performance. In this work, [Bmim][ClO4] was introduced into toluene- and xylene-based solvent systems to examine its role in heavy-oil recovery. The extraction performance was evaluated through recovery yield, viscosity, contact angle, oil–solid interaction force, and SARA composition. Molecular dynamics simulation was also carried out to probe how [Bmim][ClO4] interacts with heavy-oil components and how it influences the diffusion of saturates, aromatics, resins, and asphaltenes. The results show that the addition of [Bmim][ClO4] improved heavy-oil recovery in every solvent system tested, with the highest value, 89.31 wt%, obtained in the toluene system. At the same time, the ionic liquid lowered the viscosity, reduced the contact angle, and weakened the adhesion between the oil phase and the solid surface, all of which favored oil–solid separation. SARA analysis further indicated that the extraction of heavier fractions, especially resins and asphaltenes, became more pronounced after adding the ionic liquid. Simulation results suggest that [Bmim][ClO4] interacts more strongly with resins and asphaltenes, disrupts their associated structures, and facilitates mass transfer. Taken together, these results suggest that [Bmim][ClO4] improves heavy-oil extraction by altering interfacial behavior and loosening the aggregated structure of heavy fractions, which may be useful for future process optimization.