Prospects of co-injecting ionic liquid and thermochemical fluid for recovery of extra-heavy oil

The recovery of extra-heavy oil has been challenging due to high viscosity. In this research, a hybrid recovery scheme involving co-injection of heat producing chemicals termed thermochemical fluid (TCF), and ionic liquid (IL): 1-Benzyl-3-methylimidazolium chloride, has been investigated. The studies include asphaltene dispersion tests in the IL, molecular dynamic simulation to gain an insight into the nature of local molecular forces which instigates asphaltene-IL interaction and dispersion, and rheological tests to evaluate the effects of IL additive on the flow properties of the extra-heavy oil. Subsequently, core flooding experiments were performed by co-injecting TCF and IL solutions (at 90 °C), compared with other thermal fluids including TCF only (at 90 °C), hot water (at 90 °C), and steam (at 210 °C). The results showed that, the IL caused the dispersion of asphaltene with dispersion index (DI) of 80 % at initial concentration of 1000 ppm asphaltene in the solution. The MD simulation revealed that the performance of the IL is owing to the existence of strong interaction energy which causes the dispersion of asphaltene into the IL phase. Studies of the rheology showed that by mixing 10000 ppm of the IL with the extra-heavy oil (HO), the viscosity as well as the flow activation energy can be significantly reduced. Ultimately, recovery experiments revealed that the proposed TCF-IL co-injection gave higher recovery of extra-heavy oil with 85 % OOIP (thermal efficiency E_ff = 4.77 cm³/KJ) corresponding to 20 % increment compared with the TCF injection only, which yielded 70 % OOIP (E_ff = 3.93 cm³/KJ). This performance is fairly compared with those of steam injection which gave 94 % recovery with E_ff = 3.87 cm³/KJ.