Ionic Liquid-Assisted Solvent Extraction for Unconventional Oil Recovery: Computational Simulation and Experimental Tests

• Published in: Energy & fuels Vol. 30; no. 9; pp. 7074 - 7081
• Main Authors: Li, Xingang, Wang, Junyan, He, Lin, Sui, Hong, Yin, Wentao
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15.09.2016
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.6b01291

Selection of solvents and process aids (i.e., ionic liquids (ILs)) is considered to be one of the key steps during solvent extraction for heavy hydrocarbon recovery from unconventional oil ores. In this study, the COSMOtherm software was applied to screen highly efficient solvents and ionic liquid systems based on oil fraction solubility and surface free energy calculations. It is found that the dispersion force parameter (δd) of solvents plays the dominant role in dissolving oil fractions compared with the roles of the polar force parameter (δp) and hydrogen bonding force parameter (δh). The simulation results also show that the surface free energy of oil fractions (SARA fractions) at the organic solvent-IL interface is significantly lower than that found at the IL-SARA fraction interface, which is favorable for unconventional oil dissolution in solvents. In addition, further interactive energy calculation shows that the interaction between IL and the silica surface is stronger than that between oil fraction and the silica surface. These results suggest that the presence of IL between the organic solvent and oil fraction is beneficial for the transfer of the oil fraction from the solid surface and bulk oil phase to the bulk organic solvent. Additionally, unconventional oil recovery has been found to be highly influenced by the mutual solubility between the solvent and IL, which increased the entrainments of oil components in the IL phase. Calculation of surface free energy and mutual solubility suggests that increasing the chain length of IL molecules is detrimental for bitumen extraction due to the higher mutual solubility of solvents and entrainments of bitumen in ILs. The above simulation results are confirmed by the bottle extraction tests and instrumental detection in which the oil sands ores are extracted by organic solvents with or without ILs. These findings suggest that the COSMOtherm simulation is a potential way for future solvent and IL screening as well as a way to reveal mechanism during unconventional oil exploitation, which would save time and cost.