Substantial enhancement of heavy crude oil dissolution in low waxy crude oil in the presence of ionic liquid

Enormous production losses have ascended in diverse operational and technical issues due to deposition of heavy crude oil (HCO) in various production components like tubing, near well bore (skin formation), surface storage tank, pipeline blockage, etc. Existing methods employed for the dissolution of HCO are either cumbersome or use organic solvents, which are hazardous to the environment. This study presents findings on the enhanced dissolution of HCO using low waxy crude oil (LWC) in the presence of ionic liquid (IL). The use of ILs is found to be compatible with the polar moieties in heavy crude oil, such as resins, aromatics, and asphaltenes, enhancing its dissolution. Twelve ionic liquids were tested for the dissolution of HCO using LWC. The dissolution of HCO was performed and confirmed using gravimetric analyses, ultraviolet-visible (UV-vis) spectrophotometry, Fourier transform-infrared spectroscopy (FT-IR), ¹³C-nuclear magnetic resonance (¹³C NMR), and the interfacial tension (IFT) measurements. The total percentage of dissolution of HCO in LWC (2:3 wt/wt) with 100 ppm of ionic liquid is found to be increased by a magnitude of 30% (71% from 41%) of the standard HCO+LWC alone. The increase in solubility (%) of HCO+ LWC with organic solvent (used for dilution in UV-vis) in the presence of ILs is observed to be a maximum of 38%. The results are further confirmed qualitatively through the use of FT-IR and ¹³C NMR spectroscopy. These findings are further supported by the determination of IFT substantiating the fact that the ILs possess the tendency to dissolve and recover residual oil from production systems and reservoirs. In all of the above experiments, the efficiency of the ILs with a longer alkyl chain and a larger ring size is very convincing as compared with the rest of the studied ILs.