Eco-efficient rheological improvement of heavy crude oil using lactam based ionic liquids at high temperature high pressure condition

摘要

Heavy crude oil (HCO) is still possessing concrete challenges due to its ineffective flowing characteristics. Asphaltenes and resins are the complex fractions of heavy oil, possessing relatively high polar constituents of heteroatoms, which tend to aggregate and flocculate each other, leading to precipitation and flow blockage. Consequently, this renders serious problems in several sections of the oil industry, such as production, transportation, processing, separation, and refinery, etc. Thermal and dilutions are the traditional methods that industry uses for heavy oil treatments, however, they are found to be environmentally hazardous and economically non-viable for large-scale applications. This study finds the possible alternative with the use of green ionic liquids (ILs). In this research, we have studied six different lactams based ILs on the heavy oil's viscosity reduction and for the possible viscoelasticity alteration for a wider range of temperatures (298.15-373.15 K) and pressures (0.1-10 MPa). A sequence of rheological studies was performed on HCO with and without ILs, such as shear rheology, yield stress, viscoelastic moduli, and the effect of different ILs on the HCO's rheological phenomena was analyzed. The reduction of HCO's viscosity was noticed for about 20-30% with a minor quantity (0.5 wt/v%) of ILs. Consecutively, the viscoelastic characteristics of the oil sample were also studied with ILs and observed a reduction in storage modulus and crossover point than the neat system. Additionally, microscopic investigation of the oil sample was studied with ILs, and we were able to graphically witness the tendency of the IL to break the oil's asphaltene/resin structure.