Effect of ammonium based ionic liquids on the rheological behavior of the heavy crude oil for high pressure and high temperature conditions

Heavy crude oil (HCO) production, processing, and transportation forms several practical challenges to the oil and gas industry, due to its higher viscosity. Understanding the shear rheology of this HCO is highly important to tackle production and flow assurance. The environmental and economic viability of the conventional methods (thermal or dilution with organic solvents), force the industry to find an alternative. The present study was constructed to investigate the effect of eco-friendly ionic liquids (ILs) on the HCO's rheology, at high temperature and high pressure. Eight different alkyl ammonium ILs were screened for HCO's shear rheology at the temperatures of 25-100 degrees C and for pressures 0.1-10 MPa. The addition of ILs reduced the HCO's viscosity substantially from 25 to 33% from their original HCO viscosity. Also, it aids to reduce the yield stress to about 15-20% at all the studied experimental conditions. Furthermore, the viscoelastic property of the HCO was studied for both strain-sweep and frequency -sweep and noticed the ILs helps to increase HCO's loss modulus (G) by reducing storage modulus (G'), it leads to the reduction of the crossover point around 25-32% than the standard HCO. Mean the ILs addition with HCO converts its solid-like nature into liquid-like material. Besides, the effect ILs chain length was also studied and found the ILs which has lengthier chain length shows better efficiency on the flow-ability. Finally, the microscopic investigation of the HCO sample was analyzed with and without ILs and witnessed that these ILs help to fragment the flocculated HCO into smaller fractions. These findings indicate that the ILs could be considered as the better alternative for efficient oil production, processing, and transportation.(c) 2021 Southwest Petroleum University. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Automated summary

Heavy crude oil (HCO) poses challenges to the oil and gas industry due to its high viscosity. This study investigated the effect of eco-friendly ionic liquids (ILs) on HCO's rheology at high temperature and pressure. The results showed that the addition of ILs substantially reduced the viscosity and yield stress of HCO, making it more flowable. Furthermore, ILs increased the loss modulus of HCO, transforming its solid-like nature into a liquid-like material.