Experimental Assessment of the Rheological Behaviours and Enhanced Oil Recovery Potentials of Pectin

Abstract Polymer flooding is an enhanced oil recovery (EOR) technique used to maximize oil recovery by increasing water viscosity and reducing the fingering effect. The commonly used polymer in oil fields, hydrolysed polyacrylamide (HPAM), is harmful to the ecological environment, and the product of its natural decomposition, acrylamide, poses a threat to human health. Pectin has been proposed as an eco-friendly alternative to HPAM, but its rheological properties and EOR potentials have not been extensively studied. Herein, the rheological behaviours and the ability of pectin to recover crude oil from sandpack were evaluated and compared to that of popular synthetic biopolymers (HPAM and xanthan gum). Results of this work show that pectin has the lowest viscosity compared to HPAM and xanthan gum at all concentrations tested. Precisely, Pectin viscosity is approximately 500 cP, while the viscosities of both xanthan gum and HPAM are almost 1001 cP at a shear rate of 0.5 s-1. The recovery factor (RF) of pectin was also the lowest (41.9%), compared to that of xanthan gum (46.8%) and HPAM (49%). The polymer solutions became less viscous in the presence of salts. However, the co-injection of 0.1 wt% pectin and 0.05 wt% lawsone increased the RF to 58.38%; when the lawsone concentration was increased to 0.1 wt%, the RF increased to 72.98%. These results suggest that sole injection of pectin solution would likely not improve hydrocarbon recovery better than that of conventional polymers. However, the simultaneous injection of pectin with a suitable sacrificial agent, such as lawsone, can improve oil recovery by more than 30% compared to using xanthan gum or HPAM flooding alone.