Synergistic Effects of ZnO Nanoparticles and Environmental Factors on Biopolymer Solutions for Oil Recovery via Core Flooding

This study investigates the rheological impact of salt content and zinc oxide (ZnO) nanoparticles on guar gum and xanthan gum biopolymer solutions, both individually and in blends, for potential application in enhanced oil recovery (EOR). A series of shear viscosity measurements were conducted over a wide range of shear rates, temperatures, and polymer concentrations (400–2400 ppm) to evaluate how these additives influence fluid behavior under reservoir-like conditions.The results demonstrate that guar gum viscosity increases with salinity at both low and high polymer concentrations. In contrast, xanthan gum solutions exhibit high sensitivity to salt, resulting in a significant reduction in shear viscosity. Evaluation of xanthan/guar mixtures at ratios of 1:1, 1:2, and 2:1 revealed no noticeable synergistic effect. Furthermore, although salinity strongly influenced the rheological behavior of most biopolymer–ZnO systems, formulations containing a higher proportion of guar gum remained relatively stable.The findings suggest that a combination of xanthan and guar solutions integrated with 0.3 wt% ZnO nanoparticles provides a promising strategy for controlling fluid morphology and rheological properties in EOR applications. In addition, at 2400 ppm xanthan concentration, the resistance factor (RF) and residual resistance factor (RRF) exhibited very high values of 1504.08 and 784.8, respectively. Conversely, at 1200 ppm guar gum concentration, the RF and RRF values were significantly lower, at 23.64 and 19.08, respectively.