Study on the Influence of Inorganic Salt Ions on the Performance of Fracturing Thickener

Abstract

Abstract. To facilitate the reuse of highly mineralized fracturing flowback fluid, it is imperative to examine the impact of inorganic salt ions on the performance of fracturing thickeners. This study focuses on the influence of these ions on the properties of salt-resistant oil-based suspension emulsions (OSE) and hydroxypropyl guar gum (HPG). Simultaneously, the zeta potential of the thickener solutions was measured using a zeta potential analyzer to characterize their electrochemical stability. The findings indicate that inorganic salt ions decrease the viscosity and sand-carrying performance of OSE and increase the residue content, but they have a minimal effect on the dissolution rate. The severity of these adverse effects follows the trend: high-valent cations >low-valent cations, with no significant distinction observed among anions. Precipitation of polyacrylamide polymers occurs when the concentrations of Al3+ and Fe3+ exceed 50 mg/L and 80 mg/L, respectively, potentially leading to the formation of a blockage. The combination of different cations does not exacerbate the viscosity reduction in suspension emulsions. For HPG, inorganic salt ions have a limited impact on its viscosity and the dissolution rate. However, they reduce the viscosity and sand-carrying performance of the HPG crosslinking system while increasing the crosslinking time and residue content. This influence pattern is similar to that observed for OSE. A significant reduction in the crosslinking degree is observed when the concentration of Al3+ and Fe3+ exceeds 25 mg/L and 25 mg/L, respectively. Similarly, the combination of different cations does not exacerbate the viscosity reduction in the HPG crosslinking system.