A Study on a Novel Hydrophobic Associative Polymer Thickener for High‐Salinity Water in Hydraulic Fracturing

Abstract The reuse of flowback fluid is a critical strategy for mitigating environmental pollution and reducing the costs associated with hydraulic fracturing technology in oil fields. However, in high‐salinity formations, the electrostatic shielding effect caused by high‐salinity flowback fluid significantly reduces the thickening efficiency of polyacrylamide‐based thickeners, thereby hindering the reuse of flowback fluid. In this study, we synthesized a novel, high‐salinity‐resistant, hydrophobic associative polymer (CHFR) by incorporating the hydrophobic monomer octadecyl polyoxyethylene methacrylate (N1810) into acrylamide (AM), acrylic acid (AA), 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), and methacryloxyethyl trimethylammonium chloride (DMC). FT‐IR and 1 H NMR confirmed the successful synthesis of CHFR. The polymer demonstrated a viscosity retention of 53% in a 20,000 mg/L NaCl solution and 46% in a CaCl 2 solution, exhibiting salt tolerance concentrations that were 10 and 30 times higher than those of conventional PAM/AMPS. At 100 °C and a shear rate of 100 s −1 , CHFR retained 78% of its viscosity. The interaction process between salt and CHFR can be divided into four phases: the initial period, the rapid viscosity decline period, the slow viscosity decline period, and the stable viscosity period. The CHFR polymer exhibits excellent salt resistance, providing a new type of polymer thickener for the reuse of high‐salinity flowback fluid.