Study on the Rheological Properties of Long‐Term Temperature‐Resistant and Saline‐Resistant Copolymer Systems Based on Hydrophobic Segments

ABSTRACT To improve the temperature and saline tolerance of traditional copolymer fracturing fluids, two linear water‐soluble compounds were developed with acrylamide (AM) and acrylic acid (AA) as the backbone and the introduction of sodium p‐styrene sulfonate (SSS), a strong anionic monomer. Preparation of novel polyacrylamide‐based terpolymers (PMTA) by aqueous solution polymerization. In addition, quaternary copolymers (PFTA) with hydrophobic association structures were synthesized by adding functionalized nonionic hydrophobic monomers (FNS‐15) containing polyether structures on the basis of PMTA. The results showed that PFTA performed significantly better than PMTA in saline solution. The introduction of strong anionic and nonionic groups into PFTA contributes to the formation of a compact and ordered spatially associated network in saline solutions. The 0.6 wt% PFTA solution exhibited excellent saline water and temperature resistance, and the copolymer exhibited good viscoelasticity. Furthermore, in a 20% standard saline solution, the apparent viscosities of 0.6 wt% PFTA at 90°C, 120°C, and 150°C after 1 h of shearing at 170 s −1 are 90.1, 76.8, and 42.3 mPa s, respectively, confirming the system's excellent temperature and shear resistance. In conclusion, PFTA significantly outperforms PMTA in saline solutions, making it particularly suitable for polymer fracturing fluid applications in high‐temperature and high‐salinity reservoir environments.