Development of a low-damage Zwitterionic viscoelastic fracturing fluids utilizing noncovalent bonding for unconventional reservoirs

Abstract Application of viscoelastic surfactant (VES) fracturing fluids in unconventional reservoirs is often hindered by poor thermal and shear stability. To overcome this, we report a high-performance, low-damage fluid based on a rationally designed zwitterionic surfactant, stearamidopropyl hydroxysulfobetaine (SAPHS). The SAPHS molecule was engineered to leverage a synergy of noncovalent interactions—Hydrophobic association, hydrogen bonding, and electrostatics—Which drive its self-assembly with NaSal into a robust, entangled wormlike micellar (WLM) network, confirmed by Cryo-TEM. The optimized system (3.5 wt% SAPHS, 1,1 M ratio to NaSal) exhibits exceptional thermal stability up to 120 °C. This advanced supramolecular architecture endows the fluid with superior properties compared to traditional HPG fluid, including enhanced viscoelasticity, 15.6 times better sand-carrying capacity, and smart micelle-breaking behavior. Consequently, it effectively modifies shale wettability (119.2° to 44.5°) and results in minimal core permeability damage (9.81 % vs 33.42 %). This work validates a molecule-to-material design approach, presenting a potent fracturing fluid for stimulating damage-sensitive, high-temperature unconventional reservoirs • Synthesized a novel zwitterionic VES surfactant (SAPHS) and NaSal-optimized to build a high-performance VES fracturing fluid. • The VES-FFs system shows excellent thermal and shear resistance at 120 °C and 170 s −1 . • Generalized Maxwell fits show long relaxation times and a wide LVE region, indicating strong proppant-suspension capacity. • Post-break surface tension drops significantly, enabling efficient flowback and lowering residual damage. • Versus HPG fluids, VES-FFs offer better viscoelasticity and less formation damage, ensuring long-term reservoir protection.