Development of polymer powder-based multifunctional variable-viscosity slickwater systems assisted by viscoelastic surfactants for enhanced unconventional reservoir fracturing

The study presents a groundbreaking advancement in variable-viscosity slickwater technology for unconventional reservoir stimulation through the development of a novel hydrophobically associating water-soluble polymer (TAE 23 C 12 N) and its synergistic systems with viscoelastic surfactants (VESs), which successfully addresses the challenge of real-time preparation of polymer powder-based slickwater. The innovative pentameric copolymer, synthesized via strategic incorporation of lauryl polyoxyethylene ether methacrylate, AMPS, and sulfobetaine monomers, demonstrates exceptional performance characteristics, including a high molecular weight (5.59 × 10 6  g/mol), superior salt tolerance (>10 4  mg/L mineralization resistance), and excellent thermal stability (50 % mass loss at 393 °C). A custom-designed continuous powder-liquid mixing system enabled real-time preparation of polymer powder-based slickwater, effectively solving the critical issue of polymer powder hydration and positioning TAE 23 C 12 N as a superior alternative to conventional emulsion and suspension dispersion systems for slickwater formulation. This technological breakthrough offers significant advantages, including reduced operational costs, minimized formation damage (<16.39 % permeability reduction), and enhanced transportation efficiency. Comprehensive characterization revealed remarkable synergistic effects between TAE 23 C 12 N and three VESs in polymer powder-based slickwater systems, with the EDAC/TAE 23 C 12 N system exhibiting optimal performance: rapid preparation (34 s for low-viscosity formulation), maximum drag reduction (79.1 %), and robust thermal/shear stability. All VES-enhanced polymer powder-based slickwater systems demonstrated complete gel breaking within 2 h at 120 °C, meeting stringent industry standards. These advancements address critical challenges in hydraulic fracturing through enhanced proppant transport, reduced environmental impact, and cost-effective large-scale applications of polymer powder-based slickwater, representing a paradigm shift in fracturing fluid technology with potential applications extending to enhanced oil recovery and geothermal energy development.