Nano-toughened swelling resin as a high-Performance sealing and adhering agent for cementing remediation

This study develops a nano-toughened swelling resin plugging agent by integrating water-soluble phenolic resin, acrylamide monomers, and nano-silica to address cementing quality deterioration during well workover. The agent resolves traditional resin limitations of brittleness and volumetric shrinkage through dual mechanisms: nano-silica enhances toughness via physical crosslinking and crack deflection, while acrylamide hydrolyzes into polyacrylic acid to induce osmotic pressure-driven expansion (5.0–10.0% volume increase). Key properties include ultra-low initial viscosity ( < 42.0 mPa·s), tunable curing time (8.0–72.0 hours, temperature-dependent), and exceptional stability under harsh conditions (60-day immersion in 60,000 mg·L−1 brine or 5.0% HCl reduces strength by < 30%). Physical simulations confirm outstanding injectivity (injection pressure < 0.10 MPa in micro-fractures) and interfacial bonding integrity: zero leakage at 35.0 MPa for casing bonds, > 20.0 MPa for cement sheath (leakage < 3.8 mL), and > 15.0 MPa for formations (leakage < 4.8 mL), with phenolic resin concentration directly enhancing pressure-bearing capacity. These results demonstrate that the nano-toughened swelling resin offers a reliable and adaptable solution for enhancing wellbore integrity in challenging downhole environments, thereby improving the success rate of workover operations.