Smart Plugging Agent Based on Bio-Inspired Vitrimer Chemistry for Lost Circulation Control: Synergizing Catechol Adhesion With Self-Healing Networks

Summary

Conventional lost circulation materials (LCMs) frequently fail in complex formations due to their strict dependence on fracture aperture matching and inherently weak interfacial adhesion to wet rock surfaces. To address these limitations, a thermally responsive, bio-inspired vitrimer (BIV) smart plugging agent was developed by integrating catechol-mediated wet adhesion with a dynamic disulfide-based self-healing network. Thermogravimetric and dynamic mechanical analyses indicate an onset decomposition temperature of 238°C and a thermomechanical activation threshold at 83.2°C. The precompressed BIV microparticles remain stable during surface circulation but undergo thermally triggered adaptive expansion upon encountering high-temperature fracture zones, achieving shape fixity exceeding 98.8% and recovery up to 99.5%. Above the 83.2°C threshold, dynamic disulfide exchange triggers topological network rearrangement without macroscopic melting; this behavior preserves bulk particle integrity in the fluid while enhancing chain mobility to promote conformal contact with wet rock surfaces, synergizing with catechol anchoring to amplify nanoscale interfacial adhesion to the substrate fivefold to 116 nN. Drilling fluid evaluations indicate that the BIV maintains stable rheological compatibility and contamination resistance after hot rolling at 180°C. In sealing evaluations, the BIV-modified drilling fluid reduced cumulative fluid loss by over 70% in 5–40-mesh heterogeneous sand packs and, when coformulated with auxiliary rigid bridging agents, acted as a thermally activated plugging agent that consolidated the primary bridging skeleton to resist viscous extrusion in 1-mm fractures, outperforming the thermoplastic sulfonated asphalt (FT-1) baseline. Furthermore, geomechanical tests demonstrated that the synergy between chemical anchoring and mechanical consolidation enhanced the unconfined compressive strength (UCS) of consolidated sand packs by ninefold, providing a theoretical basis for potential fracture-gradient enhancement. These laboratory findings highlight the potential of BIV as a structurally adaptive smart plugging agent for lost circulation control in complex formations, laying a critical foundation for its future field-scale evaluation.