Preparation of Temperature-Activated Nanomaterial-Enhanced Phase Transition Emulsion and Study on Self-Generating Plugging Particles

Fractured lost circulation remains a major drilling challenge due to low compatibility between conventional plugging materials and fractures. By utilizing thermosetting resin emulsification and high-temperature crosslinking coalescence, this study developed a temperature-activated nanomaterial enhanced liquid-solid phase transition plugging emulsion. The system adapts to varying fracture apertures, forming plugging particles with a broad size distribution and high strength upon thermal activation. The structural characteristics, mechanical properties, and fracture-plugging performance of the plugging particles were systematically investigated. Results demonstrate that the optimized system, comprising 8 wt.% emulsifier, 0.16 wt.% dispersant, 0.4 wt.% crosslinker, 0.4 wt.% viscosifier, 70 wt.% distilled water, and 2 wt.% nano-silica (all percentages relative to epoxy resin content), can produce particles with a size of 1-5 mm at formation temperatures of 80-120 °C. After 16 h of thermal aging at 180 °C, the particles exhibited excellent thermal stability and compressive strength, with D(90) degradation rates of 3.07-5.41%, and mass loss of 0.63-3.40% under 60 MPa. The system exhibits excellent injectability and drilling fluid compatibility, forming rough-surfaced particles for stable bridging. Microscopic analysis confirmed full curing in 140-180 min. Notably, it sealed 1-5 mm fractures with 10 MPa pressure, enabling adaptive plugging for unknown fracture apertures.