Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Schematic illustration of the modification mechanisms of epoxy resin emulsion on cement particles and cement matrix: (1) Physical modification: epoxy resin emulsion fills micro-cracks in cement particles and forms microstructural interpenetration with the cement matrix and hydration products (e.g., C-S-H); (2) Chemical bonding: carboxyl groups (-COOH) in the emulsion react with Ca2+ from cement hydration to form Ca(OOC-)2 via ionic crosslinking, while amino groups (-NH-) in the silane coupling agent form Si-N covalent bonds with silanol groups (Si-OH) on the surface of C-S-H.

ABSTRACT
Sustained Annulus Pressure (SAP) compromises wellbore integrity due to leakage and corrosion, posing significant safety and environmental risks. Traditional cement-based materials lack toughness and acid resistance, limiting their long-term sealing performance. This study develops a novel waterborne epoxy resin–ultrafine cement composite, enhanced with a silane coupling agent (KH-550), to address these limitations. With 20.0 wt% epoxy resin, the material achieves 236.0 mm fluidity (a 52.3% increase over pure cement), maintains compressive strength > 21.0 MPa at 140°C, and exhibits a 3.7-fold higher strain capacity. It demonstrates exceptional thermal stability (decomposition temperature > 440°C), superior resistance to seawater and acidic environments (< 6.28% strength loss after 30 days), and effective gas sealing performance (< 100 mL·min−1 leakage at 25.0 MPa). Microstructural analysis reveals that the epoxy resin fills microcracks and forms Si–O–Si bonds with cement hydrates, creating a reinforced interpenetrating network. Based on the specific conditions of Well A4S2, a targeted four-step remediation method is designed. Key innovations include the ternary composite design, the elucidated physical–chemical-microstructural reinforcement mechanism, and the integrated field solution protocol. This work provides a scientifically grounded, field-ready solution for SAP mitigation, advancing the design of high-performance, durable sealing materials for oil and gas wells.