Revealing a Wetting-Penetration-Interlocking Mechanism for the Interfacial Reinforcement of Degradable Liquid Plugs via Silane-Induced Microstructure Engineering.

HYPOTHESIS

Poor interfacial bonding and wetting incompatibility limit the performance of degradable liquid plugs under high-pressure conditions. It is hypothesized that silane-induced interfacial engineering can build a multiscale structure that enhances adhesion via coupled wetting, penetration, and interlocking mechanisms.

EXPERIMENTS

A C18 silane-modified steel surface was constructed and tested for its bonding behavior with an epoxy-based degradable plug. Interfacial strength, compressive capacity, and microstructure were analyzed using mechanical tests, SEM, AFM, and contact angle measurements. Surface energy was calculated via the Owens-Wendt model.

FINDINGS

The silane-treated interface exhibited a significant enhancement in interfacial bonding strength (up to 445%) and shear strength (73.8% increase), attributed to the formation of a 391.6 nm thick infiltrated interlayer and strong chemical anchoring (Si-O-Fe bonds). Contact angle decreased from 74.0° to 53.6°, with interfacial energy increasing by 26.2%, confirming improved wettability and energy compatibility. A triadic enhancement pathway of "wetting-penetration-interlocking" was established, supported by microstructural imaging and theoretical modeling. This work provides mechanistic insights and practical guidance for the design of robust liquid plug systems in complex wellbore environments.