Foam breakdown at elevated temperatures poses a major obstacle for subsurface operations, such as enhanced oil recovery. This study introduces a novel, green nanocomposite (KCl/SiO2/Xanthan/Eucalyptus, NCs) that synergistically enhances methane foam stability at high temperatures (35–95 °C). Systematic evaluation identified an optimal nanocomposites (NCs) concentration of 300 ppm, which maximized foam half-life. Bubble-scale analysis revealed the physical stabilization mechanism: NCs promote a fine-textured foam with a smaller average bubble size (∼179 μm) and thicker lamellae (∼154 μm), directly hindering coalescence and drainage. Interfacial studies confirmed that NCs reduce gas–liquid interfacial tension and shift rock wettability toward hydrophilicity, thereby aiding foam generation and film reinforcement. The work provides a thorough multiscale examination of methane foam stabilization, a system critical for gas recovery but less studied than N2 or CO2 foams, demonstrating that a single, economical nanocomposite can match the performance of complex chemical formulations. Core flooding tests validated practical effectiveness, with the NCs-foam system achieving a final oil recovery of 56.6%, a significant increase of 17.6% points over pure gas injection (38.9%). This research offers fundamental insights into the fluid dynamics of nanocomposite-stabilized foams, linking interfacial rheology, bubble-scale morphology, and macroscopic flow in porous media under extreme thermal conditions. The findings highlight the strong economic potential of this nanotechnology as a durable and efficient alternative to traditional surfactant-based foams in high-temperature reservoir applications.
