Application of polymer-reinforced methane foam in the presence of nanoparticles in increasing oil recovery from carbonate porous media at different temperatures.

Foams are vital for enhancing oil recovery (EOR) but face significant thermodynamic instability under high-temperature conditions. This study comprehensively investigates the synergistic stabilization of methane foams using silica (SiO₂) and titanium dioxide (TiO₂) nanoparticles in combination with polyacrylamide (PAM) polymer at elevated temperatures (28 °C, 50 °C, and 85 °C). The critical micelle concentration of sodium dodecyl sulfate (SDS) and the critical aggregation concentration of PAM were determined to be 0.1 wt% and 0.04 wt%, respectively, with an optimal nanoparticle concentration of 0.01 wt%. Bulk-scale tests revealed that the PAM-SiO₂ synergistic system has the best half-life in all tested temepratures, and at 28 °C the half time was 538 min. Bubble-scale analysis correlated this enhancement with the smallest average bubble size (~ 140 μm) and the thickest lamellae (~ 55 μm). Interfacial characterization confirmed that the additives reduced gas-liquid interfacial tension and altered rock wettability toward a more hydrophilic state. Critically, core flooding experiments in carbonate cores translated these superior properties into a direct EOR performance, with the PAM-SiO₂ foam achieving the highest tertiary incremental oil recovery of 7.40% OOIP. The novelty of this work lies in demonstrating that the synergy between commercially available nanoparticles and a conventional polymer creates a cost-effective and robust foam system that rivals the performance of more complex chemical formulations, offering a highly practical solution for high-temperature EOR applications in challenging carbonate reservoirs.