CO2-Switchable Foams for Enhanced Oil Recovery and Carbon Sequestration.

Carbon dioxide (CO2) foams have emerged as a promising strategy for enhanced oil recovery (EOR), providing effective gas mobility control. However, challenges in maintaining subsurface stability and enabling surface-controlled collapse persist, and a comprehensive assessment of their CO2 storage potential remains unexplored. This study presents an innovative approach using switchable foams stabilized by a CO2-responsive surfactant, N-erucamidopropyl-N,N-dimethylamine (UC22AMPM). Through integrated laboratory experiments under simulated reservoir conditions, the reversible foaming/defoaming, in situ foam generation and transport in porous media, as well as CO2 storage capacity were systematically evaluated. The results reveal a unique reversible foam modulation mechanism driven by alternating CO2 and N2 exposure with CO2-induced foams displaying distinct pressure-dependent stability profiles. Microfluidic visualization technique demonstrates efficient in situ foam generation within porous media, further corroborated by core-flooding experiments revealing resistance factors of up to 14, underscoring their robust conformance control capability. Absorption experiments operating under simulated oil reservoir indicates a 22% increase in CO2 sequestration efficiency compared to traditional brine flooding. These findings provide a quantitative framework for harnessing the potential of CO2-responsive foams in both EOR operations and sustainable carbon sequestration.