Flow-adaptive polymeric surfactant gels enabled by CO₂-triggered gelation for oil recovery enhancement

Amidst the global imperative to reconcile carbon neutrality with energy security, CO₂ enhanced oil recovery (CO₂ EOR) has emerged as a dual-purpose technology for both fossil fuel extraction and geological CO₂ storage. However, its effectiveness is severely undermined by gas channeling caused by reservoir heterogeneity and the unfavorable mobility ratio between low-viscosity CO₂ and crude oil, leading to premature breakthrough and poor sweep efficiency. Herein, we present a flow-adaptive CO₂-responsive gel system. Through rational molecular engineering, gelation is directly activated by the dynamic CO₂ signal in the reservoir. In high-permeability zones with elevated CO₂ concentration, the system rapidly forms a robust gel barrier, achieving >97.5% plugging efficiency. Conversely, in low-permeability oil-bearing zones with lower CO₂ flux, the material maintains a low-viscosity, surface-active fluid state. The polymer reduces water surface tension from 72 mN/m to below 35 mN/m and achieves an ultralow interfacial tension of 0.076 mN/m against heavy oil, enabling deep penetration and continuous emulsification-driven oil displacement. This potential spatiotemporally coordinated behavior, regulated by in situ CO₂ signals, suggests the potential for integrating macroscopic conformance control and microscopic oil mobilization, increasing oil recovery from the low-permeability core by 20.24 percentage points during the secondary CO₂ flooding stage. This CO₂-responsive polymeric surfactant gel system shows promising potential for the synergistic application of enhanced oil recovery and CO₂ storage.