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.