Stabilization mechanism of CO2-responsive foam for enhance oil recovery


Kang N. Yin X. Sarsenbekuly B. Wu H.
20 December 2025Elsevier B.V.

Colloids and Surfaces A: Physicochemical and Engineering Aspects
2025#727

Carbon dioxide (CO2) has been widely used in enhanced oil recovery technology. However, due to its low viscosity, it is prone to viscous fingering. CO2 foam can effectively prevent gas channeling through Jamin effect and apparent viscosity increase. Nevertheless, the stability of foam systems within subterranean formations has consistently been identified as a key constraint for their long-term application. In this study, a CO2-responsive viscoelastic surfactant system, designated DETA-SDS, was constructed using sodium dodecyl sulfate (SDS) and diethylenetriamine (DETA). This system was designed to achieve high foam stability upon exposure to CO2. The evolution of bubble size, liquid film thickness, and microscopic morphology during the aging process of the foam system was observed using optical microscopy. The dynamic changes in foam systems with and without CO2 injection were further studied based on the principles of dynamic light scattering. Finally, the viscoelastic properties of the foam solution and the gas-liquid interface were investigated using rheological techniques. The results demonstrate that after CO2 injection, DETA undergoes protonation. This promotes electrostatic interaction with the anionic surfactant SDS, leading to the formation of a supramolecular wormlike micellar structure. This structural transition enhances the bulk viscoelasticity of the foam solution, thereby retarding the drainage rate. Furthermore, the wormlike micelles increase the dilational modulus of the gas-liquid interfacial film. This enhanced modulus enables the interfacial film to act as an elastic spring layer, effectively inhibiting coalescence between adjacent bubbles and suppressing gas diffusion (Ostwald ripening). This study demonstrates that the stability of the foam system under subterranean conditions can be enhanced in situ through an induced response mechanism. These findings provide a novel perspective for CO2 flooding and foam profile control technologies.

CO2 foam , CO2-responsive , Enhanced oil recovery , Stability , Viscoelasticity

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School of Energy and Petroleum Industry, Kazakh-British Technical University, Almaty, 050000, Kazakhstan
Petroleum Exploration and Production Research Institute, SINOPEC, Beijing, 102206, China
Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing, 102249, China

School of Energy and Petroleum Industry
Petroleum Exploration and Production Research Institute
Unconventional Petroleum Research Institute

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