CO2-triggered synergistic self-assembly of cationic polymer and anionic surfactant systems for enhanced profile control and carbon storage

This study presents a novel CO2-responsive polymer-surfactant system (PADD-SDBS) designed to enhance CO2 sweep efficiency and storage in heterogeneous reservoirs during CO2 flooding. The system comprises a cationic polymer, poly (acrylamide-co-DMAEMA-co-D18) (PADD), and an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). Upon CO2 introduction, the tertiary amine groups in PADD undergo protonation, triggering electrostatic interactions with SDBS and forming a dense three dimensional network via hydrophobic association. This significantly increases the viscosity of the system, making it an effective profile control agent. The PADD- SDBS system exhibits rapid viscosity enhancement and shear-repair capabilities, which improve plugging performance during CO2 displacement. Our results show that this system can redirect CO2 flow into low-permeability zones, enhancing sweep efficiency and oil recovery while supporting carbon storage strategies.