CO₂-Responsive Plugging Gel with Sodium Dodecyl Sulfate, Polyethyleneimine, and Silica

Gas channeling during CO₂ flooding poses a significant challenge to enhanced oil recovery (EOR) in heterogeneous reservoirs, limiting both oil recovery and CO₂ sequestration efficiency. To address this issue, a CO₂-responsive plugging gel was developed using polyethyleneimine (PEI), sodium dodecyl sulfate (SDS), and nano-silica. The gel formulation, containing 0.8% SDS, 0.8% PEI, and 0.1% nano-silica, demonstrated excellent CO₂-responsive thickening behavior, achieving a viscosity of over 12,000 mPa·s under selected conditions. The gel exhibited reversible viscosity changes upon CO₂ and N₂ injection, shear-thinning and self-healing properties, and stability under high-temperature (90 °C) and high-salinity (up to 20,000 mg/L) conditions. Plugging experiments using artificial cores with gas permeabilities of 100 mD and 500 mD achieved a plugging efficiency exceeding 95%, reducing permeability to below 0.2 mD. These results emphasize the potential of the CO₂-responsive plugging gel as an efficient approach to reducing gas channeling, boosting oil recovery, and enhancing CO₂ storage capacity in crude oil reservoirs.