Enhanced CO2 Storage Capacity and Hydrate Formation Kinetics Using SDS-Stabilized CO2 Emulsions for Submarine Carbon Hydrate Storage

Surfactant-assisted CO2 emulsion injection into cold aquifers offers enhanced CO2 storage capacity and accelerated hydrate formation. However, prior studies have largely treated surfactants as either emulsion stabilizers or hydrate kinetic promoters in isolation, leaving unresolved whether the concentration that optimizes CO2 trapping is compatible with that needed for hydrate formation near submarine temperatures. This study addresses that gap through a systematic, multiscale evaluation of SDS-stabilized CO2 emulsions. At ∼3 °C, SDS precipitates before reaching its critical micelle concentration; solubility, interfacial tension, and bulk hydrate formation experiments identify 1000 ppm as a practical upper limit for porous-medium experiments. High-pressure, low-temperature microfluidic experiments show that SDS above 500 ppm improves CO2–water displacement efficiency by increasing effective CO2-phase viscosity and reducing interfacial tension, yielding smaller CO2 ganglia and stable, piston-like displacement. SDS up to 1000 ppm shortens induction times and increases hydrate film growth rates, following a power-law dependence on subcooling with an exponent of 2. CO2 emulsions further sustain open transport pathways via continued CO2 dissolution, enabling efficient long-term CO2-to-hydrate conversion. These results define a concentration window where SDS simultaneously enhances CO2 storage and hydrate kinetics.