Supercritical CO2-Foam Screening and Performance Evaluation for CO2 Storage Improvement in Sandstone and Carbonate Formations

Abstract

Injecting carbon dioxide (CO2) as foam during enhanced oil recovery (EOR) can improve injectate mobility and increase sweep efficiency. Integrating CO2-foam techniques with carbon capture, utilization and storage (CCUS) operations is of recent interest, as the mobility control and sweep efficiency increases seen in EOR could also benefit CO2 storage during CCUS. In this study, a variety of different charge, hydrocarbon chain length, head group surfactants were evaluated by surface tension, bulk and dynamic CO2-foam performance assessments for CCUS. The optimal foam candidate was expected to provide satisfying mobility control effects under reservoir conditions, leading to an improved water displacement efficiency during CO2-foam flooding that favors a more significant CO2 storage potential. All tested surfactants were able to lower their surface tensions against scCO2 by 4-5 times, enlarging the surface area of solution/gas contact; therefore, more CO2 could be trapped in the foam system. A zwitterionic surfactant was found to have slightly higher surface tension against CO2 while exhibiting the highest foaming ability and the most prolonged foam stability with a relatively slower drainage rate among all tested surfactants. The dynamic performance of scCO2-foam stabilized by this zwitterionic surfactant was also evaluated in sandstone and carbonate cores at 13.79 MPa and 90°C. The results show that the mobility control development in carbonate core was relatively slower, suggesting a gradual foam generation process attributed to the higher permeability than the case in sandstone core. A more significant cumulative CO2 storage potential improvement, quantified based on the water production, was recorded in sandstone (53%) over the carbonate (47%). Overall, the selected foam has successfully developed CO2 mobility control and improved water displacement in the occurrence of in-situ foam generation, hence promoting the storage capacity for the injected CO2. This work has optimized the foaming agent selection method at the actual reservoir conditions and evaluated the scCO2-foam performance in establishing high flow resistance and improving the CO2 storage capacity, which benefits integrated CCUS studies or projects utilizing CO2-foam techniques.

CO2-Soluble Nonionic Surfactants for Enhanced CO2 Storage via In Situ Foam Generation

“…30 Yu examined the foaming properties of water-soluble ionic surfactants added to the brine phase in core flooding experiments at reservoir conditions to improve CO 2 storage in porous media. 26,27 Zhou et al evaluated amphoteric surfactants to enhance the stability of CO 2 -foams at reservoir conditions. 29 Rossen et al addressed challenges associated with foam-assisted CO 2 storage where the surfactant is added to the aqueous phase.…”

“…The presence of surfactants dissolved in water has been shown to improve CO 2 sweep efficiency in the context of GCS. ,− For example, Kim et al reported that a water-soluble nonionic surfactant comprised of CO 2 -philic polypropylene groups and a hydrophilic polyethylene group increased the contact angle (θ) of CO 2 on a silica surface from 20° to 70° and decreased CO 2 –water IFT . Improved sweep efficiency was demonstrated by saturating an etched glass microfluidic chip with a surfactant solution and injecting it with CO 2 .…”

Experimental Evaluation of Zwitterionic and Cationic Surfactants to Optimize Bulk Foam Properties for Gas Mobility Control in High-Salinity Carbonates

“…21 Yu et al compared four different surfactants based on different charges, carbon chain length, and head groups to evaluate the CO 2 mobility control and CO 2 storage potential of foam. 21 They found cocamidopropyl hydroxysultaine as the best performing under high-salinity and high-temperature conditions. Cai et al synthesized two different zwitterionic surfactants with high salt tolerance and interfacial tension (IFT) lowering ability for a broad concentration range.…”

“…Some modified zwitterionic surfactants have been proposed for high-salinity reservoirs. 21 Yu et al compared four different surfactants based on different charges, carbon chain length, and head groups to evaluate the CO 2 mobility control and CO 2 storage potential of foam. 21 They found cocamidopropyl hydroxysultaine as the best performing under high-salinity and high-temperature conditions.…”

“…The screening of foaming agents for harsh reservoir conditions is rather challenging due to the sensitivity of the conventional surfactants to high-salinity brine. Some modified zwitterionic surfactants have been proposed for high-salinity reservoirs . Yu et al compared four different surfactants based on different charges, carbon chain length, and head groups to evaluate the CO 2 mobility control and CO 2 storage potential of foam .…”