Potential and challenges of foam-assisted CO₂ sequestration

Abstract

Foam is a promising means to assist in the permanent, safe subsurface sequestration of CO₂, whether in aquifers or as part of an enhanced-oil-recovery (EOR) process. Here we review the advantages demonstrated for foam that would assist CO₂ sequestration, in particular sweep efficiency and residual trapping, and the challenges yet to be overcome. We also review the research and field-trial literature on CO₂ foam sweep efficiency, capillary gas trapping in foam, issues involved in surfactant selection for CO₂ foam applications, foam field trials, and the state of the art from laboratory and modelling research on CO₂ foam properties, in order to present the prospects and challenges for foam-assisted CO₂ sequestration. Challenges to foam-assisted CO₂ sequestration include the following: 1) verifying the advantages indicated by laboratory research at the field scale 2) optimizing surfactant performance, while further reducing cost and adsorption if possible 3) long-term chemical stability of surfactant, and dilution of surfactant in the foam bank by flow of water. Residual gas must reside in place for decades, even if surfactant degrades or is diluted. 4) optimizing injectivity and sweep efficiency in the field-design strategy.