Critical review and meta-analysis of the interfacial tension of CO₂-brine and H₂-brine systems: Implications for CO₂ and H₂ geo-storage

Carbon capture utilization and storage (CCUS) and underground hydrogen storage (UHS) constitute promising potential to contribute to the net zero targets. Furthermore, CO₂ is also utilized for enhanced oil recovery (EOR) to produce trapped oil. However, these subsurface processes are a function of several properties including fluid–fluid interactions. One critical parameter in this context is the interfacial tension (IFT) of the fluid–fluid system i.e., CO₂-brine IFT for CO₂ geo-storage, H₂-brine IFT for H₂ geo-storage, and CO₂-oil-brine IFT for CO₂-based enhanced oil recovery. Importantly, IFT has a direct impact on fluid leakage and residual saturations of the fluids in place (CO₂, H₂, oil). While IFT of the subsurface systems is influenced by several thermophysical (e.g., pressure, temperature) and physicochemical (e.g., brine ionic strength and presence of impurities) factors, the current state-of-the-art suggests notable discrepancy – which thus requires a critical insight into the associated trends. Accordingly, this study presents a critical review and meta-analysis of the published IFT data sets for CO₂-brine, CO₂-oil-brine, and H₂-brine systems and their associated implications. Our review also highlights the latest developments in IFT measurements, the current knowledge gaps, and the outlook on the subject. The aim of this study is to provide a) an updated repository of the IFT dataset for multiphase geo-systems, b) systematic analysis of the influencing factors, and c) an improved understanding of the IFT phenomena pertinent to subsurface storage.