Wettability and Interfacial Tension in Carbonate Rocks for CO2 Storage: A Critical Review of Trapping Mechanisms and Governing Factors

Abstract

CO₂ geostorage is a promising strategy toward reducing CO₂ emissions in the atmosphere by storing it in deep geological formations. Safe CO₂ storage is primarily contingent upon efficient structural and capillary trapping mechanisms. These trapping mechanisms are strongly governed by rock wettability and interfacial properties, which can significantly be altered by reservoir geochemistry and in situ conditions. Carbonate reservoirs are geochemically reactive systems, and their wettability behavior can be influenced by organic acids, pressure, temperature, salinity conditions, and mineralogical composition, potentially compromising CO₂ trapping efficiency. Despite extensive experimental studies, a systematic quantitative comparison of the relative and interacting impacts of these governing factors on CO₂ trapping in carbonate reservoirs remains limited. This work presents a mechanistic critical review of wettability alteration and interfacial tension behavior in carbonate rocks under CO₂ storage conditions, synthesizing experimental evidence to elucidate the underlying physicochemical mechanisms. To complement this analysis, a data-driven statistical and machine learning–based evaluation of compiled data is employed to assess and rank the relative influence of key controlling parameters. Emerging nanoparticle-based approaches for mitigating unfavorable wettability are also systematically reviewed. Dominant governing factors and their coupled effects under representative storage conditions are identified. Overall, this review provides an integrated mechanistic and data-supported framework for understanding CO₂ trapping efficiency in carbonate reservoirs and highlights research priorities for improving the reliability of long-term geological CO₂ storage.