CO₂ sequestration in subsurface geological formations: A review of trapping mechanisms and monitoring techniques

Carbon capture and storage (CCS) in subsurface formations has emerged as a promising strategy to address global warming. In light of this, this review aims to provide a comprehensive understanding of the mechanisms involved in the geological trapping of CO₂. Additionally, it aims to identify the techniques used to evaluate the potential for CO₂ sequestration before injecting CO₂ into subsurface formations and the methods used to monitor the progress of CO₂ sequestration after injection. The review also presents future research directions based on current research trends in the field. Four principal trapping mechanisms were identified: structural, capillary (residual), solubility, and mineral trapping. These mechanisms vary in their CO₂ trapping capacity over time and the storage security they offer. Structural trapping provides the most significant contribution to CO₂ trapping, whereas mineral trapping offers the highest storage security. In terms of monitoring and assessment, three main approaches were identified, including seismic and borehole geophysical methods, atmospheric monitoring methods, and laboratory-scale experiments. One of the novel aspects of this review is that it outlines the various experimental techniques used for investigating CO₂ trapping mechanisms, an area that prior reviews have not addressed. At the laboratory level, various tests and experiments are used to study CO₂ trapping characteristics. These are categorized into petrophysical characterization, pore-scale experiments, CO₂-fluid-rock interaction experiments, and CO₂ adsorption evaluation. Another novel contribution of this review is the development of a qualitative assessment approach for the applicability of various monitoring techniques throughout the stages of CO₂ sequestration projects. This innovative approach has not been reported in the previous literature. Our review was prepared following a scoping review methodology, ensuring the inclusion of the most recent and relevant studies.

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Published in: Earth-Science Reviews
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.earscirev.2024.104793