Field‐Scale Modeling of CO2 Mineral Trapping in Reactive Rocks: A Vertically Integrated Approach

• Published in: Water resources research 2022-01, Vol.58 (1), p.n/a
• Main Authors: Postma, T. J. W., Bandilla, K. W., Peters, C. A., Celia, M. A.
• Format: Article
• Language: English
• Subjects: Basalt; Carbon capture and storage; Carbon dioxide; carbon mineralization; Carbon sequestration; Carbonate minerals; Carbonates; Climate change; Formations; Geochemistry; geological carbon storage; Injection; Integrated approach; Mathematical models; Methods; mineral trapping; Mineralization; Mineralogy; Modelling; Numerical simulations; Porosity; Porous media; Questions; reactive transport; Rocks; Simulation; Subsurface flow; Transport processes; Trapping; vertical equilibrium
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2021WR030626

Unlike sedimentary formations, flood basalts have the potential for relatively rapid mineral trapping when used as an injection target for CO2 storage. However, there are still open questions surrounding the implementation of CO2 storage in basalt at a large scale. These include how the porosity of the target formation will be altered by the geochemical activity, as well as whether a large‐scale CO2 storage project can expect the same fast mineralization rates observed during small‐scale pilot injections. Field‐scale numerical modeling studies can play a role in answering these questions, by improving our understanding of the way in which details such as mineralogy, temperature or injection strategy affect the timing and spatial location of geochemical processes. Simulations of reactive transport processes in the subsurface often rely on computationally demanding methods. Although these methods provide comprehensive simulation capabilities, they may not provide the efficiency needed for wide exploration of parameter spaces or for simulations over long time scales. The present work combines a vertically integrated model of two‐phase flow in porous media with a fully customizable geochemical model to create an efficient vertically integrated method for field‐scale simulation of CO2 mineral trapping in basalt. The proposed method provides a platform for extensive field‐scale modeling studies that can help address some of the remaining barriers to large‐scale implementation of CO2 storage in basalt formations. Plain Language Summary Carbon capture and storage (CCS), in which CO2 is captured and injected into the subsurface, is an important technology to combat climate change. The injected CO2 is contained in the target formation via different trapping mechanisms. Mineral trapping—CO2 precipitating as solid carbonate minerals—is the most stable and secure, but in most rock formations it proceeds extremely slowly. Basalts have the potential for relatively fast mineral trapping, due to their mineralogy. Although mineral trapping in basalts has been studied in different ways, there are still open questions about the viability of large‐scale CCS in basalt, including on how the geochemical interactions will alter the properties of the target formation. Numerical simulations can be used to help answer some of these questions. Simulating reactive transport processes (i.e., the combination of subsurface flow and geochemistry) is often done using highly detailed models.