Speaker
Description
Rising anthropogenic CO2 emissions and efforts to mitigate associated greenhouse gas effects have led to a large number of projects which aim to capture and store emitted CO2 into stable geological formations1,2. Underground storage of CO2 requires careful site selection where a porous and permeable medium is required for storage (the reservoir) and a non-porous and impermeable overlying medium for containment (the seal). Geological settings such as deep saline aquifers or depleted hydrocarbon reservoirs may be suitable for CO2 storage. Storage occurs at pressures or temperature/depths below 800m so the CO2 is transformed into its dense (supercritical) state. Once injected, CO2 dissolves into surrounding formation water, generating a state of geochemical disequilibrium leading to dissolution-(re)precipitation of host minerals. While dissolution can be beneficial to the reservoir storage interval, allowing for greater injection rates, the potential for mineralisation might reduce injectivity. The converse may be the case for an overlying seal that contains the injected CO2, where mineral precipitation in the base of any overlying units could, in effect, self-seal. CCS project proponents and regulators consider information from geochemical modelling and laboratory studies to identify potential risks related to long-term injection of CO2 Modelling accurate geochemical reactivity within these formations is a challenging task as it requires knowledge of large number of physical and geochemical parameters. Two key modelling methods are applied to predict geochemical changes and reactivity – equilibrium thermodynamics (ET) and reactive transport modelling (RTM). ET is often computationally faster than RTMs and able to resolve geochemical changes with greater resolution when compared to available RTM codes without oversimplification3. We present here a hybrid workflow which combines predictions from ET and RTM combined. We investigate changes in mineralogy and geochemistry of a hypothetical reservoir (silicate and carbonate rich cases) post-CO2 injection for a period of 100 and 1000 years. Changes in formation water chemistry, pH and mineralogy is first calculated by ET using Geochemist’s Workbench and use the findings as starting point for RTM using TOUGHREACT. We aim to reduces the number of RTM simulations required by using a recently developed sensitivity test based approach4. This integration leverages ET's computational efficiency for fast processes (CO₂ dissolution, aqueous complexation, kinetic dissolution and precipitation) while deploying RTM for slow mineral reactions and multiphase transport. This hybrid approach allows for practical and efficient pathway to established CO2-rock-fluid reactivity for large field-based projects.
Note - 1-4 are reference provided in the system further.
| References | 1) Michael, K., Golab, A., Shulakova, V., Ennis-King, J., Allinson, G., Sharma, S., & Aiken, T. (2010). Geological storage of CO2 in saline aquifers—A review of the experience from existing storage operations. International journal of greenhouse gas control, 4(4), 659-667. 2) Ma, J., Li, L., Wang, H., Du, Y., Ma, J., Zhang, X., & Wang, Z. (2022). Carbon capture and storage: history and the road ahead. Engineering, 14, 33-43. 3) De Lucia, M., Kempka, T., & Kühn, M. (2015). A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in heterogeneous CO2 storage systems. Geoscientific Model Development, 8, 279–294 4) Stalker, L., Seyyedi, M., Mei, Y., Delle Piane, C., & Noble, R. (2024, October). A Batch Geochemical Modelling Workflow for Evaluating the Impacts of Geochemical Reactions During COo2 Storage in Quartz-rich Rocks. In Proceedings of the 17th Greenhouse Gas Control Technologies Conference (GHGT-17) (pp. 20-24). |
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| Country | Australia |
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