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Weber UW, Rinaldi AP, Roques C, Wenning QC, Bernasconi SM, Brennwald MS, Jaggi M, Nussbaum C, Schefer S, Mazzotti M, Wiemer S, Giardini D, Zappone A, Kipfer R. In-situ experiment reveals CO 2 enriched fluid migration in faulted caprock. Sci Rep 2023; 13:17006. [PMID: 37813929 PMCID: PMC10562487 DOI: 10.1038/s41598-023-43231-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 09/21/2023] [Indexed: 10/11/2023] Open
Abstract
The sealing characteristics of the geological formation located above a CO2 storage reservoir, the so-called caprock, are essential to ensure efficient geological carbon storage. If CO2 were to leak through the caprock, temporal changes in fluid geochemistry can reveal fundamental information on migration mechanisms and induced fluid-rock interactions. Here, we present the results from a unique in-situ injection experiment, where CO2-enriched fluid was continuously injected in a faulted caprock analogue. Our results show that the CO2 migration follows complex pathways within the fault structure. The joint analysis of noble gases, ion concentrations and carbon isotopes allow us to quantify mixing between injected CO2-enriched fluid and resident formation water and to describe the temporal evolution of water-rock interaction processes. The results presented here are a crucial complement to the geophysical monitoring at the fracture scale highlighting a unique migration of CO2 in fault zones.
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Affiliation(s)
| | | | - Clément Roques
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
- Centre for Hydrogeology and Geothermics, University of Neuchâtel, Neuchâtel, Switzerland
| | - Quinn C Wenning
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | | | - Matthias S Brennwald
- Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
| | - Madalina Jaggi
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | | | | | - Marco Mazzotti
- Institute of Energy and Process Engineering, ETH Zürich, Zürich, Switzerland
| | - Stefan Wiemer
- Swiss Seismological Service, ETH Zürich, Zürich, Switzerland
| | | | - Alba Zappone
- Swiss Seismological Service, ETH Zürich, Zürich, Switzerland.
- Institute of Energy and Process Engineering, ETH Zürich, Zürich, Switzerland.
| | - Rolf Kipfer
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
- Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
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Surrogate Model for Multi-Component Diffusion of Uranium through Opalinus Clay on the Host Rock Scale. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11020786] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multi-component (MC) diffusion simulations enable a process based and more precise approach to calculate transport and sorption compared to the commonly used single-component (SC) models following Fick’s law. The MC approach takes into account the interaction of chemical species in the porewater with the diffuse double layer (DDL) adhering clay mineral surfaces. We studied the shaly, sandy and carbonate-rich facies of the Opalinus Clay. High clay contents dominate diffusion and sorption of uranium. The MC simulations show shorter diffusion lengths than the SC models due to anion exclusion from the DDL. This hampers diffusion of the predominant species CaUO2(CO3)32−. On the one side, species concentrations and ionic strengths of the porewater and on the other side surface charge of the clay minerals control the composition and behaviour of the DDL. For some instances, it amplifies the diffusion of uranium. We developed a workflow to transfer computationally intensive MC simulations to SC models via calibrated effective diffusion and distribution coefficients. Simulations for one million years depict maximum uranium diffusion lengths between 10 m and 35 m. With respect to the minimum requirement of a thickness of 100 m, the Opalinus Clay seems to be a suitable host rock for nuclear waste repositories.
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