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In-situ experiment reveals CO 2 enriched fluid migration in faulted caprock.

Authors :: 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
Source :: Scientific reports [Sci Rep] 2023 Oct 09; Vol. 13 (1), pp. 17006. Date of Electronic Publication: 2023 Oct 09.
Publication Year :: 2023
Abstract: The sealing characteristics of the geological formation located above a CO <subscript>2</subscript> storage reservoir, the so-called caprock, are essential to ensure efficient geological carbon storage. If CO <subscript>2</subscript> 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 CO <subscript>2</subscript> -enriched fluid was continuously injected in a faulted caprock analogue. Our results show that the CO <subscript>2</subscript> 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 CO <subscript>2</subscript> -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 CO <subscript>2</subscript> in fault zones.<br /> (© 2023. Springer Nature Limited.)