HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems

Abstract : Efforts to maintain and enhance reservoir permeability in geothermal systems can contribute to sourcing more sustainable energy, and hence to lowering CO 2 emissions. The evolution of permeability in geothermal reservoirs is strongly affected by interactions between the host rock and the fluids flowing through the rock's permeable pathways. Precipitation of secondary mineral phases, the products of fluidrock interactions, within the fracture network can significantly reduce the permeability of the overall system, whereas mineral dissolution can enhance reservoir permeability. The coupling between these two competing processes dictates the long-term productivity and lifetime of geothermal reservoirs. In this study, we simulate the conditions within a geothermal system from induced fracturing to the final precipitation stage. We performed batch and flow-through experiments on cores of the Carnmenellis granite, a target unit for geothermal energy recovery in Cornwall (UK), to understand the role of mineral dissolution and precipitation in controlling the permeability evolution of the system. The physico-chemical properties of the cores were monitored after each reaction-phase using ICP-OES, SEM, hydrostatic permeability measurements, and X-ray Computed Tomography. Results show that permeability evolution is strongly dependent on fluid chemistry. Undersaturated alkaline fluids dissolve the most abundant mineral phases in granite (quartz and feldspars), creating cavities along the main fractures and generating pressure-independent permeability in the core. Conversely, supersaturated alkaline fluids, resulting from extended periods of fluid-rock interactions, promote the precipitation of clay minerals, and decrease the permeability of the system. These results suggest that chemical dissolution during geothermal operations could generate permeable pathways that are less sensitive to effective stress and will remain open at higher pressures. Similarly, maintaining the circulation of undersaturated fluids through these granitic reservoirs can prevent the precipitation of pore-clogging mineral phases and preserve reservoir permeability in granite-hosted geothermal systems.
Document type :
Journal articles
Complete list of metadata

Contributor : Nathalie Pothier Connect in order to contact the contributor
Submitted on : Friday, April 2, 2021 - 2:41:09 PM
Last modification on : Monday, May 16, 2022 - 8:20:26 AM
Long-term archiving on: : Saturday, July 3, 2021 - 6:35:22 PM


Publication funded by an institution


Distributed under a Creative Commons Attribution - NoDerivatives 4.0 International License




C. Sanchez-Roa, G.D. Saldi, T.M. Mitchell, F. Iacoviello, J. Bailey, et al.. The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems. Earth and Planetary Science Letters, Elsevier, 2021, 553, pp.116641. ⟨10.1016/j.epsl.2020.116641⟩. ⟨insu-03188813⟩



Record views


Files downloads