UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

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

Sanchez-Roa, C; Saldi, GD; Mitchell, TM; Iacoviello, F; Bailey, J; Shearing, PR; Oelkers, EH; ... Striolo, A; + view all (2020) The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems. Earth and Planetary Science Letters , Article 116641. 10.1016/j.epsl.2020.116641. (In press). Green open access

[img]
Preview
Text
1-s2.0-S0012821X20305859-main.pdf - Published version

Download (4MB) | Preview

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 fluid-rock 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.

Type: Article
Title: The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.epsl.2020.116641
Publisher version: https://doi.org/10.1016/j.epsl.2020.116641
Language: English
Additional information: © 2020 The Authors. Published by Elsevier B.V. under a Creative Commons license (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: permeability, fluid-rock interaction, dissolution, clay mineral, precipitation, geothermal systems
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10115696
Downloads since deposit
11Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item