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DOI	10.1016/j.epsl.2020.116641
	The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems
	Sanchez-Roa C.; Saldi G.D.; Mitchell T.M.; Iacoviello F.; Bailey J.; Shearing P.R.; Oelkers E.H.; Meredith P.G.; Jones A.P.; Striolo A.
发表日期	2021
ISSN	0012821X
卷号	553
英文摘要	Efforts to maintain and enhance reservoir permeability in geothermal systems can contribute to sourcing more sustainable energy, and hence to lowering CO2 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. © 2020 The Authors
关键词	clay mineral precipitation dissolution fluid-rock interaction geothermal systems permeability
英文关键词	Alkalinity; Computerized tomography; Dissolution; Feldspar; Fracture; Geothermal fields; Geothermal wells; Granite; Precipitation (chemical); Rock products; Anthropogenic systems; Flow-through experiments; Fluid-rock interaction; Mineral dissolution and precipitations; Permeability evolution; Permeability measurements; Reservoir permeability; X-ray computed tomography; Petroleum reservoir engineering; alkalinity; clay mineral; dissolution; effective stress; fluid composition; geothermal engineering; geothermal system; granite; igneous geochemistry; permeability; precipitation (chemistry)
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203282
作者单位	Department of Earth Sciences, University College London, London, WC1E 6BT, United Kingdom; Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, London, WC1E 6BT, United Kingdom; Géosciences Environnement Toulouse (GET), CNRS, UMR 5563, Observatoire Midi-Pyrénées, 14 Ave. E. Belin, Toulouse, 31400, France; Department of Chemical Engineering, University College London, London, WC1E 6BT, United Kingdom
推荐引用方式 GB/T 7714	Sanchez-Roa C.,Saldi G.D.,Mitchell T.M.,et al. The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems[J],2021,553.
APA	Sanchez-Roa C..,Saldi G.D..,Mitchell T.M..,Iacoviello F..,Bailey J..,...&Striolo A..(2021).The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems.Earth and Planetary Science Letters,553.
MLA	Sanchez-Roa C.,et al."The role of fluid chemistry on permeability evolution in granite: Applications to natural and anthropogenic systems".Earth and Planetary Science Letters 553(2021).