KG²B, a collaborative benchmarking exercise for estimating the permeability of the Grimsel granodiorite—Part 2: modelling, microstructures and complementary data

David, Christian; Wassermann, J.; Amann, Florian; Klaver, Jop; Davy, Catherine; Sarout, Joël; Esteban, Lionel; Rutter, E. H.; Hu, Qinhong; Louis, L.; Delage, Pierre; Lockner, D. A.; Selvadurai, A. P. S.; Vanorio, Tiziana; Hildenbrand, A.; Meredith, P. G.; Browning, John; Mitchell, Thomas M.; Madonna, Claudio; Billiotte, Joël; Reuschlé, Thierry; Lasseux, Didier; Fortin, Jérôme; Lenormand, R.; Loggia, D.; Nono, Frank; Boitnott, G. N.; Jahns, Eberhard; Fleury, Marc; Berthe, Guillaume; Braun, Philipp; Grégoire, David; Perrier, Laurent; Polito, P. J.; Jannot, Yves; Sommier, Alain; Krooß, Bernhard M.; Fink, Reinhard; Clark, Anthony C.

doi:10.1093/gji/ggy305

Cited by 12 publications

(9 citation statements)

References 52 publications

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“…The fluid flow interaction between the fracture and the matrix is neglected in this study. Given the low porosity and permeability of the granodiorite rocks (David et al., 2018) this is a plausible assumption commonly made in similar studies (Grimm Lima et al., 2020; Salimzadeh et al., 2018a; Slatlem Vik et al., 2018).…”

Section: Methodsmentioning

confidence: 78%

No‐Flow Fraction (NFF) Permeability Model for Rough Fractures Under Normal Stress

Javanmard

Ebigbo

Walsh

et al. 2021

Water Resources Research

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Accurate estimation of rock permeability is a major challenge in industrial projects such as oil and gas extraction, geothermal energy production, radioactive waste containment, and CO 2 geosequestration. For many of these projects, the targeted formation exhibits low matrix permeability and the main fluid conduit is the fracture network (Berkowitz, 2002; Neuman, 2005; Sahimi, 2011). To accurately evaluate the hydraulic properties of such geoformations, understanding the behavior of a single rock fracture under in situ conditions is necessary. The permeability of fluids through a single rock fracture is often estimated using the Cubic law-a simplification of the Navier-Stokes (NS) equations based on several key assumptions. These include assuming that the fracture consists of two smooth and parallel plates (Witherspoon et al., 1980). Therefore, the geometry of the flow path can be represented by a single value, the uniform spacing between the two walls. However, no rock fracture is perfectly smooth and, as a result, its aperture field is heterogeneous. A natural way to reduce the heterogeneous aperture field to a single value is to average the fracture aperture distribution. Various averaging methods have been proposed in the literature (

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Section: Methodsmentioning

confidence: 78%

No‐Flow Fraction (NFF) Permeability Model for Rough Fractures Under Normal Stress

Javanmard

Ebigbo

Walsh

et al. 2021

Water Resources Research

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“…Permeability measurements were performed on the room-equilibrated starting material using the pore pressure oscillation method (Bernabé et al, 2006;David et al, 2018;Turner, 1958). A 4-mm-thick dry gouge layer was sandwiched between two aluminum half-cylinders, cut parallel to the cylindrical axis.…”

Section: Permeability Measurementsmentioning

confidence: 99%

Water Availability and Deformation Processes in Smectite‐Rich Gouges During Seismic Slip

et al. 2019

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Smectite clays occur in subduction zone fault cores at shallow depth (approximately 1 km; e.g., Japan Trench) and landslide décollements (e.g., Vajont, Italy, 1963). The availability of pore fluids affects the likelihood that seismic slip propagates from deeper to shallow fault depths or that a landslide accelerates to its final collapse. To investigate the deformation processes active during seismic faulting we performed friction experiments with a rotary machine on 2-mm-thick smectite-rich gouge layers (70/30 wt % Ca-montmorillonite/opal) sheared at 5-MPa normal stress, at slip rates of 0.001, 0.01, 0.1, and 1.3 m/s, and total displacement of 3 m. Experiments were performed on predried gouges under vacuum, under room humidity and under partly saturated conditions. The fault shear strength measured in the experiments was included in a one-dimensional numerical model incorporating frictional heating, thermal, and thermochemical pressurization. Quantitative X-ray powder diffraction and scanning electron microscopy investigations were performed on pristine and deformed smectite-rich gouges. Under dry conditions, cataclasis and amorphization dominated at slip rates of 0.001-0.1 m/s, whereas grain size sensitive flow and, under vacuum, frictional melting occurred at fast slip rates (1.3 m/s). Under partly saturated conditions, frictional slip in a smectite foliation occurred in combination with pressurization of water by shear-enhanced compaction and, for V = 0.01-1.3 m/s, with thermal pressurization. Pseudotachylytes, the only reliable microstructural markers for seismic slip, formed only with large frictional power (>2 MW/m 2 ), which could be achieved at shallow depth with high slip rates, or, at depth, with high shear stress in dehydrated smectites.

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“…Permeability links directly to the rock porous network, in terms of its concentration and its connectivity (Bernabé, ; C. David et al, , ; Guéguen & Dienes, ; Pimienta, Sarout, et al, ; Sarout, ). Assuming simple geometries of either tubes (i.e., connected spherical pores) or penny‐shaped cracks, one could predict the permeability of a material.…”

Section: Interpretationsmentioning

confidence: 99%

Variations in Elastic and Electrical Properties of Crustal Rocks With Varying Degree of Microfracturation

2019

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This work aims at investigating the effect of varying degrees of microfracturing on the joint elastic and electrical transport properties of rocks. Different crustal rocks were subjected to thermal treatment, expected to induce microfracturing, up to different target temperatures from 100 up to 900°C. The rocks bulk and pore volumes, P and S wave velocities, and frequency-dependent electrical impedance were measured before and after the treatment. As the temperature of treatment increased, P and S wave velocities and the electrical formation factor drop and pore and bulk volumes increase. As indicated by the microscopic images, this is consistent with the creation of microcracks. These created microcracks do not affect the properties in the exact same manner, and a strong effect of the initial porosity is observed for electrical formation factor. Extrapolating to low-frequency field-scale measurements in water-saturated reservoir rocks highlights an interesting observation: Both seismic and electrical properties at the field scale might highlight similar variations with increasing damage in all rocks. The maximum amount of decrease expected for all rocks is about 1 order of magnitude in electrical formation factor and 40% decrease in P and S wave velocities. Finally, temperature proved to affect very differently the rocks of varying porosity and mineral content, in ways not fully covered by existing works. Porosity, by increasing the matrix compressibility, damps the degree of microfracturing and crack opening. The distinct behavior in calcite-pure marble evidences a dominance of anisotropic of thermal expansion over isotropic expansion mismatch.

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KG²B, a collaborative benchmarking exercise for estimating the permeability of the Grimsel granodiorite—Part 2: modelling, microstructures and complementary data

Cited by 12 publications

References 52 publications

No‐Flow Fraction (NFF) Permeability Model for Rough Fractures Under Normal Stress

No‐Flow Fraction (NFF) Permeability Model for Rough Fractures Under Normal Stress

Water Availability and Deformation Processes in Smectite‐Rich Gouges During Seismic Slip

Variations in Elastic and Electrical Properties of Crustal Rocks With Varying Degree of Microfracturation

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