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29 results on '"Gischig, V."'

1. The importance of earthquake interactions for injection-induced seismicity: Retrospective modeling of the Basel Enhanced Geothermal System

Author

Catalli, F, Rinaldi, AP, Gischig, V, Nespoli, M, and Wiemer, S

Subjects
Meteorology & Atmospheric Sciences
Abstract

We explore the role of earthquake interactions during an injection-induced seismic sequence. We propose a model, which considers both a transient pressure and static stress redistribution due to event interactions as triggering mechanisms. By calibrating the model against observations at the Enhanced Geothermal System of Basel, Switzerland, we are able to reproduce the time behavior of the seismicity rate. We observe that considering earthquake interactions in the modeling leads to a larger number of expected seismic events (24% more) if compared to a pressure-induced seismicity only. The increase of the number of events is particularly evident after the end of the injection. We conclude that implementing a model for estimating the static stress changes due to mutual event interactions increases significantly the understanding of the process and the behavior of induced seismicity.

Published
2016

10. Balancing reservoir creation and seismic hazard in enhanced geothermal systems

Author

Gischig, V., Wiemer, S., Alcolea, A., Gischig, V., Wiemer, S., and Alcolea, A.

Abstract

Fracture shear-dilatancy is an essential process for enhancing the permeability of deep geothermal reservoirs, and is usually accompanied by the radiation of seismic waves. However, the hazard and risk perspective of induced seismicity research typically focuses only on the question of how to reduce the occurrence of induced earthquakes. Here we present a quantitative analysis of seismic hazard as a function of the two key factors defining an enhanced geothermal system: The permeability enhancement, and the size of the stimulated reservoir. Our model has two coupled components: (1) a pressure diffusion model and (2) a stochastic seismicity model. Permeability is increased in the source area of each induced earthquake depending on the amount of slip, which is determined by the magnitude. We show that the few largest earthquakes (i.e. 5-10 events with M ≥ 1.5) contribute more than half of the total reservoir stimulation. The results further indicate that planning and controlling of reservoir engineering operations may be compromised by the considerable variability of maximum observed magnitude, reservoir size, the Gutenberg-Richter b-value and Shapiro's seismogenic index (i.e. a measure of seismic reactivity of a reservoir) that arises from the intrinsic stochastic nature of induced seismicity. We also find that injection volume has a large impact on both reservoir size and seismic hazard. Injection rate and injection scheme have a negligible effect. The impact of site-specific parameters on seismicity and reservoir properties is greater than that of the injected volume. In particular, conditions that lead to high b-values—possibly a low differential stress level—have a high impact on seismic hazard, but also reduce the efficiency of the stimulation in terms of permeability enhancement. Under such conditions, target reservoir permeability can still be achieved without reaching an unacceptable level of seismic hazard, if either the initial reservoir permeability is hig

Published
2017

16. Slow rock-slope deformation

Author

Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, Crosta, G, AGLIARDI, FEDERICO, CROSTA, GIOVANNI, FRATTINI, PAOLO, Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, Crosta, G, AGLIARDI, FEDERICO, CROSTA, GIOVANNI, and FRATTINI, PAOLO

Abstract

Giant, deep-seated gravitational slope deformations (DSGSD) affecting entire high-relief valley walls are common in alpine areas, and influence the evolution of mountain landscapes and the related hazards. In the last few years, new characterisation approaches and emerging technology shed new light on the occurrence, distribution, activity, and mechanisms of these spectacular slope failures. This chapter is aimed at providing an overview of alpine DSGSD, as well as a discussion of outstanding issues and future research needs. We review the definition of DSGSD and its typical features, field evidence, settings, and mechanisms. We discuss the distribution and controls on DSGSD occurrence based on the analysis of the first-ever orogen-scale inventory of these phenomena, including over 900 individual phenomena in the European Alps. We demonstrate that DSGSDs are widespread in active orogenic settings and chiefly occur in formerly glaciated areas under significant structural controls, and show that alpine DSGSDs are often active phenomena with a engineering significance. We use the emblematic case study of the Cima di Mandriole sackung to illustrate the complex relations among rock structure, the morpho-climatic evolution of Alpine valleys, and man-made structures, and point out future research needs.

Published
2012

17. Rockfall characterization and modeling

Author

Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, Crosta, G, FRATTINI, PAOLO, CROSTA, GIOVANNI, AGLIARDI, FEDERICO, Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, Crosta, G, FRATTINI, PAOLO, CROSTA, GIOVANNI, and AGLIARDI, FEDERICO

Abstract

Rockfalls pose a significant threat to life and property, although significant advances in rockfall protection have been made in the past decade. Determining rockfall processes and related hazard, however, remains a difficult task, because of the complexity and intrinsic stochastic nature of the physics involved. Appropriate application of rockfall modelling tools requires a thorough understanding of their logic, assumptions, advantages, and limitations, as well as careful assessment of rockfall sources, block and slope characteristics, and model calibration data. This chapter provides a discussion of major issues in rockfall definition, characterisation, and modelling, with special emphasis on rockfall runout. Our discussion is supported by modelling examples carried out using the 3D simulator Hy-STONE. Different modelling approaches are critically evaluated, including the empirical shadow angle method, and 2D and 3D mathematical models. Application of the shadow angle concept requires the user to be aware of several issues related to definition of the shadow angle and the effects of morphological constraints. Most limitations of empirical approaches can be overcome with mathematical models that account for slope morphology and roughness, energy dissipation at impact or by rolling, and the effects of vegetation, block fragmentation, and block-structure interaction. We discuss different modelling approaches and calibration problems and the important dependency of model parameters and results on correct characterisation of topography.

Published
2012

21. Development of connected permeability in massive crystalline rocks through hydraulic fracture propagation and shearing accompanying fluid injection.

Author

Preisig, G., Eberhardt, E., Gischig, V., Roche, V., Baan, M., Valley, B., Kaiser, P. K., Duff, D., and Lowther, R.

Subjects
CRYSTALLINE rocks, PERMEABILITY, HYDRAULIC fracturing, BOREHOLES, MINERAL industries
Abstract

The ability to generate deep flow in massive crystalline rocks is governed by the interconnectivity of the fracture network and its permeability, which in turn is largely dependent on the in situ stress field. The increase of stress with depth reduces fracture aperture, leading to a decrease in rock mass permeability. The frequency of natural fractures also decreases with depth, resulting in less connectivity. The permeability of crystalline rocks is typically reduced to about 10−17-10−15 m2 at targeted depths for enhanced geothermal systems ( EGS) applications, that is, >3 km. Therefore, fluid injection methods are required to hydraulically fracture the rock and increase its permeability. In the mining sector, fluid injection methods are being investigated to increase rock fragmentation and mitigate high-stress hazards due to operations moving to unprecedented depths. Here as well, detailed understanding of permeability and its enhancement is required. This paper reports findings from a series of hydromechanically coupled distinct-element models developed in support of a hydraulic fracture experiment testing hypotheses related to enhanced permeability, increased fragmentation, and modified stress fields. Two principal injection designs are tested as follows: injection of a high flow rate through a narrow-packed interval and injection of a low flow rate across a wider packed interval. Results show that the development of connected permeability is almost exclusively orthogonal to the minimum principal stress, leading to strongly anisotropic flow. This is because of the stress transfer associated with opening of tensile fractures, which increases the confining stress acting across neighboring natural fractures. This limits the hydraulic response of fractures and the capacity to create symmetric isotropic permeability relative to the injection wellbore. These findings suggest that the development of permeability at depth can be improved by targeting a set of fluid injections through smaller packed intervals instead of a single longer injection in open boreholes. [ABSTRACT FROM AUTHOR]

Published
2015
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22. Coupled seismogenic geohazards in Alpine regions

Author

Fäh, D., Moore, J., Burjanek, J., Iosifescu, I., Dalguer, L., Dupray, F., Michel, C., Woessner, J., Villiger, A., Laue, J., Marschall, I., Gischig, V., Loew, S., Marin, A., Gassner, G., Alvarez, S., Balderer, W., Kästli, P., Giardini, D., Iosifescu, C., Hurni, L., Lestuzzi, P., Karbassi, A., Baumann, C., Geiger, A., Ferrari, Alessio, Laloui, L., Clinton, J., Deichmann, N., Fäh, D., Moore, J., Burjanek, J., Iosifescu, I., Dalguer, L., Dupray, F., Michel, C., Woessner, J., Villiger, A., Laue, J., Marschall, I., Gischig, V., Loew, S., Marin, A., Gassner, G., Alvarez, S., Balderer, W., Kästli, P., Giardini, D., Iosifescu, C., Hurni, L., Lestuzzi, P., Karbassi, A., Baumann, C., Geiger, A., Ferrari, A., Laloui, L., Clinton, J., and Deichmann, N.

Subjects
landslides, seismic ground motion, Landslide, non-linear phenomena, earthquake precursors, Oceanography, Earthquake precursor, Geophysic, earthquakeforecasting, Earthquake forecasting, Switzerland
Abstract

COupled seismogenic GEohazards in Alpine Regions (COGEAR) is an interdisciplinary natural hazard project investigating the hazard chain induced by earthquakes. It addresses tectonic processes and the related variability of seismicity in space and time, earthquake forecasting and short-term precursors, and strong ground motion as a result of source and complex path effects. We study non-linear wave propagation phenomena, liquefaction and triggering of landslides in soil and rock, as well as earthquake-induced snow avalanches. The Valais, and in particular parts of the Rhone, Visper, and Matter valleys have been selected as study areas. Tasks include detailed field investigations, development and application of numerical modeling techniques, assessment of the susceptibility to seismically induced effects, and installation of different monitoring systems to test and validate our models. These systems are for long-term operation and include a continuous GPS and seismic networks, a test installation for observing earthquake precursors, and a system to study site-effects and non-linear phenomena in two test areas (Visp, St. Niklaus / Randa). Risk-related aspects relevant for buildings and lifelines are also considered. © 2012-OGS.

24. Coupled seismogenic geohazards in alpine regions

Author

Fäh D., Moore J.R., Burjanek J., Iosifescu I., Dalguer L., Dupray F., Michel C., Woessner J., Villiger A., Laue J., Marschall I., Gischig V., Loew S., Alvarez S., Balderer W., Kästli P., Giardini D., Iosifescu C., Hurni L., Lestuzzi P., Karbassi A., Baumann C., Geiger A. Ferrari A., Lalou L. Clinton J., and Deichmann N.

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25. Balancing reservoir creation and seismic hazard in enhanced geothermal systems

Author

Gischig, V., Wiemer, S., Alcolea, A., Gischig, V., Wiemer, S., and Alcolea, A.

Abstract

Fracture shear-dilatancy is an essential process for enhancing the permeability of deep geothermal reservoirs, and is usually accompanied by the radiation of seismic waves. However, the hazard and risk perspective of induced seismicity research typically focuses only on the question of how to reduce the occurrence of induced earthquakes. Here we present a quantitative analysis of seismic hazard as a function of the two key factors defining an enhanced geothermal system: The permeability enhancement, and the size of the stimulated reservoir. Our model has two coupled components: (1) a pressure diffusion model and (2) a stochastic seismicity model. Permeability is increased in the source area of each induced earthquake depending on the amount of slip, which is determined by the magnitude. We show that the few largest earthquakes (i.e. 5-10 events with M ≥ 1.5) contribute more than half of the total reservoir stimulation. The results further indicate that planning and controlling of reservoir engineering operations may be compromised by the considerable variability of maximum observed magnitude, reservoir size, the Gutenberg-Richter b-value and Shapiro's seismogenic index (i.e. a measure of seismic reactivity of a reservoir) that arises from the intrinsic stochastic nature of induced seismicity. We also find that injection volume has a large impact on both reservoir size and seismic hazard. Injection rate and injection scheme have a negligible effect. The impact of site-specific parameters on seismicity and reservoir properties is greater than that of the injected volume. In particular, conditions that lead to high b-values—possibly a low differential stress level—have a high impact on seismic hazard, but also reduce the efficiency of the stimulation in terms of permeability enhancement. Under such conditions, target reservoir permeability can still be achieved without reaching an unacceptable level of seismic hazard, if either the initial reservoir permeability is hig

26. Rockfall characterization and modeling

Author

Paolo Frattini, Giovanni B. Crosta, Federico Agliardi, Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, and Crosta, G

Subjects
geography, Rockfall, geography.geographical_feature_category, Geotechnical engineering, rockfall, modeling, 3D, hazard, impact, fragmentation, energy line, Geology, GEO/05 - GEOLOGIA APPLICATA
Abstract

Rockfalls pose a significant threat to life and property, although significant advances in rockfall protection have been made in the past decade. Determining rockfall processes and related hazard, however, remains a difficult task, because of the complexity and intrinsic stochastic nature of the physics involved. Appropriate application of rockfall modelling tools requires a thorough understanding of their logic, assumptions, advantages, and limitations, as well as careful assessment of rockfall sources, block and slope characteristics, and model calibration data. This chapter provides a discussion of major issues in rockfall definition, characterisation, and modelling, with special emphasis on rockfall runout. Our discussion is supported by modelling examples carried out using the 3D simulator Hy-STONE. Different modelling approaches are critically evaluated, including the empirical shadow angle method, and 2D and 3D mathematical models. Application of the shadow angle concept requires the user to be aware of several issues related to definition of the shadow angle and the effects of morphological constraints. Most limitations of empirical approaches can be overcome with mathematical models that account for slope morphology and roughness, energy dissipation at impact or by rolling, and the effects of vegetation, block fragmentation, and block-structure interaction. We discuss different modelling approaches and calibration problems and the important dependency of model parameters and results on correct characterisation of topography.

Published
2012
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27. Slow rock-slope deformation

Author

Giovanni B. Crosta, Federico Agliardi, Paolo Frattini, Clague, JJ, Stead, D, Roberts, N, Korup, O., Hovius, N, Meunier, P, Waythomas, CF, Davies, T, McSaveney, M, Hermanns, RL, Longva, O, Jakob, M, Holm, K, Torrance, JK, Piper, DJW, Mosher, DC, Campbell, DC, Bornhold, BD, Thomson, RE, Huggel, C, Khabarov, N, Obersteiner, M, Fell, R, Stapledon, D, MacGregor, P, Coggan, J, Petley, D, Griffiths, JS, Whitworth, M, McDougall, S, McKinnon, M, Hungr, O, Jibson, RW, Agliardi, F, Crosta, GB, Frattini, P, Eberhardt, E, Picarelli, L, Leroueil, S, Olivares, L, Pagano, L, Tommasi, P, Urciuoli, G, Bromhead, EN, Hosseyni, S, Torii, N, Jaboyedoff, M, Derron, MH, Jakubowski, J, Oppikofer, T, Pedrazzini, A, Loew, S, Gischig, V, Willenberg, H, Alpiger, A, Moore, JR, Froese, CR, Charrière, M, Humair, F, Blikra, LH, Bianchi Fasani,G, Esposito, C, Lenti, L, Martino, S, Pecci, M, Scarascia Mugnozza, G, Kalenchuk, KS, Hutchinson, DJ, Diederichs, M, Moore, D, Ghirotti, M, Hencher, SR, Malone, AW, Chigira, M, Wang, G, Wu, X, Bulmer, MHK, and Crosta, G

Subjects
geography, geography.geographical_feature_category, Landslide classification, deep seated slope deformation, landslide, inventory, modeling, slope-struvture interation, Rockslide, Deformation (meteorology), GEO/05 - GEOLOGIA APPLICATA, Slump, Rockfall, Creep, Interferometric synthetic aperture radar, Geotechnical engineering, Shear strength (discontinuity), Geomorphology, Geology
Abstract

Giant, deep-seated gravitational slope deformations (DSGSD) affecting entire high-relief valley walls are common in alpine areas, and influence the evolution of mountain landscapes and the related hazards. In the last few years, new characterisation approaches and emerging technology shed new light on the occurrence, distribution, activity, and mechanisms of these spectacular slope failures. This chapter is aimed at providing an overview of alpine DSGSD, as well as a discussion of outstanding issues and future research needs. We review the definition of DSGSD and its typical features, field evidence, settings, and mechanisms. We discuss the distribution and controls on DSGSD occurrence based on the analysis of the first-ever orogen-scale inventory of these phenomena, including over 900 individual phenomena in the European Alps. We demonstrate that DSGSDs are widespread in active orogenic settings and chiefly occur in formerly glaciated areas under significant structural controls, and show that alpine DSGSDs are often active phenomena with a engineering significance. We use the emblematic case study of the Cima di Mandriole sackung to illustrate the complex relations among rock structure, the morpho-climatic evolution of Alpine valleys, and man-made structures, and point out future research needs.

Published
2012
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28. In situ observation of helium and argon release during fluid-pressure-triggered rock deformation.

Author

Roques C, Weber UW, Brixel B, Krietsch H, Dutler N, Brennwald MS, Villiger L, Doetsch J, Jalali M, Gischig V, Amann F, Valley B, Klepikova M, and Kipfer R

Abstract

Temporal changes in groundwater chemistry can reveal information about the evolution of flow path connectivity during crustal deformation. Here, we report transient helium and argon concentration anomalies monitored during a series of hydraulic reservoir stimulation experiments measured with an in situ gas equilibrium membrane inlet mass spectrometer. Geodetic and seismic analyses revealed that the applied stimulation treatments led to the formation of new fractures (hydraulic fracturing) and the reactivation of natural fractures (hydraulic shearing), both of which remobilized (He, Ar)-enriched fluids trapped in the rock mass. Our results demonstrate that integrating geochemical information with geodetic and seismic data provides critical insights to understanding dynamic changes in fracture network connectivity during reservoir stimulation. The results of this study also shed light on the linkages between fluid migration, rock deformation and seismicity at the decameter scale.

Published
2020
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29. Comprehensive geological dataset describing a crystalline rock mass for hydraulic stimulation experiments.

Author

Krietsch H, Doetsch J, Dutler N, Jalali M, Gischig V, Loew S, and Amann F

Abstract

High-resolution 3D geological models are crucial for underground development projects and corresponding numerical simulations with applications in e.g., tunneling, hydrocarbon exploration, geothermal exploitation and mining. Most geological models are based on sparse geological data sampled pointwise or along lines (e.g., boreholes), leading to oversimplified model geometries. In the framework of a hydraulic stimulation experiment in crystalline rock at the Grimsel Test Site, we collected geological data in 15 boreholes using a variety of methods to characterize a decameter-scale rock volume. The experiment aims to identify and understand relevant thermo-hydro-mechanical-seismic coupled rock mass responses during high-pressure fluid injections. Prior to fluid injections, we characterized the rock mass using geological, hydraulic and geophysical prospecting. The combination of methods allowed for compilation of a deterministic 3D geological analog that includes five shear zones, fracture density information and fracture locations. The model may serve as a decameter-scale analog of crystalline basement rocks, which are often targeted for enhanced geothermal systems. In this contribution, we summarize the geological data and the resulting geological interpretation.

Published
2018
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