Reply to comment by F. H. Cornet on 'Large-scale in situ permeability tensor of rocks from induced microseismicity'

Shapiro, Serge A.; Audigane, Pascal; Royer, Jean‐Jacques

doi:10.1046/j.1365-246x.2000.00017.x

Cited by 72 publications

(109 citation statements)

References 16 publications

Supporting

Mentioning

104

Contrasting

Order By: Relevance

“…The spatiotemporal evolution of the triggering front depends on different parameters, including stress, injection rate, diffusivity and rock properties (e.g., friction coefficient). For example, an elliptical shape of the induced seismic cloud can be caused by the anisotropy of hydraulic diffusivity (Shapiro et al, 1997(Shapiro et al, , 1999, or by an anisotropic stress tensor (Schoenball et al, 2010). Due to poroelastic effects, it is impossible to distinguish between the two types of anisotropy from geothermal seismicity alone.…”

Section: Discussionmentioning

confidence: 99%

Analysis of induced seismicity in geothermal reservoirs – An overview

et al. 2014

View full text Add to dashboard Cite

In this overview we report results of analysing induced seismicity in geothermal reservoirs in various tectonic settings within the framework of the European Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs (GEISER) project. In the reconnaissance phase of a field, the subsurface fault mapping, in situ stress and the seismic network are of primary interest in order to help assess the geothermal resource. The hypocentres of the observed seismic events (seismic cloud) are dependent on the design of the installed network, the used velocity model and the applied location technique. During the stimulation phase, the attention is turned to reservoir hydraulics (e.g., fluid pressure, injection volume) and its relation to larger magnitude seismic events, their source characteristics and occurrence in space and time. A change in isotropic components of the full waveform moment tensor is observed for events close to the injection well (tensile character) as compared to events further away from the injection well (shear character). Tensile events coincide with high Gutenberg-Richter -values and low Brune stress drop values. The stress regime in the reservoir controls the direction of the fracture growth at depth, as indicated by the extent of the seismic cloud detected. Stress magnitudes are important in multiple stimulation of wells, where little or no seismicity is observed until the previous maximum stress level is exceeded (Kaiser Effect). Prior to drilling, obtaining a 3D -wave ( ) and -wave velocity ( ) model down to reservoir depth is recommended. In the stimulation phase, we recommend to monitor and to locate seismicity with high precision (decametre) in real-time and to perform local 4D tomography for velocity ratio ( / ). During exploitation, one should use observed and model induced seismicity to forward estimate seismic hazard so that field operators are in a position to adjust well hydraulics (rate and volume of the fluid injected) when induced events start to occur far away from the boundary of the seismic cloud.

show abstract

Section: Discussionmentioning

confidence: 99%

Analysis of induced seismicity in geothermal reservoirs – An overview

et al. 2014

View full text Add to dashboard Cite

show abstract

“…During all these stimulations, induced seismicity has been extensively studied (Charléty et al 2007;Cuenot et al 2008). For all of them, fluid pressure increase has been considered as the main source of seismicity initiation (Shapiro et al 1999). The 1993 stimulation is certainly the first stimulation for which a precise influence of the fluid pressure has been demonstrated (Cornet et al 1997;Cornet et al 2007).…”

Section: Fluid-induced Seismicity At Soultz-sous-forêtsmentioning

confidence: 99%

Induced seismicity in EGS reservoir: the creep route

et al. 2014

View full text Add to dashboard Cite

Background: Observations in enhanced geothermal system (EGS) reservoirs of induced seismicity and slow aseismic slip ruptures on related faults suggest a close link between the two phenomena. Methods: We base our approach on the case study of the EGS site of Soultz-sous-Forêts where seismicity has been shown in particular during the 1993 stimulation to be induced not only by fluid pressure increase during stimulation but also by aseismic creeping effects. We propose an interpretation of the field observations of induced seismicity using a laboratory experiment that explores, in great detail, the deformation processes of heterogeneous interfaces in the brittle-creep regime. We track the evolution of an interfacial crack over 7 orders of magnitude in time and 5 orders of magnitude in space using optical and acoustic sensors. Results: We show that a creep route for induced seismicity is possible when heterogeneities exist along the fault. Indeed, seismic event occurrences in time and space are in strong relation with the development of the aseismic motion recorded during the experiments. We also infer the statistical properties of the organization of the seismicity that shows strong space-time clustering. Conclusions: We conclude that aseismic processes might drive seismicity besides the classical effects related to fluid pressure and show that a creep route for induced seismicity is possible.

show abstract

“…Ledésert et al 1996;Aquilina et al 1997) and as a heat-exchanger, the majority of studies aimed at assessing or quantifying the permeability at the geothermal sites at Soultz-sous-Forêts and Rittershoffen, for example, have focussed on the granite basement (e.g. Genter and Traineau 1996;Shapiro et al 1999;Sausse et al 2006;Dezayes et al 2010;Ledésert et al 2010;Vogt et al 2012a, b;Vidal et al 2017). Few studies, especially laboratory studies that offer values of porosity and permeability, have targeted the overlying Permo-Triassic sedimentary units (e.g.…”

Section: Introductionmentioning

confidence: 99%

Microstructural and petrophysical properties of the Permo-Triassic sandstones (Buntsandstein) from the Soultz-sous-Forêts geothermal site (France)

et al. 2017

View full text Add to dashboard Cite

Geothermal projects in the Upper Rhine Graben aim to harness thermal anomalies that have arisen due to hydrothermal circulation within the granitic basement and the overlying Permo-Triassic sedimentary units. We present here a systematic microstructural, mineralogical, and petrophysical characterisation of the lowermost unit of this Permo-Triassic sedimentary succession-the Buntsandstein-sampled from exploration well EPS-1 at the Soultz-sous-Forêts geothermal site (France). Twelve depths were sampled (from 1008 to 1414 m) and cylindrical cores were prepared perpendicular and parallel to bedding. These cores were described in terms of their microstructure, grain size and shape, specific surface area, pore size and pore throat size distribution, mineral content, porosity, P-wave velocity, and permeability. The Buntsandstein sandstones are predominantly feldspathic sandstones, often characterised by pores filled or partially filled (with clays (R3 illite-smectite), dolomite, siderite, and barite) as a consequence of diagenesis, tectonics, and the circulation of hydrothermal fluids. The porosity, dry P-wave velocity, and permeability of these sandstones vary from ~ 0.03 to 0.2, ~ 2.5 to 4.5 km s −1 , and ~ 10 −18 to 10 −13 m 2 , respectively. Our data show that P-wave velocity decreases and permeability increases as porosity increases. P-wave velocities are significantly higher when measured parallel to bedding (by about 10 to 25%), and that saturation with water increases P-wave velocity (by about 5 to 50%, depending on sample orientation). The pervasive pore-filling precipitation has significantly reduced the permeabilities of the Buntsandstein sandstones, which are orders of magnitude less permeable than similarly porous unaltered sandstone. We also find that their permeability can be up to an order of magnitude more permeable when measured parallel to bedding than perpendicular to bedding. Although Buntsandstein units with low matrix permeabilities (as low as ~ 10 −18 m 2 ) require macroscopic fractures to attain the high permeability required to sustain regional hydrothermal circulation, matrix permeability is important for units with low fracture densities and high matrix permeabilities. We anticipate that these data will aid future fluid flow modelling and seismic investigations at geothermal sites within the Upper Rhine Graben. Open Access© The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

show abstract

Reply to comment by F. H. Cornet on 'Large-scale in situ permeability tensor of rocks from induced microseismicity'

Cited by 72 publications

References 16 publications

Analysis of induced seismicity in geothermal reservoirs – An overview

Analysis of induced seismicity in geothermal reservoirs – An overview

Induced seismicity in EGS reservoir: the creep route

Microstructural and petrophysical properties of the Permo-Triassic sandstones (Buntsandstein) from the Soultz-sous-Forêts geothermal site (France)

Contact Info

Product

Resources

About