Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forêts, France

Cuenot, Nicolas; Charléty, Jean; Dorbath, L.; Haessler, H.

doi:10.1016/j.geothermics.2006.11.007

Cited by 73 publications

(67 citation statements)

References 15 publications

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“…Cuenot et al (2006) analyzed data from the 2003 hydraulic stimulation experiment and observed a higher proportion of the non-DC component for earthquakes near the injection well. On the other hand, Horalek et al (2010) studied 45 of the largest M 1.4-2.9 earthquakes from a 2003 borehole injection experiment and found that DC mechanisms dominated the sequence.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California

Boyd¹,

Dreger²,

Lai³

et al. 2015

Bulletin of the Seismological Society of America

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The Geysers geothermal field is one of the most seismically active regions in northern California. Most of the events occur at shallow depths and are related to stress and hydrological perturbations due to energy production operations. To better understand the relationships between seismicity and operations, better source mechanism information is needed. Seismic moment tensors offer insight into the nature of equivalent forces causing the seismicity. Fifty-three M >3 events located at The Geysers geothermal field were selected from the University of California Berkeley Moment Tensor Catalog for analysis of seismic moment tensor solutions and associated uncertainties. Deviatoric and full moment tensor solutions were computed, and statistical tests were employed to assess solution stability, resolution, and significance. In this study, we examine several source models including double-couple (DC), pure isotropic (ISO; volumetric change), and volume-compensated linear vector dipole (CLVD) sources, as well as compound sources such as DC CLVD, DC ISO, and shear-tensile sources. In general, we find from a systematic approach toward characterizing uncertainties in moment tensor solutions that The Geysers earthquakes, as a population, deviate significantly from northern California seismicity in terms of apparent volumetric source terms and complexity.

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Section: Introductionmentioning

confidence: 99%

A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California

Boyd¹,

Dreger²,

Lai³

et al. 2015

Bulletin of the Seismological Society of America

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“…Moreover, other fracture zones not permeable prior stimulation have been reactivated during the stimulation and have been taking into account in this study. 3 Thus, fracture zones form the main potential fluid pathways connected to the dense network of mesoscale fractures to form the geothermal reservoir, which is about 1,125km 3 for the upper reservoir and 8 km 3 for the deeper reservoir, based on induced micro-seismicity study [7].…”

Section: Introductionmentioning

confidence: 99%

Structure of the low permeable naturally fractured geothermal reservoir at Soultz

Dezayes

Genter²,

Valley

2009

Comptes Rendus. Géoscience

127

105

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The permeability of the granite geothermal reservoir of Soultz is primarily related to major fracture zones, which, in turn, are connected to dense networks of small-scale fractures.The small-scale fractures are nearly vertical and the major direction is about N0°E. This direction differs from that of the Rhine graben, which is about N20°E to N45E in northern Alsace.A total of 39 fracture zones, with a general strike of N160°E, have been identified in six wells between 1400 and 5000 m depth. These fracture zones are spatially concentrated in three clusters. The upper cluster at 1800-2000m TVD (True Vertical Depth) is highly permeable. At 3000-3400m TVD, the intermediate cluster in composed of a dense network developed in an altered matrix and forms the upper reservoir. In the lower part of the wells, the deeper cluster appears as a fractured reservoir developed within a low permeable matrix.Fracture zones represent a key element to take into account for modeling of geothermal reservoir life time submitted to various thermo-hydro-mechanical and chemical processes generated by hydraulic or chemical stimulations and hydraulic circulations. RésuméLe réservoir géothermique de Soultz est constitué par des zones de fracture majeures connectées à un réseau dense de fractures secondaires.Les méso-fractures sont pratiquement verticales et la direction majeure est à peu près N-S. Cette direction diffère de la direction régionale du fossé rhénan qui est localement à dominante N20°E à N45°E dans le Nord.Un total de 39 zones de fracture a été identifiées et caractérisées dans six puits entre 1400 et 5000 m de profondeur. Ces structures sont réparties en trois clusters suivant la profondeur. Le premier cluster à 1800-2000m TVD (profondeur verticale) est très perméable. A 3000-3400m TVD, le cluster intermédiaire apparaît comme un réseau plus dense dans un milieu plus altéré et constitue le réservoir supérieur. Dans la partie inférieure des puits, le cluster profond apparaît comme un réservoir fracturé développé dans une matrice très peu perméable. 2La caractérisation des zones de fracture représente un élément important à prendre en compte dans la modélisation de la durée de vie du réservoir géothermique soumis à des processus thermo-hydromécaniques et chimiques engendrés par les stimulations hydrauliques et chimiques et les circulations de fluide. Key words: Rhine graben, fractures, fracture zones, cores, borehole images, Enhanced GeothermalSystem. Mots-clés : Fossé rhénan, fractures, zones de fractures, carottes, image de paroi, Système GéothermalAmélioré. IntroductionSince 1980 [27; 28], the EGS project at Soultz (France) goals to experiment and develop a new geothermal technology. After an initial Hot Dry Rock (HDR) concept of artificial fractures creation in a homogeneous rock by hydraulic fracturing, the concept at Soultz has progressively evolved to an Enhanced Geothermal System (EGS) where reservoir development involved the reactivation of the preexisting fractures in the granite [16; 29]. Thus, a good knowledge...

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“…Various spatial structures of seismicity were observed including planes with sizes much smaller than the source dimension of the individual events suggesting a multiple breakdown of the asperities. Hundreds of double-couple fault plane solutions were calculated (Cuenot et al, 2006;Charléty et al, 2007) indicating a normal faulting environment in the proximity of injection wells with strike-slip components at greater distances. Indications for non-double-couple seismic events were observed and considered to be related neither to numerical artifacts, nor to possible curvature of the faults (i.e.…”

mentioning

confidence: 99%

“…Indications for non-double-couple seismic events were observed and considered to be related neither to numerical artifacts, nor to possible curvature of the faults (i.e. complex source processes) nor to the opening and shearing mode of failure (Cuenot et al, 2006). They were attributed to either cooling around the injection or large increase in overpressure.…”

mentioning

confidence: 99%

Microseismicity induced during fluid-injection: A case study from the geothermal site at Groß Schönebeck, North German Basin

et al. 2010

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Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forêts, France

Cited by 73 publications

References 15 publications

A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California

A Systematic Analysis of Seismic Moment Tensor at The Geysers Geothermal Field, California

Structure of the low permeable naturally fractured geothermal reservoir at Soultz

Microseismicity induced during fluid-injection: A case study from the geothermal site at Groß Schönebeck, North German Basin

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