A 3D hydrogeological and geomechanical model of an Enhanced Geothermal System at The Geysers, California

Jeanne, Pierre; Rutqvist, Jonny; Vasco, D. W.; García, Julio; Dobson, Patrick; Walters, Mark; Hartline, Craig; Borgia, Andrea

doi:10.1016/j.geothermics.2014.01.013

Cited by 45 publications

(52 citation statements)

References 9 publications

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“…The coupled THM models of the EGS used for calibration of permeability distribution were developed progressively, e.g., going from a 2D plane model with a shear-zone network (Jeanne et al, 2014a) to a full 3D model (Jeanne et al, 2014b), and an explicit well model that considered well-head pressure rather than bottom-hole pressure (Jeanne et al, 2014c). More pressure monitoring data were also included in the analysis as they became available, ending in Jeanne et al (2014c) with a calibration to pressure monitoring data from three wells (PS-31, P-25, P-38) over a 450-day period.…”

Section: Estimation Of Permeability Distribution Using Pressure Monitmentioning

confidence: 99%

“…Associated with this modeling, Jeanne et al (2014b) investigated the observed cyclic behavior in ground-surface deformation data that appeared to be correlated with precipitation in the area. Such cyclic seasonal response to precipitation would likely be strongly dependent on the local ground conditions, e.g., soft swelling clay would respond differently than bare rock or engineered structures.…”

Section: Estimation Of Elastic Properties Using Ground-surface Deformmentioning

confidence: 99%

“…Another complicating factor is that the overall injection rates at The Geysers vary with the season in a similar way as that of precipitation, e.g., with increased injection during the rainy winter months. The approach taken by Jeanne et al (2014b) was to identify measurement points in the SAR data on the ground surface around the EGS area that were most stable prior to the start of the injection. The hypothesis was that those would be points where the ground conditions are favorable or are engineered structures that would not be significantly affected by seasonal, weather-related effects.…”

Section: Estimation Of Elastic Properties Using Ground-surface Deformmentioning

confidence: 99%

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The Northwest Geysers EGS Demonstration Project, California – Part 2: Modeling and interpretation

et al. 2016

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a b s t r a c tIn this paper, we summarize the results of coupled thermal, hydraulic, and mechanical (THM) modeling in support of the Northwest Geysers EGS Demonstration Project, which aims at enhancing production from a known High Temperature Reservoir (HTR) (280-400 • C) located under the conventional (240 • C) geothermal steam reservoir. The THM modeling was conducted to investigate geomechanical effects of cold-water injection during the stimulation of the EGS, first to predict the extent of the stimulation zone for a given injection schedule, and then to conduct interpretive analyses of the actual stimulation. By using a calibrated THM model based on historic injection and microseismic data at a nearby well, we could reasonably predict the extent of the stimulation zone around the injection well, at least for the first few months of injection. However, observed microseismic evolution and pressure responses over the one-year stimulation-injection revealed more heterogeneous behavior as a result of more complex geology, including a network of shear zones. Therefore, for an interpretive analysis of the one-year stimulation campaign, we included two sets of vertical shear zones within the model; a set of more permeable NWstriking shear zones and a set of less permeable NE-striking shear zones. Our modeling indicates that the microseismic events in this system are related to shear reactivation of pre-existing fractures, triggered by the combined effects of injection-induced cooling around the injection well and rapid (but small) changes in steam pressure as far as a kilometer from the injection well. Overall, the integrated monitoring and modeling of microseismicity, ground surface deformations, reservoir pressure, fluid chemical composition, and seismic tomography depict an EGS system hydraulically bounded by some of the NE-striking low permeability shear zones, with the more permeable NW-striking shear zone providing liquid flow paths for stimulation deep (several kilometers) down into the HTR. The modeling indicates that a significant mechanical degradation (damage) inferred from seismic tomography, and potential changes in fracture porosity inferred from cross-well pressure responses, are related to shear rupture in the stimulation zone driven by both pressure and cooling effects.

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Section: Estimation Of Permeability Distribution Using Pressure Monitmentioning

confidence: 99%

Section: Estimation Of Elastic Properties Using Ground-surface Deformmentioning

confidence: 99%

Section: Estimation Of Elastic Properties Using Ground-surface Deformmentioning

confidence: 99%

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The Northwest Geysers EGS Demonstration Project, California – Part 2: Modeling and interpretation

et al. 2016

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“…It sequentially couples the geomechanical code FLAC3D [164] with the multi-phase flow and heat transport code TOUGH2 [167]. Jeanne et al [168] simulate the geothermal reservoir by an equivalent continuum with implicit representation of fractures and by explicit description of identified shear zones which will have different hydraulic and mechanical properties. A MohrCoulomb failure criterion is applied and the medium is assumed to be critically stressed to compute the relative variation of the maximum and minimum effective stresses necessary to induce shear.…”

Section: Alternative Models Of Rockmentioning

confidence: 99%

Induced seismicity in geothermal reservoirs: A review of forecasting approaches

Gaucher

Schoenball

Heidbach

et al. 2015

Renewable and Sustainable Energy Reviews

144

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In order to reach Europe's 2020 and 2050 targets in terms of greenhouse gas emissions, geothermal resources will have to contribute substantially to meeting carbon-free energy needs. However, public opinion may prevent future large-scale application of deep geothermal power plants, because induced seismicity is often perceived as an unsolicited and uncontrollable side effect of geothermal development. In the last decade, significant advances were made in the development of models to forecast induced seismicity, which are either based on catalogues of induced seismicity, on the underlying physical processes, or on a hybrid philosophy. In this paper, we provide a comprehensive overview of the existing approaches applied to geothermal contexts. This overview will outline the advantages and drawbacks of the different approaches, identify the gaps in our understanding, and describe the needs for geothermal observations. Most of the forecasting approaches focus on the stimulation phase of enhanced geothermal systems which are most prone to generate seismic events. Besides the statistical models suited for realtime applications during reservoir stimulation, the physics-based models have the advantage of considering subsurface characteristics and estimating the impact of fluid circulation on the reservoir. Hence, to mitigate induced seismicity during major hydraulic stimulations, application of hybrid methods in a decision support system seems the best available solution. So far, however, little attention has been paid to geochemical effects on the failure process and to production periods. Quantitative modelling of induced seismicity still is a challenging and complex matter. Appropriate resources remain to be invested for the scientific community to continue its research and development efforts to successfully forecast induced seismicity in geothermal fields. This is a prerequisite for making this renewable energy resource sustainable and accessible worldwide.

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“…Indeed, previous geodetic analyses of geothermal regions have already been performed and have shown that vertical and horizontal displacements have been caused by geothermal exploitation (e.g. Massonnet et al 1997;Carnec and Fabriol 1999;Fialko and Simons 2000;Nishijima et al 2005;Glowacka et al 2010;Jeanne et al 2014). Note that surface displacement can also be observed during the drilling phase (Lubitz et al 2013).…”

Section: Introductionmentioning

confidence: 96%

Uplift around the geothermal power plant of Landau (Germany) as observed by InSAR monitoring

et al. 2015

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A 3D hydrogeological and geomechanical model of an Enhanced Geothermal System at The Geysers, California

Cited by 45 publications

References 9 publications

The Northwest Geysers EGS Demonstration Project, California – Part 2: Modeling and interpretation

The Northwest Geysers EGS Demonstration Project, California – Part 2: Modeling and interpretation

Induced seismicity in geothermal reservoirs: A review of forecasting approaches

Uplift around the geothermal power plant of Landau (Germany) as observed by InSAR monitoring

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