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Arno Zang - One of the best experts on this subject based on the ideXlab platform.
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Induced Seismicity in Geothermal Reservoirs : Physical Processes and Key Parameters
2020Co-Authors: Emmanuel Gaucher, Arno Zang, Martin Schoenball, Oliver Heidbach, P A Fokker, Jan Diederik Van Wees, Thomas KohlAbstract:In order to reach Europe’s 2020 and 2050 targets on greenhouse gas emissions, geothermal resources have to contribute substantially to carbon-free energy needs. Deep geothermal developments, however, are often accompanied by Induced Seismicity due to stimulation. The Induced Seismicity can be a threat for the development of future large scale application of deep geothermal power plants. Therefore, understanding the physical processes at the origin of the Seismicity Induced by forced fluid circulation in geothermal fields is essential, and this paper reviews the current knowledge in connection with field cases. The driving force of a seismic event is a change of the stress state in the crust. To asses this quantitatively, one needs to know the initial stress state, the spatio-temporal stress changes, the failure criterion, and the rupture dynamics that describes how a seismic event is produced. Several existing geomechanical-numerical models are, in theory, capable of predicting the spatio-temporal changes of the stress state and few of their effects on Induced Seismicity. They consider coupling between geomechanical, fluid flow, and heat transport processes, with different levels of complexity. The characteristics of the recorded Seismicity Induced in geothermal fields play a major role to calibrate and to assess the models. The Soultz-sous-Forets enhanced geothermal system in France, where thousands of seismic events were Induced during stimulations, is an example representative for fields developed in deep crystalline rocks. In such formations, Induced Seismicity mainly occurs on a network of pre-existing faults and fractures oriented in accordance with the stress field, and shearing on these structures is apparently the dominating failure mechanism. Several physics-based models have been tested on this well-documented field to reproduce the observations. By contrast, the hydraulic fracturing operations carried out in Gros Schonebeck (Germany) geothermal reservoir, which is located in sedimentary formations at a depth similar to Soultz-sous-Forets, Induced very few and weak seismic events. This behavior is consistent with a less seismogenic tensile fracture opening as being the dominant failure mechanism. Interestingly, the few recorded and located seismic events at this site likely occurred on a pre-existing fault. To characterize a geothermal field with regards to the expected Induced Seismicity, the following key factors are proposed: natural Seismicity at a field scale, stress field, structural fracture/fault characterization, rock type, history of pressure and injection/circulation rates, and past Induced Seismicity. To mitigate Induced Seismicity during major hydraulic stimulations, and to prevent large-magnitude event occurrence once injection stopped, early-warning systems and decision support systems are required. To feed these systems, we advocate the application of hybrid methods and the development of fast models. Hybrid methods would combine the best a priori knowledge of the expected behavior of the field underground, inherited from geomechanical-numerical modeling, with a statistical approach based on the real-time observation of the Induced Seismicity. Fast models would capture the essential physics while minimizing computing time. The quantitative understanding of Induced Seismicity, however, remains a challenging and complex matter. Only an integration of all current research and development efforts, in the fields of modeling, measuring, monitoring, and matching, will make a chance on success.
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Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs — The European GEISER Project
2020Co-Authors: Dan Bruhn, Arno Zang, Stefan Wiemer, J D Van Wees, Ernst Huenges, K. Áǵustsson, Grzegorz Kwiatek, X. Rachez, P. Calcagno, Thomas KohlAbstract:The GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs) project is co-funded by the European Commission to address the mitigation and understanding of Induced Seismicity (IS) in geothermal engineering. The aim of the project is to contribute to the improvement of the concept of EGS by investigating the role of IS, which is twofold: 1. as an instrument to image fluid pathways Induced by hydraulic stimulation treatments, which has been done to some extent in previous projects; and 2. as an implication of such treatments to potential seismic hazards. Work started in 2010 by addressing four major points: - Analysis of Induced Seismicity - Understanding the geomechanics and - Consequences of Induced Seismicity - Strategies for the mitigation of Induced Seismicity Within the first year of the project, a number of reference sites were defined where data sets with seismic and downhole data are available for further processing and analysis. In addition, laboratory experiments and mechanical models as well as hazard assessment tools are developed on the basis of existing data. At the end of the project, guidelines for regulatory bodies will present the basis for future licensing procedures of geothermal projects.
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Summary of the EU Project GEISER on Induced Seismicity in Geothermal Engineering
Proceedings 76th EAGE Conference and Exhibition 2014, 2020Co-Authors: Dan Bruhn, Arno Zang, Stefan Wiemer, J D Van Wees, X. Rachez, P. Calcagno, Kristján Ágústsson, Ernst HuengesAbstract:GEISER was a European project on understanding and mitigation of Induced seismicty in geothermal operations. The project involved several European research institutions as well as industry and was funded by the European Commission within FP7. GEISER addressed a better understanding of the key parameters that control Induced Seismicity in response to an injection. Data from several events of Induced Seismicity were collected and analysed. Mechanical models were developed to understand the processes leading to Induced Seismicity and were combined with probabilistic seismic hazard assessment approaches to propose a new, physics based probabilistic forewarning system. This system requires the determination of a maximum acceptable seismic magnitude and its accepted probability of occurrence. The reliability of the dynamic model is based on the availability of rock physics and seismic data, with models updated from real-time monitoring. In addition to this new approach, a number of recommendations and guidelines for licensing authorities, developers and operators of geothermal projects are proposed.
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Induced Seismicity in geothermal reservoirs a review of forecasting approaches
Renewable & Sustainable Energy Reviews, 2015Co-Authors: Emmanuel Gaucher, Arno Zang, Martin Schoenball, Oliver Heidbach, P A Fokker, Jan Diederik Van Wees, Thomas KohlAbstract: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 real-time applications during reservoir stimulation, the physics-based models have the advantage of considering sub-surface 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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Discrete element modeling of fluid injection–Induced Seismicity and activation of nearby fault1
Canadian Geotechnical Journal, 2015Co-Authors: Jeoung Seok Yoon, Arno Zang, Günter Zimmermann, Ove StephanssonAbstract:Enhanced geothermal systems, shale gas, and geological carbon sequestration all require underground fluid injection in high-pressure conditions. Fluid injection creates fractures, induces Seismicity, and has the potential to reactivate nearby faults that can generate a large magnitude earthquake. Mechanisms of fluid injection–Induced Seismicity and fault reactivation should be better understood to be able to mitigate larger events triggered by fluid injection. This study investigates fluid injection, Induced Seismicity, and triggering of fault rupture using hydromechanical-coupled discrete element models. Results show that a small amount of fluid pressure perturbation can trigger fault ruptures that are critically oriented and stressed. Induced Seismicity by rock failure shows in general higher b-values (slope of magnitude–frequency relation) compared to Seismicity triggered by the fault fracture slip. Numerical results closely resemble observations from geothermal and shale-gas fields and demonstrate tha...
Dan Bruhn - One of the best experts on this subject based on the ideXlab platform.
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Summary of the EU Project GEISER on Induced Seismicity in Geothermal Engineering
Proceedings 76th EAGE Conference and Exhibition 2014, 2020Co-Authors: Dan Bruhn, Arno Zang, Stefan Wiemer, J D Van Wees, X. Rachez, P. Calcagno, Kristján Ágústsson, Ernst HuengesAbstract:GEISER was a European project on understanding and mitigation of Induced seismicty in geothermal operations. The project involved several European research institutions as well as industry and was funded by the European Commission within FP7. GEISER addressed a better understanding of the key parameters that control Induced Seismicity in response to an injection. Data from several events of Induced Seismicity were collected and analysed. Mechanical models were developed to understand the processes leading to Induced Seismicity and were combined with probabilistic seismic hazard assessment approaches to propose a new, physics based probabilistic forewarning system. This system requires the determination of a maximum acceptable seismic magnitude and its accepted probability of occurrence. The reliability of the dynamic model is based on the availability of rock physics and seismic data, with models updated from real-time monitoring. In addition to this new approach, a number of recommendations and guidelines for licensing authorities, developers and operators of geothermal projects are proposed.
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Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs — The European GEISER Project
2020Co-Authors: Dan Bruhn, Arno Zang, Stefan Wiemer, J D Van Wees, Ernst Huenges, K. Áǵustsson, Grzegorz Kwiatek, X. Rachez, P. Calcagno, Thomas KohlAbstract:The GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs) project is co-funded by the European Commission to address the mitigation and understanding of Induced Seismicity (IS) in geothermal engineering. The aim of the project is to contribute to the improvement of the concept of EGS by investigating the role of IS, which is twofold: 1. as an instrument to image fluid pathways Induced by hydraulic stimulation treatments, which has been done to some extent in previous projects; and 2. as an implication of such treatments to potential seismic hazards. Work started in 2010 by addressing four major points: - Analysis of Induced Seismicity - Understanding the geomechanics and - Consequences of Induced Seismicity - Strategies for the mitigation of Induced Seismicity Within the first year of the project, a number of reference sites were defined where data sets with seismic and downhole data are available for further processing and analysis. In addition, laboratory experiments and mechanical models as well as hazard assessment tools are developed on the basis of existing data. At the end of the project, guidelines for regulatory bodies will present the basis for future licensing procedures of geothermal projects.
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analysis of Induced Seismicity in geothermal reservoirs an overview
Geothermics, 2014Co-Authors: Arno Zang, Roland Gritto, Nicholas Deichmann, Philippe Jousset, Ernest L. Majer, Art Mcgarr, Dan BruhnAbstract: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 b-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 P-wave (Vp) and S-wave velocity (Vs) 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 (Vp/Vs). 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.
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Analysis of Induced Seismicity in geothermal reservoirs - An overview
Geothermics, 2014Co-Authors: Arno Zang, Roland Gritto, Volker Oye, Nicholas Deichmann, Philippe Jousset, Ernest L. Majer, Art Mcgarr, Dan BruhnAbstract: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 b-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 P-wave (Vp) and S-wave velocity (Vs) 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 (Vp/. Vs). 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. © 2014 Elsevier Ltd.
Ernest L. Majer - One of the best experts on this subject based on the ideXlab platform.
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analysis of Induced Seismicity in geothermal reservoirs an overview
Geothermics, 2014Co-Authors: Arno Zang, Roland Gritto, Nicholas Deichmann, Philippe Jousset, Ernest L. Majer, Art Mcgarr, Dan BruhnAbstract: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 b-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 P-wave (Vp) and S-wave velocity (Vs) 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 (Vp/Vs). 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.
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Analysis of Induced Seismicity in geothermal reservoirs - An overview
Geothermics, 2014Co-Authors: Arno Zang, Roland Gritto, Volker Oye, Nicholas Deichmann, Philippe Jousset, Ernest L. Majer, Art Mcgarr, Dan BruhnAbstract: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 b-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 P-wave (Vp) and S-wave velocity (Vs) 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 (Vp/. Vs). 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. © 2014 Elsevier Ltd.
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protocol for addressing Induced Seismicity associated with enhanced geothermal systems
2012Co-Authors: Ernest L. Majer, Jim Nelson, Ann Robertsontait, Jean Savy, Ivan G WongAbstract:This Protocol is a living guidance document for geothermal developers, public officials, regulators and the general public that provides a set of general guidelines detailing useful steps to evaluate and manage the effects of Induced Seismicity related to EGS projects.
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Induced Seismicity associated with enhanced geothermal systems
Geothermics, 2007Co-Authors: Ernest L. Majer, Mitch Stark, Julian Bommer, Bill Smith, S. Oates, Roy Baria, Hiroshi AsanumaAbstract:Enhanced Geothermal Systems (EGS) offer the potential to significantly add to the world energy inventory. As with any development of new technology, some aspects of the technology has been accepted by the general public, but some have not yet been accepted and await further clarification before such acceptance is possible. One of the issues associated with EGS is the role of microSeismicity during the creation of the underground reservoir and the subsequent extraction of the energy. The primary objectives of this white paper are to present an up-to-date review of the state of knowledge about Induced Seismicity during the creation and operation of enhanced geothermal systems, and to point out the gaps in knowledge that if addressed will allow an improved understanding of the mechanisms generating the events as well as serve as a basis to develop successful protocols for monitoring and addressing community issues associated with such Induced Seismicity. The information was collected though literature searches as well as convening three workshops to gather information from a wide audience. Although microSeismicity has been associated with the development of production and injection operations in a variety of geothermal regions, there have been no or few adverse physical effects on the operations or on surrounding communities. Still, there is public concern over the possible amount and magnitude of the Seismicity associated with current and future EGS operations. It is pointed out that microSeismicity has been successfully dealt with in a variety of non-geothermal as well as geothermal environments. Several case histories are also presented to illustrate a variety of technical and public acceptance issues. It is concluded that EGS Induced Seismicity need not pose any threat to the development of geothermal resources if community issues are properly handled. In fact, Induced Seismicity provides benefits because it can be used as a monitoring tool to understand the effectiveness of the EGS operations and shed light on the mechanics of the reservoir.
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Induced Seismicity associated with Enhanced Geothermal Systems
Geothermics, 2007Co-Authors: Ernest L. Majer, Mitch Stark, Julian Bommer, Bill Smith, S. Oates, Roy Baria, Hiroshi AsanumaAbstract:Enhanced Geothermal Systems (EGS) have the potential to make a significant contribution to the world energy inventory. One controversial issue associated with EGS, however, is the impact of Induced Seismicity or microSeismicity, which has been the cause of delays and threatened cancellation of at least two EGS projects worldwide. Although microSeismicity has in fact had few (or no) adverse physical effects on operations or on surrounding communities, there remains public concern over the amount and magnitude of the Seismicity associated with current and future EGS operations. The primary objectives of this paper are to present an up-to-date review of what is already known about the Seismicity Induced during the creation and operation of EGS, and of the gaps in our knowledge that, once addressed, should lead to an improved understanding of the mechanisms generating the events. Several case histories also illustrate a number of technical and public acceptance issues. We conclude that EGS-Induced Seismicity need not pose a threat to the development of geothermal energy resources if site selection is carried out properly, community issues are handled adequately and operators understand the underlying mechanisms causing the events. Induced Seismicity could indeed prove beneficial, in that it can be used to monitor the effectiveness of EGS operations and shed light on geothermal reservoir processes. © 2007 CNR.
Jean Schmittbuhl - One of the best experts on this subject based on the ideXlab platform.
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Induced Seismicity in EGS reservoir: the creep route
Geothermal Energy, 2014Co-Authors: Jean Schmittbuhl, Nicolas Cuenot, François Cornet, Olivier Lengliné, Albert GenterAbstract: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. We base our approach on the case study of the EGS site of Soultz-sous-Forets 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. 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. 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.
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Induced Seismicity in EGS reservoir: the creep route
Geothermal Energy, 2014Co-Authors: Jean Schmittbuhl, Nicolas Cuenot, Olivier Lengliné, François Cornet, Albert GenterAbstract:Observations in EGS reservoirs of Induced Seismicity and slow aseismic slip ruptures on related faults suggest a close link between the two phenomena. 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. 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. We conclude that aseismic processes might drive Seismicity beside classical effects related to fluid pressure and show that a creep route for Induced Seismicity is possible.
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Self-Induced Seismicity due to fluid circulation along faults
Geophysical Journal International, 2014Co-Authors: Hideo Aochi, Xavier Rachez, B. Poisson, Roger Toussaint, Jean SchmittbuhlAbstract:In this article, we develop a system of equations describing fluid migration, fault rheology, fault thickness evolution and shear rupture during a seismic cycle, triggered either by tectonic loading or by fluid injection. Assuming that the phenomena predominantly take place on a single fault described as a finite permeable zone of variable width, we are able to project the equations within the volumetric fault core onto the 2D fault interface. From the basis of this “fault lubrication approximation”, we simulate the evolution of Seismicity when fluid is injected at one point along the fault to model Induced Seismicity during an injection test in a borehole that intercepts the fault. We perform several parametric studies to understand the basic behaviour of the system. Fluid transmissivity and fault rheology are key elements. The simulated Seismicity generally tends to rapidly evolve after triggering, independently of the injection history and end when the stationary path of fluid flow is established at the outer boundary of the model. This self-Induced Seismicity takes place in the case where shear rupturing on a planar fault becomes dominant over the fluid migration process. On the contrary, if healing processes take place, so that the fluid mass is trapped along the fault, rupturing occurs continuously during the injection period. Seismicity and fluid 2 migration are strongly influenced by the injection rate and the heterogeneity.
W. Foxall - One of the best experts on this subject based on the ideXlab platform.
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Induced Seismicity and Carbon Storage: Risk Assessment and Mitigation Strategies
2020Co-Authors: Joshua A. White, Thomas M. Daley, W. Foxall, C. E. Bachmann, Laura ChiaramonteAbstract:1 1. INTRODUCTION 2 2. SCIENTIFIC AND TECHNICAL BACKGROUND 5 2.1 BASIC Seismicity CONCERNS 5 2.2 EVENT CHAIN VIEW OF SEISMIC IMPACTS 9 2.3 SITE CHARACTERISTICS 10 2.4 SEISMIC MONITORING 17 2.5 EARTHQUAKE STATISTICS 22 3. RISK MANAGEMENT FOR Induced Seismicity 26 3.1 A PHASED APPROACH TO RISK ASSESSMENT 26 3.2 PROBABILISTIC SEISMIC RISK ASSESSMENT 29 3.3 PROBABILISTIC LEAKAGE RISK ASSESSMENT 38 4. RECOMMENDATIONS 41 5. REFERENCES 44 Induced Seismicity and Carbon Storage: Risk Assessment and Mitigation Strategies
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assessing Induced Seismicity risk at co2 storage projects recent progress and remaining challenges
International Journal of Greenhouse Gas Control, 2016Co-Authors: Joshua A. White, W. FoxallAbstract:It is well established that fluid injection has the potential to induce earthquakes—from microSeismicity to magnitude 5+ events—by altering state-of-stress conditions in the subsurface. This paper reviews recent lessons learned regarding Induced Seismicity at carbon storage sites. While similar to other subsurface injection practices, CO2 injection has distinctive features that should be included in a discussion of its seismic hazard. Induced events have been observed at CO2 injection projects, though to date it has not been a major operational issue. Nevertheless, the hazard exists and experience with this issue will likely grow as new storage operations come online. This review paper focuses on specific technical difficulties that can limit the effectiveness of current risk assessment and risk management approaches, and highlights recent research aimed at overcoming them. These challenges form the heart of the Induced Seismicity problem, and novel solutions to them will advance our ability to responsibly deploy large-scale CO2 storage.