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Induced Seismicity and Its Implications for Co2 Storage Risk

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Induced Seismicity and Its Implications for Co2 Storage Risk INDUCED SEISMICITY AND ITS IMPLICATIONS FOR CO2 STORAGE RISK Report: 2013/09 June 2013 INTERNATIONAL ENERGY AGENCY The International Energy Agency (IEA) was established in 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. The IEA fosters co-operation amongst its 28 member countries and the European Commission, and with the other countries, in order to increase energy security by improved efficiency of energy use, development of alternative energy sources and research, development and demonstration on matters of energy supply and use. This is achieved through a series of collaborative activities, organised under more than 40 Implementing Agreements. These agreements cover more than 200 individual items of research, development and demonstration. IEAGHG is one of these Implementing Agreements. DISCLAIMER This report was prepared as an account of the work sponsored by IEAGHG. The views and opinions of the authors expressed herein do not necessarily reflect those of the IEAGHG, its members, the International Energy Agency, the organisations listed below, nor any employee or persons acting on behalf of any of them. In addition, none of these make any warranty, express or implied, assumes any liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product of process disclosed or represents that its use would not infringe privately owned rights, including any parties intellectual property rights. Reference herein to any commercial product, process, service or trade name, trade mark or manufacturer does not necessarily constitute or imply any endorsement, recommendation or any favouring of such products. COPYRIGHT Copyright © IEA Environmental Projects Ltd. (IEAGHG) 2013. All rights reserved. ACKNOWLEDGEMENTS AND CITATIONS This report describes research sponsored by IEAGHG. This report was prepared by: CO2CRC The principal researchers were: • M. Gerstenberger, GNS Science • A. Nicol, GNS Science • C. Bromley, GNS Science • R. Carne, GNS Science • L. Chardot, GNS Science • S. Ellis, GNS Science • C. Jenkins, CSIRO • T. Siggins, CSIRO • E. Tenthorey, Geoscience Australia • P. Viskovic, GNS Science To ensure the quality and technical integrity of the research undertaken by IEAGHG each study is managed by an appointed IEAGHG manager. The report is also reviewed by a panel of independent technical experts before its release. The IEAGHG manager for this report was: Millie Basava-Reddi The expert reviewers for this report were: • Sue Hovorka, University of Texas • Mike Godec, ARI • Stefan Baisch, QCon • Tom Daley, LBNL • Steve Whittaker, Global CCS Institute • Gunter Siddiqi, Swiss Federal Office of Energy • Malcolm Wilson, PTRC • Hubert Fabriol, BRGM • David Lumley, University of Western Australia • Dave Ryan, NRCan The report should be cited in literature as follows: ‘IEAGHG, Induced Seismicity and its Implication for CO2 Storage Risk, 2013/09, June 2013.’ Further information or copies of the report can be obtained by contacting IEAGHG at: IEAGHG, Orchard Business Centre, Stoke Orchard, Cheltenham, GLOS., GL52 7RZ, UK Tel: +44(0) 1242 680753 Fax: +44 (0)1242 680758 E-mail: [email protected] Internet: www.ieaghg.org INDUCED SEISMICITY AND ITS IMPLICATIONS FOR CO2 STORAGE RISK Key Messages • The risks associated with induced seismicity at CCS sites can be reduced and mitigated using a systematic and structured risk management programme. • Statistical models presently show the most promise for forecasting seismicity, but improved physical models are under development and may be key in the future. Both types will need to be tailored to the injection site. • Site performance and management guidelines should be established prior to injection to facilitate: 1) definition of the acceptable levels and impacts of induced seismicity; 2) optimisation of the monitoring and mitigation programmes; and 3) the establishing of key control measures. Such guidelines have been developed for Enhanced Geothermal Systems and should provide the starting point for a management strategy of induced seismicity at CCS sites. Background to the Study Induced seismicity refers to seismicity caused by human/external activity above natural background levels in a given tectonic setting and is distinguished from triggered seismicity, where human activity affects earthquake recurrence intervals, magnitude or other attributes. The physics of triggered and induced seismicity is thought to be identical and both need to be considered during geological storage of CO2. Induced seismicity may be observed during impounding of dams, mining and tunnelling operations, quarrying, underground solids/cuttings disposal, waste fluids disposal, oil and gas production, geothermal energy production and geological storage of gases and occasionally by rainfall. In some cases induced seismicity has led to projects being suspended, for example enhanced geothermal activities in Basel, Switzerland. Injection and consequent geological storage of CO2 may affect subsurface stress and alter in- situ fluid pressure and hence potentially induce seismicity. It is necessary to evaluate potential for and effects of induced seismicity during risk assessment of storage projects. A best practice approach has already been proposed by the US WESTCARB Partnership based on protocols related to geothermal activities. Induced seismicity may be caused by mechanical loads which can cause changes to the stress regime. Fluid pressures also play a key role in seismicity as pore pressures act against gravitational and tectonic forces and, if increased sufficiently, may cause rock failure. Pre- existing fractures may be stable in the stress regime before fluid injection, but fluid injection increases the pore pressure, which acts in opposition to the normal stress. If pore pressure is great enough to overcome the normal stress, then shear failure will occur. Other factors that may affect seismicity are thermal and chemical stresses, which can have a weakening effect on the rock. This is likely in geothermal reservoirs, though usually occurs in conjunction with seismicity caused by changes in fluid pressure. Induced seismicity can also be associated with hydraulic fracturing; this is when a rock is purposefully fractured by injecting water at high pressure with an aim to increase permeability. This has been observed during enhanced geothermal activities and in shale gas production. Learnings from induced seismicity in other areas, e.g. geothermal activities and hydrocarbon exploration may be applied, but differences with CCS need to be taken into account; such as depth differences, type of sediment into which injection will take place, tectonic activity in the area, injection pressure, volume injected and the length of injection. These values will, for example be very different from those for enhanced geothermal activity which will likely be deeper, into basement rock, possibly in a tectonic area with higher injection pressures for short bursts. Induced seismicity will also depend on several other factors, which may include the stress regime, fault orientation and locations, and rock friction. It is necessary that site characterisation takes into account any potential for induced seismicity; however, as more information becomes available during the lifetime of the project, through the monitoring programme, the risk in regards to induced seismicity can be reassessed. This may be in the form of real-time monitoring of any ongoing induced seismicity. CO2CRC, a consortium based in Australia and New Zealand, was commissioned by IEAGHG to undertake this study. Scope of Work This study would provide a review of the mechanisms that cause induced seismicity and their application to geological storage of CO2. The study would involve a detailed literature review of recent and ongoing research in this topic and an analysis drawn from the findings. Importantly, the study would focus on induced seismicity that may be caused by CO2 injection and storage. Owing to the paucity of large scale CO2 storage projects, it may be necessary to use findings from analogues (for example, steam assisted gravity drainage of heavy oil, cyclic steam stimulation in heavy oil recovery or produced water re-injection (also at hydraulic fracturing conditions) in oil and gas field operations). Particular issues to be considered and reviewed by the study include: Weaknesses and threats to storage projects: • Mechanisms that could potentially cause induced seismicity during injection and storage of CO2 and the scale of the effect. • Possible negative impacts on parameters associated with injection and storage, such as maximum injection pressure. Strengths and Opportunities for storage projects: • Increase in storage capacity owing to microseismic activity • Monitoring of reservoir behaviour (caprock integrity) and displacement phenomena General Overview of Risk Management Concepts (HSE Management): • Hazards, threats, top events and consequences associated with induced seismicity • Any preventative and recovery measures that may be taken The study aims to highlight the current state of knowledge, to recommend further research priorities on these topics, and establish links and best practice sharing where applicable in other subsurface operations. The contractor was referred to the following recent IEAGHG reports relevant to this study, to avoid obvious duplication of effort and to ensure that the reports issued by the programme
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