eprintid: 1793 rev_number: 23 eprint_status: archive userid: 6 dir: disk0/00/00/17/93 datestamp: 2017-01-03 12:06:55 lastmod: 2019-02-06 09:44:36 status_changed: 2017-01-03 12:06:55 type: article metadata_visibility: show creators_name: Zang, Arno creators_name: Oye, Volker creators_name: Jousset, Philippe creators_name: Deichmann, Nicholas creators_name: Gritto, Roland creators_name: McGarr, Arthur F. creators_name: Majer, Ernest L. creators_name: Bruhn, David corp_creators: German Research Center for Geosciences (GFZ),Germany corp_creators: NORSAR, P.O., Norway corp_creators: GFZ, International Center for Geothermal Research, Germany corp_creators: Swiss Seismological Service, ETH Zürich, Switzerland corp_creators: Array Information Technology, USA corp_creators: U.S. Geological Survey, USA corp_creators: Lawrence Berkeley National Laboratory, Berkeley, USA corp_creators: GFZ, International Center for Geothermal Research,Germany title: Analysis of induced seismicity in geothermal reservoirs – An overview subjects: MP2 subjects: MP4 subjects: RA subjects: RF1 subjects: RG2 subjects: RN subjects: RS1 subjects: RSS1 subjects: RU1_1 subjects: RUK subjects: SG divisions: EPOS-ESI2 divisions: IP4 divisions: SHEER-5 full_text_status: none keywords: Fluid-induced seismicity; Key reservoir parameters; Enhanced geothermal systems; Larger magnitude events; Maximum observed magnitude; Crustal stress abstract: 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. date: 2014 date_type: published publication: Geothermics volume: 52 publisher: Elsevier Science pagerange: 6-21 id_number: doi:10.1016/j.geothermics.2014.06.005 issn: 0375-6505 official_url: http://doi.org/10.1016/j.geothermics.2014.06.005 access_IS-EPOS: limited owner: Publisher citation: Zang, Arno and Oye, Volker and Jousset, Philippe and Deichmann, Nicholas and Gritto, Roland and McGarr, Arthur F. and Majer, Ernest L. and Bruhn, David (2014) Analysis of induced seismicity in geothermal reservoirs – An overview. Geothermics, 52. pp. 6-21. DOI: https://doi.org/10.1016/j.geothermics.2014.06.005