Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation
In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The two week injection of water generated a high level of microseismic activity. About 90,000 microearthquakes were triggered during and after this fluid inj...
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| Format: | Technical Report |
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Massachusetts Institute of Technology. Earth Resources Laboratory
2012
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| Online Access: | http://hdl.handle.net/1721.1/67917 |
| _version_ | 1811068525664534528 |
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| author | Michelet, Sophie Toksoz, M. Nafi |
| author2 | Massachusetts Institute of Technology. Earth Resources Laboratory |
| author_facet | Massachusetts Institute of Technology. Earth Resources Laboratory Michelet, Sophie Toksoz, M. Nafi |
| author_sort | Michelet, Sophie |
| collection | MIT |
| description | In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The two week injection of water generated a high level of microseismic activity. About 90,000 microearthquakes were triggered during and after this fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and, ultimately, of the fracture network. The accuracy of these initial locations was around 70 meters, not sufficient to map detailed fracture patterns.
We undertook a relocation effort using two different techniques: Joint Hypocenter Determination (JHD) and Multiplet analysis. The JHD technique allows for the simultaneous location of a group of events and the determination of a common set of station corrections. We added the “collapsing” method to the JHD results to further consolidate the hypocenters. This was followed by a multiplet analysis for identifying microearthquakes with similar waveforms. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. For the relative location of the correlated events, we computed the delay in travel-time by wavelet analysis. We found that multiplets were located on small planes with lengths of a hundred to several hundred meters striking mostly along N150°E. Comparing the distribution of seismicity with fluid outflows during the fluid injection, we observed that majority of events were concentrated along the newly created fractures. |
| first_indexed | 2024-09-23T07:57:16Z |
| format | Technical Report |
| id | mit-1721.1/67917 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T07:57:16Z |
| publishDate | 2012 |
| publisher | Massachusetts Institute of Technology. Earth Resources Laboratory |
| record_format | dspace |
| spelling | mit-1721.1/679172019-04-09T15:43:11Z Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation Michelet, Sophie Toksoz, M. Nafi Massachusetts Institute of Technology. Earth Resources Laboratory Michelet, Sophie Toksoz, M. Nafi In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The two week injection of water generated a high level of microseismic activity. About 90,000 microearthquakes were triggered during and after this fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and, ultimately, of the fracture network. The accuracy of these initial locations was around 70 meters, not sufficient to map detailed fracture patterns. We undertook a relocation effort using two different techniques: Joint Hypocenter Determination (JHD) and Multiplet analysis. The JHD technique allows for the simultaneous location of a group of events and the determination of a common set of station corrections. We added the “collapsing” method to the JHD results to further consolidate the hypocenters. This was followed by a multiplet analysis for identifying microearthquakes with similar waveforms. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. For the relative location of the correlated events, we computed the delay in travel-time by wavelet analysis. We found that multiplets were located on small planes with lengths of a hundred to several hundred meters striking mostly along N150°E. Comparing the distribution of seismicity with fluid outflows during the fluid injection, we observed that majority of events were concentrated along the newly created fractures. Massachusetts Institute of Technology. Earth Resources Laboratory 2012-01-05T19:26:46Z 2012-01-05T19:26:46Z 2006 Technical Report http://hdl.handle.net/1721.1/67917 Earth Resources Laboratory Industry Consortia Annual Report;2006-05 application/pdf Massachusetts Institute of Technology. Earth Resources Laboratory |
| spellingShingle | Michelet, Sophie Toksoz, M. Nafi Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title | Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title_full | Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title_fullStr | Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title_full_unstemmed | Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title_short | Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation |
| title_sort | fracture mapping in the soultz sous forets geothermal field from microearthquake relocation |
| url | http://hdl.handle.net/1721.1/67917 |
| work_keys_str_mv | AT micheletsophie fracturemappinginthesoultzsousforetsgeothermalfieldfrommicroearthquakerelocation AT toksozmnafi fracturemappinginthesoultzsousforetsgeothermalfieldfrommicroearthquakerelocation |