Limited Earthquake Interaction During a Geothermal Hydraulic Stimulation in Helsinki, Finland
| Autor: | Kwiatek, Grzegorz, Martínez‐Garzón, Patricia, Davidsen, Jörn, Malin, Peter, Karjalainen, Aino, Bohnhoff, Marco, Dresen, Georg, 1 Section 4.2 Geomechanics and Scientific Drilling Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Potsdam Germany, 2 Complexity Science Group Department of Physics and Astronomy University of Calgary Calgary AB Canada, 4 ASIR Advanced Seismic Instrumentation and Research Dallas TX USA, 5 St1 Oy Helsinki Finland |
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| Rok vydání: | 2022 |
| Předmět: |
hydraulic stimulation
Poissonian distribution ddc:551.22 magnitude correlations earthquake clustering Geophysics Space and Planetary Science Geochemistry and Petrology earthquake interactions Earth and Planetary Sciences (miscellaneous) 500 Naturwissenschaften und Mathematik::550 Geowissenschaften Geologie::550 Geowissenschaften interevent times induced seismicity |
| Zdroj: | Journal of Geophysical Research: Solid Earth |
| DOI: | 10.17169/refubium-36554 |
| Popis: | We investigate induced seismicity associated with a hydraulic stimulation campaign performed in 2020 in the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland as part of the St1 Deep Heat project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures −1.9 ${M}_{\mathrm{L}}^{\mathrm{H}\mathrm{e}\mathrm{l}} > -1.9$ were recorded during and after the stimulation campaign. The analyzed statistical parameters include magnitude‐frequency b‐value, interevent time and interevent time ratio, as well as magnitude correlations. We find that the b‐value remained stationary for the entire injection period suggesting limited stress build‐up or limited fracture network coalescence in the reservoir. The seismicity during the stimulation neither shows signatures of magnitude correlations, nor temporal clustering or anticlustering beyond those arising from varying injection rates. The interevent time statistics are characterized by a Poissonian time‐varying distribution. The calculated parameters indicate no earthquake interaction. Focal mechanisms suggest that the injection activated a spatially distributed network of similarly oriented fractures. The seismicity displays stable behavior with no signatures pointing toward a runaway event. The cumulative seismic moment is proportional to the cumulative hydraulic energy and the maximum magnitude is controlled by injection rate. The performed study provides a base for implementation of time‐dependent probabilistic seismic hazard assessment for the project site. Plain Language Summary: We investigate anthropogenic seismicity associated with fluid injection into the 5.8 km deep geothermal OTN‐2 well near Helsinki, Finland, as a part of St1 Deep Heat Project. A total of 2,875 m3 of fresh water was injected during 16 days at well‐head pressures Key Points: Induced seismicity associated with stimulation campaign in a 5.8 km deep geothermal OTN‐2 well passively responds to injection operations. Seismicity is a non‐stationary Poisson process with seismicity rate and maximum magnitude modulated by the hydraulic energy input rate. Seismicity clusters in space and time in response to fluid injection but no interaction between earthquakes is observed. Helmholtz Association http://dx.doi.org/10.13039/501100009318 https://doi.org/10.5880/GFZ.4.2.2022.001 |
| Databáze: | OpenAIRE |
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