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Sci Adv. 2019 May 1;5(5):eaav7224. doi: 10.1126/sciadv.aav7224. eCollection 2019 May.

Controlling fluid-induced seismicity during a 6.1-km-deep geothermal stimulation in Finland.

Author information

1
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Section 4.2: Geomechanics and Scientific Drilling, Potsdam, Germany.
2
Free University Berlin, Berlin, Germany.
3
St1 Deep Heat Oy, Helsinki, Finland.
4
Arup, London, UK.
5
University of Potsdam, Potsdam, Germany.
6
Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland.
7
ASIR Advanced Seismic Instrumentation and Research, Dallas, TX, USA.

Abstract

We show that near-real-time seismic monitoring of fluid injection allowed control of induced earthquakes during the stimulation of a 6.1-km-deep geothermal well near Helsinki, Finland. A total of 18,160 m3 of fresh water was pumped into crystalline rocks over 49 days in June to July 2018. Seismic monitoring was performed with a 24-station borehole seismometer network. Using near-real-time information on induced-earthquake rates, locations, magnitudes, and evolution of seismic and hydraulic energy, pumping was either stopped or varied-in the latter case, between well-head pressures of 60 and 90 MPa and flow rates of 400 and 800 liters/min. This procedure avoided the nucleation of a project-stopping magnitude M W 2.0 induced earthquake, a limit set by local authorities. Our results suggest a possible physics-based approach to controlling stimulation-induced seismicity in geothermal projects.

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