Seismic monitoring for Geothermal (EGS) in Finland • ASIR Seismic

As an example of the range of its current capabilities, ASIR was selected to fabricate, install, maintain, and support the advanced seismic monitoring system for an Enhanced Geothermal System (EGS) in Espoo, Finland.

This selection was in part based on our previous successful installation and monitoring of the Basel Engineered Geothermal System effort. Our accurate monitoring of induced-earthquakes there helped to legally establish that a Traffic Light System (TLS) limit-exceeding earthquake had taken place. Our monitoring of the Helsinki EGS helped the ST1 Deep Heat operating company avoid exceeding the local TLS for this project. ST1 Deep Heat contracted installation included a 25-level 3-component digital seismic array for the 2000 m deep OTN-I, a second 12 level, 2200-2600 m deep borehole array, plus a 12-station satellite-network of 350-1140 m deep borehole 3-component sensors (AG4.5). Data from these networks are continuously telemetered to an ASIR developed and operated central recording facility. Data from these installations are analyzed with fastloc.reel and other software for the detection and interpretation of a full range of induced earthquake events. ASIR staff are also providing both short courses and onsite-training to its Helsinki-based customer.

Aerial view of the project site in Otaniemi, Espoo. (Source: st1)

Aerial view of the project site in Otaniemi, Espoo. (Source: st1)

Schematic view of the project site (from Kwiatek et al., 2019)

Locations of seismic and ground motion monitoring equipment (Source: st1)

ASIR borehole station — Seismic borehole station in Tapiola with an AG4.5 sonde installed at ~300m depth

ASIR seismic borehole station — Seismic borehole station ELFV with an AG4.5 sonde installed at ~300m depth

Seismic Traffic Light System (TLS) implemented for hydraulic stimulation

Example of fastloc.REEL dashboard showing near-real time seismic events

Seismicity during different stages (1-5) of hydraulic stimulation over a period of 49 days (from Kwiatek et al., 2019)

Seismic event recorded by 12-level array installed at a depth of 2.2 - 2.6 km in OTN-2 well close to the stimulation well

Small ML0.5 earthquake recorded by 12 seismic stations equipped with our AG4.5 sondes across Espoo and Helsinki

Small ML0.8 earthquake recorded by 12 seismic stations equipped with our AG4.5 sondes across Espoo and Helsinki

For further information and background on this project, please visit st1 Deep Heat and related Wikipedia page.

PUBLICATIONS

Hillers, G., Vuorinen, T., Uski, M., Kortström, J., Mäntyniemi, P., Tiira, T., Malin, P., Saarno, T.: The 2018 Geothermal Reservoir Stimulation in Espoo/Helsinki, Southern Finland: Seismic Network Anatomy and Data Features. Seismological Research Letters; 91 (2A): 770–786 (2020)

Ader, T., Chendorain, M., Free, M., Saarno, T., Heikkinen, P., Malin, P., Leary, P., Kwiatek, G., Dresen, G., Blümle, F., Vuorinen, T.: Design and implementation of a traffic light system for deep geothermal well stimulation in Finland. Journal of Seismology (2019)

Kwiatek, G., Saarno, T., Ader, T., Blümle, F., Bohnhoff, M., Chendorain, M., Dresen, G., Heikkinen, P., Kukkonen, I., Leary, P., Leonhardt, M., Malin, P., Martínez-Garzón, P., Passmore, K, Passmore, P., Valenzuela, S., Wollin, C.: Controlling fluid-induced seismicity during a 6.1- km-deep geothermal stimulation in Finland. Science Advances, 5 (5) (2019)

Malin, P., Kwiatek, G., Dresen, G., Saarno, T.: Near-realtime management of induced seismicity during an EGS stimulation. SEG Technical Program Expanded Abstracts: 2079-2083 (2019)

Leary, P., Malin, P., Saarno, T. Kukkonen, I.: Prospects for Assessing Enhanced Geothermal System (EGS) Basement Rock Flow Stimulation by Wellbore Temperature Data. Energies, 10, 1979 (2017)

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