Seismic Response of Hectometer-Scale Fracture Systems to Hydraulic Stimulation in the Bedretto Underground Laboratory, Switzerland
OPEN ACCESS
Loading...
Author / Producer
Date
2024-11
Publication Type
Journal Article
ETH Bibliography
yes
OPEN ACCESS
Data
Abstract
We performed a series of hydraulic stimulations at 1.1 km depth in the Bedretto underground laboratory, Switzerland, as part of an overall research strategy attempting to understand induced seismicity on different scales. Using an ultra-high frequency seismic network we detect seismic events as small as Mw < −4, revealing intricate details of a complex fracture network extending over 100 m from the injection sites. Here, we outline the experimental approach and present seismic catalogs as well as a comparative analysis of event number per injection, magnitudes, b-values, seismogenic index and reactivation pressures. In our first-order seismicity analysis, we could make the following observations: The rock volume impacted by the stimulations in different intervals differs significantly with a lateral extent from a few meters to more than 150 m. In most intervals multiple fractures were reactivated. The seismicity typically propagates upwards toward shallower depth on parallel oriented planes that are consistent with the stress field and seem to a large extent associated with preexisting open fractures. This experiment confirms the diversity in seismic behavior independent from the injection protocol. The overall seismicity patterns demonstrate that multi-stage stimulations using zonal isolation allow developing an extended fracture network in a 3D rock volume, which is necessary for enhanced geothermal systems. Our stimulations covering two orders of magnitude in terms of injected volume will give insights into upscaling of induced seismicity from underground laboratory scale to field scale.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
129 (11)
Pages / Article No.
Publisher
American Geophysical Union
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Organisational unit
09797 - Aaron, Jordan / Aaron, Jordan
03953 - Robertsson, Johan / Robertsson, Johan
02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)
03476 - Giardini, Domenico / Giardini, Domenico
02334 - BULGG - Bedretto Underground Lab / BULGG - Bedretto Underground Lab
Notes
Funding
189632 - Monitoring and scientific equipment for the Bedretto Deep Underground Laboratory for Geoenergies (SNF)
Related publications and datasets
Is compiled by: