A Prospective Evaluation of Borehole Distributed Acoustic Sensing Technologies for Detecting and Locating Out‐of‐Network Microseismicity
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Date
2024-12-09
Publication Type
Book Chapter
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yes
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Abstract
Downhole distributed acoustic sensing (DAS) has proven effective in monitoring microseismicity produced during hydraulic stimulations. It is also a promising tool for monitoring microseismicity occurring beyond the stimulation region. Downhole DAS arrays exhibit reduced sensitivity to surface noise compared to surface deployments, and they can remain in place undisturbed after operations cease, unlike downhole geophones. Identifying and locating microseismicity occurring at remote distances is crucial for reservoir monitoring, allowing us to assess stress conditions and the presence of pre-existing faults. Here, we evaluate the potential of downhole DAS in detecting and locating out-of-network microseismicity through two case studies: a field-scale investigation at the Frontier Observatory for Research in Geothermal Energy (FORGE) site in Utah and a mesoscale experiment in the Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG) in Switzerland. We demonstrate that DAS data have sufficient quality to detect and locate low-magnitude earthquakes (M < 0) occurring several hundred meters away. However, azimuthal ambiguity is unavoidable when only a single vertical borehole is available. We show that DAS signal characteristics and location capabilities perform equally at different scales, ranging from full-reservoir scale to mesoscale. Our evaluation supports the employment of longer-term experiments to explore downhole DAS suitability for passive microseismic monitoring.
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Publication status
published
Book title
Distributed Acoustic Sensing in Borehole Geophysics
Journal / series
Geophysical Monograph Series
Volume
289
Pages / Article No.
311 - 329
Publisher
American Geophysical Union
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Software
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Subject
Downhole Distributed Acoustic Sensing (DAS); Microseismicity Monitoring; out-of-network earthquake location
Organisational unit
03476 - Giardini, Domenico / Giardini, Domenico