Towards real-time monitoring of induced microseismicity in enhanced geothermal systems

Shi, Peidong 2021. Towards real-time monitoring of induced microseismicity in enhanced geothermal systems. Presented at: 19th Swiss Geoscience Meeting, Geneva, Switzerland, 19-20 November 2021. p. 19.

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Abstract

In Enhanced Geothermal systems (EGS), real-time monitoring of the induced seismic events is crucial for assessing the stimulation effects as well as mitigating the induced seismic risk. Here we develop a new framework to detect micro-seismic events and simultaneously build earthquake catalogs directly from continuous seismic data. The new framework combines machine learning (ML) and waveform migration techniques (Grigoli et al. 2018), and harnesses the advantages provided by both methods. The proposed method does not require phase detection nor association, instead the probabilities of P- and S-phases generated by ML models are directly back-projected into the space and time domain to obtain source location and origin time. The automated nature and parallel efficiency make it capable of real-time monitoring. We present a real�data application to continuous data from the Hengill geothermal site in Iceland. To obtain accurate relative event locations, we further propose an innovative high-resolution earthquake relative relocation technique that makes use of the emergent Distributed Acoustic Sensing (DAS) sensors. In this new approach, we adapt the software package HADES (Grigoli et al. 2021) to work for the multitude of channels that DAS offers and compute the relative distance between clustered earthquakes from the S- and P-wave arrival time differences, leading to event locations in a relative frame. The correct orientation and position of seismic cluster are found by minimising the differences between observed and calculated S- and P-wave arrival times. Tests show that with a good estimate of the local velocity, the location and orientation of the seismic cluster can be retrieved. We will apply the proposed approaches to the data set from the Utah FORGE EGS site and test the real-time performance of induced seismicity monitoring during the upcoming enhanced geothermal stimulation. The developed methods and operational experience will offer a unique opportunity for testing an operational real-time seismic monitoring system in EGS and could have a profound impact on the geothermal energy exploitation in Switzerland

Item Type:	Conference or Workshop Item (Paper)
Status:	Unpublished
Related URLs:	https://geoscience-meeting.ch/sgm2021/
Last Modified:	27 Nov 2024 17:01
URI:	https://orca.cardiff.ac.uk/id/eprint/174089

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