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Towards Inversion of the Microseismic Moment Tensor With DAS: Application to Boreholes

We present preliminary results on a workflow for moment tensor inversion with Distributed Acoustic Sensing (DAS) data. It makes use of a fast-marching Eikonal solver and synthetically modeled data. This study focuses on borehole settings for geothermal sites, specifically in the Utah FORGE geothermal test site. The DAS measurement captures the wavefield with high spatial and temporal resolution. On the one hand, in borehole settings, individual DAS traces generally prove to be noisier than co-located geophones. On the other hand, the densely spaced DAS shot-gathers show features that would have otherwise been missed by the commonly more sparsely distributed geophone chains. The high coherency and detail in DAS data can therefore help to constrain the moment tensor of the microseismic source. The synthetic tests focus on different source types and positions relative to the deployed fiber to assess the resolvability of the moment tensor. Further tests include the addition of a three-component seismometer at different positions to investigate an optimal network configuration, as well as various noise conditions to mimic real data. The synthetic tests are done as preparation for data from future microseismicity monitoring in enhanced geothermal projects as part of the EU-funded DEEP project (De-risking Enhanced geothermal Energy Projects). The proposed method aims at improving amplitude-based moment tensor inversion for DAS deployed in downhole or underground lab contexts.

Session: Fiber Optic Seismology: Understanding Earth Structure and Dynamics with Distributed Sensors [Poster]

Type: Poster

Room: Evergreen Ballroom

Date: 4/21/2022

Presentation Time: 08:00 AM Pacific

Presenting Author: Katinka B. Tuinstra

Student Presenter: Yes

Additional Authors