EGS Collab Experiment 2: Distributed Fiber Optic Acoustic Data (DAS)

Distributed fiber optic sensing was an important part of the monitoring system for EGS Collab Experiment #2. A single loop of custom fiber package was grouted into the four monitoring boreholes that bracketed the experiment volume. This fiber package contained two multi-mode fibers and four single-mode fibers. These fibers were connected to an array of fiber optic interrogator units, each targeting a different measurement.

The distributed acoustic systems (DAS) included one Silixa iDAS unit, one Terra15 Treble unit, and one Optasense ODH3 unit. Each interrogator was connected to both ends of one of the four single-mode fibers. Each interrogator functions in a slightly different way and recorded at a different sampling rate, but all are essentially recording strain rate along the fiber. This dataset includes raw data in the native format of each interrogator, organized by instrument name and timestamp. A formal report describing the data collection and file structures is in progress and will be provided here when complete. In the meantime, important metadata can be found embedded in the HDF5 and TDMS files themselves. That is, the files (namely from the iDAS and Optasense interrogators) include useful fields like sampling rate, pulse width, raw data units, and so forth.