Using Dark Fiber and Distributed Acoustic Sensing to Characterize a Geothermal System in the Imperial Valley, Southern California

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dc.citation.articleNumbere2022JB025240
dc.citation.issueNumber3
dc.citation.journalTitleJournal of Geophysical Research: Solid Earth
dc.citation.volumeNumber128
dc.contributor.authorCheng, Feng
dc.contributor.authorAjo-Franklin, Jonathan B.
dc.contributor.authorNayak, Avinash
dc.contributor.authorTribaldos, Veronica Rodriguez
dc.contributor.authorMellors, Robert
dc.contributor.authorDobson, Patrick
dc.contributor.authorTeam, the Imperial Valley Dark Fiber
dc.date.accessioned2023-04-25T14:47:41Z
dc.date.available2023-04-25T14:47:41Z
dc.date.issued2023
dc.description.abstractThe Imperial Valley, CA, is a tectonically active transtensional basin located south of the Salton Sea; the area hosts numerous geothermal fields, including significant hidden hydrothermal resources without surface manifestations. Development of inexpensive, rugged, and highly sensitive exploration techniques for undiscovered geothermal systems is critical for accelerating geothermal power deployment as well as unlocking a low-carbon energy future. We present a case study utilizing distributed acoustic sensing (DAS) and ambient noise interferometry for geothermal reservoir imaging, utilizing unlit fiber-optic telecommunication infrastructure (dark fiber). The study exploits two days of passive DAS data acquired in early November 2020 over a ∼28-km section of fiber from Calipatria, CA to Imperial, CA. We apply ambient noise interferometry to retrieve coherent signals from DAS records and develop a bin stacking technique to attenuate the effects from persistent localized noise sources and to enhance retrieval of coherent surface waves. As a result, we are able to obtain high-resolution two-dimensional (2D) S wave velocity (Vs) structure to 3 km depth, based on joint inversion of both the fundamental and higher overtones. We observe a previously unmapped high Vs and low Vp/Vs ratio feature beneath the Brawley geothermal system, which we interpret to be a zone of hydrothermal mineralization and lower porosity. This interpretation is consistent with a host of other measurements including surface heat flow, gravity anomalies, and available borehole wireline data. These results demonstrate the potential utility of DAS deployed on dark fiber for geothermal system exploration and characterization in the appropriate geological settings.
dc.identifier.citationCheng, Feng, Ajo-Franklin, Jonathan B., Nayak, Avinash, et al.. "Using Dark Fiber and Distributed Acoustic Sensing to Characterize a Geothermal System in the Imperial Valley, Southern California." <i>Journal of Geophysical Research: Solid Earth,</i> 128, no. 3 (2023) Wiley: https://doi.org/10.1029/2022JB025240.
dc.identifier.digital2023-Cheng
dc.identifier.doihttps://doi.org/10.1029/2022JB025240
dc.identifier.urihttps://hdl.handle.net/1911/114811
dc.language.isoeng
dc.publisherWiley
dc.rightsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
dc.rights.urihttps://creativecommons.org/licenses/by-nc/4.0/
dc.titleUsing Dark Fiber and Distributed Acoustic Sensing to Characterize a Geothermal System in the Imperial Valley, Southern California
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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