Characterizing Geothermal Systems in California’s Imperial Valley Using Low-Frequency Passive Seismic Data Recorded Using Distributed Acoustic Sensing (DAS) Deployed on Dark Fiber
Session: Fiber-Optic Seismology II [Poster]
Type: Poster
Date: 4/23/2021
Presentation Time: 03:45 PM Pacific
Description:
Characterization of basins associated with geothermal systems is critical to understanding the availability of geothermal resources. However, large portions of these basins remain poorly understood, especially regarding buried structures that may control fluid flow. One of the main reasons is the difficulty of acquiring high-resolution geophysical data at regional scale, including high costs of active seismic surveys and long-term deployments, and limited coverage of dense arrays. These issues decrease understanding of relevant regional structures and can lead to missed geothermal resources.
Here, we explore the use of Distributed Acoustic Sensing (DAS) deployed on existing, unused telecommunication fiber-optic cables (dark fibers) to seismically characterize subsurface structures associated with geothermal systems. DAS enables acquisition of seismic data along a single fiber out to 10’s of km at spatial densities of a few meters. Using dark fibers provides a cost-effective way of acquiring regional, high-resolution data. We present preliminary results of a proof-of-concept study being conducted in the Imperial Valley, CA, which combines a complex geologic context with extensive and productive geothermal systems. In November 2020, a DAS system was deployed on a 25 km long dark fiber that traverses the northern portion of the valley between Calipatria and El Centro, crossing significant tectonically active areas and the eastern margin of the Brawley geothermal field. We investigate the feasibility of recording low-frequency (< 2 Hz) ambient seismic noise and teleseismic surface waves for seismic velocity imaging at depth. Microseismic noise from the Pacific Ocean, as well as possible seismic noise originating in the neighboring Salton Sea are explored. Observations are contrasted with seismic data from co-located and nearby broadband seismometers, and with local strain-meters. Our observations will shed light into the potential of using DAS and dark fiber for basin-scale, high-resolution characterization of deep structure and its utility as a tool for geothermal exploration.
Presenting Author: Verónica Rodríguez Tribaldos
Student Presenter: No
Authors
Verónica Rodríguez Tribaldos Presenting Author Corresponding Author vrodrigueztribaldos@lbl.gov Lawrence Berkeley National Laboratory |
Feng Cheng marscfeng@rice.edu Rice University |
Avinash Nayak anayak7@lbl.gov Lawrence Berkeley National Laboratory |
Todd Wood tjwood@lbl.gov Lawrence Berkeley National Laboratory |
Michelle Robertson mcrobertson@lbl.gov Lawrence Berkeley National Laboratory |
Robert Mellors rmellors@ucsd.edu University of California, San Diego |
Patrick Dobson pfdobson@lbl.gov Lawrence Berkeley National Laboratory |
Jonathan Ajo-Franklin ja62@rice.edu Rice University |
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Characterizing Geothermal Systems in California’s Imperial Valley Using Low-Frequency Passive Seismic Data Recorded Using Distributed Acoustic Sensing (DAS) Deployed on Dark Fiber
Category
Fiber-optic Seismology