Abstract
Low-velocity zones located deep in the subsurface can act as seismic waveguides. Traditionally, their experimental observation has been limited by the practical challenges of in situ recording. We use a measurement technique in which optical fibers are turned into seismic sensors. The fiber is deployed along a horizontal well drilled inside a 15-m-thin shale formation at a depth of about 2 km. Owing to the high-resolution recording of the optical fiber, we can distinctly observe three previously elusive guided wave modes over a wide frequency range. As their propagation is primarily confined to the waveguide and strongly depends on its seismic properties, such guided waves hold tremendous potential for high-resolution imaging of deep low-velocity structures, such as fault zones, saline aquifers, and hydrocarbon reservoirs.
- Received 15 September 2020
- Accepted 4 February 2021
DOI:https://doi.org/10.1103/PhysRevResearch.3.013164
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society