A study of the geophysical response of distributed fibre optic acoustic sensors through laboratory‐scale experiments

Papp, B.; Donno, Daniela; Martin, James E.; Hartog, Arthur H.

doi:10.1111/1365-2478.12471

Cited by 48 publications

(39 citation statements)

References 23 publications

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“…Other experiments have found this transfer function to be linear for small strains [ Henault et al ., ]. Laboratory tests using interferometry has also shown that cable construction can affect the magnitude of strain transfer through FO cable [ Papp et al ., ]. Finally, it is possible that slippage of the FO cable between the flexible liner and the rock wall may have occurred.…”

Section: Discussionmentioning

confidence: 99%

Fracture hydromechanical response measured by fiber optic distributed acoustic sensing at milliHertz frequencies

Becker

Ciervo

Cole

et al. 2017

Geophysical Research Letters

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A new method of measuring dynamic strain in boreholes was used to record fracture displacement in response to head oscillation. Fiber optic distributed acoustic sensing (DAS) was used to measure strain at mHz frequencies, rather than the Hz to kHz frequencies typical for seismic and acoustic monitoring. Fiber optic cable was mechanically coupled to the wall of a borehole drilled into fractured crystalline bedrock. Oscillating hydraulic signals were applied at a companion borehole 30 m away. The DAS instrument measured fracture displacement at frequencies of less than 1 mHz and amplitudes of less than 1 nm, in response to fluid pressure changes of less 20 Pa (2 mm H2O). Displacement was linearly related to the log of effective stress, a relationship typically explained by the effect of self‐affine fracture roughness on fracture closure. These results imply that fracture roughness affects closure even when displacement is a million times smaller than the fracture aperture.

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Section: Discussionmentioning

confidence: 99%

Fracture hydromechanical response measured by fiber optic distributed acoustic sensing at milliHertz frequencies

Becker

Ciervo

Cole

et al. 2017

Geophysical Research Letters

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“…Laboratory investigations are beginning to provide a bottom-up understanding of how the isolated fiber-optic, or fiber cable package act as a sensing element (Becker et al, 2018;Papp et al, 2017). A few models have been proposed to upscale these results to seismic field data (Kuvshinov, 2016;Reinsch et al, 2017).…”

Section: Ground-to-fiber Strain Transfermentioning

confidence: 99%

On the Broadband Instrument Response of Fiber‐Optic DAS Arrays

2020

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Distributed Acoustic Sensing (DAS) is a novel tool in array seismology that measures the phase of backscattered laser pulses traveling in a fiber‐optic cable, and relates this measurement to the axial strain induced on the cable by a propagating seismic wavefield. Combining DAS with telecommunications optical fiber networks has begun to address a range of earth science questions where cost and field logistics have historically hindered observations. Unlike classic inertial seismometers, DAS instrument response is presently unquantified. This topic includes a variable sensing element—the fiber, including packaging and installation—which changes between experiments. Ignoring this element, one DAS record should approximate a fixed‐length strain gauge, which exactly measures Earth's motion down to quasi‐static frequencies relevant to geodesy. In this paper, we test this hypothesis using seismological observations of teleseismic earthquakes and microseism noise spanning the 1 to 120 s period range. We use a commercial DAS interrogator unit connected to an optical fiber previously used for telecommunication and a colocated broadband seismometer to estimate the DAS transfer function. We find a 1:1 correspondence with actual ground motion from 10–120 s. At shorter periods (1–10 s), DAS amplitude response is enhanced by 3–11 dB. Phase response is flat over this range of periods. We interpret the recovered DAS response function in terms of hypothesized fiber coupling and photonic effects. We propose this calibration methodology for future DAS experiments where seismic amplitude information is desired.

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“…Although distributed vibration measurements are found to respond well to small, dynamic strains even in loose-tube packages (Mullens et al, 2010;Strong et al, 2009), it should be noted that the distributed vibration measurement is in fact a measure of dynamic axial strain (Dean et al, 2015(Dean et al, , 2016. As a result, the measurement is insensitive (Papp et al, 2016) to compressional acoustic waves arriving at right angles from the fiber axis. Omnidirectional cables have been designed (Kuvshinov, 2016) and tested (Hornman et al, 2013), in which the fiber is wrapped helically around a central former, with the fiber segments being exposed roughly equally to components of the sound wave arriving from any direction.…”

Section: Development Of Bespoke Cables For Distributed Sensingmentioning

confidence: 98%

Advances in Distributed Fiber-Optic Sensing for Monitoring Marine Infrastructure, Measuring the Deep Ocean, and Quantifying the Risks Posed by Seafloor Hazards

Hartog¹,

Belal²,

Clare³

2018

mar technol soc j

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A study of the geophysical response of distributed fibre optic acoustic sensors through laboratory‐scale experiments

Abstract: International audienc

Cited by 48 publications

References 23 publications

Fracture hydromechanical response measured by fiber optic distributed acoustic sensing at milliHertz frequencies

Fracture hydromechanical response measured by fiber optic distributed acoustic sensing at milliHertz frequencies

On the Broadband Instrument Response of Fiber‐Optic DAS Arrays

Advances in Distributed Fiber-Optic Sensing for Monitoring Marine Infrastructure, Measuring the Deep Ocean, and Quantifying the Risks Posed by Seafloor Hazards

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