Security monitoring of smart campus using distributed fiber optic acoustic sensing

Over the past 1-2 decades, seismological measurements have provided new and unique insights into glacier and ice sheet dynamics. At the same time, sensor coverage is typically limited in harsh glacial environments with littile or no access. Turning kilometer-long fiber optic cables placed on the Earth&#8217;s surface into thousands of seismic sensors, Distributed Acoustic Sensing (DAS) may overcome the limitation of sensor coverage in the cryosphere.First DAS applications on the Greenland and Antarctic ice sheets and on Alpine glacier ice have highlighted the technique&#8217;s superiority. Signals of natural and man-made seismic sources can be resolved with an unrivaled level of detail. This offers glaciologists new perspectives to interpret their seismograms in terms of ice structure, basal boundary conditions and source locations. However, previous studies employed only relatively small network scales with a point-like borehole deployment or < 1 km cable aperture at the ice surface.Here we present a DAS installation, which aims to cover the majority of an Alpine glacier catchment: For one month in summer 2020 we deployed a 9 km long fiber optic cable on Rhonegletscher, Switzerland, and gathered continuous DAS data. The cable followed the glacier&#8217;s central flow line starting in the lowest kilometer of the ablation zone and extending well into the accumulation area. Even for a relatively small mountain glacier such as Rhonegletscher, cable deployment was a considerable logistical challenge. However, initial data analysis illustrates the benefit compared to conventional cryoseismological instrumentation: DAS measurements capture ground deformation over many octaves, including typical high-frequency englacial sources (10s to 100s of Hz) related to crevasse formation and basal sliding as well as long period signals (10s to 100s of seconds) of ice deformation. Depending on the presence of a snow cover, DAS records contain strong environmental noise (wind, meltwater flow, precipitation) and thus exhibit lower signal-to-noise ratios compared to conventional on-ice seismic installations. This is nevertheless outweighed by the advantage of monitoring ground unrest and ice deformation of nearly an entire glacier. We present a first compilation of signal and noise records and discuss future directions to leverage DAS data sets in glaciological research.&#160;&#160;&#160;

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Investigation of the Effects of Surrounding Media on the Distributed Acoustic Sensing of Helically-Wound Fiber-Optic Cable with Application to the New Afton Deposit, British Columbia

10.5194/se-2020-197 ◽

2020 ◽

Author(s):

Sepidehalsadat Hendi ◽

Mostafa Gorjian ◽

Gilles Bellefleur ◽

Christopher D. Hawkes ◽

Don White

Keyword(s):

British Columbia ◽

Numerical Modeling ◽

Analytical Model ◽

Field Data ◽

Fiber Optic ◽

Incident Angle ◽

Acoustic Sensing ◽

Distributed Acoustic Sensing ◽

Straight Fiber

Abstract. Fiber optic sensing technology has recently become popular for oil and gas, mining, geotechnical engineering, and hydrogeology applications. With a successful track record in many applications, distributed acoustic sensing using straight fiber optic cables has become a method of choice for seismic studies. However, distributed acoustic sensing using straight fiber optic cables is not able to detect off-axial strain, hence a helically wound cable design was introduced to overcome this limitation. The helically wound cable field data in New Afton deposit showed that the quality of the data is tightly dependent on the incident angle (the angle between the ray and normal vector of the surface) and surrounding media. We introduce a new analytical two-dimensional approach to determine the dynamic strain of a helically wound cable in terms of incident angle in response to elastic plane waves propagating through multilayered media. The method can be used to quickly and efficiently assess the effects of various materials surrounding a helically wound cable. Results from the proposed analytical model are compared with results from numerical modeling obtained with COMSOL Multiphysics, for scenarios corresponding to a real installation of helically wound cable deployed underground at the New Afton mine in British Columbia, Canada. Results from the analytical model are consistent with numerical modeling results. Our modeling results demonstrate the effects of cement quality, and casing installment on the quality of the helically-wound cable response. Numerical modeling results and field data suggest that, even if reasonably effective coupling achieved, the soft nature of the rocks in these intervals would result in low fiber strains for the HWC. The proposed numerical modeling workflow would be applied for more complicated scenarios (e.g., non-linear material constitutive behaviour, and the effects of pore fluids). The results of this paper can be used as a guideline for analyzing the effect of surrounding media and incident angle on the response of helically wound cable, optimizing the installation of helically wound cable in various conditions, and to validate boundary conditions of 3-D numerical model built for analyzing complex scenarios.

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Detection of Leak-Induced Pipeline Vibrations Using Fiber—Optic Distributed Acoustic Sensing

Sensors ◽

10.3390/s18092841 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2841 ◽

Cited By ~ 14

Author(s):

Pavol Stajanca ◽

Sebastian Chruscicki ◽

Tobias Homann ◽

Stefan Seifert ◽

Dirk Schmidt ◽

...

Keyword(s):

Fiber Optic ◽

Broadband Noise ◽

Gas Pipeline ◽

Accelerometer Data ◽

Acoustic Sensing ◽

System Sensitivity ◽

Spectral Integration ◽

Detection Approach ◽

Distributed Acoustic Sensing ◽

Pipeline Vibration

In the presented work, the potential of fiber-optic distributed acoustic sensing (DAS) for detection of small gas pipeline leaks (<1%) is investigated. Helical wrapping of the sensing fiber directly around the pipeline is used to increase the system sensitivity for detection of weak leak-induced vibrations. DAS measurements are supplemented with reference accelerometer data to facilitate analysis and interpretation of recorded vibration signals. The results reveal that a DAS system using direct fiber application approach is capable of detecting pipeline natural vibrations excited by the broadband noise generated by the leaking medium. In the performed experiment, pipeline vibration modes with acceleration magnitudes down to single μg were detected. Simple leak detection approach based on spectral integration of time-averaged DAS signals in frequency domain was proposed. Potential benefits and limitations of the presented monitoring approach were discussed with respect to its practical applicability. We demonstrated that the approached is potentially capable of detection and localization of gas pipeline leaks with leak rates down to 0.1% of the pipeline flow volume and might be of interest for monitoring of short- and medium-length gas pipelines.

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Downhole Fiber-optic Distributed Acoustic Sensing for Seismic Imaging and Monitoring in Coal Mining: Case Study from Northern Shaanxi Province, China

10.3997/2214-4609.202070017 ◽

2020 ◽

Author(s):

W. Du ◽

S. Peng ◽

Q. Wu ◽

R. Pevzner ◽

O. Valishin ◽

...

Keyword(s):

Coal Mining ◽

Fiber Optic ◽

Seismic Imaging ◽

Shaanxi Province ◽

Acoustic Sensing ◽

Northern Shaanxi ◽

Distributed Acoustic Sensing

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Fiber-Optic Resonators for Strain-Acoustic Sensing and Chemical Spectroscopy

Springer Series in Optical Sciences - Cavity-Enhanced Spectroscopy and Sensing ◽

10.1007/978-3-642-40003-2_13 ◽

2014 ◽

pp. 463-484 ◽

Cited By ~ 1

Author(s):

Saverio Avino ◽

Antonio Giorgini ◽

Paolo De Natale ◽

Hans-Peter Loock ◽

Gianluca Gagliardi

Keyword(s):

Fiber Optic ◽

Acoustic Sensing

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Distributed fiber-optic acoustic sensing for petroleum geology exploration

Journal of Physics Conference Series ◽

10.1088/1742-6596/1065/25/252029 ◽

2018 ◽

Vol 1065 ◽

pp. 252029 ◽

Cited By ~ 3

Author(s):

Jiasheng Ni ◽

Chang Wang ◽

Ying Shang ◽

Xiaolei Zhang ◽

Yanjie Zhao

Keyword(s):

Fiber Optic ◽

Petroleum Geology ◽

Acoustic Sensing

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Localization of Transient Events Threatening Pipeline Integrity by Fiber-Optic Distributed Acoustic Sensing

Sensors ◽

10.3390/s19153322 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3322 ◽

Cited By ~ 2

Author(s):

Maria-Teresa Hussels ◽

Sebastian Chruscicki ◽

Detlef Arndt ◽

Swen Scheider ◽

Jens Prager ◽

...

Keyword(s):

Acoustic Waves ◽

Fiber Optic ◽

Optical Fiber Sensor ◽

Pressure Waves ◽

Fast Time ◽

Acoustic Sensing ◽

Damage Scenarios ◽

Pressure Transducers ◽

Transient Events ◽

Distributed Acoustic Sensing

Pipe integrity is a central concern regarding technical safety, availability, and environmental compliance of industrial plants and pipelines. A condition monitoring system that detects and localizes threats in pipes prior to occurrence of actual structural failure, e.g., leakages, especially needs to target transient events such as impacts on the pipe wall or pressure waves travelling through the medium. In the present work, it is shown that fiber-optic distributed acoustic sensing (DAS) in conjunction with a suitable application geometry of the optical fiber sensor allows to track propagating acoustic waves in the pipeline wall on a fast time-scale. Therefore, short impacts on the pipe may be localized with high fidelity. Moreover, different acoustic modes are identified, and their respective group velocities are in good agreement with theoretical predications. In another set of experiments modeling realistic damage scenarios, we demonstrate that pressure waves following explosions of different gas mixtures in pipes can be observed. Velocities are verified by local piezoelectric pressure transducers. Due to the fully distributed nature of the fiber-optic sensing system, it is possible to record accelerated motions in detail. Therefore, in addition to detection and localization of threatening events for infrastructure monitoring, DAS may provide a powerful tool to study the development of gas explosions in pipes, e.g., investigation of deflagration-to-detonation-transitions (DDT).

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Fiber-optic distributed acoustic sensing of microseismicity, strain and temperature during hydraulic fracturing

Geophysics ◽

10.1190/geo2017-0396.1 ◽

2019 ◽

Vol 84 (1) ◽

pp. D11-D23 ◽

Cited By ~ 20

Author(s):

Martin Karrenbach ◽

Steve Cole ◽

Andrew Ridge ◽

Kevin Boone ◽

Dan Kahn ◽

...

Keyword(s):

Hydraulic Fracturing ◽

Hydraulic Fracture ◽

Fiber Optic ◽

Data Set ◽

New Approach ◽

Acoustic Sensing ◽

Fiber Optic Technology ◽

Physical Effects ◽

Distributed Acoustic Sensing ◽

Temperature Strain

Hydraulic fracturing operations in unconventional reservoirs are typically monitored using geophones located either at the surface or in the adjacent wellbores. A new approach to record hydraulic stimulations uses fiber-optic distributed acoustic sensing (DAS). A fiber-optic cable was installed in a treatment well in the Meramec formation to monitor the hydraulic fracture stimulation of an unconventional reservoir. A variety of physical effects, such as temperature, strain, and microseismicity are measured and correlated with the treatment program during hydraulic fracturing of the well containing the fiber and also an adjacent well. The analysis of this DAS data set demonstrates that current fiber-optic technology provides enough sensitivity to detect a considerable number of microseismic events and that these events can be integrated with temperature and strain measurements for comprehensive hydraulic fracture monitoring.

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