Turning a Telecom Fiber-Optic Cable into an Ultradense Seismic Array for Rapid Postearthquake Response in an Urban Area

Abstract Aftershock-monitoring networks deployed in the epicentral area of a damaging earthquake play important roles in earthquake early warning and ShakeMap estimation, which contribute to hazard mitigation. Using distributed acoustic sensing (DAS) technology with dark fiber can significantly reduce deployment time and cost, and improve spatial sampling, both of which help capture more aftershocks. In this study, we used a 7.6 km dark fiber in Tangshan, China, to monitor seismicity after the 12 July 2020 Ms 5.1 earthquake. The DAS array detected dozens of earthquakes missed by the local permanent network that doubled the number of aftershocks. The relocated aftershocks are distributed mainly north of the DAS array, and the ground-motion pattern changes also hint small-scale features. Our successful results demonstrate the feasibility of using DAS and dark fiber for rapid postearthquake response.

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Detecting and Correcting Pipeline Leaks Before They Become a Big Problem

Marine Technology Society Journal ◽

10.4031/mtsj.49.1.1 ◽

2015 ◽

Vol 49 (1) ◽

pp. 31-46 ◽

Cited By ~ 5

Author(s):

Ron Cramer ◽

David Shaw ◽

Robert Tulalian ◽

Pabs Angelo ◽

Maarten van Stuijvenberg

Keyword(s):

Acoustic Wave ◽

Real Time ◽

Fiber Optic ◽

Cost Effective ◽

Leak Detection ◽

Rate Of Change ◽

Fiber Optic Cable ◽

History Of ◽

Distributed Acoustic Sensing ◽

Critical Lines

AbstractTimely pipeline leak detection is a significant business issue in view of a long history of catastrophic incidents and growing intolerance for such events. It is vital to flag containment loss and location quickly, credibly, and reliably for all green or brown field critical lines in order to shut down the line safely and isolate the leak. Pipelines are designed to transport hydrocarbons safely; however, leaks have severe safety, economic, environmental, and reputational effects. This paper will highlight robust, reliable, and cost-effective methods, most of which leverage real-time instrumentation, telecommunications, SCADA, DCS, and associated online leak detection applications. The purpose of this paper will be to review the underlying leak detection business issues, catalogue the functional challenges, and describe experiences with available technologies. Internal and external techniques will be described, including basic rate of change of flow and pressure, compensated mass balance, statistical, real-time transient modeling, acoustic wave sensing, fiber optic cable (distributed temperature, distributed acoustic sensing), and subsea hydrophones. The paper will also describe related credibility, deployment, organizational, and maintenance issues with an emphasis on upstream applications. The scope will include leak detection for pipelines conveying various flowing fluids—gas, liquid, and multiphase flow. Pipeline environments will include subsea and onshore. Advantages, disadvantages, and experiences with these techniques will be described and analyzed.

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Real Time Measurement of Airplane Flutter via Distributed Acoustic Sensing

Aerospace ◽

10.3390/aerospace7090125 ◽

2020 ◽

Vol 7 (9) ◽

pp. 125

Author(s):

Ezzat G. Bakhoum ◽

Cheng Zhang ◽

Marvin H. Cheng

Keyword(s):

Optical System ◽

Fiber Optic ◽

New Technology ◽

Time Measurement ◽

Fiber Optic Cable ◽

Acoustic Sensing ◽

Real Time Measurement ◽

Distributed Acoustic Sensing ◽

Mechanical Disturbances ◽

New System

This research group has recently used the new technology Distributed Acoustic Sensing (DAS) for the monitoring and the measurement of airplane flutter. To the authors’ knowledge, this is the first such use for this new technology. Traditionally, the measurement of airplane flutter requires the mounting of a very large number of sensors on the wing being monitored, and extensive wiring must be connected to all these sensors. The new system and technology introduced in this paper dramatically reduces the hardware requirements in such an application: all the traditional sensors and wiring are replaced with one fiber optic cable with a diameter of 2 mm. An electro-optical system with the size of a desktop PC monitors simultaneously one or more of such fiber optic cables and detects/characterizes any mechanical disturbances on the cables. Theoretical and experimental results are given.

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High precision and high resolution monitoring of subsurface changes with DAS and airgun

10.5194/egusphere-egu2020-10096 ◽

2020 ◽

Author(s):

Baoshan Wang ◽

Xiangfang Zeng ◽

Jun Yang ◽

Yuansheng Zhang ◽

Zhenghong Song ◽

...

Keyword(s):

Large Scale ◽

Fiber Optic ◽

Epicentral Distance ◽

Low Cost ◽

Fiber Optic Cable ◽

The Road ◽

Air Gun ◽

Distributed Acoustic Sensing ◽

On The Road ◽

Road Crossing

<p>Recently large-volume airgun arrays have been used to explore and monitor the subsurface structure. The airgun array can generate highly repeatable seismic signals, which can be traced to more than 200 km. And the airgun source can be ignited every 10 minutes. The airgun source makes it possible to precisely monitor subsurface changes at large scale. The spatial resolution of airgun monitoring is poor subjecting to the receiver distribution. The distributed acoustic sensing (DAS) technique provides a strategy for low-cost and high-density seismic observations. Two experiments combing DAS technique and airgun source were conducted at two sites with different settings. At the first site, a telecommunication fiber-optic cable in urban area was used. After moderate stacking, the airgun signal emerges on the 30-km DAS array at about 9 km epicentral distance. In the second experiment, a 5-km cable was deployed from the airgun source to about 2 km away. About 800-m cable was frozen into the ice above the air-gun, the rest cable was cemented on the road crossing through a fault. And the airgun has been fired continuously for more than 48 hours with one-hour interval. On the stacking multiple shots&#8217; records, the wavefield in fault zone emerges too. These two experiments demonstrate the feasibility of using various fiber-optic cables as dense array to acquire air-gun signal in different environments and to monitor the subsurface changes.</p>

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Repeat well logging using earthquake wave amplitudes measured by distributed acoustic sensors

The Leading Edge ◽

10.1190/tle39070513.1 ◽

2020 ◽

Vol 39 (7) ◽

pp. 513-517

Author(s):

Roman Pevzner ◽

Boris Gurevich ◽

Anastasia Pirogova ◽

Konstantin Tertyshnikov ◽

Stanislav Glubokovskikh

Keyword(s):

Seismic Waves ◽

Fiber Optic ◽

Synthetic Data ◽

Seismic Source ◽

Small Scale ◽

Acoustic Sensors ◽

Linear Strain ◽

Subsurface Characterization ◽

Distributed Acoustic Sensing ◽

Subsurface Monitoring

Well-based technologies for seismic subsurface monitoring increasingly utilize fiber-optic cables installed in boreholes as distributed acoustic sensing (DAS) systems. A DAS cable allows measuring linear strain of the fiber and can serve as an array of densely spaced seismic receivers. The strain amplitudes recorded by the DAS cable depend on the near-well formation properties (the softer the medium, the larger the strain). Thus, these properties can be estimated by measuring relative variations of the amplitudes of seismic waves propagating along the well. An advantage of such an approach to subsurface characterization and monitoring is that no active seismic source is required. Passive sources such as earthquakes can be utilized. A synthetic data example demonstrates viability of the approach for monitoring of small-scale CO2 injection into an aquifer. Two field DAS data examples based on signal recordings from several distant earthquakes show that the relevant properties of the near-well formation can be estimated with an accuracy of approximately 5%.

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Backward piping erosion detection in levees by fiber optic acoustic sensing

10.5194/egusphere-egu2020-7465 ◽

2020 ◽

Author(s):

Juan Pablo Aguilar-López ◽

Andres Garcia-Ruiz ◽

Thom Bogaard ◽

Miguel Gonzalez-Herraez

Keyword(s):

Ambient Noise ◽

Fiber Optic ◽

Geophysical Methods ◽

Innovative Technology ◽

Fiber Optic Cable ◽

Acoustic Sensing ◽

Characteristic Frequencies ◽

Distributed Acoustic Sensing ◽

Piping Erosion ◽

Set Up

<p>Backward piping erosion (BEP) is considered the most dangerous failure mode for levees due to its unpredictable nature. This erosive process happens most of the time underneath the impermeable layers on which levees are commonly founded. This makes it very difficult to detect as conventional geophysical methods are either too expensive or too imprecise for real time monitoring of longitudinal soil made structures such as Dams or levees. Fiber optic based distributed acoustic sensing (DAS) is an innovative technology which allows to retrieve information from an acoustic propagating medium in a spatially dense manner by using a fiber optic cable. The present study aimed to explore the potential of DAS for early detection of BEP&#160; under levees based on the frictional emissions of the sand grains during the erosive process. The tests were performed in the lab under controlled ambient noise conditions. The technology was tested by embedding fiber optic based microphones underneath and outside a laboratory scaled aquifer set up capable of recreating BEP. The results show that indeed the process emits certain characteristic frequencies which may be located between 1200 to 1600 Hz and and that they can easily be captured by the fiber optic cables.</p>

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Real-Time Well-Integrity Monitoring Using Fiber-Optic Distributed Acoustic Sensing

SPE Journal ◽

10.2118/195678-pa ◽

2019 ◽

Vol 24 (05) ◽

pp. 1997-2009 ◽

Cited By ~ 3

Author(s):

T.. Raab ◽

T.. Reinsch ◽

S. R. Aldaz Cifuentes ◽

J.. Henninges

Keyword(s):

Life Cycle ◽

Strain Rate ◽

Real Time ◽

Fiber Optic ◽

Axial Strain ◽

Fiber Optic Cable ◽

Integrity Monitoring ◽

Well Integrity ◽

Distributed Acoustic Sensing ◽

Cement Integrity

Summary Proper cemented casing strings are a key requirement for maintaining well integrity, guaranteeing optimal operation and safe provision of hydrocarbon and geothermal resources from the pay zone to surface facilities. Throughout the life cycle of a well, high–temperature/high–pressure changes in addition to shut–in cyclic periods can lead to strong variations in thermal and mechanical load on the well architecture. The current procedures to evaluate cement quality and to measure downhole temperature are mainly dependent on wireline–logging campaigns. In this paper, we investigate the application of the fiber–optic distributed–acoustic–sensing (DAS) technology to acquire dynamic axial–strain changes caused by propagating elastic waves along the wellbore structure. The signals are recorded by a permanently installed fiber–optic cable and are studied for the possibility of real–time well–integrity monitoring. The fiber–optic cable was installed along the 18⅝–in. anchor casing and the 21–in.–hole section of a geothermal well in Iceland. During cementing operations, temperature was continuously measured using distributed–temperature–sensing (DTS) technology to monitor the cement placement. DAS data were acquired continuously for 9 days during drilling and injection testing of the reservoir interval in the 12¼–in. openhole section. The DAS data were used to calculate average–axial–strain–rate profiles during different operations on the drillsite. Signals recorded along the optical fiber result from elastic deformation caused by mechanical energy applied from inside (e.g., pressure fluctuations, drilling activities) or outside (e.g., seismic signals) of the well. The results indicate that the average–axial–strain rate of a fiber–optic cable installed behind a casing string generates trends similar to those of a conventional cement–bond log (CBL). The obtained trends along well depth therefore indicate that DAS data acquired during different drilling and testing operations can be used to monitor the mechanical coupling between cemented casing strings and the surrounding formations, hence the cement integrity. The potential use of DTS and DAS technology in downhole evaluations would extend the portfolio to monitor and evaluate qualitatively in real time cement–integrity changes without the necessity of executing costly well–intervention programs throughout the well's life cycle.

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Very broadband strain-rate measurements along a submarine fiber-optic cable off Cape Muroto, Nankai subduction zone, Japan

Earth Planets and Space ◽

10.1186/s40623-021-01385-5 ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Satoshi Ide ◽

Eiichiro Araki ◽

Hiroyuki Matsumoto

Keyword(s):

Subduction Zone ◽

Fiber Optic ◽

Ocean Current ◽

Small Scale ◽

Distributed Temperature Sensing ◽

Fiber Optic Cable ◽

Deep Ocean Water ◽

Wide Range ◽

Rapid Temperature ◽

Nankai Subduction Zone

AbstractDistributed acoustic sensing (DAS) is a new method that measures the strain change along a fiber-optic cable and has emerged as a promising geophysical application across a wide range of research and monitoring. Here we present the results of DAS observations from a submarine cable offshore Cape Muroto, Nankai subduction zone, western Japan. The observed signal amplitude varies widely among the DAS channels, even over short distances of only ~ 100 m, which is likely attributed to the differences in cable-seafloor coupling due to complex bathymetry along the cable route. Nevertheless, the noise levels at the well-coupled channels of DAS are almost comparable to those observed at nearby permanent ocean-bottom seismometers, suggesting that the cable has the ability to detect nearby micro earthquakes and even tectonic tremors. Many earthquakes were observed during the 5-day observation period, with the minimum and maximum detectable events being a local M1.1 event 30–50 km from the cable and a teleseismic Mw7.7 event that occurred in Cuba, respectively. Temperature appears to exert a greater control on the DAS signal than real strain in the quasi-static, sub-seismic range, where we can regard our DAS record as distributed temperature sensing (DTS) record, and detected many rapid temperature change events migrating along the cable: a small number of large migration events (up to 10 km in 6 h) associated with rapid temperature decreases, and many small-scale events (both rising and falling temperatures). These events may reflect oceanic internal surface waves and deep-ocean water mixing processes that are the result of ocean current–tidal interactions along an irregular seafloor boundary.

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Very broadband strain-rate measurements along a submarine fiber-optic cable off Cape Muroto, Nankai subduction zone, Japan

10.21203/rs.3.rs-121961/v2 ◽

2021 ◽

Author(s):

Satoshi Ide ◽

Eiichiro Araki ◽

Hiroyuki Matsumoto

Keyword(s):

Subduction Zone ◽

Fiber Optic ◽

Ocean Current ◽

Small Scale ◽

Distributed Temperature Sensing ◽

Fiber Optic Cable ◽

Deep Ocean Water ◽

Wide Range ◽

Rapid Temperature ◽

Nankai Subduction Zone

Abstract Distributed acoustic sensing (DAS) is a new method that measures the strain change along a fiber-optic cable and has emerged as a promising geophysical application across a wide range of research and monitoring. Here we present the results of DAS observations from a submarine cable offshore Cape Muroto, Nankai subduction zone, western Japan. The observed signal amplitude varies widely among the DAS channels, even over short distances of only ~100 m, which is likely attributed to the differences in cable-seafloor coupling due to complex bathymetry along the cable route. Nevertheless, the noise levels at the well-coupled channels of DAS are almost comparable to those observed at nearby permanent ocean-bottom seismometers, suggesting that the cable has the ability to detect nearby micro earthquakes and even tectonic tremors. Many earthquakes were observed during the five-day observation period, with the minimum and maximum detectable events being a local M1.1 event 30–50 km from the cable and a teleseismic Mw7.7 event that occurred in Cuba, respectively. Temperature appears to exert a greater control on the DAS signal than real strain in the quasi-static, sub-seismic range, where we can regard our DAS record as distributed temperature sensing (DTS) record, and detected many rapid temperature change events migrating along the cable: a small number of large migration events (up to 10 km in 6 hours) associated with rapid temperature decreases, and many small-scale events (both rising and falling temperatures). These events may reflect oceanic internal surface waves and deep-ocean water mixing processes that are the result of ocean current–tidal interactions along an irregular seafloor boundary.

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Very Broadband Strain-Rate Measurements Along a Submarine Fiber-Optic Cable Off Cape Muroto, Nankai Subduction Zone, Japan

10.21203/rs.3.rs-121961/v1 ◽

2020 ◽

Author(s):

Satoshi Ide ◽

Eiichiro Araki ◽

Hiroyuki Matsumoto

Keyword(s):

Subduction Zone ◽

Fiber Optic ◽

Ocean Current ◽

Small Scale ◽

Ocean Bottom ◽

Fiber Optic Cable ◽

Deep Ocean Water ◽

Wide Range ◽

Rapid Temperature ◽

Nankai Subduction Zone

Abstract Distributed acoustic sensing (DAS) is a new method that measures the strain change along a fiber-optic cable and has emerged as a promising geophysical application across a wide range of research and monitoring. Here we present the results of DAS observations from an submarine cable offshore Cape Muroto, Nankai subduction zone, western Japan. The observed signal amplitude varies widely among the DAS channels, even over short distances of only ~100 m, which is likely attributed to the differences in cable-seafloor coupling due to complex bathymetry along the cable route. Nevertheless, the noise levels at the well-coupled channels of DAS are almost comparable to those observed at nearby permanent ocean-bottom seismometers. Many earthquakes were observed during the five-day observation period, with the minimum and maximum detectable events being a local M1.1 event 30–50 km from the cable and a teleseismic Mw7.7 event that occurred in Cuba, respectively. Temperature appears to exert a greater control on the DAS signal than real strain in the quasi-static, sub-seismic range. We observed many rapid temperature change events migrating along the cable: a small number of large migration events (up to 10 km in 6 hours) associated with rapid temperature increases, and many small-scale events (both rising and falling temperatures). These events may reflect deep-ocean water mixing processes that are the result of ocean current–tidal interactions along an irregular seafloor boundary.

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Geotechnical effects on fiber optic distributed acoustic sensing performance

10.21079/11681/41325 ◽

2021 ◽

Author(s):

Meghan Quinn

Keyword(s):

Soil Moisture ◽

Fiber Optic ◽

Impact Testing ◽

Test Bed ◽

Fiber Optic Cable ◽

Vehicle Loading ◽

Flowable Fill ◽

Distributed Acoustic Sensing ◽

Over Time

Distributed Acoustic Sensing (DAS) is a fiber optic sensing system that is used for vibration monitoring. At a minimum, DAS is composed of a fiber optic cable and an optic analyzer called an interrogator. The oil and gas industry has used DAS for over a decade to monitor infrastructure such as pipelines for leaks, and in recent years changes in DAS performance over time have been observed for DAS arrays that are buried in the ground. This dissertation investigates the effect that soil type, soil temperature, soil moisture, time in-situ, and vehicle loading have on DAS performance for fiber optic cables buried in soil. This was accomplished through a field testing program involving two newly installed DAS arrays. For the first installation, a new portion of DAS array was added to an existing DAS array installed a decade prior. The new portion of the DAS array was installed in four different soil types: native fill, sand, gravel, and an excavatable flowable fill. Soil moisture and temperature sensors were buried adjacent to the fiber optic cable to monitor seasonal environmental changes over time. Periodic impact testing was performed at set locations along the DAS array for over one year. A second, temporary DAS array was installed to test the effect of vehicle loading on DAS performance. Signal to Noise Ratio (SNR) of the DAS response was used for all the tests to evaluate the system performance. The results of the impact testing program indicated that the portions of the array in gravel performed more consistently over time. Changes in soil moisture or soil temperature did not appear to affect DAS performance. The results also indicated that time DAS performance does change somewhat over time. Performance variance increased in new portions of array in all material types through time. The SNR in portions of the DAS array in native silty sand material dropped slightly, while the SNR in portions of the array in sand fill and flowable fill material decreased significantly over time. This significant change in performance occurred while testing halted from March 2020 to August 2020 due to the Covid-19 pandemic. These significant changes in performance were observed in the new portion of test bed, while the performance of the prior installation remained consistent. It may be that, after some time in-situ, SNR in a DAS array will reach a steady state. Though it is unfortunate that testing was on pause while changes in DAS performance developed, the observed changes emphasize the potential of DAS to be used for infrastructure change-detection monitoring. In the temporary test bed, increasing vehicle loads were observed to increase DAS performance, although there was considerable variability in the measured SNR. The significant variation in DAS response is likely due to various industrial activities on-site and some disturbance to the array while on-boarding and off-boarding vehicles. The results of this experiment indicated that the presence of load on less than 10% of an array channel length may improve DAS performance. Overall, this dissertation provides guidance that can help inform the civil engineering community with respect to installation design recommendations related to DAS used for infrastructure monitoring.

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