The ubiquitous wind listener - distributed optical fiber acoustic sensor

Xu Tuanwei, Li Fang, Ma Lilong

Institute of Semiconductor, Chinese Academy of Sciences

Distributed acoustic sensing（Distributed Acoustic Sensing，DAS）The technology utilizes the phase of coherent backscattered Rayleigh light instead of light intensity to detect signals such as sound or vibration within the audio range. Not only can the phase amplitude be used to provide information on the intensity of sound or vibration events, but linear quantitative measurement values are also used to obtain phase and frequency information of sound or vibration events, as shown in the figure 1。 This technology has advantages such as long-distance (tens of kilometers) continuous (spatial resolution of several meters) acquisition of vibration or acoustic information, real-time measurement of tens of thousands of channels of information at full scale (amplitude, frequency, phase), resistance to harsh environments such as high temperature and pressure, and resistance to electromagnetic interference.

chart 1 Schematic diagram of distributed fiber optic acoustic sensing system

Research progress at home and abroad

As early as1993Year,TaylorProposed by othersPhase sensitive optical time-domain reflection technologyDetect disturbances by measuring the intensity changes of backscattered Rayleigh light from highly coherent light sources for intrusion detection. Due to the nonlinear response between vibration and light intensity changes, it is mainly used for qualitative measurements, commonly referred to asDistributed vibration sensing technology（DVS）。

since2010Since then, researchers both domestically and internationally have quantitatively reconstructed sound by measuring the phase change of backscattered Rayleigh light/Vibration information, commonly referred to asDistributed Acoustic Wave Sensing Technology（DAS）。

At present, this technology has many phase demodulation and quantitative measurement schemes, including2010UK SilixaProposed by the company3×3Coupler Phase Demodulation Technology[1]，2010UKOptaSenseDual pulse heterodyne demodulation technology proposed by the company[1]，2011Digital coherent phase demodulation technology proposed by Shanghai Institute of Optics and Mechanics, Chinese Academy of Sciences in[3]，2014Phase generation carrier demodulation technology proposed by the Institute of Semiconductors, Chinese Academy of Sciences in[2]，2015Time gated optical frequency domain demodulation technology proposed by Shanghai Jiao Tong University in[6]，2016Zero deviation proposed by the University of Electronic Science and Technology in I/Q Orthogonal demodulation technology[4]，2016Chirped pulse direct measurement scheme at the University of Acara in Spain in[5]。

In recent years, in response to the improvementDASThe performance indicators of the system, such as spatial resolution, frequency response bandwidth, noise reduction, and sensing distance expansion, were proposed by Huazhong University of Science and Technology, and the frequency modulation pulse compression technology was proposed by Shanghai Institute of Optics and Mechanics[6]Semiconductor from the Chinese Academy of Sciences proposed differential interferometer technology, while the University of Electronic Science and Technology proposed Raman amplification technology, among others[7]。

At present, distributed fiber optic acoustic sensing technology is gradually maturing, and multiple high-performance sensors have been launched in the marketDASEquipment, such asSilixaCorporateiDASTM，OptasenseCorporateODHSeries,FotechCorporate Helios® DASCNPC Aobo's μDASInstitute of Semiconductors, Chinese Academy of SciencessemiDASEtc.

Industrialized application

DASTechnology can meet the qualitative judgment of events while providing quantitative information, greatly expanding the signal detection capabilities and application fields of distributed acoustic sensing technology, especially providing a new, effective, and low-cost technical solution for oil and gas resources, transportation, marine geophysics, natural earthquakes, and perimeter security, It has shown great application prospects and has been rapidly developed.

Oil and gas resources field

DAS Technology can be used for vertical seismic logging in wells（VSP）In terms of surface seismic acquisition, time delay or permanent reservoir monitoring, hydraulic fracturing monitoring, etc., due toDASTechnology can play an important role in the entire lifecycle of oil wells and is receiving increasing attention from geophysical scientists, as shown in the figure below2。

chart 2 Application of Distributed Fiber Optic Sensing Technology in the Oil and Gas Field

Compared to conventional ground detectors and downhole detectors,DAS The technology has advantages such as low cost, high efficiency, dense sampling, and data quality no lower than traditional seismic detectors. Multiple oil service companies (Schlumberger, Halliburton), geophysical companies (CNPC Eastern Geophysical ExplorationCGG、PGS、TGS）Experiments have been conducted in borehole seismic acquisition, surface seismic acquisition, microseismic monitoring, and reservoir monitoring.

Recently in the UKSilixaIn carbon capture and storage projects, the company utilizesDAS Technology for 3DVSPTime lapse seismic and well completion dynamic monitoring, active and passive seismic monitoring of the entire life cycle of carbon oxide storage equipment and formations. China National Petroleum Eastern Geophysical Exploration Company collaborated with the University of Electronic Science and Technology in Changqing, Xinjiang, and Southwest China 6 An oil field has been completed34Conduct well production tests to obtain high-quality data. The Institute of Semiconductors of the Chinese Academy of Sciences, in collaboration with CNPC Eastern Geophysical Exploration Company and Sinopec Group Geophysical Company, conducted research in oil fields such as Daqing, Jidong, Qinghai, Changqing, Tahe, and FushanVSP In seismic acquisition, good results have been achieved.

Transportation sector

DAS The technology can be used for monitoring the status of road vehicles and railway trains. By laying along the road and equipped withDAS The optical cable technology can pick up the movement of vehicles, determine the vehicles using the road, calculate the formation mode and type of congestion, and evaluate the status of infrastructure. By laying optical cables on the railway network, the sensing network can be extended along the railway tracks to track train trajectories and monitor rail status, continuously providing real-time location information along the entire length of the monitored section.

2016Year, UKOptaSenseThe company uses it for high-speed rail monitoringDASThe system has been put into use with a monitoring length of1000 kmIt is laid in the Dammam and Riyadh sections of the Saudi high-speed railway and has the function of monitoring train operation and illegal intrusion (personnel, animals).

2017In, the Shanghai Institute of Optics and Mechanics of the Chinese Academy of Sciences proposed a railway safety detection technology based on multidimensional comprehensive analysis and deep learning. The use of dynamic frequency space image analysis methods to eliminate environmental noise, multi-dimensional comprehensive analysis methods for train identification and disturbance recognition, and deep network extraction of signal features and classification recognition have been fully validated in multiple actual lines.

2020In, the Institute of Semiconductors of the Chinese Academy of Sciences, in collaboration with Beijing Jiaotong University, conducted dynamic monitoring of high-speed trains, passenger trains, and heavy-duty trains at a certain location in Qinhuangdao using optical cables. The trains were classified and clearly obtained16Information on the wheels of the high-speed train.

The field of marine geophysics

DASThe technology can be used in marine geophysical exploration, submarine earthquake early warning and underwater target detection. By utilizing existing submarine optical cables andDASThe advantage of high spatial resolution allows for more precise mapping of seafloor faults and wave information, thereby helping scientists make more accurate predictions of earthquakes and tsunamis. Gas gun seismic sources can be used for seabed resource exploration, providing support for monitoring and unconventional oil and gas field development during the trial production process of natural gas hydrates.

2019In, scientists from the University of California, Lawrence Berkeley National Laboratory, Monterey Bay Aquarium Research Institute, and Rice University conducted research on a20A kilometer long submarine optical cable was studied for four days and a tectonic fault zone from Monterey Bay off the coast of California was recorded 3.4A magnitude earthquake.2019In, the Institute of Semiconductors of the Chinese Academy of Sciences, in collaboration with the Deep Sea Institute of the Chinese Academy of Sciences, conducted an underwater optical cable observation experiment at the entrance of Hainan, and obtained the dominant frequency of1.2 Hz 3D wave information and ship dynamic signals.

Earthquake monitoring field

DASThe use of existing communication optical cables can achieve seismic detection with low cost and high accuracy.2018In, the Potsdam Earth Science Research Center in Germany achieved high resolutionDASSystem, utilizing the existing Reykjaya Peninsula 15 km The communication cable conducts seismic wave detection, and detects local earthquakes and ocean microseisms related to seismicity of Mid-Atlantic Ridge. The research results indicate that communication optical cables can be used to detect earthquakes and other ground activities, providing a new technological means for seismic wave detection.

Other fields

DASThe technology combines its advantages of long-distance, high spatial density, and real-time dynamic monitoring, and is also widely used in perimeter security and pipelines / Pipeline gallery leakage monitoring, underwater target detection, etc.

Summary and Outlook

DASIn recent years, technology has developed rapidly and has broad prospects, covering multiple aspects of scientific research and industrial applications, and has achieved fruitful scientific research results. recent yearsDASThe technical performance is constantly improving, and the frequency band extends to low and high frequencies (with low frequencies reaching tens of thousands)mHzHigh frequency toMHz）The sensing distance ranges from several kilometers to hundreds of kilometers, and the spatial resolution is reduced to the sub meter level. Special optical fibers are used to reduce noise levels20 dB。DASThe functionality of technology is also constantly being extended, using spiral fibers toDASThe one-dimensional sensing capability has been enhanced to have three-dimensional sensing capabilities, and relevant detection technologies have been used to achieve quasi-static high-precision measurement of physical quantities such as temperature and strain.

DASThe technology will present the following development trends:

（1）DASThe standardization and standardization of technology, the transition from high-performance scientific research equipment to standardized industrial equipment, provides effective distributed seismic wave detection tools for scientific research and industrial applications;

（2）NewDASTechnology improves system performance and expands functionality, enabling it to have a wider response frequency band, detection distance, and spatial resolution, moving from single dynamic signal detection to multi-parameter joint distributed detection;

（3）Relying on its own advantages to further expand its application fields, Expanding from the surface to the deep ground, deep sea, and deep space, especially providing technical means for seismic wave detection of oceans and planets.

reference

1.A.Maso udi,T.P.Ne wson High s patial resolution distributed optical fiber dynamic strain sensor with enhanced frequency and strain resolution[ J].Optics Letters,2017,42(2):290.

2.G.Fang,T.Xu,S.Feng,et al .Phase-Sensitive Optical Time Domain Reflectometer Based on Phase-Generated Carrier Algorithm[J]. Journal of Lightwave Technology,2015,33(13):2811-2816.

3.Z.Pan,K.Liang,Q.Ye,et al .Phase-sensitive OTDR system based on digital coherent detection[C].Asia Communications & Photonics Conference & Exhibition. IEEE, 2012.

4. Z.Wang,L.Zhang,S.Wang,et al.Coherent Φ-OTDR based on I/Q demodulation and homodyne detection[ J]. Optics Express, 2016,24(2):853-858.

5.J.P.Graells,et al.Single-shot distributed temperature and strain tracking using direct detection phase-sensitive OTDR with chirped pulses[ J].Optics Express,2016,24(12):13121.

6.Q.Liu,X.Fan,Z.He.Time-gated digital optical frequency domain reflectometry with 1.6-m spatial resolution over entire 110-km range[ J].Optics Express,2015,23(20):25988.

7.Cai Haiwen,Ye Qing,Wang Zhaoyong.Distributed Fiber Optic Acoustic Wave Sensing Technology Based on Coherent Rayleigh Scattering [J].Progress in Laser and Optoelectronics,2020,57(5).

Author Introduction

Xu Tuanwei, Associate Research Fellow of Institute of Semiconductor, Chinese Academy of Sciences, mainly engaged in the application research of special fiber grating, ultra narrow linewidth fiber laser, distributed fiber optic acoustic sensing system, and fiber optic sensing technology in oil and gas exploration, marine earth monitoring, perimeter security and other fields.

Li Fang,Researcher, Institute of Semiconductor, Chinese Academy of Sciences, Mainly engaged in the application research of fiber optic sensing technology in fields such as marine information and security, resource exploration, and major disaster monitoring.

Ma Lilong,Doctor candidate of Institute of Semiconductor, Chinese Academy of Sciences, mainly engaged in signal processing of distributed optical fiber sensing and its application in perimeter security.