Distributed acoustic sensing of subsea wells

2020 ◽  
Vol 39 (11) ◽  
pp. 801-807
Author(s):  
Andreas Ellmauthaler ◽  
Brian C. Seabrook ◽  
Glenn A. Wilson ◽  
John Maida ◽  
Jeff Bush ◽  
...  
Keyword(s):  
Single Mode ◽  
Field Trials ◽  
Single Mode Fiber ◽  
Optical Losses ◽  
Acoustic Sensing ◽  
Well Integrity ◽  
Sand Control ◽  
Processing Algorithms ◽  
Distributed Acoustic Sensing ◽  
Optical Circulator

Topside distributed acoustic sensing (DAS) of subsea wells requires advanced optical engineering solutions to compensate for reduced acoustic bandwidth, optical losses, and back reflections that are accumulated through umbilicals, multiple wet- and dry-mate optical connectors, splices, optical feedthrough systems, and downhole fibers. To address these issues, we introduce a novel DAS solution based on subsea fiber topology consisting of two transmission fibers from topside and an optical circulator deployed in the optical flying lead at the subsea tree. This solution limits the sensing fiber portion to the downhole fiber, located below the subsea tree, and enables dry-tree-equivalent acoustic sampling frequencies of more than 10 kHz while eliminating all back reflections from multiple subsea connectors above the tree. When combined with enhanced backscatter single-mode fiber, this gives rise to a DAS interrogation system that is capable of providing dry-tree-equivalent acoustic sensing performance over the entire length of the subsea well, regardless of the tie-back distance. It also enables the same spectral-based DAS processing algorithms developed for seismic, sand control, injector/producer profiling, and well integrity on dry-tree wells to be applied directly to subsea DAS data. The performance of this subsea DAS system has been validated through a series of laboratory and field trials. We show the results of the tests and discuss how the system is deployed within subsea infrastructure.

Well Integrity Diagnostics Using Acoustic Event Classification on Distributed Acoustic Sensing Data

2021 ◽  
Author(s):  
Lilia Noble ◽  
Hugh Rees ◽  
Pradyumn Thiruvenkatanathan ◽  
Tommy Langnes
Keyword(s):  
Detection Methods ◽  
Distributed Temperature Sensing ◽  
Injection Wells ◽  
Acoustic Sensing ◽  
Well Integrity ◽  
Injection Use ◽  
Sustained Casing Pressure ◽  
Distributed Acoustic Sensing ◽  
Operational Practices ◽  
Intervention Costs

Abstract Injection wells experience extremes of pressure and temperature as well as expansion and contraction during their normal operating cycles. This can cause numerous well integrity issues related to corrosion, leakage, degradation of barrier elements, operational practices that all put the health of the well at risk and require appropriate management. This paper will describe a case of a North Sea injection well that over time had developed sustained casing pressure (SCP) in the B-annulus. As a critical well in the development it was necessary to understand the origin and nature of the SCP as this would set further operational plans for the well helping to decide whether the well could continue to be operated safely, would require an intervention, or potentially will be abandoned. A leak investigation was needed to try to determine the source of the pressure, the type of fluid causing the pressure, the fluid path, and whether there was an injection out-of-zone as a result. To address all of the set objectives Distributed Fibre Optic (DFO) system was selected as a technology of choice. DFO provides an advantage over traditional leak detection methods through the ability to simultaneously monitor entire length of the well recording both acoustic and temperature profiles. Distributed Acoustic Sensing (DAS) was used to record acoustic signature of the well helping to determine the leak origin and likely pathway, while Distributed Temperature Sensing (DTS) was used to record well outflow profile and advise on possibility of out-of-zone injection. Use of pattern recognition techniques allowed to extract leak signature from background noise and other acoustic signals helping to pinpoint leak location. As a result of the application of DFO technology coupled with appropriate processing techniques way ahead for the well was identified providing an operator with a confident answer and saving on further intervention costs.

Field trials of distributed acoustic sensing for geophysical monitoring

2011 ◽  
Author(s):  
J. Mestayer ◽  
B. Cox ◽  
P. Wills ◽  
D. Kiyashchenko ◽  
J. Lopez ◽  
...  
Keyword(s):  
Field Trials ◽  
Geophysical Monitoring ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing

scholarly journals Quasi-single mode operated few-mode fiber for distributed acoustic sensing

2019 ◽  
Author(s):  
Islam Ashry ◽  
Yuan Mao ◽  
Tien Khee Ng ◽  
Frode Hveding ◽  
Muhammad Arsalan ◽  
...  
Keyword(s):  
Single Mode ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing

Precise Distributed Acoustic Sensing measurements by using seafloor optical fiber cable system for seismic monitoring

2020 ◽  
Author(s):  
Masanao Shinohara ◽  
Tomoaki Yamada ◽  
Takeshi Akuhara ◽  
KImihiro Mochizuki ◽  
Shin'ichi Sakai
Keyword(s):  
Optical Fiber ◽  
Single Mode ◽  
Gauge Length ◽  
Observation System ◽  
High Signal ◽  
Seismic Observation ◽  
Acoustic Sensing ◽  
Seafloor Observation ◽  
Optical Fiber Cable ◽  
Distributed Acoustic Sensing

<p>Distributed Acoustic Sensing (DAS) measurements which utilize an optical fiber itself as a sensor can be applied for various purposes. An observation of earthquakes using an optical fiber deployed on the seafloor with DAS technology is attractive because DAS measurements enable a dense seismic observation as a long linear array. Spatial resolution of the observation reaches a few meters. The length of the array is determined by the measurement range of the DAS interrogator deployed on the optical fiber, and a fine spatial sensor interval can be configured. DAS measurements have become increasingly accurate and the current state of technology exhibit high signal quality. Because DAS measurement is useful for earthquake observation, there were some trials for an observation of earthquakes using an optical fiber deployed on the land or the seafloor. However, There are few observations using DAS technology on seafloor until the present.</p><p>In 1996, a seafloor seismic tsunami observation system using an optical fiber cable was deployed off the coast of Sanriku by Earthquake Research Institute, the University of Tokyo. The system has three seismic stations and two tsunami-meters, and a length of the cable is approximately 115 km. The system has six spare (dark) optical fibers which are dispersion shifted single mode type, and have been incorporated for future extension of the observation system. We have started development of a seafloor seismic observation system utilizing DAS technology on the Sanriku cable observation system as a next generation of marine seismic observation system. In 2019, we performed DAS measurements using a dark fiber from Sanriku seafloor observation system three times. An interrogator was installed in the cable landing station temporarily. Data were recorded with various values of parameters, such as length of data collection (array aperture), gauge length, ping rate, acquisition offset, for evaluation of data quality and signal to noise ratios. The total recording period for three measurements was approximately three weeks. As a result, many earthquakes including micro-earthquakes were recorded. The obtained data will be used to develop data processing techniques for seismic observations utilizing DAS measurements.</p><p> </p>

Model Analysis of Underwater Acoustic Sensing with Hollow-Core Photonic Bandgap Fiber

2014 ◽  
Vol 568-570 ◽  
pp. 581-589
Author(s):  
Adel Abdallah ◽  
Chao Zhu Zhang ◽  
Zhi Zhong
Keyword(s):  
Acoustic Pressure ◽  
Photonic Bandgap ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Elastic Model ◽  
Hollow Core ◽  
Detection Range ◽  
Acoustic Sensing ◽  
Underwater Acoustic ◽  
Photonic Bandgap Fiber

Recently, using hollow-core photonic bandgap fiber (HC-PBF) for underwater acoustic sensing has been tested experimentally. Besides its unique characteristics and advantages over conventional single mode fiber (SMF), it provides higher responsivity to acoustic pressure. A robust deep water ray tracing model for multipath acoustic signals propagation and the elastic model of HC-PBF are both required to study the effects of underwater enviroment on the propagating acoustic signal for sensing with HC-PBF hydrophones. The combination of the two models allows studying the frequency response, sensitivity, detection range, and maximum operating depth of the HC-PBF hydrophones. The models analysis and simulations show the considerations that must be taken into account for the design and field operation of the HC-PBF hydrophones. In this paper, a complete package to study, design, optimize, and analyze the simulation results of the interferometric HC-PBF hydrophones is proposed.

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