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EAGE GeoTech 2021 Second EAGE Workshop on Distributed Fibre Optic Sensing
- Conference date: March 1-5, 2021
- Location: Online
- Published: 01 March 2021
21 - 26 of 26 results
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Engineered Distributed Acoustic Flow Profiling Sensing Solutions
Authors M. Farhadiroushan, C. Milne, T. Parker, S. Hafezi, R. Aghayev, V. Mahue and S. ShatalinSummaryThe sensing fibre, cable design, installation method, including the coupling, together with the high-performance phase coherent DAS are combined to measure the fluid-borne acoustic and strain waves along a pipe. Advancements in processing techniques using distributed acoustic and temperature data are improving answers such as inflow contribution across the reservoir and detection of unwanted fluids and solids. These techniques are also expanding the range of well integrity issues that can be diagnosed successfully with DFOS either from permanently installed fibres or intervention surveys.
In addition, with optical fibre placed around the circumference of a pipe, we can monitor the flow. In its basic form, this gives a useful flow assurance tool, but with further processing we get closer to a quantitative meter performance. Ongoing development aims to make this a rapidly deployable, retrofittable and intrinsically safe metering solution that can be daisy-chained across multiple flow lines at a production location.
Awareness of the current state of complementary DFOS application development will be a useful element for geophysicists building the case for DAS seismic in their fields.
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Feasibility of reservoir monitoring using nonlinear seismic effects measured by downhole distributed acoustic sensors
Authors A. Yurikov, R. Isaenkov, K. Tertyshnikov, B. Gurevich, E. Sidenko, S. Glubokovskikh, V. Shulakova, B. Freifeld, J. Correa, T. Wood and R. PevznerSummaryElastic nonlinearity of the earth results in generation of higher harmonics and combinational frequencies of transmitted and interacting seismic waves. Such effects can be used to broaden the seismic frequency band of modern seismic sources. Another application of these effects is the subsurface monitoring and characterisation using physical nonlinearity of heterogeneous rocks, which originates from the nonlinear relation between stress and strain and depends on composition, saturation, porosity and other properties of the medium. To assess the feasibility of reservoir monitoring using nonlinear seismic effects, two field experiments were conducted. The first experiment was done using two seismic vibrators positioned in the near and far fields and generating two signals with different frequencies. The second experiment was done using a surface orbital vibrator with two eccentric motors working at different frequencies. In both experiments, the resulting wavefield was recorded by a downhole fibre optic distributed acoustic sensing cable. The combinational frequencies were observed in both experiments on the surface and at depth, which confirmed that nonlinear components of the wavefield are generated in rocks and propagate in a form of body waves. These outcomes form a basis for future development of reservoir monitoring and characterisation methods using nonlinear seismic effects.
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Dark fiber for subsurface characterization along railways
Authors E. Obando, P. Doornenbal, P. Hölscher, A. Van Uitert, C. Mas, H. Zandberg and A. ChalariSummaryDAS measurements were performed utilizing 8 km of an existing telecommunication fiber optic cable that is parallel to a busy railroad. The survey cable provided high energy of low frequency generated by travelling trains, comparable to 1 Hz high sensitivity geophones. A cross-correlation technique was utilized to enhance the coherent dispersion active - like MASW virtual shotgather averaged along 30 minutes. The phase velocity spectrum computed at a test site over 90 m, depicted a very consistent and coherent dispersion pattern. The inverted shear wave velocity profile depicted a good correlation with the existing main geological transitions at the test site down to 40 m depth.
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Keynote: Listening to Ice Sheets - Fibre Optic Cables as Seismic Sensors in the Antarctic
Authors M. Kendall, A. Brisbourne, T. Hudson, S. Kufner, A. Butcher, A. Baird, A. Smith, A. Chalari and A. ClarkeSummaryThe use of fibre as a Distributed Acoustic Sensor (DAS) is a recently developed technology with enormous potential, and, until recently, never tested in Antarctica. Here we show how DAS methods can be used to record icequakes, and to interrogate the internal properties of ice using seismic refraction studies and vertical seismic profiling. In the Austral Summer of 2020, we used fibre optic cables to study the Rutford Ice Stream and the Skytrain Ice Rise of the West Antarctic Ice Sheet.
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Integration of Machine Learning on Distributed Acoustic Sensing acquisition for pipeline integrity monitoring
Authors C. Jestin, C. Huynh, P. Clément and C. HibertSummaryWe present in this study results of the application of Machine Learning techniques to Distributed Acoustic Sensing (DAS) records. Our work is focussed on tests lead in the FEBUS OPTICS’s test centre located in Pau, South-West of France. This facility is equipped with a 22m-long buried pipeline instrumented with different fibre-optic cables: Single-Mode (SM), Multi-Mode (MM) fibres in tight or loose tube configurations, fibre cables directly buried in the ground or inside conduit and located at various distances from the pipe. Different events were simulated along the fibre (footsteps, compactor, vehicle, etc.) and simultaneously recorded with the different kind of fibres. The classification is run, using the Random Forest supervised algorithm, in order to identify the different events. We obtain a good quality of the classification with an accuracy equal to 91,82% emphasizing the good efficiency and reliability of our Machine Learning algorithm.
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Combining optical regeneration and enhanced optical fiber for DAS measurement on high losses condition
Authors G. Calbris, S. Richard and V. LanticqSummaryDistributed Acoustic Sensing (DAS) is a very active field. Nowadays, this technology is used for a broad range of applications. These applications are always asking for higher measurement quality despite specific constraints such as high optical losses and lack of signal at long range. We show here a combination of optical signal regeneration together with enhanced optical fiber is well adapted to retrieve low noise-floor DAS measurements despite a very high losses context such as subsea well or flowline monitoring.
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