Directivity performance of optical fibre for distributed Acoustic Sensing
With the advent of high performance, Distributed Acoustic Sensing (DAS) has gained great interest in the oil and gas industry. This acquisition technology offers immense improvement in terms of efficiency when compared with current geophysical acquisition methods. However, the fundamentals of the me...
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| Format: | Thesis |
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2019
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| Summary: | With the advent of high performance, Distributed Acoustic Sensing (DAS) has gained great interest in the oil and gas industry. This acquisition technology offers immense improvement in terms of efficiency when compared with current geophysical acquisition methods. However, the fundamentals of the measurement are still not fully investigated for optical fibre sensor that is directional and mainly sensitive along the cable direction. It’sinsensitivity to the direction of arrival of the acoustic wave is found to be difficult during field tests. This information is very important to the design of seismic surveys. Hereby, downscaled laboratory experiments enable for characterization of the relationship between the signals recorded by directivity variations of the distributed optical fibre sensors. Interrogation of the distributed optical fibre sensor was performed with the amplitude and the phase of the Rayleigh backscattered light measured by PR7300 interrogator unit. This interrogator system is suitable for compact test configurations, and it requires only a simple data processing workflow for extracting the signal outputs. Acoustic data were recorded to investigate the directivity, sensitivity of different optical fibre used in Distributed Acoustic Sensing and thus, enabling the comparison of performance on the directionality of optical fibre measurements. As well as the amplitude variation with angle of incidence, transformed into optical fibre signals well reported. It can be concluded that the optical fibre response matched with the characterization specialty optical fibre for Distributed Acoustic Sensing, with enhanced directivity influence by various Young Modulus figure of optical fibre cable. This emphasizes the importance of the listed parameters for field seismic acquisitions using the distributed optical fibre technology. |
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