Proceedings [EAGE Publications BV 76th EAGE Conference and Exhibition 2014 - Amsterdam, Netherlands (2014.06.16-2014.06.19)] Proceedings 76th EAGE Conference and Exhibition 2014 - Fundamentals of Vibration Sensing with Distributed Fibre Optic Sensors through Downscaled Experiments

摘要： In the past few years the Distributed Vibration Sensing of fibre optic sensors (also called Distributed Acoustic Sensing) has gained great interest in geophysics, despite the fundamentals of the measurement being poorly understood. The technology offers immense improvement in terms of efficiency when compared with current geophysical methods and also could be preferred for applications such as permanent reservoir monitoring. We present a method for downscaled experimentation that enabled us to define the fundamentals of the optical fibre measurement. We show seismic data that were recorded simultaneously by both the fibre optical interferometer and conventional geophones, thus enabling the comparison of sensor performance. We present results focused on wave-polarity sensitivity and the directionality of fibre measurements. The current interrogation method of optical fibre cables cannot distinguish between wavefields coming from opposite azimuthal directions, which can be an issue in certain applications where the identification of up-going and down-going wavefields is essential. Observations are also presented that describe the relationship between the velocity signal that is measured using a geophone array and the phase difference measurement from the fibre optic sensing system.