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The Determination of the Seismic Quality Factor Q from VSP Data Acquired Using Distributed Acoustic Sensing
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
The spectral ratio method is the most commonly used approach to estimate the Quality factor (Q) from vertical seismic profile (VSP) data. An assumption behind this method, indeed all Q-estimation methods, is that the ability of the VSP sensor to record data is not affected by depth. Distributed Acoustic Sensing (DAS) is a relatively new method for acquiring VSP data that utilises a fibre optic cable as the sensor. DAS has the advantage of being a highly efficient method to acquire densely sampled VSP data over a large depth range simultaneously but unfortunately the frequency response of DAS data varies with velocity and thus depth. In this paper we describe a methodology that can be used to correct the frequency spectra and thus successfully estimate unbiased Q values. The methodology is demonstrated using both synthetic and real data.