Investigation of collar properties on data-acquisition scheme for acoustic logging-while-drilling
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Investigation of collar.pdf
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7.78 MB
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Author(s)
Wang, Hua
Tao, Guo
Wei, Zhoutuo
Fehler, Michael
Date Issued
September 2016
Journal
Geophysics
Publisher
Society of Exploration Geophysicists
Citation
Wang, Hua; Fehler, Mike; Tao, Guo and Wei, Zhoutuo. “Investigation of Collar Properties on Data-Acquisition Scheme for Acoustic Logging-While-Drilling.” Geophysics 81, no. 6 (November 2016): D611–D624. © 2016 Society of Exploration Geophysicists
Version
Final published version
Abstract
We have used the wavenumber integration, velocity-time semblance, and dispersion methods to investigate the influence of collar properties including velocities, density, and attenuation on acoustic logging-while-drilling wavefields. We have found that when the velocities of the collar wave and the P-wave of the formation are similar, they interfere. However, the interference disappears when the velocity difference increases. Having a collar with large velocities (especial large shear velocity) and density makes the direct P-velocity determination possible in a fast formation even without isolators. For a slow formation, the interference of the collar flexural wave with the formation flexural and leaky P-waves is slight for a dipole tool when collar velocities are large. For this case, the S velocity can be determined by the flexural formation wave at low frequency (approximately 2 kHz). Based on these observations, we propose that the measurement of the P- and S-velocities can be easier if the collar is made of an advanced composite material that has high compressional and shear velocities as well as density. This is a direct and easy change to implement and a new idea for an acoustic logging-while-drilling tool design.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1190/GEO2016-0016.1
