Determination of Shear Wave Velocity and Attenuation From Waveforms in Low Velocity Formations
Name
1984.8 Toksoz et al.pdf
Size
318.18 KB
Format
Adobe PDF
Checksum (MD5)
6ea8187042df539da13c7d2e9cdd1050
Author(s)
Toksoz, M. Nafi
Wilkens, R. H.
Cheng, C. H.
Date Issued
1984
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1984-08
Abstract
In boreholes where formation shear velocity is lower than borehole fluid velocity neither refracted shear waves nor pseudo-Rayleigh waves can propagate. When frequency response of the sonde does not extend to low frequencies (e.g. 2 kHz) Stoneley waves are not excited efficiently. In such cases refracted P, leaking modes (PL) and fluid waves become dominant phases on a full waveform acoustic log. The P wave velocity can be determined from the first arrivals. Then, using synthetic microseismograms and a waveform
matching technique, formation shear wave velocity and attenuation can be determined. This method· is demonstrated using data from a well in the Baltimore Canyon Trough area of the Atlantic margin.
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