Full Waveform Inversion of P Waves for V[subscript s] and Q[subscript p]
Name
1987.10 Cheng.pdf
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334.84 KB
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Adobe PDF
Checksum (MD5)
2cc83f0edc662e2d9196ecb8b06d8487
Author(s)
Cheng, C. H.
Date Issued
1987
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1987-10
Abstract
We present an indirect method of determining shear wave velocities from full waveform
acoustic logs based on the inversion of the spectral ratio of the P-wave trains at two
source-receiver separations. This method simultaneously inverts for the formation shear
wave velocity and compressional wave attenuation. The P-wave response is calculated
by means of branch-cut integration. This method is useful in "soft" formations where
the shear wave velocity is lower than the acoustic velocity of the borehole fluid and
thus there are no refracted shear wave or pseudo-Rayleigh wave arrivals. The method
is shown to give good estimates of formation shear wave velocity in both synthetic and
field data. The inversion algorithm is sensitive to local minima; care must be taken to
avoid them.
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