Effects of Casing on Full Waveform Acoustic Logs
Name
1983.3 Tubman et al.pdf
Size
510.92 KB
Format
Adobe PDF
Checksum (MD5)
b0340aa0e6a8cf586bd28261cce6f5c5
Author(s)
Tubman, Kenneth M.
Cheng, C. H.
Toksoz, M. Nafi
Date Issued
1983
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1983-03
Abstract
A general expression is derived for the dispersion relations and the impulse response of a radially layered borehole. The. model geometry consists of a central fluid cylinder surrounded by an arbitrary number of solid annuli. A Thomson-Haskell type propagator matrix is used to relate stresses and displacements across the layers. Although the model is completely general, the geometries considered here are restricted to those of a cased hole. Layers of steel, cement, and an infinite, outermost layer of a formation surround the fluid layer. Synthetic seismograms containing all body and interface waves are calculated for a variety of model parameters.
Formation body wave arrivals are relatively unaffected by the presence of a casing. They may, however, be hard to identify if the cement velocities are close to or larger than those of the formation. The Stoneley and pseudo-Rayleigh wave arrivals are predominantly influenced by the casing parameters. They respond to the combined effects of the steel, the cement, and the formation.
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