Tube Wave Generation At A Layer Boundary For An Incident Compressional Plane Wave
Name
1992.14 Peng_Toksoz.pdf
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718.79 KB
Format
Adobe PDF
Checksum (MD5)
683583a2df772c297144c1eeb6f17725
Author(s)
Peng, Chengbin
Toksoz, M. Nafi
Date Issued
1992
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1992-14
Abstract
An approximate theory for the scattering of an incident plane P wave into tube waves
in a fluid-filled borehole drilled through two homogeneous half-spaces is proposed in
this paper. This theory is in excellent agreement with the zero frequency formulation
(White, 1983) for frequencies below hundreds of Hertz (in the range of conventional
crosshole or VSP experiments) and finite difference simulation at high frequencies. At
low frequency the excited tube wave is found to be independent of the borehole radius
and shows stronger sensitivity to the formation shear velocity contrast across the layer
boundary. The sensitivity towards the compressional velocity perturbation is opposite
to that of the shear wave and density such that little tube wave can be generated if the
compressional and shear velocities are both increased or decreased accordingly. Unlike
the tube wave excited in the borehole when an incident plane wave hits a fracture,
the reflected and transmitted tube waves generated at a layer boundary show opposite
polarities.
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