Appeal No. 97-1628
Application No. 08/442,610
which the borehole is located. As the examiner has
acknowledged, Broding fails to disclose or teach this feature.
Vogel discloses a system for interrogating the borehole
environment with acoustic waves. This reference discusses in
the prior art section the actions of both shear and
compressional acoustic waves. In a discussion of the prior
art, Vogel points out that the propagation of “S-waves,” which
we presume to be “shear waves,” is not supported by borehole
fluid, and thus these waves cannot escape from the formation.
Vogel explains that what happens is that the S-waves propagate
through the sidewall material, mechanically exciting
corresponding compressional waves in the fluid, and creating
“converted-compressional” waves (column 1, line 53 et seq.).
In accordance with the method of the Vogel invention, a
logging tool having acoustic transmitter and receiver elements
transverses the borehole and “[t]he receiver element detects
converted-compressional waves emanating from the casing”
(column 3, line 67 et seq.). This use of converted
compressional waves is repeated with regard to two other
aspects of the invention (column 4, lines 19 and 27).
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