Full Wave Synthetic Acoustic Logs In Saturated Porous Media Part Ill: Pore Shape And Pore Geometry Effects
Name
1986.7 Schmitt.pdf
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959.64 KB
Format
Adobe PDF
Checksum (MD5)
7806c88f79e7b1edc3edef2922d22698
Author(s)
Schmitt, D. P.
Date Issued
January 1, 1986
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1986-07
Abstract
Homogenization theory states that the viscous and mass coupling coefficients of a fully
saturated porous medium depend upon the pore shape and the pore geometry. Using
an approximate formula, the three body wave velocities and attenuations are analyzed
for different configurations. The results show a strong influence of the mass coupling
coefficient on these properties. The greater it is, the less biphase the porous medium is.
Hence, in the high frequency range, the body wave velocities and attenuations decrease.
Using the discrete wavenumber method, synthetic microseismograms are computed in
an axisymmetric water-filled borehole. In the presence of a given porous formation with
a permeable interface, whatever the mass coupling coefficient, Stoneley wave attenuation
and dispersion characteristics are only slightly affected. The reliability of the indirect
permeability determination is then ensured. On the other hand, the pseudo-Rayleigh
modes are less attenuated with increasing mass coupling coefficient. In the absence of
any borehole fluid attenuation, they may become dominant with a high source center
frequency. This emphasizes the requirement for low band pass frequency records to be
able to easily determine the rheological parameters of a formation.
Complex geometries are shown which would allow one to take into account an anisotropic
permeability distribution.
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