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Applications Of Perturbation Theory To Acoustic Logging

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dc.contributor.author Ellefsen, K. J.
dc.contributor.author Cheng, C. H.
dc.contributor.other Massachusetts Institute of Technology. Earth Resources Laboratory en_US
dc.date.accessioned 2012-11-29T20:26:38Z
dc.date.available 2012-11-29T20:26:38Z
dc.date.issued 1989
dc.identifier.uri http://hdl.handle.net/1721.1/75111
dc.description.abstract For guided wave propagation in boreholes, perturbation theory is used to calculate (1) the partial derivative of the wavenumber or frequency with respect to an elastic modulus or density, (2) group velocity, and (3) the effect of a borehole with a slightly irregular cross section upon the phase velocity. The method, which is developed for a fluid-filled, cylindrical borehole through a transversely isotropic formation, relates perturbations in formation properties (i.e., elastic moduli, densities, and interface locations) and wave properties (i.e., wavenumber and frequency) for guided waves with any azimuthal order number. Velocity perturbations, which are calculated for three common cross sections of irregular boreholes, show several general characteristics. The tube and pseudo-Rayleigh waves, which have no azimuthal dependence, completely smooth the effects of the irregularity making the velocity perturbation independent of the wave's orientation. The perturbations for the tube wave are small because it is a Stoneley wave, but those for the pseudo-Rayleigh wave are much larger because the borehole shape affects the multiply-reflected part of this wave. The velocity perturbations for the flexural and screw waves are similar in character to those for the pseudo-Rayleigh wave, but because these waves are directional, they can interact with the irregularity to amplify or diminish the velocity perturbation. en_US
dc.description.sponsorship Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortium en_US
dc.description.sponsorship Phillips Petroleum Fellowship en_US
dc.publisher Massachusetts Institute of Technology. Earth Resources Laboratory en_US
dc.relation.ispartofseries Earth Resources Laboratory Industry Consortia Annual Report;1989-02
dc.title Applications Of Perturbation Theory To Acoustic Logging en_US
dc.type Technical Report en_US
dc.contributor.mitauthor Ellefsen, K. J.
dc.contributor.mitauthor Cheng, C. H.
dspace.orderedauthors Ellefsen, K. J.; Cheng, C. H. en_US


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