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Fluid Dependence of Anisotropy ParametersNormal access

Author: L.A. Thomsen
Event name: 75th EAGE Conference & Exhibition incorporating SPE EUROPEC 2013
Session: Rock Physics I
Publication date: 10 June 2013
DOI: 10.3997/2214-4609.20130348
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 337.45Kb )
Price: € 20

The generally accepted theory governing the effect of fluid content on seismic velocities is due to Biot and Gassmann, with further refinements proposed more recently. Most applications of the theory use its isotropic special case, and without these refinements (resulting in a well-known theoretical prediction for the fluid dependence of the longitudinal elastic stiffness). The present work concerns the extension of this theory to the case of anisotropy, and including these recent refinements. For thinly bedded (inhomogeneous) sequences, the theory as formulated for homogeneous formations requires special handling, in general. For the case of weak polar anisotropy, closed expressions are derived for the well-known anisotropy parameters delta, eta, and gamma. The most remarkable new result is that the anisotropy parameter eta is approximately independent of fluid content, and this applies to thinly bedded sequences without special handling.

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