The Speed of a Wave Along a Fluid/solid Interface in the Presence of Anisotropy and Prestress

The classical solution for the Scholte wave along a fluid and isotropic substrate .s well known. However, when the subshate is either a weakly anisotropic solid, or the adjoining fitrid is subject o a hydrostatic pressure, the analysis of Scholte wave propagation becomes rather complex and lengthy computations are required to obtain the solution. The purpose of this paper is to apply simple and computationally efficient expressions in the determination of Scholte wave speeds for substrates with either weak anisotropy or in lhe,presence of uniform initial stresses and strains in the substrate and fluid media. Both of these two simple expressions are for the incremental change in the Scholte wave speed Av/v from an appropriately selected isotropic, reference substrate and adjoining fluid under no hydrostatic pressure. The predictions of the Scholte wave speeds from the derived expressions agree to well within 1%-2% with the other approximation techniques for the high-frequency asymptotes of the Stoneley wave velocity dispersions in a fluid-filled borehole traversing either a weakly anisotropic formation or a formation with initial stres:;es and strains caused by a borehole pressurization. ̧ 1995 Acoustical Socie.ty of America.