Abstract:

The authors presented theoretical solution and numerical analysis of the acoustic field of Stoneney and flexural waves in a fluid\|filled borehole surrounded by the transversely isotropic two-phase formation with the Biot\|squirt mechanisms. The effects of the characteristic squirt\|flow length on the dispersion and attenuation of fundamental guided waves were emphatically studied. The results show that the velocity dispersions are almost independent of characteristic quirt\|flow length; attenuation coefficients of Stoneley wave and flexural wave based on BISQ model are obviously bigger than that based on Biot model only. The attenuation coefficient of stoneley wave tends to increase with the  increase of horizontal characteristic squirt\|flow length R₁, and decrease with the  increase of vertical characteristic squirt\|flow length R₃. The attenuation coefficient of flexural wave tends to increase with the increase of R₁ below a certain frequency and  to decrease with the increase of R₁ above a certain frequency, while the variation tendency of attenuation coefficient due to R₃  is just opposite to above variation trend.

Key words: squirt-flow, transversely isotropic, Stoneley wave, flexural wave, dispersion, attenuation