Leon A. Thomsen

The Ninth International Workshop on Seismic Anisotropy (9IWSA)Discussion

The Eighth International Workshop on Seismic Anisotropy (8IWSA) was held on April 20-24, 1998, in Boussens, France, at the CISFAB Training Center of Elf Aquitaine (for more information, see http://8IWSA.seg.org). This conference, held every two years since 1984, brings together many of the worlds experts on seismic anisotropy for a week of intense discussion of recent advances. The anisotropic community is highly informal, with no society, no officers, and no journal. Because of the increasingly importance of the subject of anisotropy to exploration geophysics, SEG has supported the publication of past proceedings volumes (Brown and Lawton, 1993; Fjaer et al., 1996; Hood, 1999).

Means for obtaining shear wave velocities

The present invention provides a method of logging a subterranean formation through a wellbore containing a fluid, wherein no shear wave signal is obtainable utilizing conventional sonic well logging tools suspended in the wellbore. The shear wave signal is not obtainable usually because the acoustic velocity of the wellbore fluid is greater than the shear wave velocity of the formation to be logged. In the present method, the acoustic velocity of the wellbore fluid is adjusted until a shear velocity signal is obtainable by lowering the acoustic velocity of the wellbore fluid until it is less than the shear wave velocity of the formation. Thereafter, the formation is logged through the wellbore to obtain a shear wave signal.