Abstract: SH wave field excited by circumferential shear source in cylindrically double layered media is theoretically analysed.Dispersion equation of cylindrical Love waves (guide waves) has been derived.Both existence condition and existence range of cylindrical Love waves are discussed.Dispersion and excitation of cylindrical Love waves are investigated by numerical calculation.It is discovered that the lowest order cylindrical Love waves have cut off frequency,which differs from Love waves in half space with horizontally double layered elastic media.The asymptotic expression of dispersion equation of cylindrical Love waves as well radius r₁→∞ consistently tends to the dispersion equation in the horizontal half space case,and cut off frequency tends to zero.The transient full waveform calculation is also calculated and illustrated, showing that realizing direct shear wave logs through exciting SH wave would be a more forthright way.

Key words: acoustic logging, cylindrical Love waves, dispersion equation, SH waves field, shear velociL