Propagation of flexural modal waves in a fluid-filled borehole

The propagation of multipole modal waves along the well-axis in a fluid-filled borehole surrounded respectively by elastic and nonelastic, infinite and finite formations is analyzed from the wave equations. The phase velocity dispersions and the exicitation curves are numerically calculated. The waveforms excited by attenuating bursts are also calculated. Measurements with long-spacing dipole transducers made of PZT thin diske vibrating in bending mode are carried out in a concrete model well and the experimental results are compared with the theoretical results.