Space–time dependence of acoustic waves in a borehole

A combined theoretical and experimental study, using a scale laboratory model with a cylindrical borehole, has been performed to study the space–time dependence of modal propagation. Wave analysis has been expanded to include cased hole as well as the more usual situation of open hole propagation. A general formalism for cylindrically layered media is presented. Experimental results include 40 waveforms with transmitter–receiver spacings in increments of 12.7 mm which is sufficient to avoid significant spatial aliasing. Wavenumber-frequency spectral estimation is used to resolve trapped modes in the data set. Good agreement between theory and experiment has been obtained for both modal dispersion and mode cutoff frequencies.