Dispersion estimation from borehole acoustic arrays using a modified matrix pencil algorithm

A new array processing algorithm is presented for estimating dispersion characteristics from borehole acoustic measurements. It involves estimating the propagating modes of the borehole response function by first Fourier transforming the space-time array in the time dimension, then at each temporal frequency, the spatial wavenumber of the modes are obtained using a modified matrix pencil algorithm. This modification is referred to as "forward/backward averaging" as the complex wavenumber estimates are formed from the average of a "forward" matrix pencil and a "backward" matrix pencil. Use of a tolerance specification between the estimates allows a natural discrimination between signal and noise wavenumbers.