Reduction of dispersive ground-roll using time delay spectrometry

Velocity filtering seismic traces requires fulfilment of the sampling theorem in the time domain and in the space domain. Since the latter condition is seldom met in exploration seismics, a method based on τ-p transformation combined with time varying filtering is proposed for solving the problem of reducing dispersive ground-roll in a seismic trace. Although it is possible to mask out ground-roll in the τ-p domain, mapping of the τ-p domain back into the original x-t domain involves numerical difficulties because the used inverse discrete Radon transform is ill-posed. To circumvent this problem the seismic trace is applied to a time varying filter with a stop-band which at any instant corresponds to the instantaneous frequency of the ground-roll, thus reducing the ground-roll with minimum distortion of the wanted seismic rate