Reduction of NMO-stretch using non-stationary scaling transformation in time-frequency domain

The NMO-stretch causes decrease in the dominant frequency of seismic wavelet after conventional NMO correction. It severely damages the quality of the stacked data for shallower reflectors at far offsets. Muting, which is commonly used to handle this problem, reduces seismic fold and negatively affects results of the AVO analysis within the stretched area. Here, we introduce an alternative approach to reduce the stretching phenomenon through compensating for the reduced frequencies of the seismic wavelet before applying the NMO correction. The added so-called compensated frequencies are defined according to the difference between the dominant frequency of the original seismic wavelet and the assumed stretched wavelet after the NMO correction. The corresponding procedure considers frequency content around each time sample along each trace in time-frequency domain using the Gabor transform. As such, the dominant frequency of seismic wavelets is increased in a nonstationary fashion. Performance of the proposed method is evaluated by applying it to synthetic as well as field data examples. The obtained results suggest that the proposed approach provides CMP gathers with reduced stretching effect, with the potential to be considered an alternative for non-stretch NMO correction. However, it should be noted that the presented method resolves neither the problem of intersecting events, nor the multiples in the CMP gather.