Non-Stretch Fourth Order NMO through Iterative Partial Corrections and Deconvolution

Source to receiver distances employed in seismic data acquisition have been steadily increasing and it is now common to work with data acquired with more than 10 km of offset. Sub-basalt exploration and seismic undershooting are just two applications where long-offset reflections are valuable. However, such reflections are often subjected to muting to avoid NMO stretch artifacts, thus causing a loss of valuable information. It is therefore of interest to find ways to avoid the distortions caused by the standard NMO correction and to retrieve these portions of the recorded wavefield for a better use in the processing. To this end we develop a non-stretch NMO correction based on a wavelet estimation and on a iterative procedure of partial NMO correction and deconvolution. To drive the corrections we make use of 4th order traveltime curves, that further extend the offset range of usable reflections. Then we estimate time and space variant wavelets, by means of SVD along the sought traveltimes, that become the desired output for the deconvolution trying to retrieve the original shapes of the partially stretched wavelets. We test our method on synthetic data and we perform a blind test on real data simulating an undershooting acquisition.