Attenuation of the seismic dispersion associated to foothills topography: application to real data

Abstract

Land seismic data is contaminated commonly with coherent and high amplitude back-scattered noise generated from roughness in the surface topography; these events make generally the key information on deeper layers unclear. In Colombian foothill areas with rough topography and high lateral velocity variation, this noise has been difficult to attenuate. Conventional methods aimed at this purpose usually yield unsatisfactory results. We present a strategy based in prediction and subtraction of the unwanted waves. Assuming knowledge of the source wavelet and the shallow velocity model we use a finite-element solution of the acoustic wave equation to model the back-scattered noise; this modeled response is then subtracted from the prestack data, resulting in a noticeable attenuation of noise in field seismograms.   The method was applied to prestack real data from colombian foothills in order to observe the enhancement in seismic records, planning in a close future to show results on stacked data.