Removal of reflection point smearing and the dip-dependence of the stacking velocities

Abstract

The philosophy behind dip-moveout (Hale, 1984) is a slightly different approach to the problem of dip filtering, previously attacked by a number of methods such as a prestack process known generally as DEVILISH, which stands for dipping event velocity inequalities licked (Judson et al., 1978) and prestack partial migration (Yilmaz and Claerbout, 1980). The importance of the problem of dip filtering applied to common mid-point gathers is stated in great detail by the authors mentioned above. On the one hand, the conventional normal-moveout and common-midpoint stacking process reinforces reflections having a particular slope in a given common mid-point gather; on the other hand it attenuates reflections having different slopes. Therefore this process behaves as a dip filter on a common mid-point gather and decreases lateral resolution of events on a seismic section. A synthetic model and real field data have been employed to examine the algorithm of dip-moveout. These examples have shown that the algorithm may be included in the sequence of seismic data processing whenever it is needed. However, in terms of computer time and economy dip-moveout is not a cheap process. In order to overcome this difficulty, in this study some computational expense has been reduced by neglecting evanescent waves and only working in the seismic frequency spectrum.