Dip moveout in shot profiles

Abstract

All the known dip‐moveout (DMO) algorithms that are not integral methods require the seismic data to be sorted in regularly sampled constant‐offset sections. In contrast, the dip‐moveout method proposed here can be applied directly to recorded shot profiles and thus can handle data that cannot be sorted in regular constant‐offset sections. The definition of the shot‐DMO operator is analogous to that of the dip‐moveout operator for constant‐offset sections. The two operators have impulse responses with the same projection on the zero‐offset plane, i.e., the stacking plane; therefore, the application of dip moveout in constant‐offset sections or in shot profiles gives the same stacked section. Dip moveout transforms shot profiles to zero‐offset data, to which any poststack migration can be applied. The shot‐DMO operator is space‐variant and time‐ variant; thus direct application of the operator would be computationally expensive. Fortunately, after a logarithmic transformation of both the time and the space coordinates, the operator becomes time‐invariant and space‐invariant; then dip moveout can be performed efficiently as a multiplication in the Fourier domain. Shot dip moveout is also a useful tool for improving the accuracy of residual velocity analysis performed after the DMO process. Field‐data examples show that the shot‐profile dip‐moveout method yields stacked sections similar to those from Hale’s (1984) dip moveout for constant‐offset sections.