Seismic migration by demodeling

We numerically investigate the inverse operation to the classical Kirchhoff-Helmholtz integral. This operation, which we call Kirchhoff demodeling, is completely analogous to the forward modeling operation. In the same way as the latter integrates along the depth reflector, the new inverse demodeling operation integrates along the corresponding reflection traveltime surface. The result is a seismic pulse at the reflector depth, multiplied with the corresponding reflection coefficient. In this way, we have a new and promising migration technique at hand. We will refer to this method as migration by demodeling, in accordance to its position in the triangle of modeling, migration, and modeling by demigration. A particular attraction of the proposed migration method is that it is a much faster process than conventional Kirchhoff migration, even when applied with full true-amplitude weights, Demodeling is a target-oriented operation as it can be restricted to a target reflector. It requires an identification and picking of the events to be migrated. This should. however, not pose a severe restriction to the applicability of the method since the identification of horizons of interest is always necessary at some stage of the seismic processing sequence. In this sense, the new process is not to be seen as a replacement for Kirchhoff migration, but as a complementary procedure. Possible applications include the fast true-amplitude migration of an identified event to determine whether a promising AVO trend in the CMP section is confirmed after migration.1041699597