f Estimation of Velocity-Depth Models for 3D Structural Targets - a Case Study from the North Sea

Three-dimensianal seismic data from the North Sea were analyzed to obtain an accurate depth structure map of the top Rotliegendes formation in the survey area. This required estimation of a 3-D velocity-depth model above the Zechstein diapiric formation and removal of its deleterious effect on the underlying Permian Bands of Rotliegendes and deeper targets. We used coherency inversion based on 3-D-prestaclc traveltime inversion to estimate lager velocities and 3-D poststack depth migration to delineate reflector geometries. We also want to use 3-D prestack depth migration and analyze image gathers to estimate a vetocity-depth model and verify it for the substratum which includes the Zechstein and underlying formations.