Anisotropic prestack depth migration using the equivalent offset method

John C. Bancroft, Robert W. Vestrum

The principles of equivalent-offset prestack time migration are applied to anisotropic depth migration. This is accomplished with the use of source and receiver anisotropic traveltime maps of depth migration to define the two-way traveltime to a scatter point. This time is then equated to a hyperbolic moveout equation that defines the equivalent offset for the scatter point. Samples from all input traces are mapped to a common scatter point (CSP) gather for each vertical array of scatter points. After the CSP gathers are formed, hyperbolic Kirchhoff NMO and stacking completes the prestack depth migration.