Equivalent offset prestack migration for rugged topography

Hugh D. Geiger, John C. Bancroft

The process of prestack migration using equivalent offset and common scatter point gathers was initially based on input data converted to a horizontal datum (Bancroft et al. 1994). This short paper demonstrates how the process may be adapted for rugged topography, and allow the prestack migration to be from surface. Equivalent offset gathers were created for a model data set with a single scatter point in the subsurface. The results indicate that the algorithm works for both positive and negative datum shifts, although large shifts may move data of a single input trace over a wide range of offsets. An Alberta Foothills data set was prestack migrated using the rugged topography method. The initial results show excellent imaging of subsurface structure.