Prestack depth migration of an Alberta Foothills seismic survey from the shaw‐basing area

Abstract

In performing explicit finite-difference prestack depth imaging on Alberta Foothills structures, we compared several prestack and poststack migrations. The results from the Shaw-Basing data set demonstrated that, due to the lack of near-surface velocity information, prestack depth migration from the floating datum provided the best imaging result compared to migration from a flat datum, migration from topography and poststack depth migration. Although poststack depth migration was limited because of the failure of assumptions inherent in NMO / Stack / Migration in Foothills settings, it could be still used as an intermediate result and consequently provided the initial velocity model for prestack depth migration. Through iterative and interpretative migration/velocity analysis, constrained by poststack migration and prestack depth migration (smiles/frowns analysis), we built a macro velocity model for the final prestack depth migration, which provided improved depth imaging.