A theoretical comparison of equivalent‐offset migration and dip moveout‐prestack imaging

Abstract

Equivalent‐offset migration is a methodology for prestack‐Kirchhoff time migration that partially reverses the order of velocity analysis, normal moveout correction, stack, and migration. Though claimed to be computationally and analytically superior to earlier time‐domain approaches, it is not independent of velocity. Velocity‐independent dip moveout followed by prestack imaging is similar to equivalent‐offset migration in that it also postpones normal moveout correction to the postmigration stage, but it is independent of velocity. This paper investigates the theoretical relationship between these two processes, showing that equivalent‐offset migration and prestack imaging are asymptotically equivalent. Moreover, equivalent‐offset migration has little, if any, computational or analytic advantage. The fact that the combination of dip moveout followed by prestack imaging is independent of velocity is a major advantage and suggests that this latter method is better suited to problems of velocity estimation.