Optimal Surface and Subsurface Parameters for a Successful Migration Velocity Analysis

Summary Migration velocity analysis is a method to estimate both reflectivity model and macromodel. We study here the sensitivity of the final result with respect to the selection of input surface offsets and subsurface parameters. We show that the velocity gradient used to update the macromodel highly depends on these parameters. We provide rules to ensure proper gradient by avoiding the dominance of the migration smiles. These rules are developed in the case of simple configurations. We apply them to the Marmousi model and show that final velocity model contains artefacts when the optimal parameters are not selected.