Z-99 MIGRATION VELOCITY ANALYSIS BY RECURSIVE WAVEFIELD EXTRAPOLATION

We present a wave-equation method of migration velocity analysis, based on the linear relation that can be established between a perturbation in the migrated image and the corresponding perturbation in the slowness function. Our method formulates an objective function in the image space, in contrast with other wave-equation tomography techniques which formulate objective functions in the data space. We iteratively update the slowness function to account for improvements in the focusing quality of the migrated image. We overcome the major limitation of the Born approximation by analytically creating image perturbations consistent with this approximation. The image perturbation operator is computed as a derivative of prestack Stolt residual migration, thus our method directly exploits the power of prestack residual migration.