Lameloise, Charles-Antoine, Quantitative migration

Lameloise, Charles-Antoine

Combining reflected and transmitted waves for velocity analysis

H. Chauris (MINES)

Migration Velocity Analysis aims at determining the long wavelength velocity model. Based on DSO (Differential Semblance Optimization), this method is automatic. However, its application remains limited by the presence of migration velocity artifacts due to the spatial limitation of any acquisi- tion surveys and to the non-uniform illumination of the subsurface. We propose here quantitative migration to reduce these artifacts and analyze the associated CIGs (Common Image Gathers) and gradients of the objective function with respect to the medium velocity, needed for the iterative minimization. We apply this migration to a very simple, one-layer homogeneous velocity model and to a more complex, heterogeneous model. In both cases, better inversion results are obtained with quantitative migration.