| Popis: |
Velocity model building for time imaging generally involves an iterative process involving several loops of PreSTM, picking, and velocity update. We propose a new approach allowing the full interpretation of kinematic information picked on PreSTM gathers in a single loop. We determine the effective (V,η) velocity model using a slope tomography. The kinematic information picked on PreSTM gathers, i.e. dips and residual move-out, is demigrated to get kinematic information in the un-migrated domain, as required by our slope tomography. Considering that a single picking step is required our picking must be as accurate as possible. Approaches involving volumetric picking of dips and scanning of parametric RMO curves can be used but we also discuss the benefit of using a multidimensional dip picking tool. Such a tool insures spatial consistency, introduces dip variation with offset and no more uses parametric RMO curve picking. We present an application to a field data demonstrating the ability of our approach to fully interpret kinematic information in a single tomographic step. |
