DIP CORRECTIONS FOR VELOCITY ANALYSIS IN SUPER-GATHERS

摘要

This paper shows that structural dip information can be used for practical enhancements to velocity analysis workflows. During the analysis of stacking velocities, a dip field is computed from a preliminary stack section. By using the travel-time formulas of the Common Reflection Surface (CRS) method, the dip information alleviates the need for dip move-out (DMO) correction and improves the resolution of semblance panels by correcting for lateral changes in reflection times. Optimal construction of larger super-gathers may be used to increase the quantity of data used for the calculation. A similar improvement can be achieved for pre-stack migration velocity analysis. Dips are measured on a migrated stack section and then applied during the residual move-out (RMO) process as corrections to semblance computations on the migrated super-gathers. Alternatively, a dip field measured on a zero-offset stack can be used for a pre-migration mix, allowing for velocity updates with less computation cost than a full pre-stack migration. Examples of both stacking and migration velocity analysis are shown for a 3D land dataset.