Near-surface velocity and static model estimation from downgoing VSP multiples

摘要

Processing land walkaway or 3D VSP data often requires the application of source static corrections. Because of the effect of statics on the final image, the determination of an accurate near-surface velocity model and statics are critical, especially in desert areas such as in Saudi Arabia. For statics in walkway VSP processing, a common approach is to apply datum statics obtained from surface seismic measurements and residual statics derived from VSP first-break times. The residual statics approach is based on fitting a symmetric polynomial to the first-break times in common receiver gathers (assuming zero subsurface dips) and computing derivations from this smooth curve as the static corrections.