Finding the Edge of Salt Via a Dual-Velocity Flood

Imaging an overturned salt edge with turning waves often requires large apertures, long recording times and a sediment velocity profile that appropriately increases with depth and that is unobstructed by other salt bodies within the aperture of interest, conditions that may not always be available in practice. In some situations, data that may not meet all of the turning-wave-image criteria can be used to find the salt face via a dual-velocity-model flood technique similar to a vertical-seismic-profile (VSP) proximity survey. In this case, the reflectors that truncate against salt are imaged at their truncation point in the correct position, helping to define the salt face.