Velocity as an Attribute - Continious Velocity Estimation from PreSDM CRP Gathers

Here we present a technique for estimating the velocity associated with a final preSDM image in great detail. Essentially we employ techniques of continuons velocity estimation used for iterative model update, but apply them in a different context. Rather that using the velocity estimator strictly for velocity model building (on a set of sparse lines), we employ the estimation techniques to the ARP gathers resulting from the final migration for all CRPs in the 3D survey. This achieves two things: firstly it estimates a residual velocity correction for stacking the final CRP gathers to obtain an enhanced image, and secondly, it delivers a dense estimate of velocity for the entire 3D volume in a geologically coherent manner. It is this second feature which is the subject of this paper.