A time migration before stack

The 1970\u27s saw the introduction and development of post-stack migration algorithms to the extent that migrated stacks were routinely produced as part of the basic processing sequence. Today it is common to incorporate a Dip Moveout (DMO) correction into the processing sequence prior to stacking. In this paper we present a processing technique which cascades Dip Moveout with zero-offset time migration before stack. The method overcomes the limitations of DMO in the presence of lateral and vertical velocity gradients, symptomatic in areas of complex geology. A velocity analysis is inherent in the process producing a more accurate velocity field for migration and depth conversion. The robust nature of the method allows its application to routine data processing and we foresee that such migration strategies will be as commonly employed in the future as DMO is today