Wave-equation extended images for semblance and depth focusing velocity analysis

Conventional velocity analysis applied to images produced by wave-equation migration makes use either of moveout information from space-lags, or of focusing information from timelags. However, more robust velocity estimation methods can be designed to take advantage at the same time of the moveout and focusing information provided by the migrated images. Such joint velocity estimation requires characterization of the analytic moveout surface defined for space-lag and time-lag common-image gathers. The analytic expressions for such surfaces are nonlinear, but reduce naturally to the conventional space-lag (linear) and time-lag (nonlinear) moveout functions. A joint migration velocity analysis technique exploiting the entire extended imaging condition information has the potential to benefit from the robustness of depth focusing analysis and of the high resolution of conventional semblance analysis.