Cost-effective datuming in presence of rough topography and complex near-surface

We review the derivation of a new prestack operator, the Topographic Datuming Operator (TDO). TDO, unlike static corrections, allows for the movement of reflections laterally to their true locations corresponding to the new datum level. Thus, it mitigates mis-positioning of events and velocity bias introduced by the unphysical time-invariant vertical shifts carried out by static corrections. In the particular case of infinite (in practice, very high with respect to the shallow layers) velocity beneath the datum, the TDO impulse response collapses to the conventional surface-consistent time shift (static correction), which may, therefore, be regarded as a special case of the newly derived operator. Low sub-weathering velocity also shrinks the spatial extension of the TDO impulse response. The application of TDO on onshore data from the Arabian Peninsula provided better continuity of reflections at the new datum than those obtained by static corrections with only a minor additional cost. Moreover, stacking velocities after TDO are not affected by a spurious positive bias.