Depth Migration of Edge Diffractions by Adaptive Weighting of Migration Operator Amplitudes

In this paper we demonstrate the potential of a new migration technique for easy detection of subtle reflector discontinuities, such as due to faults with minor throw or reflector pinch-outs in wedge-shaped geological units. Such discontinuities cannot easily be identified on images produced with conventional migration methods. The novelty of our method concerns the computation of edge-diffraction-specific weightings for migration operator amplitudes. These weighting factors can be easily obtained from the operators already computed for a conventional true-amplitude Kirchhoff migration of reflection data. An advantage of combining a conventional true-amplitude Kirchhoff migration and our edge-diffraction migration method, providing a second migration image containing only the diffracting edges, are the diagnostic power for velocity model refinement and seismic interpretation of complex structures. The simplicity of use and relatively small computing effort are important practical benefits. The additional cost of computing the edge-diffraction migration weightings in addition to the conventional true-amplitude Kirchhoff operator attributes is negligible and therefore the extra cost for computing the additional edge-diffraction migration image is approximately equal to the cost of applying one additional migration with just new amplitude weightings applied to already available migration operators.