We demonstrate a method for 2D velocity estimation in complex media characterized by triplicated ray fields. Due to multipathing, Migration Velocity Analysis (MVA) principle has to be revisited, requiring in particular the use of Common Angle Gathers (CAGs) instead of the classical common offset panels. For the inversion itself, locally coherent events are automatically picked in the prestack d...

We apply 2-D wave-equation prestack depth migration to a North Sea basalt dataset. High velocity and impedance contrasts across a basalt layer causes low P-wave reflection signal-to-noise ratio under the basalt. We first migrate the P-wave data with a provided depth velocity model, and then replace sub-basalt P-wave velocity with a simple estimate of shear wave velocity and migrate locally-conv...

The wide-angle screen propagator can be used for fast and accurate depth migration. In this study, we applied the method to the prestack depth migration of a complex 2D model. The model shows a number of challenging features to migration algorithms, e.g., strong velocity contrast and steep structures. Our results show that the wide angle algorithm gives good results in a complex model. We also ...

Prestack migration methods based on data binning produce kinematic artifacts, i.e. coherent events not corresponding to actual reflectors, in the prestack image volume, when the medium is strongly refracting. Shot-geophone (“survey sinking”) migration, on the other hand, does not produce such artifacts when events to be migrated arrive in the data along non-turning rays. In contrast to prestack...

Poststack MD has been shown to be an effective method for attenuating migration noise, improving lateral resolution, and correcting for some migration amplitude distortion in 2-D and 3-D data (Hu and Schuster, 1998; and Hu and Valasek, 1999). In field data tests, poststack MD has successfully improved the 3-D poststack migration images (Hu and Valsek, 1999) obtained from both synthetic and fiel...

Seismic imaging based on single-scattering approximation is based on analysis of the match between the source and receiver wavefields at every image location. Wavefields at depth are functions of space and time and are reconstructed from surface data either by integral methods (Kirchhoff migration) or by differential methods (reverse-time or wavefield extrapolation migration). Different methods...

We present a review of common-azimuth prestack depth migration theory and propose a new extension to the original method. In common-azimuth migration theory, source and receiver raypaths are constrained to lie on the same plane at each depth level. By using data with a broader range of cross-line offsets, we increase the number of raypaths examined and consider more information. Consequently, o...

Prestack depth migration of shot profiles by downward continuation is a practical imaging algorithm that is especially cost-effective for sparse-shot wide-azimuth geometries. The interpretation of offset as the displacement between the downward-propagating (shot) wavefield and upward-propagating (receiver) wavefield enables us to extract offset-domain common imagepoint (CIP) gathers during shot...