We present an advanced velocity model building and imaging methodology that resulted in significant enhancements in defining the salt flanks with overhangs and subsalt structures. The key technologies used were (a) True Azimuth Multiple Elimination (TAME), (b) Tilted Transverse Isotropy (TTI) model building (FAN), (c) TTI Reverse Time Migration (RTM), (d) RTM Delayed Imaging Time (DIT) scans and (e) post-migration multiple attenuation. Approximately 39 OCS blocks of the Lena narrow-azimuth survey located in the Mississippi Canyon area of the Gulf of Mexico were imaged. The area was previously imaged with the Vertical Transverse Isotropy (VTI) Kirchhoff migration. Significant improvements have been achieved by reprocessing the same data with the new imaging methodology.

The Florida escarpment is one of the most dramatic bathymetric features in the Eastern Gulf. In places it reaches more than 1600m above the abyssal seafloor. Dips of 40 degrees are frequent, and vertical cliffs are not uncommon 1. This feature along with geological complexities of carbonate and salt regimes present imaging challenges that are addressed through the use of: • True azimuth 3D SRME

Accuracy and efficiency of every aspect of Kirchhoff migration (travel time calculation and interpolation, seismic data I/O, anti-aliasing, amplitude and illumination compensation, job partitioning, etc.) are critical in obtaining a timely, high-quality depth imaging result. A good algorithm however, does not necessarily always warrant a satisfactory and interpretable depth image in practice. Geological interpretation, regional understanding and careful 3D velocity model building are essential to the success of pre-stack depth imaging of sub-salt structures in the Deepwater, GOM. Many case history studies in the Deepwater GOM (area shown in Figure 1) indicate that Kirchhoff depth migration is still one of the important tools in production imaging of complex structures.

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