Seismic Imaging of Rift-Related Subsalt Structures Using Prestack Depth Migration

The North Sea and the Gulf of Suez contain classic examples of rift-type graben structures. Typical of such geologic regimes, substantial thicknesses of evaporites were accumulated during the inijiation of rifling. Evaporites, especially salt, provided ideal seals for the faulted pregraben and graben-fill sediments. Subsequent burial then yielded the mechanism for halokinesis and the resultant traps associated wijh salt diapirislm. Anhough contributing to many of the conditions necessary for hydrocarbon trapping, salt presents a severe impediment to seismic imaging. Irregular masses of salt act as distorting lenses to refiected seismic energy. To form accurate images of the subsurface, prestack depth migration is needed.