Sub-basalt imaging in the Faeroe-Shetland Basin with large-offset data

On two profiles from the Faeroe-Shetland Basin, where Tertiary basalt flows cover an older sedimentary section, we demonstrate that the seismic image of a sub-basalt target can be much improved by using the velocity and reflectivity information contained in the wide-angle wavefield. While conventional short-offset processing provides a detailed image down to the top of the basalt flows, pre-stack depth migration of selected portions of the wide-angle wavefield allows a composite image to be built which reveals the base of the basalt flow and the underlying sedimentary and basement structure. The velocity field derived from wide-angle traveltimes also assists in identifying the geological origin of the imaged structures.