Using the Full Wavefield in Shallow Water Offshore Equatorial Guinea with MP-FWI Imaging

Summary Conventional seismic processing techniques treat large parts of the wavefield as noise e.g. source and receiver ghosts, sea surface and internal multiples, and, in the case of Kirchhoff migration, muti-pathing arrivals. These arrivals contain valuable information about the subsurface, which, if harnessed, can provide dramatic improvements in the illumination of the ultra-shallow. We use multi-parameter full waveform inversion (MP-FWI) imaging up to a maximum frequency of 50 Hz to produce a step-change improvement in imaging of both the very shallow and the deep subsurface in a towed streamer dataset offshore Equatorial Guinea. When compared to the legacy Kirchhoff pre-stack depth migration, the MP-FWI imaging reflectivity produces a clearer image of the deeper subsurface without the extensive pre-processing of the conventional workflow. Illumination of the shallow is significantly improved through the use of the full wavefield, which includes all ghosts and multiples. This shows how MP-FWI imaging can produce significant improvements in imaging of legacy datasets through the use of information that would usually be discarded in the conventional processing flow.