Full-waveform Seismic Inversion at Reservoir Depths

We apply 3D anisotropic acoustic full-waveform tomographic seismic inversion to a North Sea wide-angle OBC dataset, and demonstrate that our recovered velocity model is realistic within the chalk reservoir sequence to depths of up to 4000 m. Because we use predominantly wide-angle refracted arrivals in the inversion, we are able to undershoot and image within the otherwise seismic obscured area beneath a shallow gas cloud that overlies the reservoir. Wide-angle FWI techniques using similar datasets have not previously been used to image successfully at these depths.