Improving images under complex salt with ocean bottom node data

Subsalt imaging at Stampede field in the Gulf of Mexico has remained challenging for decades due to the existence of a large and complex sediment inclusion inside thick tabular salt. Recently, appropriate full-waveform inversion (FWI) algorithms have been developed for automatic salt model updating (Shen et al., 2017; Zhang et al., 2018). By applying this technology to newly acquired ocean bottom node (OBN) data with good low-frequency content and ultra-long offsets, we are able to invert both the shape and velocity of this complex sediment inclusion at Stampede and provide significant improvement to the subsalt image. A good starting model for FWI is still needed in this workflow, but detailed interpretation efforts are not necessary. Moreover, we expect further improved subsalt imaging if data with even longer offsets becomes available.