Improving Atlantis TTI Model Building: OBN+NATS, Prism Waves & 3D RTM Angle Gathers

Ocean Bottom Node (OBN) acquisition has provided many advantages for building a more accurate salt geometry and subsalt velocity at Atlantis. Around the end of 2009, BP started to reprocess the data and rebuild the salt model using a Tilted Transverse Isotropy Reverse Time Migration (TTI RTM) workflow. TTI RTM 3D Angle Gather technology, developed in early 2010, was used in both supra-salt and subsalt velocity tomography updates, taking advantage of the full azimuthal coverage of the OBN acquisition. RTM’s capacity to image prism waves also contributed to the imaging and interpretation of complex salt fingers in the survey. Furthermore, migrating OBN common receiver gathers was more efficient than migrating towed-streamer common shot gathers and allowed us to test over one hundred different salt scenarios. The TTI model building was a success and the subsalt image at Atlantis was substantially improved.