Long offset aided full waveform inversion

Abstract

Full Waveform Inversion (FWI) has become a new tool in recent practice for velocity model updating. When using the FWI, the common scheme was to use data sets which have relatively large offsets up to 7 to 8 km and frequencies as low as 2.5 Hz. In marine environment Wide Azimuth towed streamer (WAZ) or Ocean Bottom Cable (OBC) acquisition provide the above mentioned specifications. Recent advances in data collection such as dual coil offers significant characteristics over WAZ and OBC such as better illumination, noise attenuation and lower frequencies which allow the FWI to more accurately determine a velocity field with the data's higher maximum offset and wider azimuth ranges. The methodology of the use of FWI in this paper follows the traditional layer striping approach where we developed the supra salt sediment followed by the top of salt, salt flanks, base of salt and finish with a limited subsalt update. This approach has been successfully applied in the Gulf of Mexico (GoM) using wide azimuth data and we propose the same workflow with the dual coil acquisition. With the dual coil data, the inversion stages were carefully QC'd through gather displays to ensure the kinematics were honored. In order to approximate the observed data, the acoustic inversion had attenuation, anisotropy, acquisition source and receiver depth incorporated in the propagator.