Full-waveform inversion of variable-depth streamer data: An application to shallow channel modeling in the North Sea

Abstract

Full-waveform inversion of variable-depth streamer data: An application to shallow channel modeling in the North Sea I ndustry implementations of full-waveform inversion (FWI) are driven by the lower frequencies in the seismic data. is is in conflict with conventional acquisition scenarios where the free-surface ghost attenuates these desired low frequencies. In this article, we discuss the application of FWI to variable-depth streamer data and show that FWI adapts naturally to this acquisition geometry, hence benefitting from the improved low frequencies recorded in this configuration. We illustrate this with an example from the central North Sea, where detailed velocity features associated with the shallow channels in the near-surface geology are revealed by FWI. Migration with this updated velocity model improves the imaging through the near surface.

Full waveform inversion using preserved amplitude reverse time migration

“…We start our FWI workflow at 4 Hz, a reasonable starting frequency in real data cases. We perform conventional FWI (Ratcliffe et al, 2013) updates in a 4 Hz to 11 Hz multi-scale inversion process. Six frequency ranges are defined and we use 6 iterations in each range.…”

Using full waveform inversion to update supra-salt velocity models: A case study in the Gulf of Mexico

“…Wave-equation based FWI, pioneered by Lailly (1983) and Tarantola (1984), updates a velocity model by minimizing the mismatch between the observed and modeled seismic data. Studies have proven that FWI can provide detailed and interpretive velocity models, especially in the presence of shallow channel features and gas pockets (Sirgue et al, 2009;Jones et al, 2013;Ratcliffe et al, 2013;Mothi et al, 2013). In this study we applied FWI to resolve complex overburden velocities in a geologically challenging area where shallow geo-bodies, fractures and carapaces co-exist with shallow salt.…”