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.

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Full Waveform Inversion (FWI) is now used regularly by the industry to update velocity models. These algorithms often take into account anisotropy but do not update it. We introduce a set of parameters, new in the scope of FWI, which have better orthogonal properties in comparison to other equivalent sets. This was done in an attempt to mitigate the existing ambiguity when jointly estimating anisotropy and velocity from FWI. After demonstrating the properties of this new parameter set, a practical application to a North Sea field dataset is then presented. Our FWI result reveals interesting velocity and anisotropy details associated with features in the near surface geology; an associated improvement in the seismic image is also observed.

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