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Soft Dynamic Time Warping Divergence As A Misfit Measure In Full Waveform Inversion

1 Jan 2023

Soft-dynamic time warping divergence as a misfit measure in full-waveform inversion

Year: 2023First Published: EAGEAuthors: Mahesh Kalita, Chris Purcell, and Lorenzo Casasanta


Full-waveform inversion finds a subsurface model that minimizes the misfit between modelled seismic data and observations. It’s well known that the L2-norm of the waveforms difference is prone to cycle-skipping due to the presence of local minima. We introduce the soft-dynamic time warping divergence distance as a misfit metric in FWI. This formulation contains a hyper-parameter (γ) that renders the functional differentiable, thereby enabling the adjoint state method to compute the FWI gradient. A large value of γ produces a smooth gradient but limits the basin of attraction in the inversion process. Contrary to soft-dynamic time warping, its divergence form is always positive, and its minimum exists only when the modelled trace matches the observed trace. We present its application to a synthetic dataset from the Marmousi model and a marine field dataset from offshore Australia.

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