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The importance of including density in multiparameter asymptotic linearized direct waveform inversion: a case study from the Eastern Nankai Trough

Abstract : SUMMARY Iterative least-squares reverse time migration (LSRTM) is the state-of-the-art linearized waveform inversion method to obtain quantitative subsurface parameters. The main drawback of such an iterative imaging scheme is the significant computational expense of many modelling/adjoint cycles through iterations. In the context of the extended domain, an interesting alternative to LSRTM is the asymptotic linearized direct waveform inversion, providing quantitative results with only a single iteration. This approach was first proposed for constant-density acoustics and recently extended to the variable-density case. The former is based on the application of the asymptotic inverse Born operator, whereas the latter has two more extra steps: building an angle-dependent response of the asymptotic inverse Born operator and then solving a weighted least-squares approach for simultaneous inversion of two acoustic parameters. To examine the importance of accounting for density variations, we compare constant- and variable-density linearized direct waveform inversion techniques applied to a marine real data set from the Eastern Nankai Trough, offshore Japan. The inversion results confirm the efficiency of the asymptotic linearized direct waveform inversion in estimating quantitative parameters within a single iteration. The variable-density direct inversion yields subsurface images that (1) exhibit a superior resolution and (2) better reconstruct the field data than does the constant-density approach, even if the data set does not contain large enough surface offset to fully decompose velocity and density perturbations.
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https://hal-mines-paristech.archives-ouvertes.fr/hal-03549596
Contributor : Mark Noble Connect in order to contact the contributor
Submitted on : Monday, January 31, 2022 - 2:53:04 PM
Last modification on : Friday, February 25, 2022 - 12:30:11 PM

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Milad Farshad, Hervé Chauris, Mark S. Noble. The importance of including density in multiparameter asymptotic linearized direct waveform inversion: a case study from the Eastern Nankai Trough. Geophysical Journal International, Oxford University Press (OUP), 2022, 228 (2), pp.1373-1391. ⟨10.1093/gji/ggab405⟩. ⟨hal-03549596⟩

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