Robust wavefield inversion via phase retrieval

Aghamiry, Hossein S.; Gholami, Ali; Operto, S.

doi:10.1093/gji/ggaa035

Cited by 9 publications

(11 citation statements)

References 50 publications

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“…Unlike previous synthetic studies combining TTT and FWI that use both sources and receivers fixed and placed all along the model (e.g. [2], [3], [8]), our approach is a more realistic geometry of a marine experiment facing the problems of limited coverage and illumination. The main issue to perform TTT is the identification of refractions as first arrivals, especially 2a).…”

Section: Discussionmentioning

confidence: 99%

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Toward a Practical Appraisal for Waveform Tomography of Band- and Offset-Limited Marine Seismic Data

Gras¹,

Tejero

Sallarès

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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We present a generalized workflow to retrieve highresolution P-wave velocity (VP ) models of complex Earths subsurface structures from traditional marine near-vertical seismic reflection experiments. These records have typically offsets too short to map refraction phases and lack low frequency information. The workflow is composed of three steps: (1) downward continuation (DC) of seismic records to the seafloor to recover diving wave information; (2) travel-time tomography (TTT) of first arrivals obtained from DC data, to retrieve a kinematically correct model, and (3) full-waveform inversion (FWI) of the original streamer data set, starting with the model obtained with TTT and sequentially introducing higher wavenumber details into the model. We show that the TTT allows overcoming the issues associated to the non-linearity intrinsic to FWI. We also disentangle envelope and phase from the waveform to choose the objective function most suitable for FWI. We assess the accuracy of initial models and predict the quality of the FWI results by quantifying the early-arrival cycle skipping between original and simulated data. The efficiency of the workflow is tested with a challenging synthetic target model, containing vertical boundaries with a strong velocity contrasts and velocity inversions embedded in a checkerboard-like pattern. We show that workflow steps (1) and ( 2) provide a TTT model that is not cycle-skipped at the frequencies available in most marine seismic experiments, and thus allow step (3) FWI to obtain highresolution VP models of the subsurface using band-and offsetlimited field data sets, traditionally collected in marine airgun and streamer acquisitions.

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Section: Discussionmentioning

confidence: 99%

“…[17], [29]), to employ more robust objective functions to compare the recorded and simulated wavefield ( e.g. [2], [30], [31], [59]) or to implement signal-and/or gradient-based preconditioning or regularization techniques (e.g. [3], [55]).…”

Section: B Seismic Data Inversionmentioning

confidence: 99%

Toward a Practical Appraisal for Waveform Tomography of Band- and Offset-Limited Marine Seismic Data

Gras¹,

Tejero

Sallarès

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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“…Here, we focus on the optimization subproblem (3a). The readers are referred to Aghamiry et al (2019aAghamiry et al ( , 2020aAghamiry et al ( , 2021 for the closed-form expression of the optimization subproblem (3b) with bound constraints and different regularizations and to Aghamiry et al (2020b) for a more robust implementation of this subproblem against velocity model errors with phase retrieval. Optimization problem (3a) is quadratic in u i and s i and can be written as…”

Section: Notation and Problem Statementmentioning

confidence: 99%

Efficient extended-search space full-waveform inversion with unknown source signatures

Aghamiry,

Mamfoumbi-Ozoumet,

Gholami

et al. 2021

Preprint

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Full waveform inversion (FWI) requires an accurate estimation of source signatures. Due to the coupling between the source signatures and the subsurface model, small errors in the former can translate into large errors in the latter. When direct methods are used to solve the forward problem, classical frequency-domain FWI efficiently processes multiple sources for source signature and wavefield estimations once a single Lower-Upper (LU) decomposition of the wave-equation operator has been performed. However, this efficient FWI formulation is based on the exact solution of the wave equation and hence is highly sensitive to the inaccuracy of the velocity model due to the cycle skipping pathology. Recent extended-space FWI variants tackle this sensitivity issue through a relaxation of the wave equation combined with data assimilation, allowing the wavefields to closely match the data from the first inversion iteration. Then, the subsurface parameters are updated by minimizing the wave-equation violations. When the wavefields and the source signatures are jointly estimated with this approach, the extended wave equation operator becomes source dependent, hence making direct methods and, to a lesser extent, block iterative methods ineffective. In this paper, we propose a simple method to bypass this issue and estimate source signatures efficiently during extended FWI. The proposed method replaces each source with a blended source during each data-assimilated wavefield reconstruction to make the extended wave equation operator source independent. Besides computational efficiency, the additional degrees of freedom introduced by spatially distributing the sources allows for a better signature estimation at the physical location when the velocity model is rough. We implement the source signature estimation with a variable projection method in the recently proposed iteratively-refined wavefield reconstruction inversion (IR-WRI) method. Numerical tests on the Marmousi II and 2004 BP salt synthetic models confirm the efficiency and the robustness against velocity model errors of the new method compared to the case where source signatures are known.

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“…Beyond these theoretical questions of the existence and uniqueness of solutions, an efficient method that recovers the phase object f is needed. To invert for the object f from the measurements in (1), iterative algorithms that serve as approximate inverses are usually employed. Gerchberg and Saxton [19], and later Fienup [17], introduced a scheme based on iterative projections which is simple to implement and proved to be very flexible in practice.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, we mention that the proposed algorithm also finds applications in other fields such as exploration seismology in which strong phase errors in the data can make the classical algorithms fail because they try to match the incorrect phase information, so the measured phases are discarded and the inverse problem is formed for intensities-only [20,1].…”

Section: Introductionmentioning

confidence: 99%

Quantitative phase and absorption contrast imaging

Moscoso¹,

Novikov²,

Papanicolaou³

et al. 2022

Preprint

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Phase retrieval in its most general form is the problem of reconstructing a complex valued function from phaseless information of some transform of that function. This problem arises in various fields such as X-ray crystallography, electron microscopy, coherent diffractive imaging, astronomy, speech recognition, and quantum mechanics. The mathematical and computational analysis of these problems has a long history and a variety of different algorithms has been proposed in the literature. The performance of which usually depends on the constraints imposed on the sought function and the number of measurements. In this paper, we present an algorithm for coherent diffractive imaging with phaseless measurements. The algorithm accounts for both coherent and incoherent wave propagation and allows for reconstructing absorption as well as phase images that quantify the attenuation and the refraction of the waves when they go through an object. The algorithm requires coherent or partially coherent illumination, and several detectors to record the intensity of the distorted wave that passes through the object under inspection. To obtain enough information for imaging, a series of masks are introduced between the source and the object that create a diversity of illumination patterns.

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Robust wavefield inversion via phase retrieval

Cited by 9 publications

References 50 publications

Toward a Practical Appraisal for Waveform Tomography of Band- and Offset-Limited Marine Seismic Data

Toward a Practical Appraisal for Waveform Tomography of Band- and Offset-Limited Marine Seismic Data

Efficient extended-search space full-waveform inversion with unknown source signatures

Quantitative phase and absorption contrast imaging

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