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  • December 15th 2019: H. Aghamiry, A. Gholami and S. Operto submitted the abstract entitled Robust Full Waveform Inversion for sparse ultra-long offset OBN data to the EAGE Seabed Seismic Today: From Acquisition to Application workshop. * December 18th 2019: H. Aghamiry defended his PhD thesis entitled "Multi-parameter Wavefield Reconstruction Inversion with the Alternating-Direction Method of Multipliers (ADMM) and Compound Regularization" at University of Tehran. This thesis has been performed in the framework of a co-supervizion agreement between University of Tehran and University of Nice-Sophia Antipolis.

  • January 6th 2020: L. Combe joins the WIND project as a permanent CNRS HPC engineer. L. Combe will supervize the development of the time-domain and frequency-domain FWI codes developed during WIND.
  • January 15th 2020: The WIND team submitted the following abstracts to the annual EAGE meeting
1 H. Aghamiry, A. Gholami and S. Operto, Wavefield inversion with adaptive regularization .

2 H. Aghamiry, A. Gholami and S. Operto, On the robustness of sparsity-promoting regularized wavefield inversion with phase retrieval against coarse sampling of sources and receivers .

3 H. Aghamiry, A. Gholami and S. Operto, Computationally-efficient frequency-domain wavefield reconstruction inversion with direct solver .

4 H. Aghamiry, A. Gholami and S. Operto, Proximal-Newton methods to solve non-linear problems with non-smooth regularization .

5 V. Dolean, P. Jolivet, P.-H. Tournier and S. Operto, Iterative frequency-domain seismic wave solvers based on multi-level domain-decomposition preconditioner.

  • January 27th 2020: H. Aghamiry, A. Gholami and S. Operto submitted the masnuscript entitled "Full Waveform Inversion with Adaptive Regularization" to the Geophysical Journal International. This paper discusses two algorithms to implement non smooth and adaptive regularizations in nonlinear inverse problem such as FWI through proximal Newton optimization. The first algorithm relies on FISTA, while the second one relies on the alternating-direction method of multipliers (ADMM).
  • February 3rd 2020: Frichnel-Wilma Mamfoumbi-Ozoumet started her PhD on frequency-domain FWI for long-offset node data. The main objective of this PhD is to assess the robustness of wavefield reconstruction inversion (WRI) and leading-edge regularization techniques as those developed by H. Aghamiry and A. Gholami these last two years against challenging ultra-long offset data sets starting from crude initial models. At least two case studies are targeted: the first is based upon the 2D SFJ OBN data set collected offshore the eastern Nankai trough (offshore Japan). The second relies on a 3D OBC dataset collected in the North Sea. In the first case, the goal is to check whether we can use a less accurate velocity model and a simpler workflow than those designed by Gorszczyk et al., 2017 to reach equivalent results. In the second case, the goal is to start from a basic velocity gradient model and assess also the improvement provided by sparsity promoting regularization to improve the results of Operto & Miniussi, 2018. Subsampled version of this OBC data set will be also used to assess to which extent sparsity-promoting regularization helps to mitigate the detrimental aliasing effects and low fold coverage. This will also used to assess the scheduled theoretical and numerical analysis of node acquisition design recast as an optimization problem.
  • March 5th 2020: New codes are provided in the sponsor area: 1 FDFDMATRIX package generates an impedance matrix for 3D frequency-domain seismic wave modelling in visco-acoustic VTI media with the method of Operto et al. (2014). A smple code calling the MUMPS sparse direct solver can be used to check the wavefield solution. 1 Two toy codes test the FISTA and ADMM based regularization methods for nonlinear optimization problem developed in Full Waveform Inversion with Adaptive Regularization by Aghamiry et al., submitted to IEEE Transactions on Computational Imaging (preprint available in the sponsor area). We use the Rosenbrock function for this assessment.
  • Schedule of the WIND presentations at the next EAGE meeting
1 V. Dolean, P. Jolivet, P.-H. Tournier and S. Operto. Iterative frequency-domain seismic wave solvers based on multi-level domain-decomposition preconditioners, Paper number 1328, Oral presentation, Wave Field Modelling 1, Tuesday, Jun 9, 2020, 8:30 AM - 12:10 PM, E104.

2 H. Aghamiry, A. Gholami, and S. Operto. Proximal-Newton methods to solve non-linear problems with non-smooth regularizations , Paper number 1801, ePoster: FWI B, Tuesday, Jun 9, 2020, 1:30 PM - 5:10 PM, ePosters 02.

3 H. Aghamiry, A. Gholami, and S. Operto. Computationally-efficient frequency-domain wavefield reconstruction inversion with direct solver , Paper number 1844, Oral presentation, FWI 1 - Cycle Skipping & Others, Wednesday, Jun 10, 2020, 8:30 AM - 12:10 PM, E102.

4 H. Aghamiry, A. Gholami, and S. Operto. Wavefield inversion with adaptive regularization , Paper number 1903, Oral presentation, FWI 3 - Regularization & Workflow, Thursday, Jun 11, 2020, 8:30 AM - 12:10 PM E102.

5 H. Aghamiry, A. Gholami, and S. Operto. On the robustness of sparsity-promoting regularized wavefield inversion with phase retrieval against sparse long-offset acquisitions , Paper number 1479, FWI 3 - Regularization & Workflow, Thursday, Jun 11, 2020, 8:30 AM - 12:10 PM, E102. Let's hopefully meet in December.

  • April 15th 2020 The WIND team submitted the following abstracts to the annual SEG meeting
1 H. Aghamiry, A. Gholami and S. Operto, Simultaneous wavespeed and attenuation reconstruction with adaptive BM3D by complex-valued optimization regularization.

2 H. Aghamiry, A. Gholami and S. Operto, Wavefield inversion for microseismic imaging. 1 S. Sambolian, S. Operto, A. Ribodetti and L. Combe, From slope tomography to FWI: is the conventional workflow viable in complex settings?

3 S. Sambolian, S. Operto, A. Ribodetti, and J. Virieux, Revisiting the hypocenter-velocity problem through a slope tomography inspiration

4 V. Dolean, P. H. Tournier, P. Jolivet, and S. Operto, Large-scale frequency-domain seismic wave modeling on h-adaptive tetrahedral meshes with iterative solver and multi-level domain-decomposition preconditioners In the abstract 1, H. Aghamiry formulates visco-acoustic wavefield reconstruction inversion (WRI) with the alternating-method of multipliers (ADMM) in the complex field, namely the optimization parameter is the complex-valued velocity. An adaptive regularization operates also directly on the complex-valued velocity with the 3D block-matching filtering method BM3D. This approach implies that the inversion does not require a priori mathematical attenuation model as the Kolsky-Futterman model. Instead, the real phase velocity and the attenuation (or Q factor) are extracted a posteriori with arbitrary model of complex velocity. We explain how dispersion effects are taken into account during inversion. In the abstract 2, H. Aghamiry tackles the microseismic imaging problem in a FWI framework. He jointly update the wavefield, the source and the velocity model with ADMM-based WRI with appropriate sparsifying regularizations tailored to the last two variables (source and velocity model). No prior assumption on the number of events is made. In the abstract 3, S. Sambolian assesses whether a workflow combining first-arrival slope tomography and a brute-force FWI can reconstruct a complex model such as the original 2004 BP salt model (without rescaling) from an ultra-long offset (97km maximum offset) sparse OBN survey assuming a starting frequency of 1.5 Hz. The results are promising (the salt bodies are fully captured, subsalt imaging is more challenging). Improvement should come from feeding slope tomography with short-spread and post-critical reflections in addition to the first arrivals to supplement these latters in complex or poorly-illuminated area and by equipping FWI with sparsifying regularization as those developed by H. Aghamiry. Ongoing work... In the abstract 4, S. Sambolian tackles the hypocenter-velocity problem with a slope tomography inspiration. This supplements the abstract 2 with a ray-theory based approach. In the abstract 5, V. Dolean, P. H. Tournier and P. Jolivet revisit the results of the EAGE abstract dealing with frequency-domain seismic wave modeling on tetrahedral meshes with ORAS domain-decompositon preconditioners. They investigate which Lagrange polynomials should be used to achieve a sufficient accuracy for a discretization rule of 4-5 grid points per wavelength. They also clarify which backward error tolerance should be used to get accurate wavefield solution, while minimzing the iteration count. They test whether single precision arithmetic provides accurate solution, compare the performance and accuracy of the preconditioner when Cholesky and incomplete LU factorization are used to solve the local problems, and assess the potential of a second level of preconditioning on a coarse grid. The preprint of these abstracts are available on the sponsor page.

  • April 16th 2020: Matlab codes developed by Hossein Aghamiry are provided in the sponsor page to practice various implementations of IR-WRI.
  • May 8th 2020: The WIND technical report n°1 entitled "A practical guide to implement smooth and nonsmooth regularization in Full Waveform Inversion with ADMM" is provided in the sponsor area. This technical report describes a generic procedure based on the alternating-direction method of multiplier (ADMM) to implement smooth and nonsmooth regularization in classical FWI. We review a vast catalog of regularizers including bound constraints, Tikhonov regularizer, Total-Variation (TV) regularizer, compound regularizer such as the Total Generalized Variation regularizer (TGV).
  • May 29th 2020: Hossein Aghamiry submitted the paper entitled "Full Waveform Inversion by Proximal Newton Method using Adaptive Regularization" to the Geophysical Journal International. The preprint is provided on the sponsor page.
  • June 14th 2020: Hossein Aghamiry submitted the paper entitled "Complex-valued Imaging with Total Variation Regularization: An Application to Full-Waveform Inversion in Visco-acoustic Media" to the SIAM Journal on Imaging Science. The preprint is provided on the sponsor page.
  • June 22th 2020: The SEG abstracts submitted by the WIND group (see the list above) are accepted for presentation.
  • June 25th 2020: The WIND Kick-off meeting will be held on Tuesday June 30 and Wednesday July 1st by visio conference.
  • June 25th 2020: A new release of the Matlab codes developed by Hossein Aghamiry are provided on the sponsor page.
  • June 26th 2020: The massively-parallel 2D/3D time-domain FWI code Geoinv3D_fwk have been uploaded on the sponsor page by L. Combe. The platform will be used to test the concepts developed during the WIND project on large-scale synthetic and real case studies.
  • June 28th 2020: The presentations of the Kick-off meeting have been uploaded in the sponsor page.
  • August 4th 2020: the preprint of the publication On efficient frequency-domain full-waveform inversion with extended search space submitted by H. Aghamiry, A. Gholami and S. Operto to Geophysics has been uploaded on the sponsor page.
  • August 4th 2020: the preprint of the publication Consistent seismic event location and subsurface parameters inversion through slope tomography: a variable-projection approach submitted by S. Sambolian, S. Operto, A. Ribodetti and J. Virieux to the Geophyslcal Journal International has been uploaded on the sponsor page.
  • September 10th: S. Operto gave a presentation co-authored with H. Aghamiry and A. Gholami at the EAGE workshop EAGE Seabed Seismic Today: Acquisition to Application (https://eage.eventsair.com/seabed-seismic-ws). The talk was entitled: Robust Full Waveform Inversion for sparse ultra-long offset OBN data.
  • October 1st 2020: Sebastian Riffo joined the WIND staff as a postdoc. He will work on Helmholtz problem with the ORAS method in collaboration with V. Dolean, P. Jolivet and P.H. Tournier and its interfacing with WRI codes. Sebastian Riffo has a background in applied mathematics, in particular on optimization, data assimilation and domain decomposition methods.
  • October 12th 2020: The paper entitled "Complex-valued imaging with total variation regularization: an application to full-waveform inversion in visco-acoustic media" by H. Aghamiry, A. Gholami and S. Operto is accepted for publication in "SIAM Journal on Imaging Sciences".
  • November 2nd 2020: The SEG presentations of the WIND team are available on the intranet page for sponsors.
  • November 2nd 2020: The 2020 activity report of the WIND project is available on the intranet page for sponsors.
  • November 25th 2020: The paper entitled "Consistent event location and subsurface parameters inversion through slope tomography: a variable projection approach" by S. Sambolian, S. Operto, A. Ribodetti and J. Virieux is accepted for publication in the Geophysical Journal International.
  • November 25th 2020: The paper entitled "On efficient frequency-domain Full-Waveform Inversion with extended search space" by H. Aghamiry, A. Gholami and S. Operto is accepted for publication in Geophysics. The last versions have been uploaded in the sponsor page.
  • December 7th 2020: The final version of "Full Waveform Inversion by Proximal Newton Method using Adaptive Regularization" is published in the Geophysical Journal International. The PDF is available on the sponsor page.
  • January 4th 2021: Gaoshan Guo joins the WIND group as PhD student. The main focus of his PhD is the application and assessment of extended time-domain FWI to various real data sets. * Xiaole Zhou also joins the WIND group in the framework of a co-supervizion agreement with the Chinese Academic of Science, Institute of Geology and Geophysics (main supervisors: Prof. Ling Chen and Prof. Haiqiang Lan). In collaboration with Serge Sambolian, she will extend slope tomography based upon eikonal solver and adjoint method to 3D with a special emphasis on the application to 3D areal acquisitions. * Serge Sambolian will defend his PhD on February 8th 2021 (online). The PhD thesis is entitled "Kinematically consistent slope tomography: theory and applications to velocity model building and event location". The committee will be composed of Romain Brossier (ISTerre - Université Grenoble Alpes), Stefan Buske (TU Bergakademie Freiberg), Hervé Chauris (Mines ParisTech - PSL), Jean-Xavier Dessa (Geoazur - Sorbonne UNiversité), Gilles Lambaré (CGG), Stéphane Operto (Geoazur), Alessandra Ribodetti (Geooazur), Steven Roecker (Rensselaer Polytechnic Institute) and Jean Virieux (Université Grenoble Alpes).
  • January 15th 2021: Two extended abstracts are submitted to the annual EAGE meeting. One deals with the time-domain formulation of IR-WRI and the second one with Anderson acceleration of IR-WRI.
  • January 20th 2021: The paper entitled "Efficient extended-search space full-waveform inversion with unknown source signatures" by H. Aghamiry, F. Mamfoumbi, A. Gholami and S. Operto" was submitted to the Geophysical Journal International. H. Aghamiry proposes a computationnaly-efficient method to estimate source signature in IR-WRI when the latter is implemented in the frequency domain. The draft is available on the sponsor page.
  • January 2021: The 3D FFWI frequency-domain FWI code has been revalidated with the Valhall case study on the Occigen super computer of CINES. Mono-parameter FWI for vertical wavespeed and Multi-parameter FWI for vertical wavespeed, density and attenuation have be rerun in the 3.5Hz-10Hz frequency band. Next step involves pushing the inversion up to 15Hz using the BLR version of MUMPS. The code will be released on the sponsor page soon. * February 10th 2021: The paper entitled "Mitigating the ill-posedness of first-arrival traveltime tomography with slopes: application to the eastern Nankai Trough OBS dataset (Japan)" by S. Sambolian, A. Gorszczyk, S. Operto, A. Ribodetti and B. Tavakoli F. has been submitted for publication in the Geophysical Journal International. The draft is available on the sponsor page.
  • February 10th 2021: The PhD thesis and the oral defense of Serge Sambolian can be downloaded from the sponsor page.

  • The paper entitled On efficient frequency-domain Full-Waveform Inversion with extended search space by H. Aghamiry, A. Gholami and S. Operto is published in the March-April issue of Geophysics. The final version have been uploaded in the sponsor page. This paper has been selected as the Geophysics bright spot.
  • March 2021: The 3D FFWI frequency-domain FWI code is performing the Valhall case study on the Jean-Zay super computer of IDRIS. Mono-parameter FWI for vertical wavespeed and Multi-parameter FWI for vertical wavespeed, density and attenuation have be rerun in the 3.5Hz-10Hz frequency band. Next step involves pushing the inversion up to 15Hz using the BLR version of MUMPS.
  • March 12th 2021: The paper entitled Extended-space Full Waveform Inversion in the time domain with the augmented Lagrangian method by H. Aghamiry, A. Gholami and S. Operto has been submitted for publication in Geophysics. This paper describes an efficient algorithm to implement extended-space FWI with the Augmented Lagrangian method in the time domain. The search space extension is generated by a relaxation of the wave equation allowing for an accurate data fit with inaccurate subsurface models. This search space extension generates extended sources in time and space. The subsurface parameters are updated by minimizing both the residual data mismatch and the artificial source extension. The method is formulated with a variable projection method to enforce the reconstructed wavefields in the parameter estimation problem. The draft of the paper is available on the sponsor page.
  • March 25th: Two abstracts are submitted to the Fifth EAGE Workshop on High Performance Computing for Upstream. The first is entitled "Up to date assessment of 3D frequency-domain full waveform inversion based on the sparse multifrontal solver MUMPS" by P. R. Amestoy, A. Buttari, L. Combe, M. Gerest, J.-Y. L'Excellent, T. Mary, S. Operto, and C. Puglisi is proposed in the frame of a colaboration with the MUMPS developer team. It provides an up to date discussion about the kinds of 3D frequency-domain FWI applications (in terms of size) that can be performed today with the sparse direct solver MUMPS. Simulations are performed on the Jean-Zay supercomputer of IDRIS and the occigen supercomputer of CINES.

The solver is re-assessed with the MUMPS solver for problems involving 50 millions of unknowns. 3D frequency-domain VTI visco-acoustic FWI of OBC data in the north sea using the Jean-Zay supercomputer of IDRIS (http://www.idris.fr/jean-zay) and the MUMPS multifrontal solver. (a-d) Horizontal and vertical sections in the final FWI model. Maximum frequency is 10 Hz (see also Operto & Miniussi (2018)). (e-f) Reflectivity images (sum of the horizontal and vertical derivatives). (g-h) Attenuation (Q) reconstruction across and away from the gas cloud. (i) Wavefield simulation at 13Hz involving 45M of unknowns. 70 nodes and 140 MPI processes were used for this simulation. FWI is currently performed at this frequency. The second is entitled "Large-scale finite-difference and finite-element frequency-domain seismic wave modeling with multi-level domain-decomposition preconditioner" by P.-H. Tournier, V. Dolean, P. Jolivet, L. Combe, S. Operto, S. Riffo. This abstract discusses an alternative to performing large-scale seismic modeling in the frequency domain based upon a direct/iterative solver and the multi-level ORAS (Optimized Restricted Additive Scharwz) domain decomposition preconditioner. An optimal setup and a scalability analysis of the solver are discussed as well as a comparison of the accuracy and complexity of a Lagrange-polynomial finite-element discretization on unstructured tetrahedral meshes and the 27-point finite difference stencil with adaptive coefficients using an analytical solution in a velocity gradient model. The draft of the two abstracts is available on the sponsor page.

  • 5 April 2021: The paper entitled "GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment and next -generation 3D survey design (version 1.0)" by A. Gorszczyk and S. Operto is published in Geoscientific Model Development. This paper describes a realistic 3D isotropic visco-elastic geomodel discretized on a Cartesian grid representative of a subduction zone. This geomodel has been designed by A. Gorszczyk to assess imaging techniques and design large-scale 3D surveys for regional crustal scale exploration. The geomodel is freely available on https://dataportal.igf.edu.pl/dataset/go_3d_obs. The publication can befreely dowloaded on https://doi.org/10.5194/gmd-14-1773-2021

Inline vertical section N° 1001 of the GO_3D_OBS geomodel.

  • April 2021: Submission to EAGE 2021 and SEG 2021
  1. H. S. Aghamiry, F. W. Mamfoumbi-Ozoumet, A. Gholami, and S. Operto, ADMM-based full-waveform inversion with unknown source signatures, Submitted to the 91st Annual SEG meeting (Denver).
  2. K. Aghazadeh, A. Gholami, H. S. Aghamiry, and S. Operto, Stochastic extended full-waveform inversion with augmented Lagrangian method, submitted to the 91st Annual SEG meeting (Denver).
  3. A. Gholami, H. Aghamiry and S. Operto. Clarifying some issues on Extended FWI: scattered-field equation, time reversal and source reconstruction, submitted to the 91st Annual SEG meeting (Denver).
  4. A. Gholami, H. Aghamiry and S. Operto. A data reconstruction inversion approach to extended FWI, submitted to the 91st Annual SEG meeting (Denver).
  5. A. Rezaei, H. S. Aghamiry, A. Gholami, and S. Operto, Iterative reconstruction of data assimilated wavefields in the extended-source full-waveform inversion, Submitted to 82th Annual EAGE Meeting (Amsterdam).
  6. A. Gholami, H. Aghamiry, and S. Operto. Data Reconstruction Inversion: an augmented Lagrangian based full-waveform inversion in the time domain. Submitted to 82th Annual EAGE Meeting (Amsterdam).
  7. K. Aghazadeh, A. Gholami, H. S. Aghamiry, and S. Operto, Augmented Lagrangian based full-waveform inversion with Anderson acceleration, Submitted to 82th Annual EAGE Meeting (Amsterdam)
Abstract 1 proposes an approach to perform source signature estimation during frequency-domain WRI. Abstract 2 proposes to mitigate the computational burden of multi-source modeling in IR-WRI with random source encoding. Abstract 3 clarifies the mechanisms through which wavefield reconstruction inversion with extended sources works. Abstract 4 reformulates the wavefield reconstruction inversion method where the concept of intermediate data is introduced following the heuristic approach of Yao et al. (2019). Abstract 5 assesses different preconditioners to compute data-assimilated wavefields with the iterative linear conjugate gradient method. Abstract 6 describes an efficient algorithm to implement WRI in the time domain with an augmented Lagrangian method. Abstract 7 assesses the Anderson acceleration optimization scheme in the framework of WRI.

The PDF of these abstract are available on the sponsor page.

  • May 2021: The paper entitled "Efficient extended-search space full-waveform inversion with unknown source signatures" by H. Aghamiry, F. Mamfoumbi, A. Gholami and S. Operto" is accepted for publication in the Geophysical Journal International.
  • June 2021: The paper entitled "Anderson accelerated augmented Lagrangian for extended waveform inversion" by Kamal Aghazade, Ali Gholami, Hossein S. Aghamiry, and Stéphane Operto has been submited to Geophysics. This paper recasts WRI as fixed-point problem to improve its convergence rate with Anderson method. The preprint is available on the sponsor page.
  • June 30 2021: The paper entitled "Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS dataset" by S. Sambolian, A. Gorszczyk, S. Operto, A. Ribodetti and B. Tavakoli, is accepted for publication in the Geophysical Journal International.