Bibliografie tematiche / Inversion full wave

Letteratura scientifica selezionata sul tema "Inversion full wave"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Inversion full wave":

Luo, Yi, Yue Ma, Yan Wu, Hongwei Liu e Lei Cao. "Full-traveltime inversion". GEOPHYSICS 81, n. 5 (settembre 2016): R261—R274. http://dx.doi.org/10.1190/geo2015-0353.1.

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Many previously published wave-equation-based methods, which attempt to automatically invert traveltime or kinematic information in seismic data or migrated gathers for smooth velocities, suffer a common and severe problem — the inversions are involuntarily and unconsciously hijacked by amplitude information. To overcome this problem, we have developed a new wave-equation-based traveltime inversion methodology, referred to as full-traveltime (i.e., fully dependent on traveltime) inversion (FTI), to automatically estimate a kinematically accurate velocity model from seismic data. The key idea of FTI is to make the inversion fully dependent on traveltime information, and thus prevent amplitude interference during inversion. Under the assumption that velocity perturbations cause only traveltime changes, we have derived the FTI method in the data and image domains, which are applicable to transmitted arrivals and reflected waves, respectively. FTI does not require an accurate initial velocity model or low-frequency seismic data. Synthetic and field data tests demonstrate that FTI produces satisfactory inversion results, even when using constant velocity models as initials.

Brossier, Romain, Stéphane Operto e Jean Virieux. "Seismic imaging of complex onshore structures by 2D elastic frequency-domain full-waveform inversion". GEOPHYSICS 74, n. 6 (novembre 2009): WCC105—WCC118. http://dx.doi.org/10.1190/1.3215771.

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Quantitative imaging of the elastic properties of the subsurface at depth is essential for civil engineering applications and oil- and gas-reservoir characterization. A realistic synthetic example provides for an assessment of the potential and limits of 2D elastic full-waveform inversion (FWI) of wide-aperture seismic data for recovering high-resolution P- and S-wave velocity models of complex onshore structures. FWI of land data is challenging because of the increased nonlinearity introduced by free-surface effects such as the propagation of surface waves in the heterogeneous near-surface. Moreover, the short wavelengths of the shear wavefield require an accurate S-wave velocity starting model if low frequencies are unavailable in the data. We evaluated different multiscale strategies with the aim of mitigating the nonlinearities. Massively parallel full-waveform inversion was implemented in the frequency domain. The numerical optimization relies on a limited-memory quasi-Newton algorithm thatoutperforms the more classic preconditioned conjugate-gradient algorithm. The forward problem is based upon a discontinuous Galerkin (DG) method on triangular mesh, which allows accurate modeling of free-surface effects. Sequential inversions of increasing frequencies define the most natural level of hierarchy in multiscale imaging. In the case of land data involving surface waves, the regularization introduced by hierarchical frequency inversions is not enough for adequate convergence of the inversion. A second level of hierarchy implemented with complex-valued frequencies is necessary and provides convergence of the inversion toward acceptable P- and S-wave velocity models. Among the possible strategies for sampling frequencies in the inversion, successive inversions of slightly overlapping frequency groups is the most reliable when compared to the more standard sequential inversion of single frequencies. This suggests that simultaneous inversion of multiple frequencies is critical when considering complex wave phenomena.

Zhang, Chao, Ting Lei e Yi Wang. "Two-Dimensional Full-Waveform Joint Inversion of Surface Waves Using Phases and Z/H Ratios". Applied Sciences 11, n. 15 (22 luglio 2021): 6712. http://dx.doi.org/10.3390/app11156712.

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Surface-wave dispersion and the Z/H ratio are important parameters used to resolve the Earth’s structure, especially for S-wave velocity. Several previous studies have explored using joint inversion of these two datasets. However, all of these studies used a 1-D depth-sensitivity kernel, which lacks precision when the structure is laterally heterogeneous. Adjoint tomography (i.e., full-waveform inversion) is a state-of-the-art imaging method with a high resolution. It can obtain better-resolved lithospheric structures beyond the resolving ability of traditional ray-based travel-time tomography. In this study, we present a systematic investigation of the 2D sensitivities of the surface wave phase and Z/H ratio using the adjoint-state method. The forward-modeling experiments indicated that the 2D phase and Z/H ratio had different sensitivities to the S-wave velocity. Thus, a full-waveform joint-inversion scheme of surface waves with phases and a Z/H ratio was proposed to take advantage of their complementary sensitivities to the Earth’s structure. Both applications to synthetic data sets in large- and small-scale inversions demonstrated the advantage of the joint inversion over the individual inversions, allowing for the creation of a more unified S-wave velocity model. The proposed joint-inversion scheme offers a computationally efficient and inexpensive alternative to imaging fine-scale shallow structures beneath a 2D seismic array.

Yilmaz, Öz, Kai Gao, Milos Delic, Jianghai Xia, Lianjie Huang, Hossein Jodeiri e Andre Pugin. "A reality check on full-wave inversion applied to land seismic data for near-surface modeling". Leading Edge 41, n. 1 (gennaio 2022): 40–46. http://dx.doi.org/10.1190/tle41010040.1.

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We evaluate the performance of traveltime tomography and full-wave inversion (FWI) for near-surface modeling using the data from a shallow seismic field experiment. Eight boreholes up to 20-m depth have been drilled along the seismic line traverse to verify the accuracy of the P-wave velocity-depth model estimated by seismic inversion. The velocity-depth model of the soil column estimated by traveltime tomography is in good agreement with the borehole data. We used the traveltime tomography model as an initial model and performed FWI. Full-wave acoustic and elastic inversions, however, have failed to converge to a velocity-depth model that desirably should be a high-resolution version of the model estimated by traveltime tomography. Moreover, there are significant discrepancies between the estimated models and the borehole data. It is understandable why full-wave acoustic inversion would fail — land seismic data inherently are elastic wavefields. The question is: Why does full-wave elastic inversion also fail? The strategy to prevent full-wave elastic inversion of vertical-component geophone data trapped in a local minimum that results in a physically implausible near-surface model may be cascaded inversion. Specifically, we perform traveltime tomography to estimate a P-wave velocity-depth model for the near-surface and Rayleigh-wave inversion to estimate an S-wave velocity-depth model for the near-surface, then use the resulting pairs of models as the initial models for the subsequent full-wave elastic inversion. Nonetheless, as demonstrated by the field data example here, the elastic-wave inversion yields a near-surface solution that still is not in agreement with the borehole data. Here, we investigate the limitations of FWI applied to land seismic data for near-surface modeling.

Tran, Khiem T., Michael McVay, Michael Faraone e David Horhota. "Sinkhole detection using 2D full seismic waveform tomography". GEOPHYSICS 78, n. 5 (1 settembre 2013): R175—R183. http://dx.doi.org/10.1190/geo2013-0063.1.

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We have developed an application of 2D time-domain waveform tomography for detection of embedded sinkholes and anomalies. The measured seismic surface wavefields were inverted using a full-waveform inversion (FWI) technique, based on a finite-difference solution of 2D elastic wave equations and the Gauss-Newton inversion method. The key advantage of this approach is the ability to generate all possible wave propagation modes of seismic wavefields (body waves and Rayleigh waves) that are then compared with measured data to infer complex subsurface properties.The pressure-wave (P-wave) and shear-wave (S-wave) velocities are inverted independently and simultaneously. The FWI was applied to one synthetic and two real experimental data sets. The inversion results of synthetic data showed the useful capability of the waveform analysis in identifying an embedded void. The inversion results of real data sets showed that the waveform analysis was able to delineate (1) an embedded concrete culvert and (2) a complex profile with an embedded void and highly variable bedrock laterally and vertically. An independent invasive test (standard penetration test) was also conducted to verify the seismic test results.

Barnes, Christophe, e Marwan Charara. "The domain of applicability of acoustic full-waveform inversion for marine seismic data". GEOPHYSICS 74, n. 6 (novembre 2009): WCC91—WCC103. http://dx.doi.org/10.1190/1.3250269.

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Marine reflection seismic data inversion is a compute-intensive process, especially in three dimensions. Approximations often are made to limit the number of physical parameters we invert for, or to speed up the forward modeling. Because the data often are dominated by unconverted P-waves, one popular approximation is to consider the earth as purely acoustic, i.e., no shear modulus. The material density sometimes is taken as a constant. Nonlinear waveform seismic inversion consists of iteratively minimizing the misfit between the amplitudes of the measured and the modeled data. Approximations, such as assuming an acoustic medium, lead to incorrect modeling of the amplitudes of the seismic waves, especially with respect to amplitude variation with offset (AVO), and therefore have a direct impact on the inversion results. For evaluation purposes, we have performed a series of inversions with different approximations and different constraints whereby the synthetic data set to recover is computed for a 1D elastic medium. A series of numerical experiments, although simple, help to define the applicability domain of the acoustic assumption. Acoustic full-wave inversion is applicable only when the S-wave velocity and the density fields are smooth enough to reduce the AVO effect, or when the near-offset seismograms are inverted with a good starting model. However, in many realistic cases, acoustic approximation penalizes the full-wave inversion of marine reflection seismic data in retrieving the acoustic parameters.

Biondi, Biondo, e Ali Almomin. "Simultaneous inversion of full data bandwidth by tomographic full-waveform inversion". GEOPHYSICS 79, n. 3 (1 maggio 2014): WA129—WA140. http://dx.doi.org/10.1190/geo2013-0340.1.

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The convergence of full-waveform inversion can be improved by extending the velocity model along either the subsurface-offset axis or the time-lag axis. The extension of the velocity model along the time-lag axis enables us to linearly model large time shifts caused by velocity perturbations. This linear modeling was based on a new linearization of the scalar wave equation in which perturbation of the extended slowness squared was convolved in time with the second time derivative of the background wavefield. The linearization was accurate for reflected events and transmitted events. We determined that it can effectively model conventional reflection data as well as modern long-offset data containing diving waves. It also enabled the simultaneous inversion of reflections and diving waves, even when the starting velocity model was far from being accurate. We solved the optimization problem related to the inversion with a nested algorithm. The inner iterations were based on the proposed linearization and on a mixing of scales between the short- and long-wavelength components of the velocity model. Numerical tests performed on synthetic data modeled on the Marmousi model and on the “Caspian Sea” portion of the well-known BP model demonstrated the global-convergence properties as well as the high-resolution potential of the proposed method.

da Silva, Nuno V., Gang Yao e Michael Warner. "Semiglobal viscoacoustic full-waveform inversion". GEOPHYSICS 84, n. 2 (1 marzo 2019): R271—R293. http://dx.doi.org/10.1190/geo2017-0773.1.

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Full-waveform inversion deals with estimating physical properties of the earth’s subsurface by matching simulated to recorded seismic data. Intrinsic attenuation in the medium leads to the dispersion of propagating waves and the absorption of energy — media with this type of rheology are not perfectly elastic. Accounting for that effect is necessary to simulate wave propagation in realistic geologic media, leading to the need to estimate intrinsic attenuation from the seismic data. That increases the complexity of the constitutive laws leading to additional issues related to the ill-posed nature of the inverse problem. In particular, the joint estimation of several physical properties increases the null space of the parameter space, leading to a larger domain of ambiguity and increasing the number of different models that can equally well explain the data. We have evaluated a method for the joint inversion of velocity and intrinsic attenuation using semiglobal inversion; this combines quantum particle-swarm optimization for the estimation of the intrinsic attenuation with nested gradient-descent iterations for the estimation of the P-wave velocity. This approach takes advantage of the fact that some physical properties, and in particular the intrinsic attenuation, can be represented using a reduced basis, substantially decreasing the dimension of the search space. We determine the feasibility of the method and its robustness to ambiguity with 2D synthetic examples. The 3D inversion of a field data set for a geologic medium with transversely isotropic anisotropy in velocity indicates the feasibility of the method for inverting large-scale real seismic data and improving the data fitting. The principal benefits of the semiglobal multiparameter inversion are the recovery of the intrinsic attenuation from the data and the recovery of the true undispersed infinite-frequency P-wave velocity, while mitigating ambiguity between the estimated parameters.

Luo, Y., e G. T. Schuster. "Wave‐equation traveltime inversion". GEOPHYSICS 56, n. 5 (maggio 1991): 645–53. http://dx.doi.org/10.1190/1.1443081.

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This paper presents a new traveltime inversion method based on the wave equation. In this new method, designated as wave‐equation traveltime inversion (WT), seismograms are computed by any full‐wave forward modeling method (we use a finite‐difference method). The velocity model is perturbed until the traveltimes from the synthetic seismograms are best fitted to the observed traveltimes in a least squares sense. A gradient optimization method is used and the formula for the Frechét derivative (perturbation of traveltimes with respect to velocity) is derived directly from the wave equation. No traveltime picking or ray tracing is necessary, and there are no high frequency assumptions about the data. Body wave, diffraction, reflection and head wave traveltimes can be incorporated into the inversion. In the high‐frequency limit, WT inversion reduces to ray‐based traveltime tomography. It can also be shown that WT inversion is approximately equivalent to full‐wave inversion when the starting velocity model is “close” to the actual model. Numerical simulations show that WT inversion succeeds for models with up to 80 percent velocity contrasts compared to the failure of full‐wave inversion for some models with no more than 10 percent velocity contrast. We also show that the WT method succeeds in inverting a layered velocity model where a shooting ray‐tracing method fails to compute the correct first arrival times. The disadvantage of the WT method is that it appears to provide less model resolution compared to full‐wave inversion, but this problem can be remedied by a hybrid traveltime + full‐wave inversion method (Luo and Schuster, 1989).

Dettmer, Jan, Stan E. Dosso e Charles W. Holland. "Full wave-field reflection coefficient inversion". Journal of the Acoustical Society of America 122, n. 6 (dicembre 2007): 3327–37. http://dx.doi.org/10.1121/1.2793609.

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Più fonti

Tesi sul tema "Inversion full wave":

Safani, Jamhir. "Surface wave dispersion modelling by full-wavefield reflectivity and inversion for shallow subsurface imaging". 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136173.

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Macedo, Daniel Leal 1975. "Scattering-based decomposition of sensitivity kernels of acoustic full waveform inversion = Decomposição baseada em teoria de espalhamento dos núcleos de sensibilidade da inversão de onda completa acústica". [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265785.

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Orientador: Dietrich Wilhelm Schleicher
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica, Instituto de Geociências
Made available in DSpace on 2018-08-26T05:18:51Z (GMT). No. of bitstreams: 1 Macedo_DanielLeal_D.pdf: 16481305 bytes, checksum: 3d47b0427882ec03cc38bd035feee293 (MD5) Previous issue date: 2014
Resumo: A inversão de onda completa (FWI, do inglês ''full waveform inversion'') nãolinear baseada em gradientes (métodos de descida) é, a princípio, capaz de levar em conta todos os aspectos da propagação de onda contida nos dados síismicos. Porém, FWI baseada em gradientes é limitada pela sua bem conhecida sensibilidade no que diz respeito à escolha do modelo inicial. Com o intuito de melhor entender algumas questões relacionadas à convergência do modelo na FWI, nós estudamos uma decomposição baseada na teoria de espalhamento que permite dividir os núcleos de sensibilidade dos campos de onda acústica em função dos parâmetros do modelo em duas partes: uma relativa ao componente de fundo, outra relativa à componente singular do modelo. Estimativas para a perturbação de fundo, bem como para a perturbação da parte singular do modelo obtidas com os adjuntos destes subnúcleos são componentes da estimativa obtida com o adjunto do núcleo total de sensibilidade. Os experimentos numéricos suportam a tese de que a decomposiçao em subnúcleos permite que se retroprojete somente os resíduos do campo de onda espalhado de modo a obter estimativas razoáveis da perturbação de fundo do modelo. Em um experimento com geometria de aquisição restrita (dados de reflexão com afastamento curto), os subnúcleos baseados em espalhamento múltiplo se aproveitam da autoiluminacão do meio devido às ondas multiplamente espalhadas. A autoiluminação fornece estimativas melhores com conteúdo espectral mais rico nas baixas frequências
Abstract: While in principle nonlinear gradient-based full-waveform inversion (FWI) is capable of handling all aspects of wave propagation contained in the data, including full nonlinearity, in practice, it is limited due to its notorious sensitivity to the choice of the starting model. To help addressing model-convergence issues in FWI, we study a decomposition based on the scattering theory that allows to break the acoustic-wavefield sensitivity kernels with respect to model parameters into background and singular parts. The estimates for both background perturbation and/or singular-part perturbation obtained with the subkernels' adjoints are components of the estimate obtained with the total kernel's adjoint. Our numerical experiments shows the feasibility of our main claim: the decomposition into subkernels allows to backproject the scattered-wavefield residuals only so as to obtain reasonable background-model perturbation estimates. In an experiment with restricted acquisition geometry (reflection data, narrow offset), the multiple-scattering subkernels take advantage of medium self-illumination provided by the scattered wavefields. This self-illumination provides better estimates, with longer wavelengh content
Doutorado
Reservatórios e Gestão
Doutor em Ciências e Engenharia de Petróleo

Freudenreich, Yann Pierre. "P- and S-wave velocity estimation from full wavefield inversion of wide-aperture seismic data". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620695.

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Watson, Francis Maurice. "Better imaging for landmine detection : an exploration of 3D full-wave inversion for ground-penetrating radar". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/better-imaging-for-landmine-detection-an-exploration-of-3d-fullwave-inversion-for-groundpenetrating-radar(720bab5f-03a7-4531-9a56-7121609b3ef0).html.

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Humanitarian clearance of minefields is most often carried out by hand, conventionally using a a metal detector and a probe. Detection is a very slow process, as every piece of detected metal must treated as if it were a landmine and carefully probed and excavated, while many of them are not. The process can be safely sped up by use of Ground-Penetrating Radar (GPR) to image the subsurface, to verify metal detection results and safely ignore any objects which could not possibly be a landmine. In this thesis, we explore the possibility of using Full Wave Inversion (FWI) to improve GPR imaging for landmine detection. Posing the imaging task as FWI means solving the large-scale, non-linear and ill-posed optimisation problem of determining the physical parameters of the subsurface (such as electrical permittivity) which would best reproduce the data. This thesis begins by giving an overview of all the mathematical and implementational aspects of FWI, so as to provide an informative text for both mathematicians (perhaps already familiar with other inverse problems) wanting to contribute to the mine detection problem, as well as a wider engineering audience (perhaps already working on GPR or mine detection) interested in the mathematical study of inverse problems and FWI.We present the first numerical 3D FWI results for GPR, and consider only surface measurements from small-scale arrays as these are suitable for our application. The FWI problem requires an accurate forward model to simulate GPR data, for which we use a hybrid finite-element boundary-integral solver utilising first order curl-conforming N\'d\'{e}lec (edge) elements. We present a novel `line search' type algorithm which prioritises inversion of some target parameters in a region of interest (ROI), with the update outside of the area defined implicitly as a function of the target parameters. This is particularly applicable to the mine detection problem, in which we wish to know more about some detected metallic objects, but are not interested in the surrounding medium. We may need to resolve the surrounding area though, in order to account for the target being obscured and multiple scattering in a highly cluttered subsurface. We focus particularly on spatial sensitivity of the inverse problem, using both a singular value decomposition to analyse the Jacobian matrix, as well as an asymptotic expansion involving polarization tensors describing the perturbation of electric field due to small objects. The latter allows us to extend the current theory of sensitivity in for acoustic FWI, based on the Born approximation, to better understand how polarization plays a role in the 3D electromagnetic inverse problem. Based on this asymptotic approximation, we derive a novel approximation to the diagonals of the Hessian matrix which can be used to pre-condition the GPR FWI problem.

Li, Ruiping. "Inversion for the Elastic Parameters of Layered Transversely Isotropic Media". Curtin University of Technology, Department of Exploration Geophysics, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12924.

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In most cases of seismic processing and interpretation, elastic isotropy is assumed. However, velocity anisotropy is found to exist in most subsurface media. Hence, there exists a fundamental inconsistency between theory on the one hand, and practice on the other. If not recognised, this can invalidate interpretation of seismic data. In this thesis, inversion methods for elastic parameters are developed to quantify the degree of velocity anisotropy of multi-layered transversely isotropic media. This primarily involves examining the velocity fields of layered media using anisotropic elastic wave propagation theory, and developing inversion programs to recover elastic parameters from those velocity fields. The resolved elastic parameter information is used in carrying out further studies on the effects of seismic anisotropy on normal moveout (NMO). Mathematical analyses, numerical simulations, and physical modelling experiments are used in this research for verification purposes before application to field survey data. Numerical studies show the transmission velocity field through layered media appears to be equivalent to that through a single-layered medium, within the practical offset limits in field surveys. The elastic parameters, which describe the property of such equivalent single-layered media, can be used as apparent elastic parameters to describe the collective mechanical property of the layered media. During this research, Snell's law was used in ray tracing to determine ray paths through the interface between any two component layers. By analyzing the signals recorded by any receiver in a walkaway VSP survey, the apparent transmission velocity field for the layered media above this receiver depth was inverted.
Software was developed to recover the apparent elastic parameters for the layered media above this receiver depth using the transmission velocity field as input. Based on a two-layered model, another method was developed to recover the interval elastic parameters for an individual layer of interest, using the signals recorded by receivers on the upper and lower surfaces of this layer. The recovered elastic parameters may be considerably different from the real values if a transversely isotropic medium with a tilted symmetry axis (TTI) is treated as a transversely isotropic medium with a vertical symmetry axis (VTI). A large angle of tilt of the symmetry axis significantly influences the recorded velocity field through the medium. An inversion program was written to recover the value of the tilt angle of a TTI medium, and the elastic parameters of the medium. Programs were also developed to combine information from P, SV, and SH-waves in an inversion procedure. This capability in inversion programs enables us to use the additional information provided by a multi-component VSP survey to obtain accurate estimates of the elastic parameters of geological formations. Software testing and development was carried out on numerically generated input data. Up to 10 milliseconds of random noise in travel time was added to the input to confirm the stability of the inversion software. Further testing was carried out on physical model data where the parameters of the model were known from direct measurements. Finally the inversion software was applied to actual field data and found to give plausible results.
In software testing in the physical modelling laboratory, other practical problems were encountered. System errors caused by the disproportionately large size of the transducers used affected the accuracy of the inversion results obtained. Transducer performance was studied, and it was found that reducing the size of transducers or making offset corrections would decrease the errors caused by the disproportionately large transducer dimensions. In using the elastic parameters recovered, it was found that the elastic parameter δ significantly influences the seismic records from a horizontal reflector. The normal moveout velocity was found to show variations from the zero-offset normal moveout velocity depending on the value and sign of elastic parameter δ. New approximate expressions for anisotropic normal moveout, phase and ray velocity functions at short offsets were developed. The value of anisotropic parameter δ was found to be the major factor controlling these relations. If the recovered parameter δ has a large negative value, analytical and numerical studies demonstrated that the new expression for moveout velocity developed herein should be used instead of Thomsen's normal moveout equation.

Khazraj, Kaoutar. "Paramétrisation hybride champ/objet et inversion full-wave hybride de données sismiques de puits dans un contexte subsalt". Electronic Thesis or Diss., CY Cergy Paris Université, 2024. http://www.theses.fr/2024CYUN1267.

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Les techniques d'imagerie sismique jouent un rôle crucial dans l'exploration et la compréhension des structures sous la surface de la terre. Dans le domaine de l'exploration pétrolière les zones sous les corps de sel (dites subsalt) représentent un défi pour les techniques d'imagerie conventionnelles. L'application de la full-wave inversion (FWI) aux données sismiques de puits devrait permettre de résoudre au moins partiellement ces difficultés. Dans ce contexte subsalt, l'objectif principal est d'imager et aussi de caractériser les réservoirs d'hydrocarbures pouvant se trouver aux flancs et sous les corps de sel. Néanmoins, le contexte particulier de la sismique de puits, combiné aux défis liés à l'imagerie sous et autour des corps de sel nécessitent l'introduction de contraintes fortes dans le problème inverse géophysique en raison d'une sous-détermination du problème. La présente thèse propose une approche en trois étapes pour aborder ces défis. Tout d'abord, elle suggère d'incorporer de l'information géologique extit{a priori} dans le processus d'inversion en définissant des objets géologiques délimités par des discontinuités permettant aussi une introduction plus fine de l'information ext{a priori} sur les paramètres physiques par objet. Ensuite, elle vise à formaliser et à calculer le gradient par rapport aux paramètres géométriques du modèle qui définissent ces discontinuités. Enfin, elle propose de mettre en place un algorithme d'inversion full-wave hybride qui combine les approches de type champ et de type objet. Cette FWI hybride utilise à la fois le gradient des champs physiques et le gradient relatif aux paramètres géométriques. Le contenu de la thèse est réparti en quatre chapitres. Le premier chapitre présente les concepts fondamentaux utilisés dans l'algorithme FWI hybride. Il met l'accent sur des approches de représentation duale des interfaces (explicite/implicite) par l'utilisation de maillages non-structurés déformables pour la discrétisation des discontinuités et de la méthode level set pour la représentation implicite des objets géologiques dans le problème inverse. Le chapitre 2 décrit les étapes du développement d'une plateforme logicielle permettant l'implémentation numérique de ces approches et la réalisation de tests FWI hybride. Cette plateforme logicielle comprend un code de modélisation de la propagation des ondes par la méthode des éléments spectraux et un code d'inversion basé sur le calcul des gradients simples ou conjugués, avec une approche probabiliste du problème inverse. Le troisième chapitre détaille les différentes étapes de l'algorithme FWI géométrique et sa mise en application à des données de sismique de puits pour estimer la position des interfaces sel/sédiment pour un milieu 2D. Enfin, le quatrième chapitre présente l'algorithme d'inversion hybride et sa mise en oeuvre avec des données de sismique de puits dans le but d'estimer les vitesses des ondes de compression et de cisaillement, ainsi que la position de la frontière des corps de sel pour un milieu 2D. Les résultats des tests numériques présentés sont prometteurs, ce qui permet de valider notre approche d'inversion hybride
Seismic imaging techniques play a crucial role in the exploration and understanding of subsurface structures. In the field of petroleum exploration, subsalt zones present a challenge for conventional imaging techniques and full-wave inversion (FWI). The application of FWI to seismic well data is expected to overcome these challenges. The primary goal is to characterize hydrocarbon reservoirs that may be located beneath and alongside salt bodies. However, the context of well seismic imaging, combined with the challenges of imaging beneath and around salt bodies, requires the introduction of strong constraints into the geophysical inverse problem due to its underdetermined nature.This thesis presents a three-step approach to tackle these challenges. Firstly, it suggests incorporating extit{a priori} geological information into the inversion process by defining geological objects bounded by discontinuities. Secondly, it aims to formalize and compute the gradient with respect to the geometric parameters that define these discontinuities. Thirdly, it proposes the implementation of a hybrid full-wave inversion algorithm that combines field and object-based approaches. This hybrid FWI utilizes both the gradient of physical fields and the gradient relative to geometric parameters.The thesis content is divided into four distinct chapters. The first chapter introduces the fundamental concepts used in the hybrid FWI algorithm. It highlights the approach based on a dual representation of interfaces (explicit/implicit) using deformable unstructured meshes for the explicit discretization of discontinuities and the level-set method for the implicit representation of the geological objects in the inverse problem. Chapter 2 describes the development steps of a software platform for the numerical implementation of these approaches and the execution of hybrid FWI tests. This software platform includes a wave propagation modeling code based on the spectral elements method and an inversion code based on the gradient computation using the Green's function method, with a probabilistic approach to the inverse problem. The third chapter outlines the various stages of the geometric FWI algorithm and its application to well seismic data to estimate the position of salt/sediment interfaces in 2D environments. Finally, the fourth chapter presents the hybrid inversion algorithm and its implementation with well seismic data to estimate the velocities of compression and shear waves, as well as the position of salt body boundaries in 2D environments. The results of the presented numerical tests are promising, validating our hybrid inversion approach

GALUZZI, BRUNO GIOVANNI. "MODELLING AND OPTIMIZATION TECHNIQUES FOR ACOUSTIC FULL WAVEFORM INVERSION IN SEISMIC EXPLORATION". Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/545844.

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Abstract (sommario):

Full Waveform Inversion has become an important research field in the context of seismic exploration, due to the possibility to estimate a high-resolution model of the subsurface in terms of acoustic and elastic parameters. To this aim, issues such as an efficient implementation of wave equation solution for the forward problem, and optimization algorithms, both local and global, for this high non-linear inverse problem must be tackled. In this thesis, in the framework of 2D acoustic approximation, I implemented an efficient numerical solution of the wave equation based on a local order of approximation of the spatial derivatives to reduce the computational time and the approximation error. Moreover, for what concerns the inversion, I studied two different global optimization algorithms (Simulated Annealing and Genetic Algorithms) on analytic functions that represent different possible scenarios of the misfit function to estimate an initial model for local optimization algorithm in the basin of attraction of the global minimum. Due to the high number of unknowns in seismic exploration context, of the order of some thousands or more, different strategies based on the adjoint method must be used to compute the gradient of the misfit function. By this procedure, only three wave equation solutions are required to compute the gradient instead of a number of solutions proportional to the unknown parameters. The FWI approach developed in this thesis has been applied first on a synthetic inverse problem on the Marmousi model to validate the whole procedure, then on two real seismic datasets. The first is a land profile with two expanding spread experiments and is characterized by a low S/N ratio. In this case, the main variations of the estimated P-wave velocity model well correspond to the shallow events observed on the post-stack depth migrated section. The second is a marine profile extracted from a 3D volume where the local optimization, based on the adjoint method, allows to estimate a high-resolution velocity model whose reliability has been checked by the alignment of the CIGs computed by pre-stack depth migration.

Sule, Suki Dauda. "An evaluation of the performance of multi-static handheld ground penetrating radar using full wave inversion for landmine detection". Thesis, University of Hull, 2018. http://hydra.hull.ac.uk/resources/hull:16567.

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This thesis presents an empirical study comparing the ability of multi-static and bi-static, handheld, ground penetrating radar (GPR) systems, using full wave inversion (FWI), to determine the properties of buried anti-personnel (AP) landmines. A major problem associated with humanitarian demining is the occurrence of many false positives during clearance operations. Therefore, a reduction of the false alarm rate (FAR) and/or increasing the probability of detection (POD) is a key research and technical objective. Sensor fusion has emerged as a technique that promises to significantly enhance landmine detection. This study considers a handheld, combined metal detector (MD) and GPR device, and quantifies the advantages of the use of antenna arrays. During demining operations with such systems, possible targets are detected using the MD and further categorised using the GPR, possibly excluding false positives. A system using FWI imaging techniques to estimate the subsurface parameters is considered in this work. A previous study of multi-static GPR FWI used simplistic, 2D far-field propagation models, despite the targets being 3D and within the near field. This novel study uses full 3D electromagnetic (EM) wave simulation of the antenna arrays and propagation through the air and ground. Full EM simulation allows the sensitivity of radio measurements to landmine characteristics to be determined. The number and configuration of antenna elements are very important and must be optimised, contrary to the 2D sensitivity studies in (Watson, Lionheart 2014, Watson 2016) which conclude that the degree (number of elements) of the multi-static system is not critical. A novel sensitivity analysis for tilted handheld GPR antennas is used to demonstrate the positive impact of tilted antenna orientation on detection performance. A time domain GPR and A-scan data, consistent with a commercial handheld system, the MINEHOUND, is used throughout the simulated experiments which are based on synthetic GPR measurements. Finally, this thesis introduces a novel method of optimising the FWI solution through feature extraction or estimation of the internal air void typically present in pressure activated mines, to distinguish mines from non-mine targets and reduce the incidence of false positives.

Noersomadi. "Characteristics of tropical tropopause and stratospheric gravity waves analyzed using high resolution temperature profiles from GNSS radio occultation". Kyoto University, 2019. http://hdl.handle.net/2433/242617.

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Faucher, Florian. "Contributions à l'imagerie sismique par inversion des formes d’onde pour les équations d'onde harmoniques : Estimation de stabilité, analyse de convergence, expériences numériques avec algorithmes d'optimisation à grande échelle". Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3024/document.

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Dans ce projet, nous étudions la reconstruction de milieux terrestres souterrains.L’imagerie sismique est traitée avec un problème de minimisation itérative àgrande échelle, et nous utilisons la méthode de l’inversion des formes d’ondes(Full Waveform Inversion, FWI method). La reconstruction est basée sur desmesures d’ondes sismiques, car ces ondes sont caractérisées par le milieu danslequel elles se propagent. Tout d’abord, nous présentons les méthodesnumériques qui sont nécessaires pour prendre en compte l’hétérogénéité etl’anisotropie de la Terre. Ici, nous travaillons avec les solutions harmoniques deséquations des ondes, donc dans le domaine fréquentiel. Nous détaillons leséquations et l’approche numérique mises en place pour résoudre le problèmed’onde.Le problème inverse est établi afin de reconstruire les propriétés du milieu. Ils’agit d’un problème non-linéaire et mal posé, pour lequel nous disposons de peude données. Cependant, nous pouvons montrer une stabilité de type Lipschitzpour le problème inverse associé avec l’équation de Helmholtz, en considérantdes modèles représentés par des constantes par morceaux. Nous explicitons laborne inférieure et supérieure pour la constante de stabilité, qui nous permetd’obtenir une caractérisation de la stabilité en fonction de la fréquence et del’échelle. Nous revoyons ensuite le problème de minimisation associé à lareconstruction en sismique. La méthode de Newton apparaît comme naturelle,mais peut être difficilement accessible, dû au coup de calcul de la Hessienne.Nous présentons une comparaison des méthodes pour proposer un compromisentre temps de calcul et précision. Nous étudions la convergence de l’algorithme,en fonction de la géométrie du sous-sol, la fréquence et la paramétrisation. Celanous permet en particulier de quantifier la progression en fréquence, en estimantla taille du rayon de convergence de l’espace des solutions admissibles.A partir de l’étude de la stabilité et de la convergence, l’algorithme deminimisation itérative est conduit en faisant progresser la fréquence et l’échellesimultanément. Nous présentons des exemples en deux et trois dimensions, etillustrons l’incorporation d’atténuation et la considération de milieux anisotropes.Finalement, nous étudions le cas de reconstruction avec accès aux données deCauchy, motivé par les dual sensors développés en sismique. Cela nous permetde définir une nouvelle fonction coût, qui permet de prometteuses perspectivesavec un besoin minimal quant aux informations sur l’acquisition
In this project, we investigate the recovery of subsurface Earth parameters. Weconsider the seismic imaging as a large scale iterative minimization problem, anddeploy the Full Waveform Inversion (FWI) method, for which several aspects mustbe treated. The reconstruction is based on the wave equations because thecharacteristics of the measurements indicate the nature of the medium in whichthe waves propagate. First, the natural heterogeneity and anisotropy of the Earthrequire numerical methods that are adapted and efficient to solve the wavepropagation problem. In this study, we have decided to work with the harmonicformulation, i.e., in the frequency domain. Therefore, we detail the mathematicalequations involved and the numerical discretization used to solve the waveequations in large scale situations.The inverse problem is then established in order to frame the seismic imaging. Itis a nonlinear and ill-posed inverse problem by nature, due to the limitedavailable data, and the complexity of the subsurface characterization. However,we obtain a conditional Lipschitz-type stability in the case of piecewise constantmodel representation. We derive the lower and upper bound for the underlyingstability constant, which allows us to quantify the stability with frequency andscale. It is of great use for the underlying optimization algorithm involved to solvethe seismic problem. We review the foundations of iterative optimizationtechniques and provide the different methods that we have used in this project.The Newton method, due to the numerical cost of inverting the Hessian, may notalways be accessible. We propose some comparisons to identify the benefits ofusing the Hessian, in order to study what would be an appropriate procedureregarding the accuracy and time. We study the convergence of the iterativeminimization method, depending on different aspects such as the geometry ofthe subsurface, the frequency, and the parametrization. In particular, we quantifythe frequency progression, from the point of view of optimization, by showinghow the size of the basin of attraction evolves with frequency. Following the convergence and stability analysis of the problem, the iterativeminimization algorithm is conducted via a multi-level scheme where frequencyand scale progress simultaneously. We perform a collection of experiments,including acoustic and elastic media, in two and three dimensions. Theperspectives of attenuation and anisotropic reconstructions are also introduced.Finally, we study the case of Cauchy data, motivated by the dual sensors devicesthat are developed in the geophysical industry. We derive a novel cost function,which arises from the stability analysis of the problem. It allows elegantperspectives where no prior information on the acquisition set is required

Più fonti

Libri sul tema "Inversion full wave":

Fichtner, Andreas. Full Seismic Waveform Modelling and Inversion. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2011.

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Singh, Satish Chandra. Wave propogation in anisotropic media and full waveform inversion. 1987.

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Fichtner, Andreas. Full Seismic Waveform Modelling and Inversion. Springer, 2013.

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Fichtner, Andreas. Full Seismic Waveform Modelling and Inversion. Springer, 2011.

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Chen, Po, e En-Jui Lee. Full-3D Seismic Waveform Inversion: Theory, Software and Practice. Springer, 2015.

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Chen, Po, e En-Jui Lee. Full-3D Seismic Waveform Inversion: Theory, Software and Practice. Springer International Publishing AG, 2016.

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Chen, Po, e En-Jui Lee. Full-3D Seismic Waveform Inversion: Theory, Software and Practice. Springer London, Limited, 2015.

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Capitoli di libri sul tema "Inversion full wave":

Chen, Po, e En-Jui Lee. "Anelastic Wave Propagation (AWP)". In Full-3D Seismic Waveform Inversion, 15–90. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16604-9_2.

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Ali, Hassan B., e Michael K. Broadhead. "Shear Wave Properties From Inversion of Scholte Wave Data". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 371–76. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_60.

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Bibee, L. Dale, e Leroy M. Dorman. "Full Waveform Inversion of Seismic Interface Wave Data". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 377–82. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_61.

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Wiskin, James. "Full Wave Inversion and Inverse Scattering in Ultrasound Tomography/Volography". In Advances in Experimental Medicine and Biology, 201–37. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-21987-0_10.

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Badiey, M. "Influences of Sediment Variability on Broadband Acoustic Wave Propagation in Shallow Water". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 365–70. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_59.

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Athanassoulis, G., J. Papadakis, E. Skarsoulis e M. Taroudakis. "A Comparative Study of Two Wave-Theoretic Inversion Schemes in Ocean Acoustic Tomography". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 127–32. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_21.

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Fishman, L., e M. D. Collins. "Direct Wave Propagation in the Frequency Domain via the Dirichlet-to-Neumann Operator Symbol". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 27–32. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_5.

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Lindwall, Dennis A., Mrinal K. Sen e Joseph F. Gettrust. "Detection of High Shear Wave Velocities in Marine Sediment by Inversion with Simulated Annealing". In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 383–88. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_62.

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Fang, Yong, Long-mei Li, Shuang-fen Cao, Xue Li, Fan Huang, Qi Wang, Xiao-guang Liu, Jia-ding Pei e Yong-jie Liao. "Application and Discussion of Diving-Wave Land Full-Waveform Inversion in Complex Mountainous Areas of Western China". In Springer Series in Geomechanics and Geoengineering, 572–84. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-0483-5_56.

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Tran, Anh Phuong, e Sébastien Lambot. "Development of Intrinsic Models for Describing Near-Field Antenna Effects, Including Antenna-Medium Coupling, for Improved Radar Data Processing Using Full-Wave Inversion". In Civil Engineering Applications of Ground Penetrating Radar, 219–38. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-04813-0_9.

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Atti di convegni sul tema "Inversion full wave":

Hu, Y., L. Han, P. Zhang e Y. Yin. "Full Wave Traveltime Inversion". In 81st EAGE Conference and Exhibition 2019. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201900875.

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Liu, Zhaolun, Jing Li e Gerard Schuster. "3D wave-equation dispersion inversion of surface waves". In SEG 2017 Workshop: Full-waveform Inversion and Beyond, Beijing, China, 20-22 November 2017. Society of Exploration Geophysicists, 2017. http://dx.doi.org/10.1190/fwi2017-007.

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Jurado, F., V. Richard e M. Cuer. "Layer-based oriented full wave inversion". In 54th EAEG Meeting. European Association of Geoscientists & Engineers, 1992. http://dx.doi.org/10.3997/2214-4609.201410409.

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Borisov, Dmitry, Fuchun Gao, Paul Williamson, Frederik J. Simons e Jeroen Tromp. "Robust surface-wave full-waveform inversion". In SEG Technical Program Expanded Abstracts 2019. Society of Exploration Geophysicists, 2019. http://dx.doi.org/10.1190/segam2019-3215047.1.

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Uesaka, I. "Full-wave Inversion in Frequency-domain". In The 4th International Symposium on Recent Advances in Exploration Geophysics (RAEG 1999). European Association of Geoscientists & Engineers, 1999. http://dx.doi.org/10.3997/2352-8265.20140023.

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Watson, F., e Wrb Lionheart. "SVD analysis of GPR full-wave inversion". In 15th International Conference on Ground-Penetrating Radar (GPR) 2014. IEEE, 2014. http://dx.doi.org/10.1109/icgpr.2014.6970472.

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He, C., Y. Chen, H. Fu e G. Yang. "Ensemble Full Wave Inversion with Source Encoding". In 77th EAGE Conference and Exhibition 2015. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201412764.

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Watson, F. "Towards 3D full-wave inversion for GPR". In 2016 IEEE Radar Conference (RadarConf16). IEEE, 2016. http://dx.doi.org/10.1109/radar.2016.7485323.

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M. Song, Z., P. R. Williamson e M. H. Worthington. "2.5D Acoustic full-wave frequency-domain inversion". In 55th EAEG Meeting. European Association of Geoscientists & Engineers, 1993. http://dx.doi.org/10.3997/2214-4609.201411407.

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Vigh, Denes, e E. William Starr. "3D prestack plane‐wave full‐waveform inversion". In SEG Technical Program Expanded Abstracts 2007. Society of Exploration Geophysicists, 2007. http://dx.doi.org/10.1190/1.2792847.

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Rapporti di organizzazioni sul tema "Inversion full wave":

Pai, D. M. Full-Wave Inversion for Ocean Acoustical Tomography. Fort Belvoir, VA: Defense Technical Information Center, maggio 1997. http://dx.doi.org/10.21236/ada325911.

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