Imaging without a Velocity Model by Path-Summation Approach – This Time in Depth

Landa, Evgeny; Reshef, M.; Khaidukov, V.

doi:10.3997/2214-4609-pdb.1.p011

Cited by 6 publications

(3 citation statements)

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“…The constructive and destructive interference of the elementary signals contributed by each path/trajectory produces an image that converges toward the correct one obtained by a migration using the correct velocity. Landa et al ͑2005͒ andKeydar ͑2005͒ present the first applications of path-summation imaging in depth migration. Anikiev et al ͑2007͒ use a similar idea to locate seismic events in an unknown velocity field.…”

Section: Introductionmentioning

confidence: 99%

Migration velocity analysis by double path-integral migration

Schleicher

Costa

2009

11th International Congress of the Brazilian Geophysical Society &Amp; EXPOGEF 2009, Salvador, Bahia, Brazil, 24-28 August 2009

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The idea of path-integral imaging is to sum over the migrated images obtained for a set of migration velocity models. Velocities where common-image gathers align horizontally are stationary, thus favoring these images in the overall stack. The overall image forms with no knowledge of the true velocity model. However, the velocity information associated with the final image can be determined in the process. By executing the path-integral imaging twice and weighting one of the stacks with the velocity value, the stationary velocities that produce the final image can then be extracted by a division of the two images. The velocity extraction, interpolation, and smoothing can be done fully automatically, without the need for human interpretation or other intervention. A numerical example demonstrated that quantitative information about the migration velocity model can be determined by double path-integral migration. The so-obtained velocity model can then be used as a starting model for subsequent velocity analysis tools like migration velocity analysis or tomographic methods.

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Section: Introductionmentioning

confidence: 99%

Migration velocity analysis by double path-integral migration

Schleicher

Costa

2009

11th International Congress of the Brazilian Geophysical Society &Amp; EXPOGEF 2009, Salvador, Bahia, Brazil, 24-28 August 2009

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“…As shown by Keydar (2004), Landa (2004), Keydar and Shtivelman (2005) and Landa et al (2005), path integrals can also be used in the reverse process: to obtain a subsurface image without any velocity information. At first sight, it would seem that path integrals in an unknown or undefined velocity do not make sense, and even more, that an indiscriminate integration over arbitrary random trajectories does not yield a mechanism that would focus data into an image.…”

Section: Introductionmentioning

confidence: 99%

Path‐integral seismic imaging

Landa¹,

Fomel

Moser

2006

Geophysical Prospecting

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A B S T R A C TA new type of seismic imaging, based on Feynman path integrals for waveform modelling, is capable of producing accurate subsurface images without any need for a reference velocity model. Instead of the usual optimization for traveltime curves with maximal signal semblance, a weighted summation over all representative curves avoids the need for velocity analysis, with its common difficulties of subjective and timeconsuming manual picking. The summation over all curves includes the stationary one that plays a preferential role in classical imaging schemes, but also multiple stationary curves when they exist. Moreover, the weighted summation over all curves also accounts for non-uniqueness and uncertainty in the stacking/migration velocities. The path-integral imaging can be applied to stacking to zero-offset and to time and depth migration. In all these cases, a properly defined weighting function plays a vital role: to emphasize contributions from traveltime curves close to the optimal one and to suppress contributions from unrealistic curves. The path-integral method is an authentic macromodel-independent technique in the sense that there is strictly no parameter optimization or estimation involved. Development is still in its initial stage, and several conceptual and implementation issues are yet to be solved. However, application to synthetic and real data examples shows that it has the potential for becoming a fully automatic imaging technique.

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“…The path-summation method renewed attention in seismics in the last two decades after its application in seismic wave modeling (Lomax, 1999;Schlottmann, 1999). Shortly afterward, Keydar (2004), Landa (2004), Keydar and Shtivelman (2005), Landa et al (2005), Shtivelman and Keydar (2005), and Landa et al (2006) shown that path integral can be used to obtain a subsurface image without any velocity information.…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Initial depth model building using robust time-migration velocity analysis methods

Santos¹

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ResumoA necessidade de investigar regiões formadas por estruturas geológicas complexas tem motivado o desenvolvimento de métodos de imageamento que atuem no domínio da profundidade. Exemplos notáveis são as técnicas de migração pré-empilhamento em profundidade (PSDM, do inglês "prestack depth migration") e a tomografia de onda completa (FWT, do inglês "full-waveform tomography"). No entanto, a aplicação desses métodos enfrenta ao menos dois desafios: eles requerem (1) um modelo de velocidade (inicial) preciso, e (2) elevado poder computacional. Por outro lado, a migração em tempo provou ser um processo robusto e muito rápido, tornando-se rotineiramente empregado para o imageamento sísmico. Além disso, a construção de modelos de velocidade em tempo é um processo bem compreendido. Portanto, é altamente desejável usar as técnicas de conversão tempo-profundidade para construir, a partir desses modelos de velocidade no domínio do tempo, modelos de velocidade iniciais para técnicas que operam em profundidade. Neste trabalho, investigamos a aplicabilidade de um fluxo de trabalho formado por alguns recémdesenvolvidos métodos (semi-) automáticos de análise de velocidade de migração em tempo (MVA, do inglês "migration velocity analysis"), capazes de gerar modelos de velocidade e imagens migradas no tempo sem precisar de informações a priori, seguido por uma técnica robusta de conversão tempo-profundidade. Discutimos as vantagens e limitações desse fluxo de trabalho e suas perspectivas para se tornar uma ferramenta plenamente automática, capaz de gerar modelos de velocidade sísmica para o uso subsequente em métodos de FWT. Nos nossos testes em diferentes versões dos dados Marmousi, o procedimento proposto produziu modelos de velocidade iniciais suficientemente precisos para uma FWT sob condições quase ideais. Começando no modelo de velocidade do domínio do tempo convertido para profundidade, a FWT convergiu para um modelo final com qualidade comparável a quando feito a partir de uma versão suavizada do modelo de velocidade verdadeiro. Isso indica que a correta informação sobre a velocidade de fundo pode ser extraída com sucesso pela MVA automática no domínio do tempo mesmo em meios onde a migração em tempo não pode fornecer imagens sísmicas satisfatórias. Como resultado, esta tese não só contribui para o desenvolvimento de um fluxo de trabalho para a construção de modelos de velocidade iniciais para a FWT, mas também apresenta várias aplicações inovadoras.

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Imaging without a Velocity Model by Path-Summation Approach – This Time in Depth

Cited by 6 publications

References 0 publications

Migration velocity analysis by double path-integral migration

Migration velocity analysis by double path-integral migration

Path‐integral seismic imaging

Initial depth model building using robust time-migration velocity analysis methods

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