Migração FD e FFD com aproximações de grande abertura angular
Seismic Migration by downward continuation using the unidirectional wave equation approximations has two shortcomings: imaging steep dip reflectors and handling evanescent waves. Complex Padé approximations allow a better treatment of evanescent modes stabilizing the finite difference migration,...
| Autor principal: | AMAZONAS, Daniela Rêgo |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Pará
2014
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.ufpa.br/jspui/handle/2011/5978 |
| Resumo: |
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Seismic Migration by downward continuation using the unidirectional wave equation approximations
has two shortcomings: imaging steep dip reflectors and handling evanescent
waves. Complex Padé approximations allow a better treatment of evanescent modes stabilizing
the finite difference migration, and does not require special treatment for domain
boundaries. Imaging of steep dip reflectors can be improved using several terms in the Padé
expansion. This dissertation discuss the implementation and evaluation of complex Padé
approximation for finite difference migration and Fourier finite difference migration.
The study of the dispersion relation and impulsive response associated to the migration
operator is used to select the number of terms and coefficients in the Padé expansion which
assures stability for a prescribed maximum reflector dip. The implementations are validated
in the Marmousi and SEG/EAGE salt model datasets, and compared to other wave equation
migration methods. The results of FD and FFD complex Padé migrations can handle steeper
dips, and present a much lower signal to noise ratio than their real valued counterparts. |