Dissertação

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,...

ver descrição completa

Autor principal: AMAZONAS, Daniela Rêgo
Grau: Dissertação
Idioma: por
Publicado em: Universidade Federal do Pará 2014
Assuntos:
Acesso em linha: http://repositorio.ufpa.br/jspui/handle/2011/5978
Resumo:
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.