Migração FD 3D em profundidade usando aproximação de Padé complexa
Conventional implementations of 3D finite-difference (FD) migration use splitting techniques to accelerate performace and save computational cost. However, such techniques are plagued with numerical anisotropy that jeopardizes correct positioning of dipping reflectors in the directions not used f...
| Autor principal: | COSTA, Carlos Alexandre Nascimento da |
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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/2011/5974 |
| Resumo: |
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Conventional implementations of 3D finite-difference (FD) migration use splitting techniques
to accelerate performace and save computational cost. However, such techniques
are plagued with numerical anisotropy that jeopardizes correct positioning of dipping reflectors
in the directions not used for the splitted operators. We implement 3D downward
continuation migration without splitting in the space coordinates using a complex Padé
approximation and implicit finite differences. In this way, the numerical anisotropy is
eliminated at the expense of a computationally more intensive solution of a large banded
linear system. We compare the performance of the iterative stabilized biconjugate gradient
(Bi-CGSTAB) and the multifrontal massively parallel direct solver (MUMPS). It turns out
that the use of the complex Padé approximation provides an effective preconditioner for
the Bi-CGSTAB, reducing the number of iterations relative to the real Padé expansion of
the FD operator. As a consequence, the iterative Bi-CGSTABmethod ismore efficient than
the directMUMPSmethodwhen solving for a single termin the Padé expansion. Forwide
angle approximations direct methods are required. These algorithms are validated and
the properties evaluated computing themigration impulse response in the SEG/EAGE salt
model. |