Navegando por Assunto "Ondas elásticas"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Migração em profundidade pré-empilhamento utilizando os atributos cinemáticos do empilhamento por superfície de reflexão comum
(Universidade Federal do Pará, 2007-11-12) LUZ, Samuel Levi Freitas da; CRUZ, João Carlos Ribeiro; http://lattes.cnpq.br/8498743497664023
The Common-Reflection-Surface (CRS) stack is a new seismic processing method for simulating zero-offset (ZO) and common-offset (CO) sections. It is based on a second-order hyperbolic paraxial approximation of reflection traveltimes in the vicinity of a central ray. For ZO section simulation the central ray is a normal ray, while for CO section simulation the central ray is a finite-offset ray. In addition to the ZO section, the CRS stack method also provides estimates of wavefield kinematic attributes useful for solving interval velocity inversion, geometrical spreading calculation, Fresnel zone estimate, and also diffraction events simulation. In this work, Its proposed a new strategy to do a pre-stack depth migration by using the CRS derived wavefield kinematic attributes, so-called CRS based pre-stack depth migration (CRS-PSDM) method. The CRS-PSDM method uses the CRS results (ZO section and kinematic attributes) to construct an optimized stack traveltime surface along which the amplitudes of the multi-coverage seismic data are to be summed and the result is put in a point of the migration target zone in depth. In the same sense as in Kirchhoff type pre-stack depth migration (K-PSDM), the CRSPSDM method needs a migration velocity model. Unlike the K-PSDM method, the CRS-PSDM needs only to calculate the zero-offset traveltimes, i.e, along only ray conecting the considered point in depth to a given coincident position of source-receptor at surface. The final result is a zero-offset time-to-depth converted seismic image of reflectors from pre-stack seismic data.
Acesso aberto (Open Access)
Onda elástica: Galerkin com direções alternadas
(Universidade Estadual de Campinas, 1988-12-09) FERNANDES, José Augusto Nunes; BEZERRA, Maria Cristina Cunha
Acesso aberto (Open Access)
Processamento sísmico CMP e CRS de dados sintéticos acústicos e elásticos representativos das bacias paleozóicas da região Amazônica
(Universidade Federal do Pará, 2007) NAZARÉ, Cláudia Priscila Pereira; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319
Among the several difficulties found in oil and gas exploration in the Amazon area, the existence of diabase sills, although important to the process of maturation of organic matter in all Brazilian Paleozoic basins, turns difficult the seismic exploration. The diabase disturbs the seismic signal, generating multiple reflections and scathering. With the purpose of understanding the seismic wave propagation and, mainly, the difficulties found by the seismic imaging methods in these complex geological settings, in this work it is presented the results of acoustic and elastic seismic modeling in synthetics models of the Amazonas and Solimões Basin, using finite-differences techniques. I present the seismic processing of this data set by the Common Midpoint (CMP) and Common Reflection Surface (CRS) stacking methods, and the pos-stack depth migration with split-step method. The results of stacking with CRS method show that both acoustic and elastic data has a better signal-noise ratio and lateral continuity of the reflectors when compared with the results of CMP stacking. The interpretative analyzes of stacked and migrated sections show that reflection events located on the top of models (in time until 0.7sec. and in depth until 1.200 meters) present apparently better resolution, but the botton of models has not been satisfactorily imaged by the occurrence of multiple reflections overlapped to primary reflections.