Navegando por Assunto "Imaging"

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Acesso aberto (Open Access)
Migração Kirchhoff paraxial pré-empilhamento em profundidade com amplitudes verdadeiras
(Universidade Federal do Pará, 2015-08-31) MOREIRA, Marcio Fernando de Andrade; CRUZ, João Carlos Ribeiro; http://lattes.cnpq.br/8498743497664023
The seismic depth migration is one of the most important steps in the exploration of geologically complex process areas of the oil industry interest. To obtain a more realistic image of the structure, it needs is a great settings recovery process of the reflectors in the subsurface and efficient determination of reflection coefficients to characterize the oil and gas reservoirs. One of the techniques used to obtain the seismic image is the Kirchhoff migration method which can be greatly enhanced by appropriate weights, which when applied to amplitudes during the stacking diffraction provides an estimate of the reflection coefficients. In this work, we used the 2-D paraxial ray prestack Kirchhoff depth migration method. In the calculation step traveltimes makes use of second-order paraxial approximation, by which one can get a good approximation of the traveltimes in the mesh migration. The weights used during migration were calculated using the equations of dynamic radius and the extrapolation to the points of the mesh migration. Compared with the conventional Kirchhoff method, the results were quite satisfactory as regards the increase in image resolution of the reflectors as well as in obtaining the reflection coefficients. The efficiency of the proposed technique was tested on synthetic data type anticlinal geological structure and seismic data Marmousi.
Acesso aberto (Open Access)
NIP-tomografia usando método CRS e dados sísmicos marinhos
(Universidade Federal do Pará, 2013) AFONSO, João Batista Rodrigues; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
This work consisted on the application of techniques for processing, inversion and imaging of the Marmousoft synthetic data, and of the Jequitinhonha real data obtained on the eastern Atlantic continental shelf of the State of Bahia. The convencional NMO and CRS stack methods, and NIP-tomographic inversion were applied to the mentioned data. The NMO stack served to produce RMS and interval velocity distribution maps on the semblance domain. The CRS stack of both data we used for picking of re ection events to obtain the wave eld parameters that served to constrain the model as input for the NIP-tomographic inversion. The inversion characterizes as resulting in a smooth velocity model. Kirchhoff depth migration was used for verifying the obtained velocity models. We critically analyzed the applied techniques, and compared the CRS and the NMO stacks. The evolution of the visual quality of the obtained CRS and NMO sections were analyzed as measured by event continuity trace-by-trace and the signal/noise ratio. The di erences and improvements on the velocity model obtained by NIP-tomographic were also analyzed. The Kirchhoff prestack depth migration was applied aiming at geological interpretations, and to point out for better conditions of processing and imaging.
Acesso aberto (Open Access)
Utilização de múltiplas de superfície livre no imageamento sísmico
(Universidade Federal do Pará, 2014-08-29) SANTOS, Isis Tourinho dos; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660
Conventional seismic processing treats multiple reflections as noise, removing them from the imaging process. However, multiple reflections have different propagation wave paths from primary reflections and thus can be used to illuminate areas not illuminated by primary reflections. Consequently, migration of multiples can arise as possibility of imaging of complex structures in the subsurface. In this context, this work shows a abstract about the most relevant approaches from the imaging using multiples. In addition, this work shows results with free-surface multiples used in seismic imaging by reverse time migration.