Navegando por Assunto "Imageamento acústico"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Caracterização de fraturas em imagens de amplitude acústica utilizando morfologia matemática
(Universidade Federal do Pará, 2013) XAVIER, Aldenize Ruela; GUERRA, Carlos Eduardo; http://lattes.cnpq.br/7633019987920516; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
Fractures analysis is of particular interest in the characterization of carbonate reservoir since the fractures are the classic geological setting for stock and produce hydrocarbon in this kinds of reservoirs. Particularly in Brazil is growing the interest in the characterization of carbonate reservoirs, with the recent discoveries in pre-salt. The acoustic imaging tools provide valuable information about the amplitude of the reflected waves in the borehole wall, which can be interpreted to allow the characterization of fractures. However, some problems arise due to the qualitative interpretation of these images that are basically performed with the use of vision and experience of the interpreter. This work presents a methodology that performing the fractures analysis of acoustic images and can be divided into three steps. The first one presents the image modeling, which is used to infer the aspect of the fractures in different geological settings. In the second step, the mathematical morphology is used as an edge detector and performs the fractures identification in the acoustic image. The last step deals with the extraction of geometric attributes of the fractures with the adoption of a four degree polynomial according to the least square criterion. The evaluation of this methodology is performed with synthetic images generated by the presented modeling, which supports the characterization of fractures performed in real images.
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)
Modelamento e correção de descentralização das imagens de tempo de trânsito
(Universidade Federal do Pará, 2003) FISCHETTI, Anna Carmela; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
The imaging tools used to borehole wall features identification have been largely utilized by geologist and oil engineers to identify geological events in a open hole and inspect the casing tube. The acoustic borehole imaging tools generate a transit time image and an acoustic amplitude image that are used to this proposes. However those logs may have a non-realist interpretation, since some tools effect can negatively influence in the images appearance. This paper presents a transit time image model starting from the application of the Coulomb’s approach to the borehole wall rupture submitted to a plane state of tensions which will supply the borehole section that is the geometric form that will be mapped by the acoustic borehole imaging toll. The tool up displacement and the borehole wall imperfections are usually the responsible for the transducer displacement in relation to the borehole axis. This effect may have important responsibility in the acoustic images imperfections. Thus, a computational process of transducer repositioning in the borehole axis position obtains the correction of those images, called decentralization correction. A method of tool decentralization effect correction is presented too based on this model which is proposed based on the plane analytic geometry and in the ray method to the definition of the transit time of the acoustic pulse, with the objective of reconstruct the transit time images achieved by the decentralized tool, that is to say, correct these images becoming as they were achieved by the centralized tool in relation to the borehole axis.
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.