Dissertações em Geofísica (Mestrado) - CPGF/IG
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/4993
O Mestrado Acadêmico pertente a o Programa de Pós-Graduação em Geofísica (CPGF) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).
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Navegando Dissertações em Geofísica (Mestrado) - CPGF/IG por Orientadores "GOMES, Ellen de Nazaré Souza"
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Item Acesso aberto (Open Access) Uma análise de métodos de supressão de múltiplas de superfície livre aplicados a um dado real(Universidade Federal do Pará, 2011-10-14) OLIVEIRA, Andrei Gomes de; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660The seismic record in 2D linear events are common features in the seismograms. These events are overlap with interesting reflections (early reflections) complicating the stages of seismic processing and identification of possible subsurface geological horizons. It possible highlight multiple surface that distinguished from others by a low frequency, high amplitude and low velocity of propagation. The identification and removal of multiple reflflections in seismic data is a real step of great importance in seismic processing, because the attenuation can prevent many of these errors in the interpretation of geological images seismic. This study is the determination of a processing flow for multiple attenuation free surface. Methods of elimination of multiple surface (SRME, Radon filtering, predictive deconvolution domain τ - p and fk filltering) applied to a real data 2D were used in different combinations. These are analyzed and presented the results are the best combinations.Item Acesso aberto (Open Access) Análise de um esquema de inversão para estimativa de anisotropia local a partir de dados de VSP(Universidade Federal do Pará, 2012-05-18) BARRETO, Adriano César Rodrigues; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660Inversion scheme for the determination of arbitrary in a vicinity of a receiver situated inside a borehole from the data obtained during a multi-offset multi-azimuthal VSP experiment is studied. The data consist of vertical components of the slowness vector and all components of the polarization vector of P waves direct and reected. The inversion is made from a first order approximation around an reference arbitrary isotropic medium, that does the relation between the data of slowness and polarization of P waves parameters and the weakly anisotropic medium (WA parameters). This inversion scheme applies to arbitrary anisotropy medium, provided that the anisotropy is weak and independent of downhole type (vertical, horizontal or inclined). The results show that reversing is sensitive to the number and orientation of the proles of sources that are distributed on the surface. An analysis of the design of an experiment and discussion about the choice of parameters of the reference isotropic medium are presented. Within the realistic assumptions about the level of noise is possible to estimate the phase velocity for a limited angular aperture around the well.Item Acesso aberto (Open Access) Análise de um esquema linear para estimativa de anisotropia local a partir de dados de onda P em experimentos de VSP multiazimutal(Universidade Federal do Pará, 2013-08-08) MACAMBIRA, Raiza de Nazaré Assunção; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660This study presents an analysis of the linear inversion scheme for estimating anisotropy in the neighborhood of a receiver placed in a well using the vertical components of the slowness and polarization vectors of P-waves measured in multi-azimuth walkaway vertical seismic profile (VSP) surveys. Independently of the medium above the geophone (homogeneous or heterogeneous) and the shape of the well (directional or curved, vertical or sloped), an inversion is performed from a first-order approximation around a reference isotropic medium. The analysis of the inversion scheme considers factors such as the noise level of the data, the type of P-wave, the degree of the anisotropy of the medium, the choice of parameters in the reference isotropic medium and the degree of heterogeneity of the medium.Item Acesso aberto (Open Access) Aplicação de métodos hidroacústicos para estudo e dragagem na região portuária de Cabedelo - PB, Brasil(Universidade Federal do Pará, 2014-11-17) LOPES, Victor Hugo Rocha; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660This paper presents the use of hydroacoustic methods used for mapping and detection of subsurface stratigraphic features to support a project of dredging and demolishing of the left edge of the navigation channel of the Paraíba do Norte's River to expand the port zone of Cabedelo/PB. High-resolution seismic data and bathymetric data are used to map two main objectives: top of the Acoustic Rocky Basement (TARB) and the superimposed sedimentary package. This information is important to support the volume calculation of the material to be dredged and/or demolished along the navigation channel. The data analysis indicates that the expansion of the Cabedelo's Port firstly suggested by the Docas do Paraíba Company to be in the Forte Velho's locality becomes expensive due to the large volume of sedimentary and rocky material to be dredged. Thus, the Lucena region is presented as an alternative to the port expansion since presents lower volume of material to be dredged that reduces substantially the costs and time of execution of the work.Item Acesso aberto (Open Access) Aplicação de Well-Tie no imageamento de uma área da bacia Tumbes-progresso(Universidade Federal do Pará, 2014-08-29) CHAGAS, Tiago Paulo Câncio das; SILVA, Carolina Barros da; http://lattes.cnpq.br/5306784916926352; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660Geological areas with large lateral velocity variations, such as in areas with faults and salt domes are complex areas, in general, seismic imaging time is limited. In these cases, the seismic imaging depth can provide better results. However, a velocity model is needed in depth with precision, which is not an easy task. An alternative to estimate the depth velocity model is provided by Well-tie technique. With the calibration of the synthetic trace data obtained from wells, seismic section with the depth map of velocity can be obtained through the time-depth curve. In this study, we used the Well-Tie to improve the model of RMS velocity obtained from the processing of seismic data. The updated velocity model was converted to depth and used to generate an in depth migrated seismic image of a region of Tumbes Basin-Progress.Item Acesso aberto (Open Access) Avaliação geofísica e geológica de um porção de quebra de talude da Bacia do Jequitinhonha(Universidade Federal do Pará, 2013) SANTOS, Renata Vieira dos; SARGES, Roseane Ribeiro; http://lattes.cnpq.br/9737447758598999; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660The seismic reflection methods use at the exploration and development hydrocarbon reservoirs is due to its vast and dense sampling in both area and depth, combined with techniques refinement to processing seismic reflection data, from these data, are generated seismic sections, which after applying appropriate treatment, are used in the interpretation of the strata and/or the subsurface geologic structures. At this paper have made one Geophysics Geological analysis at two real marine seismic lines 2D of break portion embankment Jequitinhonha Basin. Therefore, we performed a set of seismic processing in order to mitigate the multiple reflections common marine data, moreover, were estimated velocity models in depth, used to determine the depth migrated seismic sections. At these were identified reflective surfaces. Through analysis at these surfaces markings of sismofacies. have made based on the initial concepts seismic stratigraphy in order to evaluate the product quality derived from the seismic processing used at this study for seismic stratigraphic interpretation, which is based on the analysis termination patterns of reflectors and internal standard of sismofacies.Item Acesso aberto (Open Access) Caracterização de hidratos de gás a partir de dados geofísicos da região da Bacia Tumbes-Progresso (Peru)(Universidade Federal do Pará, 2014-02-25) TEJADA SOTO, Zoraida Roxana; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660Gas hydrate is known as a potential source of hydrocarbon energy. However, the detection of exploitation of this resource is still inexpressive. This is due to two factors: the diculty of detecting pro table areas of gas hydrates and due to the high risk involved in exploration. In this study, an analysis is presented to detect possible areas of gas hydrate ocurrence in a region of Tumbes-Progresso Basin, using geophysical data: magnetic, gravity, seismic and borehole (well data). It presents three approaches to demarcate the possible zones of hydrate: First, magnetic and gravity anomalies analyzed with respect to the geology and the study area that was chosen. It was subsequently made a seismic imaging the region of interest and the gas hydrates has been identied based on the presence identication of BSR (Bottom Simulating Refletor), This reflector correspond to a limit between gas hydrate and free gas zone. BSR potential was applied the AVO analysis (Amplitude Versus Oset). Finally, in the third approach, well data are evaluated, calculating the porosity and saturation of the rock in the gas hydrate stability zone. According to the analysis presented, It was veried the occurrence of gas hydrate in the study area.Item Acesso aberto (Open Access) Caracterização de reservatórios fraturados através de dados de ondas qP em levantamentos VSP Walkaway(Universidade Federal do Pará, 2008) SILVA, Saulo da Costa e; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660This dissertation presents a method to estimate the orientation of the axis of symmetry of a medium assuming it behaves effectively as a transversely isotropic medium (TI). The fracture orientation is then achieved from the estimation of the axis of symmetry of a TI medium. This estimative is done with the slowness and polarization vectors from qP waves, measured in VSP Walkaway experiments. The inversion process is based on linearized equations of the slowness and polarization vectors from qP waves and the weakly anisotropic parameters of the medium. Numerical tests are presented, on which the sensibility to factors like the strength of anisotropy, survey geometry, type of wave utilized and noise level are analyzed. Test results for a set of real data are also shown.Item Acesso aberto (Open Access) Determinação de modelo de velocidades para a migração em profundidade de dados sísmicos 2-D da Bacia do Jequitinhonha(Universidade Federal do Pará, 2013-12-13) OLIVEIRA, Lelis Araújo de; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660The migration time domain is quite employed by the oil industry for its low computational requirements, however in areas where the velocity field has great lateral variation as result of the environment is complex subsurface structures, such as faults, salt domes, etc.., this technique becomes inefficient in the characterization of geological features. Although the computational cost is high, migration in the field of depth, proves more effective than time migration to deal with these structures. However for a section in depth there is a need for a velocity model in depth with some degree of precision. In this paper, two methodologies for time to depth conversion for obtaining the velocity model in depth to two real 2-D marine lines Jequitinhonha Basin are applied. The accuracy of the models generated were analyzed from migrated seismic sections obtained by means of these velocityes.Item Acesso aberto (Open Access) Processamento de dados sísmicos da bacia do Camamu(Universidade Federal do Pará, 2009) MATOS, Ligia Naia de; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660Seismic Imagining is one of the manners to visualize on subsurface. To get at a reliable seismic imagining, a long way must be covered. The first stage is the seismic acquisition, its the planned evil its carries serious troubles. After the seismic acquisition we need to processes the data. Seismic data processing is alteration of seismic data to suppress noise, enhance signal and migrate seismic events to the appropriate location in space. Processing steps typically include analysis of velocities and frequencies, static corrections, deconvolution, normal moveout, dip moveout, stacking, and migration, which can be performed before or after stacking. In this work, our objective is a seismic migration from a Camamu basin 2D acquisition line. In this line we have many the dificulties arise from the factors free surface multiples e peg-lags. We are going to use as seismic processing methodology the common median point stack and the pos-stack migration by ProMax (Landmark Inc) software. To attenuate multiples we have used predictive deconvolution, radon filter and f - k filter techniques . The results are satisfactory when we compare to results without theses techniques.Item 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/1134403454849660Conventional 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.