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 "CALLAPINO, German Garabito"
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Item Acesso aberto (Open Access) Aproximações hiperbólicas dos tempos de trânsito com topografia(Universidade Federal do Pará, 2005-05-23) COSTA, Manuel de Jesus dos Santos; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319The simulation of a zero-offset seismic section (ZO) from multicoverage data can be carried through the seismic stacking, which is a very used method of seismic reflection imaging in the oil industry. Seismic stacking process allows to reduce the amount of data and is aimed to improve the signal/noise ratio. Based in the hyperbolic approach of the traveltime, dependent on three parameters or kinematic attributes of wavefronts, recently it was developed a new method to simulate zero-offset sections (ZO), called seismic stack for Common Reflection Surface method (or SRC stack). This new formalism can be extended to construct ZO sections from multicoverage data, using the approach of the paraxial traveltimes in the neighborhood of a central ray with zero offset, for the case of a line of measurement with soft and rugged topography. These two approaches of traveltime also depend on three kinematic attributes of wavefronts. In this work, a theoretical revision of the paraxial theory of the ray for the attainment of the approaches of the paraxial traveltimes is presented, considering a line of measurement with rugged and soft topography. From the approaches of the paraxial traveltimes with relation to a central ray with zero-offset (ZO), two new approaches had been derived from traveltimes using the condition of a diffraction point in depth, reducing the original equations for two parameters. For the approaches of reflection and diffraction, using the same synthetic model, a graphical representation of their respective stacking surfaces were compared, using the traveltime approaches for the soft and rugged topography. After that, we analyze the behavior of the operators associated with the reflection and the diffraction surfaces when these are disturbed, where we investigate the sensibilities in relation to each one of the three parameters (β0, KNIP, KM). This sensibility analysis was perfomed in two ways: Sensibility through the disturbance of each parameter visualized in the stacking surfaces SRC-TR and SDC-TR, and the first derivative of the traveltimes SRC-TR and SDC-TR. Finally, using these hyperbolic approaches as a function of three and two parameters, and based on the results of the sensibility analysis, were considered an algorithm to simulate ZO sections from data of multi coverage.Item Acesso aberto (Open Access) Aproximações hiperbólicas dos tempos de trânsito de raios paraxiais a um raio central refletido e difratado(Universidade Federal do Pará, 2005-05-23) COSTA, Marcos Benedito Caldas; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319The simulation of a zero-offset seismic (ZO) section from multicoverage, through of stack, is a very used method of seismic reflection imaging, that reduce the amount of data and is aimed to improve the signal/noise ratio. Based on hyperbolic traveltime approximation depending on three kinematic attributes, recently, it was developed a new method to simulate zero-offset (ZO) sections called common reflection surface stack (CRS) method. Also, following this new concept of seismic imaging it was introduzed a method to simulate common-offset (CO) sections from multicoverage data by using a paraxial traveltime approximation for paraxial rays in the vicinity of the finite-offset centra ray. This new traveltime approximation depend on five kinematic attributes. In this work, from the hyperbolic paraxial traveltime approximation with finite-offset central ray, we derive a new formula of traveltime approximation by using the diffraction point condition, reducing the original formula to four parameters. For both approximations, that´s for reflection and diffractions, we show the finite-offset FO-CRS stack operators. We, also obtain these formulas to the four seismic configurations (common-shot (CS), common-receiver (CR), common-midpoint (CMP) and common-offset (CO)). To analise behaviour FO-CRS stack, when this is perturbed, we debatable the sensibility with respect to each one the five parameters (K1, K2, K3, βS and βG). This sensibility analysis was perfomed in two ways: Sensibility through the disturbance of each parameter visualized in the stacking surfaces FO-CRS- and FO-CDS, and the first derivative of the traveltimes FO-CRS and FO-CDS. After realize the sensibility analysis, we utility a new condition, K2 = 0 and therefore, we obtained a new approximation, now depend on three parameters. Using that hyperbolic traveltime approximations (in function of five, four and three parameters), we propose an algorithm multicoverage seismic reflection data. Finally, is presented a studed of Fresnel zone, to delimit the aperture of FO-CRS stacking surface.Item Acesso aberto (Open Access) Estudo comparativo entre estereotomografia e da tomografia da onda NIP: aplicação em dados sintéticos e reais(Universidade Federal do Pará, 2010) PRAXEDES FILHO, José Ribamar; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319The determination of an accurate velocity model is a fundamental requirement for the seismic imaging. New methods, such as prestack stereotomography and poststack NIP wave tomography, are powerful and very suggestive tools for this task. The prestack stereotomography is basically based on the concept of locally coherent events interpreted as primary reflections and that are associated to ray segments that are linked through the same reflection point in depth. In NIP wave tomography a seismic event is represented by a hypothetic NIP wave that is associated to a reflection point in depth. The NIP wave attributes are determined during Common Reflection Surface (CRS) procedure. The objective of this work is to compare both methods of velocity model determination in depth. Then a review of the theoretical foundations of both tomographic methods are made, considering its main differences, and then applied to a synthetic data and a real marine dataset (seismic line 214-2660 of the Jequitinhonha Basin, Brazil). In order to evaluate the velocity models determined by these two approximations, the data were prestack depth migrated using the Kirchhoff algorithm and also generated Common Image Gathers (CIG). The results have shown that both tomographic methods yield representative velocity models. However, it was noticed that the velocity model estimated by stereotomography behaved better in laterally varying media, but only applied in prestack data with a high signal-to-noise ratio.Item Acesso aberto (Open Access) Estudo do método de empilhamento SRC e aplicação em dados sintéticos e reais(Universidade Federal do Pará, 2005-04-08) PASCHOAL JUNIOR, Waldomiro Gomes; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319Seismic stacking is a method designed to simulate zero-offset (ZO) seismic sections from multi-coverage seismic data. The resulting simulated ZO section gives rise to a significant increase of the signal to noise ratio. This method is done by means of seismic processing socalled the common mid point (CMP) method, through makes use of the so-called normal moveout and dip moveout (NMO/DMO) corrections. In this work, a new seismic stacking method called common reflection surface (CRS) is used to simulate ZO seismic sections. The main characteristic of the CRS method is: 1) the use of a more general, multi-parametric stacking operator that approximates the traveltimes of the primary reflections for sources and receiver pairs arbitrarily located on the vicinity of the normal ray. The parameters or attributes of the stacking operator are the radii of curvatures of two hypothetical waves called normal incidence point (NIP) wave and normal (N) wave; as well as the emergency angle of the normal ray. The CRS method assumes that the near-surface velocity is a priori known. To determine the abovementioned parameters appropriately, main for the CRS imaging method, is necessary search strategies that use cases special of the approach of second hyperbolic order of the traveltimes. The presented search strategies are: extended-pragmatic CRS and global-local CRS. To show the efficiency of these strategies they are applied in the synthetic Marmousi and real land datasets of the Amazon palaeozoic basin. As result sections ZO simulated by three different stacking methods (CMP, CRS extended- pragmatic and global-local CRS), to compare the efficiency of these, with relationship I cost her computational and the resolution of the seismic image.Item Acesso aberto (Open Access) Estudo do método de inversão tomográfica 2D baseada nos atributos cinemáticos da onda NIP e construção de interface gráfica para o processo de picking(Universidade Federal do Pará, 2007) OLIVEIRA, Iran Gadelha de; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319In this work, a new tomographic reflection inversion method is studied, with the objective of determining smooth and isotropic velocity models for real and synthetic seismic data. The velocity model is obtained by the program NIPTOMO, which is an implementation of a tomographic inversion method of the kinematic attributes of the hypothetical waves NIP (normal incidence point). The input data for the tomographic inversion, e. g., traveltime tables and NIP attributes (wavefront curvature radius and emergence angle) are obtained through a set of picked points on a simulated zero-offset (ZO) section, previously obtained by the common-reflection surface (CRS) method. The choice of picked points in a ZO section is normally made using automatic picking programs that identify locally coherent events in a seismic section, based in user-defined parameters. The picking process is one of the most critical steps in this new method, since the choice of non primary reflection events, such as diffractions and multiples, may lead to errors in the velocity model obtained by the tomographic inversion. This work has as main objective develop an interative picking program to give to the user the control of the choice of primary reflection points that are used as input for the tomographic inversion. The present picking program was tested on the synthetic Marmousi dataset and on a real data from the Tacutu Basin, Brazil (seismic line 50-RL-90). The results obtained show that the interative picking process for the choice of primary reflection events points favors the determination of a precise velocity model.Item Acesso aberto (Open Access) Um novo algorítimo para implementação do método de empilhamento SRC 3-D e modelagem sísmica da Bacia do Amazonas(Universidade Federal do Pará, 2006-05-23) LIMA, Charles Cristiano de Assis; CALLAPINO, German Garabito; http://lattes.cnpq.br/6064981270181319The Common Reflection Surface Stack (CRS) is a seismic reflection imaging technique that is independent of velocity model to simulate Zero-Offset (ZO) seismic section or volume. This technique have been used, alternatively, in seismic reflection processing and many works have been demonstrate that the CRS method shows results with better signal to noise rate and lateral resolution in comparison with conventional methods, e. g., NMO/DMO stack. The CRS stack provides some attributes or wavefield parameters that could be used in many applications, e.g., velocity models estimation, AVO and AVA analysis, geometric spread factor estimation, projected Fresnel zone, and others. The CRS technique has a second order hyperbolic traveltimes approximation in central ray vicinity. In the 3-D case, for a normal central ray or ZO, the CRS operator depends on eight parameters, estimating by coherency analysis from seismic data. In this work, the 3-D ZO CRS operator is analyzed for both reflection and diffraction events with respect the traveltimes obtained from straight modeling. I present a new CRS stack algorithm to simulate ZO sections or volume. I still present, in this work, a 3-D seismic modeling of the sedimentary Amazon Basin with SW3D consortium packages. The geologic model was based in true geologic and geophysics data.Item 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/6064981270181319Among 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.