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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Agora exibindo 1 - 16 de 16

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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/1134403454849660
This 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.
Acesso aberto (Open Access)
Aplicação de sísmica de alta resolução em ambiente estuarino amazônico, na investigação de estruturas neotectônicas
(Universidade Federal do Pará, 2015-02-27) CORRÊA, Alberto Jacques Ribeiro; PINHEIRO, Roberto Vizeu Lima; http://lattes.cnpq.br/3251836412904734; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
Seismic methods of high resolutions have been intensely used on the mapping of the Quaternary, investigation of sedimentary processes, and others. The study area is located in the north region of the state of Pará, between the parallels 1° S and 2° S and the meridians 50.5° and 48.25°, the research being carried out in the submerged areas bordering the Marajó Island in its east and the southeast part, comprising the Bay of Marajó, the mouth of the Tocantins River and Pará River. The high resolution seismic employed in this region aims to tectonic investigation by using the data collected by the acoustic profiler SB-512I from Edgetech, and from these data to identify structural shapes, fractures, subsidence or elevations ruled by tectonism. From the analysis of the seismic data obtained in the study area, nine features were identified interpreted as tectonic occurrences. Due the specificities of equipment and geological characteristics of the region, possible areas of tectonic faults were not detected at great depths by the equipment used, however, they were found in areas where tectonic forces occurred with sufficient intensity to cause visible faults in the mapped pseudo-sections.
Acesso aberto (Open Access)
Caracterização física do estuário do rio Mojuim em São Caetano de Odivelas - PA
(Universidade Federal do Pará, 2015-02-25) ROCHA, Adriano Santos da; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
The present study has as objective describe the hydrodynamics, hydrologic and morphological aspects, of estuary of Mojuim River, it is localized in São Caetano de Odivelas city –PA (Salgado Paraense),it is analyzing the variations that happen according sea cycle seasonality (rain regime).The hydrologic and hydrodynamics data was collected in two seasonal period in 2014:March,it corresponds to rainy period (~500 mm)and September, it corresponds to dry period (~100 mm),both during tide of syzygy. The bathymetric survey happened only in the rainy period and it was realized with an echo sounder in a sampling grid with 116 spaced cross profile of 200m.In the estuarine channel,it was defined a section where it was realized profiles of strength measurement and current intensity and output, with ADCP, and in three fixed stations,right bank (RB), center(C),and left bank (LB)it was realized collections of conductivity and turbidity with a CDT and an OBS, in the water column. The pattern of tidal and the salinity they were also obtained with a pressure sensor and conductivity fixed in the LB during 56 days in the rainy period and 57 days in dry ones. The estuarine is shallow (4,5 m of average depth) and it is restrained by a regime of semidiurnal macrotidals. During a tidal cycle the salinity increases in the floods and decreases in the ebb tide in both seasonal periods. Turbidity increases in the floods and it decreases in the ebb tide of the rain period and the value measured in the center (C) is double found in the banks. In the dry period, the salinity was higher to rainy period (average 20 and 8, respectively) .This estuarine presents well mixed; it is vertically homogeneous in the rainy period and highly stratified in the dry. The flood flows occur predominantly at the center section, while the ebb flows predominate in the RB, in the two situations the highest intensity of the current occurs in the rainy season. The estuary is an importer in the two periods, however, more entering in the rainy period (resulting transport of 95,87 m³/s) .These data correspond to the first information on the hydrological and hydrodynamics characteristics of the estuary and they can support further studies in the region.
Acesso aberto (Open Access)
GPR aplicado à arqueologia nas áreas do porto da Cargill (Santarém/PA) e no Palacete Faciola (Belém/PA)
(Universidade Federal do Pará, 2012) SOUZA, Danusa Mayara de; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847
This study was conducted in two areas. The first, located at the backyard of the Palacete Faciola, Belém/PA and, the second, named 4A, in the Archaeological Site PA-ST-42, located at the Port of Santarém/PA. The geophysical survey described in this work was undertaken in order to assist in archaeological prospecting, indicating places for future excavations in order to detect structures and/or artifacts buried on the sites. The radargrams acquired in both areas showed several anomalous features. Until the finish of this work any excavation had been undertaken in Palacete Faciola. In 4A area, however, two trenches were opened revealing various archaeological fragments.
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Identificação de fácies em perfis com algoritmo heurístico
(Universidade Federal do Pará, 2015-02-27) ALMEIDA, Thelson Luiz Pinheiro de; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
The development of oil well drilling techniques and the optimization exploitation of various hydrocarbon reservoirs on the same time, an issue has drawn attention from researchers from the oil industry: identification of sedimentary facies in wells not core available. Therefore, this paper proposes the use of a heuristic algorithm based on the behavior of insects, which contributes to the interpretation of M-N Graphic on computational way. Using wells logs and plot your data in graphic M-N, we have aimed to sort of well log points in relation to fixed points, using the creation of groups (clusters) of data that have some similarity or symmetry, based on what we call attractiveness. Using the creation of these groups of points of the well log, in the neighborhood of fixed points through which suffered major attraction, we can do the identification of multiple data families which, in this work, will be taken as layers, depending on which mineral fixed point are closer, can have their main mineral composition identified without the help of the core and thus obtain the sedimentary facies knowledge overpassed by the well.
Acesso aberto (Open Access)
Identificação de fácies em perfis com rede neural direta
(Universidade Federal do Pará, 2015) GOMES, Kivia do Carmo Palheta; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
The application of coring techniques is usually carried out in a limited number of vertical wells drilled in an oil field, causing the rarefaction of facies descriptions and not allowing a realistic characterization of reservoirs. Increased production of hydrocarbons in an oil field is extremely important for the oil industry and deeply dependent on the knowledge of the reserves in accordance with their petrophysical properties, which vary depending on geological facies. A better description of facies may reflect more realistic estimates of hydrocarbon volumes. This dissertation presents an intelligent algorithm capable of producing the transport of geologic information produced by the facies analysis of cores to the non-cored wells in an oil field, through the design of a direct neural network trained to perform a mapping of geological information in terms of the physical properties registered in the well logs. The intelligent algorithm processes the result produced by the neural network through a depth coherence filter to locate the boundaries of the layers along the well trajectory. For all of our cases the intelligent algorithm presented results compatible with the core analysis and independent of the size of the training set.
Acesso aberto (Open Access)
Implementações alternativas de tomografia do tempo de trânsito utilizando a equação da onda
(Universidade Federal do Pará, 2014-04-23) CARDOSO FILHO, Josafat Lopes; COSTA, Jessé Carvalho; http://lattes.cnpq.br/7294174204296739
Wave equation tomography is a robust methodology for velocity analysis when strong velocity variations occurs. This approach has been successfully applied for reservoir monitoring and characterization using crosswell data. The choice of the objective functions, preconditioners and regularizing functionals controls the robustness, eciency and the quality of the velocity reconstruction. This dissertation investigates each of these design parameters and its consequences for the performance of the wave equation tomography using synthetic crosswell data generated from smoothly and strongly heterogeneous velocity models. Two proposals for the objective functions are used in this work; the first is sensitive to phase dierences and the other is proposal to be less sensitive to the source pulse. Both do not require velocity picking performed well in the numerical experiments. A preconditioning strategy adapted from the imaging processing literature produced a noticiable improvement the convergence rate of the algorithm by eliminating artifacts caused by limited aperture, random noise and artifacts produced by sources and receivers. A regularizing functional penalizing deviations from velocity information available near the wells additionally contributes to recover a velocity tomogram with higher resolution and consistent with the synthetic model. Wave equation tomography is a robust methodology for velocity analysis when strong velocity variations occurs.
Acesso aberto (Open Access)
Investigação de pavimento asfáltico por meio do método geofísico radar de penetração do solo
(Universidade Federal do Pará, 2011) AMARAL, Carolina Narjara Mazzini; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
Most public paved roads may have some sort of imperfection that leads to unsafe traffic, increased transport costs, and pollution. These problems could be avoided if the defects were identified on the floors before they show up at the surface because in general they begin in the underlying layers of the asphalt coverage. This paper proposes the use of GPR to identify problems in pavements based on numerical simulations of the GPR and on field surveys. Simulation of two physical models has been made: i) pavement in use, in which pipe and the most common defects (voids and infiltration) have been inserted, and ii) recent floors, both above a substrate. The interfaces of the pavement layers and the channeling were easily individualized whereas the imperfections show similar patterns of reflection, differing in the polarity of the signal amplitude and in its attenuation (smaller in the voids and higher in the infiltration). Differently from what occurs in other places, the layer interfaces in recent pavements were more easily identified with the frequency of 400 MHz than with a frequency of 900 MHz because of the conductivity of the products deriving from weathering, which occurs in the Amazon. These responses were used then to investigate two places in the city of Belém (PA): a sector of MauritiTv. which presents recurrent defects on pavement, and a newly paved stretch at Federal University of Pará (UFPA). The first survey identified and mapped defects and permitted to infer their possible causes (water loss from the drainage system) while the latter helped in delineating layers and the contact with the substrate (showing that the thickness of pavement layers differ from the projected ones). The results show how the GPR can be an important tool in maintaining and planning the recovery of paved roads by providing a diagnosis in a fast, safe, and low cost.
Acesso aberto (Open Access)
Investigação geofísica forense e antropológica com o método GPR no cemitério do Tapanã e no cemitério perdido de Mosqueiro (Belém, Pará)
(Universidade Federal do Pará, 2013-03-22) BRASIL, Diogenes Leão; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
This work was accomplished with ground penetrating radar (GPR), a geophysical method used to investigate the shallow subsurface with high resolution in a non-destructive and noninvasive way. The survey was conducted in two locations in the metropolitan region of Belém, Pará State (Brazil), with 200 and 400 MHz antennas, both in the Tapanã cemetery: the first located in the test site for Controlled Testing of Forensic Geophysics, Environmental and Rescue (FORAMB) and the second one, in a burial zone with concrete cover. Surveys were also conducted in the northwest portion of Mosqueiro Island, across Marajó Bay, with a 400 MHz antenna, where reports of traces of a non-registered cemetery that would have been abandoned for about 80 years and could have been the final destination of cabanos, slaves and indians.These reports led researchers from the Federal University of Pará (UFPA) to visit the site in 1986 to test the veracity of the reports. At FORAMB the monitoring of the three targets that were buried there in 2007 was continued: a human body in a shallow grave 0.8 m deep, a tunnel simulated by a hollow wooden box placed 1 m deep and a box with metal, simulating weapons, deposited at 0.8 m depth. In the burial zone with concrete cover, the survey efforts focused on the effect of the concrete cover.The results obtained in the Tapanã cemetery show the usefulness of GPR in viewing targets under shallow soil cover and saturated clay, typical of the Amazon region, even when it is covered by a layer of concrete. These results reinforce the importance of pooling 2D and 3D data for interpretation of results; the GPR profiles over the concrete covering the bodies in various ages of burial, moreover, show significant variations of the responses, partly observed in other studies. The Mosqueiro results showed that ancient targets in climatic and geological conditions of the Amazon region, do not allow easy detection. It is possible that the remains of the decomposed bodies are not amenable to detection, but the discontinuity of the strata above the burial due to excavation, and the resulting concavity of the collapsed grave infill material may be diagnostic.
Acesso aberto (Open Access)
O método GPR aplicado à arqueologia no Sítio PA-ST-42: porto de Santarém, Pará
(Universidade Federal do Pará, 2014-03-06) FURTADO, Carla Patrícia Queiroz; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
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Migração Kirchhoff pré-empilhamento em profundidade usando aproximação paraxial do tempo de trânsito
(Universidade Federal do Pará, 2014-08-28) CUNHA, Antonio Rizimar de Andrade; CRUZ, João Carlos Ribeiro; http://lattes.cnpq.br/8498743497664023
In order to get an accurate image of the subsurface we need efficient techniques for evaluating the wave field. In literature we find several geophysical methods based on the numerical solution of the seismic wave equation. Among the various techniques of seismic imaging, Kirchhoff prestack depth migration remains widely used because of its flexibility in processing data through several geometries of acquisition, and its practicality in solving problems related to imaging. Assuming this view, we seek to create more efficient alternatives for the accurate calculation of the parameters involved in migration processes. We consider the efficient calculation of the traveltimes as a critical factor, focusing on the fundamental amplitude in their respective points in depth using the Paraxial Ray Theory through the Runge-Kutta method of fourth order. The paraxial extrapolation of the traveltimes belongs to the class of dynamic ray tracing, where it is possible to determine information in complex geological environment on regions influenced by shadow zones. The application of this technical demands amounts previously arranged in a central reference beam that is obtained from the kinematic ray tracing, furthermore a macro velocity model of the medium is necessary for the traveltimes calculation. For comparison, we consider two different ways to calculate the traveltimes tables: The first was performed by routine RAYT2D from SEISMIC UNIX (SU) package, which is considered a robust method of evaluation; the second is based on Paraxial05 method. The depth migration required the seismic data input and the traveltimes. The images were obtained from an algorithm written in SHELL and a third image is obtained through the difference between the two initial results.
Acesso aberto (Open Access)
Modelagem hidrodinâmica 2DH no furo de Laura - Nordeste Paraense
(Universidade Federal do Pará, 2016-05-23) LOPES, Matheus Santiago; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
The estuarine environments are widely studied over the past decades due to its social, environmental and economic importance. For example, the strategies to contain oil spill are based on hydrodynamic modeling research. The application of numerical models to predict and analyze circulation patterns inside coastal water bodies is growing in the country. In northern Brazil the use of those models is still experimental. In this work was used the software SisBaHia to implement, calibrate and validate a hydrodynamic model to the water body “furo da Laura” (FL), located on Guajara-Mirin river, on the coastal region of northeastern Pará. The model was calibrated with previous data about surface elevation and current speed collected in three periods: dry season of 2013, rainy season of 2014 and dry season of 2014. The flood and ebb tide flow occurs simultaneously in two entrances that the FL presents. The goal was to locate the barotropic convergence and its seasonal variation. It was simulated one month during the rainy season (February) and one month during the dry season (August). It was simulated a lagrangian transport with particles released in Sol bay with an analysis of its horizontal dispersion. The convergence sites were found nearby the south entrance of the FL and the divergence sites have a spatial variation due the tide cycle. The particles released in the Sol bay tend to leave the modeling domain and don’t penetrate the FL, but they contribute with the erosion and sedimentation process that occurs in coast of the Colares Island.
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Modelagem hidrodinâmica aplicada ao estuário amazônico: uma abordagem em malha flexível
(Universidade Federal do Pará, 2014-08-19) BORBA, Thaís Angélica da Costa; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
Amazonian Estuary is a very complex system due to its large number of water bodies; it also encompasses four of the 20 largest rivers of world. Several hydrodynamic models have been applied on this system, but its complexity on shape makes difficult the grid definition when curvilinear grid is used. This research aimed the implementation of hydrodynamic model on this, based in flexible mesh grid that is easier to define on this kind of systems than curvilinear grids, and analyze the hydrodynamic patterns within this estuary. The methodology is based on the use of D-Flow in which a flexible mesh can be defined. The model domain encompasses the low course of Amazon River, Tapajós River, Xingu River, Tocantins River, Guajará Bay, Marajó Bay, Breves Strait and Pará River as well as the flood plain area and the adjacent continental shelf. The model presents a quite good calibration values for tidal signal as well as discharge since the Pearson's correlation coefficient presented values bigger than 0.95 for both and rmse presented values smaller than 5% for the former and 15% for the latter. The model also performed well on representation of several scenarios that represented extreme conditions regarding tide and discharge sources of Amazonian Estuary and it showed expected patterns by comparison with in situ data.
Acesso aberto (Open Access)
Modelagem numérica de dados MCSEM 2.5-D
(Universidade Federal do Pará, 2012-04-20) SILVA, Hilton Farias da; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
This work deals with the implementation of numerical 2.5-D Marine Controlled Source Electromagnetic (MCSEM) modeling applied to hydrocarbon exploration in stratified environment. In the mathematical formulation the fields were assumed to have two parts: the primary and the secondary ones. The first uses of Schelkunoff potentials in its formulation and they were employed in both (x; ky; z; !) and (x; y; z; !) domains. The secondary fields are solved in the frequency domain space (x; ky; z) by finite element method. With a Inverse Fourier transform, the secondary fields were taken in the domain (x; y; z). From the total field, we can show the influence of an oil reservoir in a stratified environment and its sensitivity to the lateral extension of a hydrocarbon reservoir.
Acesso aberto (Open Access)
Processamento, imageamento, interpretação e predição de pressão de dados sísmicos na bacia sedimentar do Jequitinhonha
(Universidade Federal do Pará, 2016-08-18) SILVA, Aucilene de Nazaré Pimenta da; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
This present work aimed to compose a seismic-stratigraphical framework for part of Jequitinhonha basin (marine east part of the State of Bahia), with data released for funded academic projects in progress. The study aims at the exploration of oil and gas, and corresponds to a proposal for for sedimentary basin revaluation. For this, the methodology is composed of velocity analysis, CRS stacking, migration, culminating in pressure prediction for the subsurface, where the aim is to map low (reservoir) and high (generator) pressure zones that act as natural pumps for fluid accumulation. The seismic data used in this study was provided by PETROBRAS for the Postgraduate Course in Geophysics (CPGF), of the Institute of Geosciences of the Federal University of Pará. The data were acquired by the PETROBRAS seismic team 214 in the offshore part or the basin. The available lines used in this study were the L214-266, L214-268, L214-270 and L214-297. Being able to separate them into two groups, we have three lines in the NE-SW directions (L214-266, L214-268, L214-270) and one in the direction NW-SE (L214-297). The velocity distributions used for the seismic sections were based on petrophysical information and empirical models, instead of using the subjective event picking in common-midpoint, stack or migration sections. The methodology presents as the first part the application of techniques based on the theory of the common reflection surface stack (CRS), which aims to generate seismic images of good quality for the interpretation of real data, and related to geologically complex media. The seismic-stratigraphic interpretation were performed using as a basis the geological information, making a correlation between the main reflectors (interfaces of higher impedance) and the stratigraphic units of the area. In this way, we constructed an empirical model for the velocity distribution (𝑣𝑅 and 𝑣𝑆) and density (𝜌) for the sections of the studied block. A higher study project aims to predict stress in sedimentary basins, as a contribution to the methods and techniques of geology and oil and gas engineering exploration. This subject is based on the knowledge of the compressional (𝑣𝑃 ) and shear (𝑣𝑆) velocities, and densities (𝜌), in order to locate areas low and high pressure zones in the subsurface, which serve as natural suction pumps for gas and oil accumulation. The theory is based on the elastodynamic equations, where the gravitational weight of the overload is responsible for the effects of strain-stress deformation in the subsurface. Therefore, to organize this problem requires the generalized Hooke’s law of linear elasticity. We presented details of the theoretical model, and an example to show how the pressure varies in the subsurface, where we highlight that pressure prediction does not necessarily increase linearly, but in a complex way that requires specific numerical formulas to be able to see important details. The applied theoretical model poses as pressure agent the vertical gravity load of the geological formations, and does not take into account the effects of curvatures, faulting and diagenesis. Also, the complex lateral tectonic events are not accounted for. The prediction of pressure and tension is an important issue for the analysis of sedimentary basins, aiming at mapping and extending potentially oil and gas productive areas. But an accurate prediction needs a 3D model for a significantly complete practical application.
Acesso aberto (Open Access)
Transformação de estimativas suaves aplicadas à interpretação de relevos descontínuos do embasamento
(Universidade Federal do Pará, 2014-08-21) MOREIRA, Mayra Moura; SANTOS, Darcicléa Ferreira; http://lattes.cnpq.br/5813659873067927
We present a method to delineate the basement relief of sedimentary basins composed by vertical faults and horizontal plans. We assume density contrast between the basement and the sediments constant or decrease with depth, and known. The developed method determines the vertical positions for horizontal plans and horizontal positions for vertical faults through an smooth initial solution of the basement relief. We produce this smooth solution through an efficient method which delineates the smooth basement relief. The horizontal positions of two adjacent faults estimates the extension of only one horizontal terrace. Similarly, the vertical position of two adjacent horizontal terraces estimates the extension of the fault between them. The performance of the proposed method is compared with the computational time of two other inversion methods, which stabilize the solution applying the Total Variation functional. The proposed method always produced solutions in less computational time as compared with the computational time required by other methods. Tests on synthetic data contaminated with zero-mean Gaussian pseudorandom noise with a standard deviation of 0.1 mGal show which proposed method produced satisfactory results and estimated basement topographies close to simulated basement topographies. The proposed method was applied to two sets of real Bouguer anomalies: Steptoe Valley (United States) and San Jacinto Graben (United States). The method produced estimated basement topographies presenting high-angle faults in accordance with the available geological information, which the basins above mentioned were formed by extensional tectonics with the consequent formation of structural settings of sedimentary basins conditioned by normal faults.

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