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 - 20 de 20

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)
Características hidrodinâmicas da plataforma interna do nordeste paraense
(Universidade Federal do Pará, 2014-08-28) ALVES, Alex Costa; BÉRGAMO, Alessandro Luvizon; http://lattes.cnpq.br/9711842025835463
This study aims to characterize the hydrodynamics of the continental shelf near the northeast coast of Pará state of in adjacent points to the municipalities of Salinópolis and Marapanim. The choice of the period of data acquisition took into account the contribution of the Tocantins River, which has a higher discharge during the month of April and lower discharge during September. Data were collected at two anchored stations on September 11, 2013 and April 25, 2014, both of 25 hours duration. Each as obtained data were not only hydrodynamic (longitudinal component of current) and hydrographic data (temperature, salinity and density), it was possible to calculate the transport of mass and volume. The observations were performed using a couple of acoustic Doppler current profilers and salinity, temperature and pressure data recorders. The data processing included filtering by moving averages and interpolation to analyze the results in dimensionless depth. The hydrographic results revealed a possible influence of continental drainage during the acquisition period. The comparison between water currents and wind during the experiments showed that the influence of the wind was not relevant in the circulation. The transport calculations indicate a circulation predominantly influenced by tide and freshwater contributions.
Acesso aberto (Open Access)
Conversão tempo-profundidade de seções sísmicas empilhadas por raio imagem e raio normal
(Universidade Federal do Pará, 2014-06-24) REZENDE, Diogo Pena; CRUZ, João Carlos Ribeiro; http://lattes.cnpq.br/8498743497664023
In general, the oil industry makes the time-to-depth conversion of seismic data by the image ray tracing method. This method takes time into the depth, point to point, the amplitudes of the time migrated seismic section. For each point of the migrated time section, it is necessary to trace a ray perpendicular to the surface. After this, the amplitude of the migrated point of the section takes place in depth. The seismic migration method pre- or post-stack consists of placing seismic events in the correct positions in time or depth sections. Seismic depth sections provide an image near of the subsurface, in order to facilitate the identification of possible oil accumulating geological structures. The conversion of sections from the time to the depth domain is an intermediate step in the construction of seismic images in depth. This work developed and tested a method of converting time to depth the zero-offset seismic sections. In this case, the construction of sections in depth uses normal ray tracing method. The proposed method makes use of the (slowness versus time of intersection) transformation on the zero-offset section. Each point in the domain provides initial conditions for the normal ray tracing: a start position of the initial rays and initial angles formed with the normal to the surface, i.e., the slowness initial parameter. Unlike ray image method, several rays use the same travel time and the same initial position, defining an isochronous curve. The amplitude of each point in the zero-offset section takes place to depth from the distribution of values along each isochronous curve in depth. The image ray based time-to-depth conversion has good recovery of the depths of reflectors as well as low computational cost, since it is necessary only one ray to convert each point of the section in time. However, the reflector continuity may be damaged in case of sharpened curvature. In turn, by normal ray the time-to-depth conversion correctly approximate the depth of the reflectors, since the same point in time assigns several times in depth. However, it has a higher computational cost, because it is necessary many rays to convert one point in time.
Acesso aberto (Open Access)
Estimativa de porosidade em lâminas petrográficas através da morfologia matemática binária
(Universidade Federal do Pará, 2013-08-02) CASTELO, Fernando Walleson Louzada; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
Oil exploration in offshore basins needs for drilling boreholes with high angle and horizontal wells, aimed at optimizing the number of exploration targets hit by a single platform. In these cases, it is technically impossible to carry out the coring operations, which prevents core analysis for direct measurement of porosity. In some situations in formation evaluation the geological knowledge of the area may help when there is low confidence in the porosity values. For the semi-submerged basins, the lateral continuity of geologic layers may allow sampling of outcrops in the immersed part of the basin. In the case of offshore basins, may be collected hand samples in outcrops of analogous formations. A relatively common problem in a petrophysical laboratory is the extraction of plugs adapted to the measuring equipment, directly from rock samples collected from outcrops. On the other hand, for this type of rock sample is trivial to obtain thin sections. The objective of this work is to estimate porosity directly on the petrographic images using the image processing method, known as mathematical morphology, which aims to describe quantitatively the geometric structures (forms) in this image.
Acesso aberto (Open Access)
Estudo hidrogeológico através de perfis geofísicos de poços e sondagens elétricas verticais (SEV's) – Salinópolis-Pa
(Universidade Federal do Pará, 2014-02-27) FREIMANN, Boris Chaves; ALVES, José Geraldo das Virgens; http://lattes.cnpq.br/8082136954133058; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
It was realized a correlation of geophysical well logs from the Sanitation Company of Pará (COSANPA) drilled in the city of Salinópolis for the local supply. The study was conducted in many areas of impound, covering 15 wells. The parameters used in the correlation were Self Potential (SP), Electrical Resistivity (ER) and Gamma Ray (GR). Also, for control purposes, was used the lithological log of the wells obtained from samples of drill cutting. This correlation was conducted to evaluate the lateral continuity of permeable and impermeable layers, in order to develop sections of the subsurface with high accuracy. I was also used Vertical Eletrical Sounding (VES) for comparation efect. It was found the probable existence of two major aquifers that lie 60 meters below sea level and have lateral continuity along the full extent of the studied area. It was also found that the top of the basement in the studied area is around 120 meters below sea level. These findings are extremely important for a better location and constructive evaluation for supply wells in the future projects in the city of Salinópolis-Pa.
Acesso aberto (Open Access)
Implantação do campo de testes da UFPA para medidas geofísicas
(Universidade Federal do Pará, 2013) ALVES, Jerry Williamis Lima; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847
We describe the results obtained during the implementation of the Federal University of Pará test site for geophysical measurements. The work was done in three stages. In the first stage, preliminary studies were accomplished to know the physical background of the area. In the second, artifacts were buried to simulate geophysical anomalies in the measurements. In the third one, new measures were performed to detect anomalies caused by the buried artifacts. Only a part of the artifacts that are scheduled for burial was buried in the site. The buried artifacts are metal pipes, metal drums, and plastic drums. The measures implemented in the first and third stages involved the methods of Electrical Resistivity, Ground Penetrating Radar (GPR), Electromagnetic and Magnetic. The measurements performed in the third stage showed the presence of artifacts in the actual position where they were buried, which turns the area suitable to serve as a training site for geophysical experimental practices.
Acesso aberto (Open Access)
Investigações ambiental e forense com os métodos geofísicos radar de penetração do solo, polarização induzida e eletrorresistividade no Cemitério do Tapanã, Belém/Pará
(Universidade Federal do Pará, 2010-04-30) CATETE, Clístenes Pamplona; SILVA, Lúcia Maria da Costa e; http://lattes.cnpq.br/8612431024609774
The cemeteries are considered potential sources of underground water contamination. Since the use of geophysics in the mapping of the hydrostatic level (HL) has become a very important tool in the environmental monitoring, it makes possible to verify adequate or inadequate areas for burials in cemeteries. In the other hand, the localization of underground clandestine hollows and tunnels, can be of utility for the Forensic Science. In this work, geophysical methods were applied for mapping the HL in a cemetery and to find buried structures related to the Forensic Science. Ground Penetrating Radar (GPR) was used in the mapping of the HL in the whole Tapanã cemetery, while the resistivity and induced polarization (IP) methods were applied on a test site built in that cemetery for forensic, environmental and resgate related geophysical studies. The results with the GPR showed that the HL depth in the Tapanã cemetery varies from 7 m, at high topographic levels, to 1 m, at low topographic levels. The IP was sensible to the presence of a body buried in a shallow hollow as the clandestine hollows are and showed only fair results for a tunnel. The resistivity was effective for both the buried body and the tunnel, with better definition of the tunnel. The methods gave good results even within the weathering layer rich in clay that normally occurs in the Amazon region.
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
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)
Modelagem matemática do sistema estuarino dos rios Mojuim e Mocajuba (Pará-BR)
(Universidade Federal do Pará, 2016-02-29) SANTOS, Arthur Souza dos; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
The estuaries of Mojuim and Mocajuba rivers are located in the eastern sector of the Amazon Coastal Zone and represent a peculiar and complex environment. They are connected by several channels and are receive influence of the Bay of Marajó and the Atlantic Ocean. The following research aims to implement a hydrodynamic model based on a flexible grid on the of Mojuim and Mocajuba rivers estuarine system; and to analyze the hydrological and hydrodynamic characteristics of the upper estuary of these rivers. The methodology involves the use of D-Flow Flexible Mesh pack a get simulate hydrodynamics patterns into the domain that covers the Mojuim Mocajuba rivers, the canals connecting these rivers, part of the mouth of the Bay of Marajó and the adjacent tidal flats. It was also performed an "in situ" systematic data collection, in which parameters of flow, salinity, turbidity and water level were analyzed during a tidal cycle in sites located at the upper estuary of Mojuim and Mocajuba rivers. In the Mojuim river two seasonal campaigns were made in two different sites and in the Mocajuba river only one campaign were made in the rainy season, however, a tide station was installed in this location that operated for 25 weeks. Part of the sample data were used as input to the hydrodynamic model. The upper estuary of Mocajuba river presented a macrotidal regime with maximum height of 5.8m recorded. In the Mojuim river, a gradual attenuation of the tidal wave is noticeable and, in the collection point and in the upper estuary a one-way flow discharge during the rainy season was observed. A different hydrodynamic pattern between the two rivers was also observed, with ebb speed more intense than floods and their hydrological properties directly influenced by the tide fluctuation. Finally a hydrodynamic model in flexible grid was implemented and calibrated in the researched area, where initial and boundary conditions were assigned, as well as adjustments to the border forcing. The model generated a good representation of the estuary conditions, showing acceptable tidal and hydrodynamic pattern when compared with the "in situ" measurement, once the error between the measured data and modeled data related to the water level were less than 5%, and errors related to transportation are lower than 15%.
Acesso aberto (Open Access)
Otimização computacional da técnica de elementos finitos para o modelamento geofísico eletromagnético
(Universidade Federal do Pará, 1991-11-25) BATISTA, Lurimar Smera; PORSANI, Milton José; http://lattes.cnpq.br/1428637808064409
Acesso aberto (Open Access)
Paleocanais: uma opção para a prospecção de água subterrânea rasa na Ilha de Marajó
(Universidade Federal do Pará, 1981-09-18) PORSANI, Milton José; RIJO, Luiz; http://lattes.cnpq.br/3148365912720676
Acesso aberto (Open Access)
Processamento e imageamento sísmico usando o CRS
(Universidade Federal do Pará, 2014-02-04) PENA, Felipe Astur Valdes; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
This work aimed at the application of the common-reflection-surface stack methods (CRSconventional), of the CRS-partial method, and of the NIP-tomography inversion method, to generate seismic data images for the interpretation related to geologically complex areas. The constructed model, and named Duveneck-Astur, was used to simulate a geological ambient formed by layers limited by smooth surface reflector interfaces, but that the paraxial ray theory was attended, differently from other synthetic common models where the presence of geological faults, and of high horizontal and vertical gradients exist, like in the Marmousi and the Sigsbee models, among others. To analyze comparatively the resolution of the applied methods, two tests were performed with the synthetic data. One test consisted of decimated data with random muting of traces in the CMP families, and another test with addition of noise. It was computer analyzed the behavior of the different stack methods to obtain a depth velocity distribution by NIP-tomography inversion, that uses the kinematic wavefield attribute constraints to estimate a velocity model consistent with the data. NIP-tomography results were mutually compared, and also to the velocity model obtained from semblance velocity analysis. The velocity distribution were used in the PSPI migration to verify consistency in the results.
Acesso aberto (Open Access)
Processamento, inversão e imageamento de dados sísmicos marinhos
(Universidade Federal do Pará, 2012) SILVA, Douglas Augusto Barbosa da; LEITE, Lourenildo Williame Barbosa; http://lattes.cnpq.br/8588738536047617
This work was there on the study and processing, inversion and imaging in time and in depthof Marmousi seismic data, and of the real Jequitinhonha obtained in the Bahia state Brazilian atlantic oriental continental platform. Were applied the NMO and CRS stack methods andthe niptomographic inversion technique of the cinematic attributes of the wave field. Withthe NMO stack was obtained a velocity distribution map throughout the velocity analysis onthe semblance coherence map and straight afterward the stacked and migrated sections in thedomain of the time and depth. The stack method of the common reflection surface (CRS)was applied with the crsstack-511 program to obtain the stacked and migrated sections inthe time domain and to extract the field wave parameters throughout the coherence analysis and of the redundancy obtained on the seismic data of multi-device. The niptomographicinversion phenomena of reflection took place throughout the aplication of the niptomo program,which is an implementation of the inversion method of the cinematic attributes ofthe NIP hypothetic wave, extracted straight from the CRS stack, to obtain an smoothedvelocity model, and subsequently, a migrated section in depth. The migrated sections areof the Kirchhoff kind. The techniques used follow a pre-determined and realized flowchartfollowing a file “makefile”, that works as an stage organizer. These stages were realized in theLinux desktop and in the Seismic Uni*x system of the Center for Wave Phenomena (CWP)of Colorado School of Mines. The results of the three techniques were compared with theaim of illustrating the evolution of the visual quality of the reluctant sections throughout theevents continuity trace-by-trace and the signal/noise relation, to analyze differences and improvementsin the migrated sections expecting a better geologic interpretation and organizebetter terms of processing and imaging, trying to aid possible well succeed drillings.
Acesso aberto (Open Access)
Reconhecimento de fáceis em perfis geofísicos de poços com rede neural competitiva
(Universidade Federal do Pará, 2015-02-27) COSTA, Jéssica Lia Santos da; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
The description of a depositional system based on the recognition of sedimentary facies is critical to the oil industry to characterize the petroleum system. In the absence of these facies description by cores or outcrop, we present a methodology based on intelligent algorithm able to identify facies of interest in wireline logs. This methodology uses a competitive neural network to extract geological information from the physical properties mapped in the M-N plot. The competition among neurons identifies the facies of interest, which have been previously identified in a cored borehole in other non-cored boreholes in the same oil field. The purpose of this methodology is to encode and transmit the geological information gained in cored boreholes to non-cored wells and thus achieve the geological interpretation of the facies of interest in an oil field. This methodology has been evaluated with synthetic data and actual wireline logs from two cored boreholes drilled in the Namorado oil field, Campos Basin, Brazil.
Acesso aberto (Open Access)
Regressão múltipla de perfilagem geofísica aplicada à estimativa de teor mineral
(Universidade Federal do Pará, 1989-10-02) SANTOS, Deusivaldo Aguiar; SAUCK, William August; http://lattes.cnpq.br/6655455534234531
Acesso aberto (Open Access)
Tomografia eletromagnética poço-a-poço usando os reguladores de suavidade global e de variação total
(Universidade Federal do Pará, 2014-07-07) SANTANA, Julielson Monteiro de; SOUZA, Victor Cezar Tocantins de; http://lattes.cnpq.br/6394094668539482
In this work, we describe the forward and inverse problems of Crosswell electromagnetic tomography. The model geometry has azimuthal symmetry, which significantly simplifies both the forward modeling and the inversion processing, reducing a 3-D tensor equation to a scalar two-dimensional form. In the forward problem we use the finite element method for the numerical solution of the Helmholtz equation. In the inverse problem, we discuss the use of three stabilizing functionals: Global smoothness (GS), Total Variation (TV), and Absolute Equality (AI). The first one uses a smoothing function on L2 norm, while the second uses smoothing on the L1 norm, which accepts abrupt changes between adjacent parameters. Our results show that the use the TV method generated good estimates of the geometry and conductivity of bodies, both for small and for large conductivity contrasts between the targets and the surrounding environment. We also note that the Total Variation regularization showed a better estimate of the parameters, compared to Global Smoothness. In most of the synthetic models used in this work, we obtained a better estimate of the bodies when we used Absolute Equality constraints to the cells at the edges of the inversion grid, in addition to the stabilizing functionals.
Acesso aberto (Open Access)
Tratamento quantitativo de anomalia de potencial espontâneo
(Universidade Federal do Pará, 1976-10) GUERREIRO, Sonia Dias Cavalcanti; LOURENÇO, José Seixas
Acesso aberto (Open Access)
Utilização da sísmica de reflexão rasa no estudo da morfodinâmica de rios na região amazônica
(Universidade Federal do Pará, 2014-09-29) FURTADO, Camila da Cunha; VIZEU, Roberto; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471
The main idea of this research is identify and characterize morphodynamic phenomena present on the lay of the Pará river and foz of the Tocantins river, this area comprises from the Bocas bay unto east portion of the Marajó island. It is a region where exists scarcity of information and data about constitution and morphology of the lay, there is necessity to search new knowledge. Sediment samples from the bottom of the river were collected with the assistance of a Van Veen sampler, 181 (one hundred eighty-one) samples submitted to macroscopic analysis aiming to identify the type of material which composes the bottom. With the data of hydrodynamic modeled assistance was possible to connect the patterns of bottom forms with the sort of sediment which composes the lay and the prevailing hydrodynamic in the local. Based on the seismic data, was possible to identify and map the sonographic patterns in 15 types of echoes, classified in four categories. The less frequent echo types are the ones which present very irregular lays and little or no acoustic signal penetration. Specially the C1 type characterized by diffraction hyperbolas presence and the D1 type which treat responses arising from large deposits of sediments, found just in two forms of acoustic. The most significant bottom forms were identified on the stretch where the Canaticu river flows to Pará river where the principal canal width decreases from 8km to 4km in upper depth to 20m. The adhibition geophysical methods (acoustics), by the use of the Sub-Bottom profiler SB-0512, enable the knowing of the bottom forms, as well as its dimensions that those submerged forms show over the studied region. The way how this region’s lay sets itself and the dimensions that those corps reach can affect the sailing on some river’s stretch, as well as it can affect future civilian building. Therefore, this work opens ways to future more appropriate investigations on the issues mentioned above.
Acesso aberto (Open Access)
Zoneamento de poços através da inferência Fuzzy
(Universidade Federal do Pará, 2015-06-26) RUIZ TAPIA, Alberto José; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
Well zoning may be understood as the geological characterization (location and facies description) of each layer crossed by the borehole trajectory. Well zoning is a common activity in conventional core analysis and important for petroleum geology, assisting the construction of stratigraphic column and also for petroleum engineering aiding in the development of the well exploitation plan. This work presents a method for well zoning wells of non cored boreholes, so that the information gained in these wells can contribute to improve the knowledge of sedimentology and oilfield engineering. The method showed here uses the core description for building the knowledge base of a fuzzy inference system, which operates with P parameter (a new combination of density log and sonic log), parameter M (M-N plot) and the natural gamma ray log and the deep resistivity log. Operation of this fuzzy inference system using log data from non cored borehole produces the well zoning of each non cored borehole. This method is presented with synthetic data satisfying the petrophysical model and the Archie Law, and real data of two cored boreholes from the Namorado oilfield, in the Campos Basin.