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).

Navegar

Agora exibindo 1 - 13 de 13

Acesso aberto (Open Access)
Estimativas de umidade no solo usando GPR
(Universidade Federal do Pará, 2011) MESQUITA, Marcelo Jorge Luz; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847
This work aims to analyze the effectiveness of GPR (Ground Penetrating Radar) as a measure of moisture in comparison to the established system TDR (Time Domain Reflectometry) and introduce changes in the calibration equations that allow estimation of the moisture from the wave velocity of the GPR. This work presents the methodologies for collecting and processing the GPR data, aimed at determining the moisture. One of the methods was applied in Cuiarana (Salinópolis - PA) with 400 MHz antenna and compared with data from TDR. The relative permittivity obtained by means of the velocities of the waves of GPR were used to infer the values of moisture from Topp and Roth's equations and thus to compare them to the values obtained with TDR. The data were statistically correlated and analyzed, enabling the establishment of a new calibration equation as a function of relative permittivity and other in terms of the speed of the GPR wave. The study successfully showed the feasibility and limitations of estimating water content with GPR.
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)
High resolution GPR applied to the “Capela Pombo”
(Universidade Federal do Pará, 2016-02-29) ESPEJO ZEBALLOS, Manuel Alejandro Junior; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
In this work was applied electromagnetic method (GPR), to identify surface layers in a speci c urban environment. The measurements were performed to map the surface layers and artifacts that make up the study area "Capela de Nosso Senhor dos Passos - a Capela Pombo" in the Barrio of Campina-Bel em. This chapel has a previous work that rescues the importance y architectural features that it has, together with the evidence recollected by the author Dominic Savio de Castro Oliveira, who noted the historical importance that has not only to be the last private chapel in the city of Belém, this author also acknowledges her design as an Italian architect's work possible Guissepi Jos e Antonio Landi. The pro les obtained after corresponding processing procedure, show that this probably presences of structures, rest of the previous building structure, which previously was in this space. The study aimed to identify anomalies. The study aimed to identify structural abnormalities, as well as possible characteristic burials of the time when it was actively used. The results of the GPR measurements were encouraging, since the method presented response of approximately 1.80 meters deep, one can identify anomalies control for the reasons as presented Chapel, and present possible anomalies related to structural foreign bodies.
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)
Inversão 1D e 2D de dados do método eletromagnético a multi-frequência - EMMF
(Universidade Federal do Pará, 2014-11-14) PIEDADE, Anderson Almeida da; RÉGIS, Cícero Roberto Teixeira; http://lattes.cnpq.br/7340569532034401
In this work is presented the rst study of data inversion from Electromagnetic Multi- Frequency Method (EMMF). In its rst part is made a presentation of the mathematical techniques used for inversion of these data. It will be shown the Gauss-Newton technique with modied Marquardt algorithm and a description of two regularization methods used in the inversion, which are Global Smoothness method (GS) and Total Variation method (TV). In the second part, they are applied to 1D inversion of EMMF synthetic data as well as are applied to real data, that were acquired in the Esprito Santo Basin, southeastern Brazil. In the third and last part, it presented the 2D inversion of EMMF synthetic data, with models, which like the 1D inversion, involving conductive and resistive targets. Results of this study show that the inversion of data from conductive targets was able to recover the resistivity structures more consistently with the true resistivity model than in the case of resistive targets. This may be due to the fact that the purely inductive radial magnetic component is naturally more strongly in uenced by conductive than by resistive regions in the geoelectrical medium.
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)
Modelagem do método MT 2D usando elementos finitos isoparamétricos
(Universidade Federal do Pará, 2017-04-07) SOUZA JUNIOR, Ivaldevingles Rodrigues de; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
The numerical modeling of the magnetotelluric (MT) method is of great importance for geophysics, since this method can be applied for several purposes, for example it can be used to study the crust of the earth as well as it can contribute to oil and gas exploration. For this reason, several researches have been carried out in recent decades to further develop MT. One of the major advantages of magnetotelluric is its relatively easy modeling, because in this technique the source is a plane wave. Existem varias ferramentas numericas que podem ser usadas para modelar o MT, There are several numerical tools that can be used to model the MT, among which stands out the nite element method (FEM). In this work the eciency of the isoparametric MEF for 2D modeling of the MT will be tested, whose main characteristic is the accomplishment of a transformation, with the purpose of mapping a distorted element to a coordinate system (natural coordinates ξ and η) where it becomes regular.
Acesso aberto (Open Access)
Modelagem numérica bidimensional de dados CSAMT com fonte dipolar elétrica usando elementos finitos
(Universidade Federal do Pará, 2016-08-20) PEREZ, Jarol David Garcia; SILVA, Valdelírio da Silva e; http://lattes.cnpq.br/9701131346395521; RÉGIS, Cícero Roberto Teixeira; http://lattes.cnpq.br/7340569532034401
This work presents the application of a 2,5D numerical modelling scheme to simulate data of the CSAMT (Controlled Source Audio MagnetoTellurics) electromagnetic method using the Finite Element method. We have applied the technique of separating the total electromagnetic field into two parts: the so called primary and secondary fields. The set of equations that govern the system has to be expressed in the spectral domain of the Fourier Transform. The solution is obtained as a composition of 2D solutions. In the first part of the dissertation, we present a validation of the answer generated for primary fields and a comparison of the 1D responses with those from the MT method. The second part of the text presents a validation of the 2,5D responses, as well as an analysis of the results, in terms of apparent resistivity and the measured electrical field related to an isolated body in a homogeneous half-space. We analyze the changes in the results resulting from changes in model parameters like the contrast of resistividade between the half-space and the anomalous body, the depth of the body and the frequency. The code developed is able to simulate with good precision the measurements of the CSAMT method in any survey configuration.
Acesso aberto (Open Access)
Prospecção de água subterrânea no município de Novo Repartimento - PA aplicando métodos elétricos e eletromagnéticos
(Universidade Federal do Pará, 2006-03-31) FREITAS FILHO, Lair da Silva; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847; VERMA, Om Prakash; http://lattes.cnpq.br/2723609019309173
This work was carried out in the rural area of the Belo Monte community in the Novo Repartimento county, localized in the SE of the Pará state. The geology of the area contains metamorphic and igneous rocks. In this geological context fractures are the only appropriate zones for groundwater storage. The objective of this work is to map those fractures. Preliminary Vertical Electrical Soundings (VES) and Radial Vertical Electrial Soundings (RVES) were carried out to determine the general fracture directions and the thickness of the overbunden. Subsequentely, HLEM profilings were carried out in directions orthogonal to the fractures. Also resistivity profiles using Wenner array and VLF profiles were carried out with the objective to compliment the HLEM data. The analysis of the all data revealed two hydrogeological domains: fractures in the crystalline basement and the overburden sediments. The later one being unsuitable for groundwater exploitation because of its small thickness, averaging 4 m. The interpreted fracture zones are NW-SE in the crystalline basement as associated to, seven conductor axes that were identified through HLEM profiles, supplemented by VLF and resistivity profiles. As a result of this work we indicate five promissory locations for wells to be drilled for groundwater exploitation.
Acesso aberto (Open Access)
Prospecção de água subterrânea no município de Piçarra-PA usando VLF e resistividade
(Universidade Federal do Pará, 2011) SOUSA, Gilvana Bezerra de; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847
This research was carried through in Piçarra city, located in the southeast of Pará state. The study had as main focus the mapping of lineaments associated with the basement fractures and the subsoil nature through geophysics, using the Very Low Frequency (VLF) electromagnetic and resistivity methods. The integrated analysis of geophysical data allowed the recognition of two hydrogeological domains in the area: Fractured zones and sediment thickness above the basement rocks, aiming to guide the location of groundwater captation wells. The study provided indications of the most promising locations for groundwater captation and the best sites to build water wells for the city supply.
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)
Utilização de medidas elétricas e eletromagnéticas para a prospecção de água subterrânea em Jacundá (Pa)
(Universidade Federal do Pará, 2014-02-27) MENDES, Marcelo Fernandes; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
The Jacundá city has a public water system supply in its infancy. From the source surface it is not perennial, small flow and serves less than 20% of the population. Open and shallow tube wells are sources of particular use, limited and seasonal. However, the flow of two deep wells, built in the city, gave evidence that alternative underground water could be a good solution for the local supply. This fact gave rise to a geophysical study to determine the deeper strata permeable. We used nine vertical electrical sounding, whose interpretation acceptd was guided by the geophysical results obtained in a hole. As a result, the models of VES's packets identified two distinct layers resistivity: A package higher, more resistive a total thickness less than 30 meters, was associated with the Itapecuru formation which, is predominantly sandy hydrogeological and weak. And the other, a substrate of low resistivity, it was assumed corresponding to the Codó Formation shales. The interpretation of Slingram data support this result. The hydrogeological potential of this second package is in the shale interbedded sandstone, which may mean the solution for the management of water supply in the city.
Acesso aberto (Open Access)
A viabilidade do método GPR para o mapeamento de camadas de bauxitas laterítica em Paragominas-PA e de goethita em Xambioá-TO
(Universidade Federal do Pará, 2011-08-31) DUARTE, Gildenilson Mendes; SILVA, Marcos Welby Correa; http://lattes.cnpq.br/3213216758254128
In this work we applied the GPR electromagnetic method mapping of layered deposits of minerals in two different environments. Measurements were made with the aim of mapping layers that form deposits of supergene origin of lateritic bauxite, and Goethite. The surveys for the mapping of layers of bauxites were conducted within the mine company Vale and also along the highway PA 256, in the municipality of Paragominas-PA. Resistivity tests were performed within the mine bauxite on a thick capping of clay in an attempt to correlate the variations of resistivity with the lithologic of the studied area, because the GPR measurements were not successful on this capping due the attenuation of the radar wave. The measures for mapping layers Goethite were carried inside a private property, located on the stretch between the towns of Xambioá and Vanderlândia, Tocantins state, near the Araguaia Belt. The study had as main objective to identify parameters such as depth and thickness of mineralized zones, which may aid in the work of exploitation of ores. The results of GPR measurements were very satisfactory, because the method presented a good response for both types of ores investigated, making it possible to characterize the layers and to verification its depths and thicknesses.

Navegar

Navegando Dissertações em Geofísica (Mestrado) - CPGF/IG por Área de Concentração "MÉTODOS ELÉTRICOS E ELETROMAGNÉTICOS"