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9th International Congress of the Brazilian Geophysical Society
- Conference date: 11 Sep 2005 - 14 Sep 2005
- Location: Salvador, Bahia, Brazil
- Published: 11 September 2005
1 - 100 of 462 results
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Especialidad “geofisica petrolera”: una plataforma de enseñanza activa
Authors R.A. Quesada García, G.M. Pagés and R.G. CaraballoLa especialidad de postgrado “Geofísica Petrolera”que se está impartiendo por el Instituto Superior Politécnico “José Antonio Echeverría” (ISPJAE) de La Habana, Cuba, contempla entre sus objetivos, el diseño curricular de las asignaturas basado en el empleo de una plataforma activa de aprendizaje, que incluye el uso de casos, conferencias interactivas, prácticas, debates en grupos, defensas de informes, etc., conformándose con estas componentes, un proyecto pedagógicamente innovador.
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El método de casos: su aplicación a la enseñanza de la sismica petrolera
Authors G.M. Pagés and R.A. Quesada GarcíaEl presente trabajo esta dedicado a exponer algunas reflexiones sobre el diseño de la Especialidad de postgrado “Geofisica Petrolera” que se imparte por el Instituto Superior Politécnico “José Antonio Echeverría” (ISPJAE) a ingenieros geólogos de CubaPetroleo (CUPET).
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Um Indicador do Valor da Informação Sísmica em Projetos de Exploração de Petróleo
Authors Alexandre A. Coelho and Saul B. SuslickThe assessment of exploratory opportunity has a fundamental importance in the upstream oil industry due to a high number of projects and the limited budget of the companies. The valuation of each project depends on the estimation of oil quantities from a given field which accuracy changes with the ability of measure the reservoir size. In the last decades, the technological progress positioned seismic data as a significant source of information for opportunities. Therefore, it is necessary that the technology used to get information should be incorporated at assessment process. This paper presents a methodology by using an indicator of seismic information which its value gives a degree of confidence of the technological seismic option used. This methodology also develops an option to estimate the value of imperfect seismic information for new surveys through the inclusion of the amount of data, its quality, the embedded geological model, the adequacy and performance of the technology used and others characteristics inherent of basin such as its signal-to-noise ratio that can influence the quality of the data. The main goal of this methodology is to support the assessment and ranking of exploratory opportunities giving valuable information to the decision process in a consistent and standard form. A case study presented shows that the indicator presents good performance by adjusting the opportunities, considering the most reliable outcomes and improving the decision-making process.
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3D Seismic Interpretation and its Implications to a New Structural Model on the South of Santos Basin, Brazil
Authors C.L. Queiroz, R.D. Damasceno, A. Pereira, J.J. Rodrigues, E.J.J. Marques, F.C. Rigon and M.M.M. CortezIn the south of Santos Basin, on the coasts of Santa Catarina and Paraná States, there are light hydrocarbon fields named Tubarão, Estrela do Mar, Coral, Caravela and Cavalo Marinho. Reservoir rocks are mainly constituted by oolitic grainstones, generally dated as Meso Albian and interpreted as oolitc bars grown over rool-overs crests.
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Emprego do método gamaespectrométrico para investigação em sítio arqueológico tipo “terra preta arqueológica” (TPA), no Estado do Amazonas
The carried through gama-ray espectrometric survey in a portion of the archaeological place of the Village of Paricatuba, located in the municipal district of Iranduba (AM), in the form of four profiles of 50m and distance equal itself of 2m, with 51 points each, disclosed significant to radiometric anomalies in the related largenesses the total counting and in the specters of the U, Th and K. The answers most intense had been observed in the canal of thorium, with intensities of up to 15 C.P.M., followed of the canal of the uranian one, with up to 9 C.P.M., while that the radiometric totals had normally revealed inferior the 6 C.P.M. e the canal of the potassium showed values of up to 170 p.p.m. Such anomalies can be associates with local concentrations of organic substance, as well as the presence of ceramic devices.
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Análise de AVO na bacia do Ceará
Authors W.N. de Amorim, D.C. Dutra, J.M. Neto, A.M. Filho and V.C. CondeIn this paper we will show the AVO analysis of a strong negative amplitude anomaly over an Upper Cretaceous disconformity at the Ceará basin. The analysis of the available seismic volumes (NEAR, MID and FAR) and the petrophisic modeling in a deep water well of the basin, require the utilization of the NEAR and MID volumes for this study.
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Lagosta - Ocorrência de Gás em AVO Classe 4 na Bacia de Santos
Authors R.D. Damasceno, F.B. da Silva and E.J. JungThe discovery of a gas field in the Santos Basin, with a class IV AVO anomaly showed that for this basin, the occurrence of this kind of AVO should be examined with special attention and must not be despised in comparison to the class III AVO, traditionally considered the best hydrocarbon diagnostic. This discovery also reaffirms the importance of AVO as a predictive exploration tool.
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Pre-Stack Seismic Data: A new Border to the Exploratory Interpretation
More LessThe Technology for petroleum exploration has been developed in an impressive way. This evolution imposes to the interpreter a constant technological updating and this, he/she needs to know different areas in a multi-disciplinary environment.
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Aprendendo a confiar em Greenberg-Castagna
More LessGreenberg and Castagna’s (1992) technique of shear-sonic construction using Vp data, is a lithology based regression which uses the Gassman equation. As an empirical relation, it should apply only to the set of rocks that generated it. But is seems to be more robust than initially imagined. The Greenberg-Castagna method was used to predict Vs in six wells from different Brazilian Basins. The analysis suggests that the method is applicable for most part of the data. Despite some good results showed here, it should always be used with a full understanding of its assumptions and limitations. It is hoped that the ideas presented herein may lead to a better understanding of the technique, and to reduce uncertainty in its application.
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Impedance-Type Inversion of the P-P Reflection Coefficient
Authors A. Davolio and L.T. SantosThe exact expression for the P-P reflection coefficient (Zoeppritz equations) has a rather complicated dependence on the medium parameters (P- and S-wave velocities and density) at both sides of the interface. For the inversion purpose, it’s required approximations formulas. In this work we discuss some approximations based on Taylor series and on the impedance concept. We also present the inversion process induced by these approximations.
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Impedance-based indicator for elastic parameters prediction
Authors V.S. Grosfeld and L.T. SantosIn the last two decades, many approximations for the P-P reflection coefficient have been proposed in the literature. Almost derived from the cassical aproximation of Aki & Richards, using additional assumptions on the medium parameters.
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Amplitude Variation with Ray Parameter Analysis Using the Reflection Impedance Concept
Authors L.T. Santos and M. TygelThe Common Relection Surface method provides semblance and attributes panels, which gives information about the ray-parameter at the reflection point at possible interfaces in the elastic model. The reflection impedance function, gives an approximation for the reflection coefficient which is suitable for inversion purposes. Combining both procedures, we have a practical amplitude versus rayparameter analysis which is suitable for inversion of rockpropertie
parameters.
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New Perspectives on Deep Ocean Exploration
By P.A. RonaOur vision of marine mineral resources is expanding with present and potential scientific and economic benefits as our understanding of the Earth advances. The introduction of the theory of plate tectonics opened new prospects for exploration in the deep ocean within and beyond the 200 nautical mile-wide Exclusive Economic Zone (EEZ) offshore coastal states. This paper presents the expanding perspective of non-living and living resources of the deep seafloor and is accompanied by the first film to clearly illuminate hydrothermal vents and their ecosystems in the deep ocean.
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Brazilian Research in Extreme Environments: New Perspectives for Integrated Biological and Geological Activities
Authors L.S. Campos, L.P. Gamboa, H.P. Lavrado and A.P.C. FalcãoExtreme sea environments are considered here as those that are difficult to access and mostly require high technology logistics for any research work to be undertaken, i.e., mainly the deep sea and polar regions. Approximately 80-90 % of the oceans have over 3000 m water column (Gage & Tyler 1991), and most ecosystems within this large area are still to be investigated in more detail. The main ecosystems of these extreme environments include the continental margins, seamounts, abyssal plains, ocean ridges, hydrothermal vents and cold seeps.
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The Brazilian expanded continental shelf beyond its Exclusive Economic Zone
By L.C. TorresThis study has the purpose of describing and showing by some pictures the Brazilian effort in order to establish the outer limit of its expanded continental shelf beyond its Exclusive Economic Zone (EEZ) on Atlantic Ocean.
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Considerations for Deepwater Seismic Imaging
Authors P. Whiting, C. Notfors and G. HodgkissDeepwater seismic imaging presents many challenges that are unique to deepwater environments, along with many familiar challenges that are emphasised by the presence of a long water column. In some cases, the depth of the water will make one or two of these challenges of paramount importance whereas, with a different water depth, the same challenges may be insignificant. It is important to have the tools to deal with all possible challenges to ensure that the image will not be compromised.
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Mega-Furrows, Contour Currents and Density Flows of the Northwest Gulf of Mexico Continental Slope and Rise
Authors W.R. Bryant, D. Bean and N. SloweyA geophysical survey of the northern Gulf of Mexico Continental Slope and Rise around Bryant Canyon in the spring of 1999, collecting deep-tow data, which consisted of a 3.5 kHz subbottom profiler and a 100 kHz side-scan-sonar, surveyed a series of longitudinal mega-bed-forms in ~3000 m of water along strike and at the base of the Sigsbee Escarpment.
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ADN method: simultaneous determination of porosity and shale content.
Authors A.I. Fischetti and A. AndradeA key step in petrophysical formation evaluation is the determination of porosity values corrected by the effect of shale content (shaliness) and consequently to produce a better estimate of oil saturation.
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Shale Characterization and Well Correlation by Competitive Neural Networks
Authors A.I. Fischetti, A.C. Fischetti and A. AndradeThe lithological characterization of a rock layer crossed by a borehole and its identification in the neighbor wells (well correlation) in an oil field are of great importance for reservoir studies that aim to improve the volume of oil recovered. In spite of the actual drilling technology is not usual to core all boreholes in a field and an alternative manner to deal with it is to use well log data.
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Determination of mineral composition of reservoir rocks by expert system and genetic algorithm
Authors A.C. Fischetti, A.I. Fischetti and A. AndradeThe information about mineral composition of reservoir rocks is important to obtain more realistic porosity estimative. The log analysts usually consider a reservoir rock composed by a solid portion (matrix) and a fluid portion (pore). The fluid portion or porosity determination is fundamental to obtain the reserve potential and reservoir qualification.
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Well Log Vertical Resolution Enhancement by Recurrent Neural Network
Authors A. de Lima Ruéla, A.I. Fischetti and A. AndradeThe reevaluation of mature or small oil fields, where there are only conventional well log data or the use of new logging technologies have not economic viability motivate us to take a new look in log vertical resolution enhancement. We talk about the paradox between depth of investigation and the vertical resolution of a logging tool.
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Three-Dimensional Numerical Simulation of Induction Loggings
Authors A. Carrasco and A. CarrasquillaThe electromagnetic induction well log method is one of the more utilized geophysical logs in oil industry, aiming to obtain petrophysical informations regarding geological formations along the well.
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Aplicação de Modelagem 3D na Perfilagem de Indução em Turbiditos da Bacia de Almada - Ba
Authors K. Tomaso, A. Carrasco and A. CarrasquillaInduction logging is one of the most important geophysical methods used in the petroleum industry. In this work, we employ a three dimensional algorithm to interpret induction well log data from Almada Basin (Bahia – Brazil).
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Associação de Estatística Multivariada com Redes Neurais e Lógica Fuzzy para Identificação automática de litologias usando perfis de poço do Campo de Namorado na Bacia de Campos, Brasil
Authors R.T. Flexa, A.A.G. Carrasquilla and J. da Conceição da SilvaIn search of the petroleum reservoir characterization, the first task executed is the identification of lithologies crossed by the well, which may be achieved through the analysis of core sampling. However, this method is considered expensive and lengthy. Another way is through the interpretation of well logs, which are calibrated with some data from core samples and then extrapolated to the entire field. Although the interpretation using well logs is considered more economic, in some cases, due to the mineralogical complexity of these rocks, satisfactory results are not attained. This fact is because of the use of conventional statistical or mathematical algorithms.
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Multicomponent offset VSP to detect gas reservoirs
More LessThe occurrence of gas filled, complex reservoirs, in Miranga field on Reconcavo onshore basin was the motivation to evaluate the seismic response of borehole seismic in that area.
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Response of the sonic dipole tool in low compacted rocks in vertical wells
More LessThe correct acquisition of shear wave slowness through the flexural mode record with dipole source tool involves several requisites that are , barely, encountered in real conditions.
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Fenômenos de Relaxação, Difusão e Convecção em Medidas de Ressonância Magnética Nuclear
More LessSeveral important reservoir parameters such as permeability and irreducible water saturation are difficult to measure by logs. Nuclear resonance involving free precession of the total magnetic momentum as described by the CPMG pulse sequence has long promised to measure these parameters.
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Resultados do primeiro levantamento 3D-VSP da PETROBRAS: Comparação entre ondas compressionais (p) e cizalhantes (S)
Authors F.A.F. Gomes, M.C. Schinelli and O.K. FilhoO trabalho descreve as etapas envolvidas no projeto pioneiro 3D-VSP, registrado pela PETROBRAS na Bacia Potiguar. A aquisição foi realizada em agosto/setembro do ano passado e o levantamento foi patrocinado pelo PRAVAP (Programa de Recuperaçao Avançada de Petróleo) e pela UN-RNCE (Unidade de negócio Rio Grande do Norte Ceará).
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Modelo Fuzzy Para Prediçao de Porosidade e Permeabilidade via Perfis Convencionais de Poço do Campo de Namorado – Bacia de Campos
Authors R.F. Mimbela and J. da Conceição da SilvaThe well logs have a great applicability in the search and evaluation of hydrocarbon. In this work we calculate porosities of the Namorado field with help of the “Fuzzy Rule”.
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Semi-analytical logs of electrical focusing tools in basic subsurface models
By K. CozzolinoThis work presents a procedure to obtain synthetic logs for the electrical tools as LLS, LLD and LL7 in subsurface models: plane-parallel layers and cylindrical shells. The synthetic focusing used to acquire semi-analytical logs is based on the superposition principle applied to all transmitter-receiver pair of electrodes. Forward models can be created for investigations of real electrical resistivity data trough inversion procedures. Also, correction charts can be constructed for these tools or any other similar configuration.
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Estudos sobre a função objetivo na estimativa de parâmetros elásticos a partir da inversão das amplitudes da onda P refletida acima do ângulo crítico em levantamentos de sísmica rasa
Authors M.V.A.G. de Lima, L.A. Diogo and R.L. PradoWe propose to implement an inversion algorithm to estimate shear wave velocity (Vs) and density (ρ) above and below the reflecting interface, extracting the information contained in phase changes in the compressional wave pulse reflected at post-critical angles of incidence.
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Utilização de Potencial Espontâneo e Caminhamento Elétrico para detecção de vazamentos em barragem
Authors J.E. da Silva, V.R. Elis, F.Y. Hiodo and E. Gomes de OliveiraGeohysical methods like dipole-dipole geoelectric profiling, and spontaneous potential measurements with non polarizable electrodes were used to identify possible zones of leakage or infiltration by water, occurring in dam structure of artificial lake in Itatiba city-SP. Electroresistivity profiling in dipole-dipole array, and spontaneous potential determinations in gradient mode allowed to identify anomalous zones with low values of resistivity and spontaneous potentials.
Resistivity data processing by an inversion software RES2Dinv provided true electrical resistivity values in five levels of investigation depth.
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Estudo da compactação do solo por meio de ensaios geotécnicos e de métodos geofísicos
Authors C.T.C. Nascimento, P.G.O. Passos, M.M. Farias, R.P. Cunha and A.C.B. PiresThe main objective of this work is to investigate the effect
of sand-gravel compaction piles on the behavior of loose
sand deposits. Reduced model tests were carried out on
an artificial sand deposit filling a trench 1.5 m wide, 3.0 m
long and 2.5 m deep, excavated in a clay rich soil. In situ
geotechnical tests and DC electrical resistivity
measurements were carried out before and after the
construction of compaction piles, in order to characterize
the changes in the sand deposit. Conductivity anomalies
were observed in the position of the compaction piles with
better performance. These anomalies are caused by the
introduction of the sand-gravel compaction piles and
possibly more related to the mineralogical composition of
these piles than compaction itself.
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Real Time Workflows for More Efficient and Safer Deepwater Drilling Operations
By B. ChmelaReal Time Operations Centers and Collaboration Rooms allow professionals the ability to create the perception of being on the rig or platform even when they are back in the office. Using leading edge high definition visualization technology and new software and standards for data transfer, new workflows have been developed to make upstream operations much more efficient and safer.
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Some Preliminary interpretation on the Marine Controlled Source Electromagnetic<br>(MCSEM) data acquired on Campos Basin, Brazil
Authors M.P.P. Buonora, R. Reddig, W. Heelan, J.D. Schofield, A. Zerilli and T. LabruzzoThe Campos Basin MCSEM data was acquired on a rectangular grid with line spacing of approximately 5 km. Three component electrical field as well as two component magnetic fields were recorded, from which the in-line electrical horizontal fields at each receiver position were processed to yield ratio maps of that field to a reference remote station.
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Contribution of the relative velocity between source and receivers to primary electromagnetic fields in the sea
More LessThe analysis of primary EM fields caused by a finite length line source below the sea level is important for submarine applied geophysics as well as for protecting ships from the threat of sea mines in both shallow and deep sea water environments. The surveys employ a source moving with a constant velocity whereas the receivers remain fixed at the sea floor. So an accurate determination of the primary field taking into account the relative velocity between the source and the receivers is necessary in order to optimize
the interpretation of both TDEM and FDEM data.
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Novas Técnicas Geoelétricas Otimizadas para Avaliar Danos Hidrológicos em Ambientes Subterrâneos
Authors O.A.L. de Lima and P. de A. PereiraIn this paper we propose two new geoelectrical techniques designed to improve the structural delineation of underground contamination plumes, using multi-electrode arrays. These techniques were tested in a selected area surrounding the garbage landfill of Alagoinhas, Bahia.
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Interpretação de dados de polarização elétrica induzida obtidos por um sistema eletromagnético a multi-freqüência na Fazenda Bela Vista, município de Jaguarari, Bahia, Brasil
Authors C.A. Dias, M.M.V. Barbosa and T.S. VieiraThis work presents the pseudo-sections of IP from a
survey carried out for the first time using a non-grounded
multi-frequency electromagnetic system, conceived by
Dias (1968). The induced electrical polarization data were
obtained from an anomaly in the Bela Vista Farm in
Jaguarari District (Bahia state, Brazil). The produced
sections permit to detect the mentioned polarizable
bodies and do good correlation with data taken using
traditional methods of geophysical prospecting.
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Modelagem geométrica de dados geoelétricos
Authors A.F. de Campos, A. Rigoti, S.P. Rostirolla and M.K. BartoszeckDesign the 3D geometry of the structural model from electrical profiles is the main objective of this work. From a electrical array of lines, align transversal to predominant tectonic structure directions, results interpretation of some fault planes. The continuity varies along the profile interpretation, equal to field work informations. Was introduced a horizon in the base of the resistivity layer, and this traces are transformed to a surface with the fault planes influence. The result was a 3D geometrical model, with fault discontinuity inside, based in geoeletrical interpretations of resistivity sections.
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Estrutura Elétrica da Contaminação Hídrica sob os Depósitos de Resíduos Sólidos Urbanos do Município de Alagoinhas, Bahia
Authors P. de A. Pereira, O.A.L. de Lima and M.J.M. do RêgoThis paper discusses the successful results of a geoelectrical survey conducted around the actual sanitary landfill of Alagoinhas, Bahia. Forty-nine Schlumberger IP-resistivity soundings were made in regularly distributed centers in the area to allow a good three-dimensional representation of its underground geohydrology. Apparent resistivity maps and cross-section were used to depict and correlate the geoelectrical sounding results.
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Prospecção para águas subterrâneas através de dois métodos geofísicos em Pureza- RJ
More LessThis paper presents a hidrogeology study carried out with two geophysical methods: the VLF– and the Resistivity Method. This study was made at State of Rio de Janeiro in Municipal of Pureza. The site was investigated by photograph aerial, map topography, map geology and the two methods were evaluated for the capacity to detect the interfaces between different layers structural, in particular the structural of area for ground water.
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Pseudo-seções de dados eletromagnéticos multi-freqüência
Authors J. da Conceição Batista and H.K. SatoThe interpretation scheme developed by Sato (1979), to construct pseudo-sections of resistivity versus depth, is analyzed using theoretical EM response due to layered earth. Some pseudo-sections of apparent resistivity were constructed for models using two and three horizontal layers, with alternating sequences of high and low resistivity values.
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MT modeling of a 2-D structure perpendicular to the Equatorial Electrojet
Authors M.W.C. Silva and L. RijoThe magnetotelluric method (MT) for the determination of subsurface electrical conductivity is based on the assumption that the incident field is laterally uniform and it is considered as plane waves. In the mid latitudes this hypothesis is valid and MT response depends only on the electrical structure of the earth. In equatorial latitudes, the geomagnetic fields shows an strong enhancement associated with electrical currents located in the ionosphere above the magnetic equator, termed Equatorial Electrojet (EEJ), which can make the primary fields nonuniform.
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Utilização de Caminhamento Elétrico para localização de canal aterrado
Authors J.E. da Silva, L.M.L. Yokoyama, L. Moutinho, V.R. Elis and F.Y. HiodoThe purpose of the geophysical work was to delineate a-buried channel of one streamlet, to landscape recovery.The studied area is located in São Carlos city -SP.To reach this objective was used electroresistivity profiling in dipole-dipole array with five meters dipole spacing. Resistivity data processing by an inversion software RES2Dinv provided true electrical resistivity values in five levels of investigation depth.The geophysical methodology of the electroresistivity allowed the localization of the overburden channel, associated with low values of resistivity.
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Mapas de isorresistividades elétricas aparentes do solo superficial de Manaus
Vertical electric surveys (VES) were performed in the city of Manaus in order to allow the elaboration of maps of apparent electric resistivity of the superficial soil. Several interpolation methods of electric resistivity were studied, however, only two methods will be approached here.
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Procedimentos informatizados na modelagem, representação e interpretação no método da eletrorresistividade
Authors E.N.A. Urasaki and H.K. SatoThe graphic implementation of the computer program SCHL, of the model of layers homogeneous, plane parallel, regarding the method of the electro-resistivity, through the technique of the vertical electrical sounding (VES) with Schlumberger and Wenner array, was accomplished from way to turn it more interactive, contributing so that the modeling, representation and interpretation of the observed data are more efficient, including automatic inversion using Gauss-Newton linearized inversion.
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Estudos dos Efeitos do Manto de Intemperismo Sobre Anomalias ( VLF ) Geradas por Corpos Inclinados Artavés de Modelagem Numérica
Authors G.E.R. Vogado and O.P. VermaWe have studied the effects of a partially conductive overburden on VLF anomaliesof an inclined prism placed in a highly resistive half space. This study is carried out
through numerical modelling using Finite Element techniques.
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Method of electrical resistivity (DC) applied in studies of contamination of soils and underground waters by gasoline
Authors M.T. Cardinali, A.C. de Oliveira Braga and T.M. CulhariUsing the geophysical method of the electrical resistivity (DC), through the techniques of the vertical electrical soundings and profiling (Schlumberger and dipole – dipole configurations), were analyzed, the temporary variations of the resistivity of sandy and clay materials, contaminated with gasoline, in reduced field scale.
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Aplicação de tomografia elétrica na detecção de tambores plásticos na área do Sítio Controlado de Geofísica Rasa do IAG/USP
Authors E.M.A. da Silva, V.R. Elis, W. Rodrigues Borges, J.L. Porsani and F.Y. HiodoO resumo mostra resultados de tomografia elétrica 2D realizada sobre tambores plásticos enterrados na área do Sítio Controlado de Geofísica Rasa do IAG/USP. A metodologia aplicada teve como objetivo identificar o padrão das anomalias elétricas dos tambores plásticos utilizando o arranjo dipolo-dipolo com espaçamento entre os dipolos de 1 metro. Os resultados mostraram que os parâmetros de campo utilizados permitiram somente identificar a posição horizontal dos tambores. Os alvos apresentaram anomalias de alta resistividade e baixo valor de cargabilidade.
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Estudo audiomagnetotelúrico (AMT) na porção onshore da Bacia de Almada, Bahia
Authors P.G. Freire, E.F. La Terra, S.L. Fontes and V.C.F. BarbosaFifty audiomagnetotelluric (AMT) measurements covering 10 KHz – 10 Hz frequency range have been carried out on the onshore portion of Almada basin, Bahia state. AMT data were recorded in two roughly orthogonal profiles and our approach interprets the AMT soundings using the first–order Tikhonov regularization 2D inversion method to estimate the resistivity distribution in the subsurface that explained the field observations to within a preset error.
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Estudos Magnetotelúricos na Bacia do Iguatu (CE): Primeiros Resultados
Authors A.J.A. Marçal, S.L. Fontes, J.M. Flexor and C.R. GermanoA multidisciplinary geophysical and geochemical project has been proposed to study the set of Iguatu basins, Ceará state, aiming at contributing to the evaluation of the groundwater resources in this semiarid region of Brazil.
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eGs 3.0 (electrical GEOPHYSICS suite) – Pacote de programas para modelagem e interpretação de dados geofísicos elétricos e eletromagnéticos
Authors L. Rijo, G.L. Pereira and R.E. Conceição SilvaThis is the third version of the suite of computer programs denominated electrical GEOPHYSICS suite (eGs 3.0) for modeling and interpretation of electric and electromagnetic geophysical data. The eGs 3.0 is software of free distribution, built to run in the MSWindows operating system.
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Potencialização de magnetômetros de precessão nuclear de prótons com o recurso de microcontroladores
Authors F.Y. Hiodo, K. Blane, N. Silva, R. Francesconi and J.E. SilvaA digital interface was developed to replace all output module with seven segments LED displays of a nuclear precession magnetometer (UNIMAG- GEOMETRICS). System based in microcontroller has low cost and one very friendly programming compiler. A two way communication in alphanumeric mode is used to link with operator through a liquid crystal display LCD with 2 lines and 16 characters by line and a 3 microswitchs keyboard.
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Sistema de prospecção geofísica pelo método Eletromagnético Indutivo (EM) com aplicações no Sítio Controlado do IAG/USP
Authors H.F. Saar, F.Y. Hiodo, N. Silva, K. Blaine, E. Bronizeski, A. Rugenski, J.L. Porsani and W.R. BorgesAn electromagnetic equipment operating in frequency domain was developed to prospect shallow conductive targets, as found in hydrogeological and archaeological surveys. Using low magnetic induction number concepts and lock-in circuits, it became possible to characterize conductors and ferromagnetics materials buried in subsurface, using the dipole electromagnetic profiling method.
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Geoelectric directionality analysis of a magnetotelluric (MT) survey in Parecis Basin (States of Mato Grosso and Rondônia), Brazil
Authors J.M. Flexor, C.M. Martins and S.L. FontesEighty eight broadband (.001 – 1000 sec) magnetotelluric (MT) soundings have been made along a profile crossing the Parecis Basin (Mato Grosso and Rondônia) in a di-rection almost perpendicular to the main geological lineaments.
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Modelagens magnetotelúricas e sísmicas da Bacia do Espírito Santo
Authors S. de A. José, L.B. Teixeira and A.A.G. CarrasquillaConstructing a consistent and reliable model of a complex geophysical/geological system is one of the main question in Geophysics. In order to solve this matter, many studies have been published about data integration of different surveys. In this work, the goal consists in making magnetotelluric and seismic modelings in areas where seismic method has shown limitations. The results have suggested that magnetotelluric method (MT) can be used as an alternative complementary geophysical tool.
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Ensaios Geoelétricos no Estudo de Dutovias em Subsuperfície
Authors M.A.M. Jeronymo and S.W.M. dos SantosO presente trabalho visa apresentar os resultados de ensaios não destrutivos utilizados na detecção de dutos diversos em subsuperfície utilizando para isso métodos geofísicos-geoelétricos tais como GPR (Ground Penetration Radar) e PCM (Pipe Current Mapper). Essas metodologias sobressaem-se de outras principalmente por não possuírem caráter invasivo e impactante no meio ambiente.
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Interfaces Instrumental e de Programação para Aquisição Automática de Dados Geoelétricos Usando Múltiplos Eletrodos
Authors L.R.P. Lisboa and O.A.L. de LimaIn this paper we describe a hardware and software
developed to perform the automatic acquisition of
geoelectrical data using multiple electrodes. The
hardware consists of an electronic switching unit
controlled by a personal computer trough a RS-232 line,
which contains a digital microcontroller that performs the
switching from the resistivity-IP measuring equipment
inputs and outputs to one of 64 electrodes of an electrode
set. Software part consists of a PC-based application
designed to control the electrode switching and to record
incoming data from equipment.
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The preconditioned biconjugate gradient algorithm applied to geophysical electromagnetic modeling
Authors V.C.T. de Souza, L. Rijo and M.W.C. SilvaSolution of the large system of equations that results from a finite-element approximation in electromagnetic modelling over a mesh strongly refined is most commonly done iteratively, because direct solution requires excessive amounts of memory and computation. The conjugate gradient – type methods used in combination with preconditioning – are among the most effective iterative procedures for solving large sparse nonsingular systems of linear equations Ax = b.
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Estatística aplicada à resistividade elétrica dos solos
By A.F. LimaThis paper ilustrates an statistical approach for geophysical data analysis. Concepts of mode and standard deviation are applied to underground electrical resistivity data. In the end a comparison between the subjective and the statistical processing data is made. The graphical and processing software applied was completely developed by the Brain Tecnologia processing and development group.
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Localização e Delineamento de Pluma de Contaminação por Hidrocarbonetos através dos Métodos GPR e Tomografia Elétrica: Resultados Preliminares
Authors R.A. Ortega and J.L. PorsaniA geophysical investigation was accomplished in a train supplying station in São Paulo state, Brazil. The research aims are to locate and delineate a possible contamination plume from hydrocarbon (diesel oil). To reach these objectives, various GPR (Ground Penetrating Radar) profiles and electric dipole-dipole (Resistivity) surveys were performed.
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Aplicação da eletrorressistividade no monitoramento ambiental de áreas urbanas
Authors M.A. Zago, L.H. Santos and L.S. BatistaThe information derived from the geophysical surveys are useful for the location of the monitoring wells, as also they supply to estimates of area and volume the activities of removal and contaminated ground remediation.
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Aplicação do método da eletroresistividade no monitoramento ambiental da bacia hidrográfica do Riacho Caboblé
Authors M.J.C. Brito and L.S. BatistaThe use of geophysical methods for the ambient diagnosis of potentially contaminated areas has for basic objective the identification of the presence of the underground contamination, beyond the definition of the geologic and hidrogeologic structures of the investigated places.
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Impacto nos cetáceos das atividades de prospecção sísmica de hidrocarbonetos
Authors R.D.M. Donald and L.S. BatistaThe oceans serve as food source and as source of would materia of some industrial sectors. The industry of the oil is without doubts most important in the present time. With the interest to produce each time plus this well mineral one, technologies had been developed to explore new wells and to maximize the production of already the existing ones.
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Riscos Sísmicos em Barragens
Authors J.X.C. Neto and M.J. PorsaniThis paper presents an important method of study for investigation of the potential induced seismic risk in reservoir impoundment’s (SIR). The method involves the investigation of the relationship of regional faults and fractures with local structures by the application of the Wiener shaping filter.
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Técnica de Sondagem Elétrica Vertical utilizada no estudo de uma área de disposição de resíduos sólidos urbanos
More LessThe aim of the present work is the characterization of an waste disposal area placed in Bauru, São Paulo State, trough the application of Vertical Electrical Sounding. The geophysical technique employed in this work provided a considerable amount of informations among several characters related to interaction between urban solid waste disposal area and the natural environment.
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Sísmica de alta freqüência (10 kHz) e características de ecocaráter no estuário do rio São João-RJ
Authors N.R. Silva, J.A. Baptista Neto, C.G. Silva, G.T.M. Dias, M.R. Torquato and G.B. FernandezThe aim of this work is to present the geophysical characterization of the São João river estuary. It was done utilizing a high frequency seismic profiler (10 kHz) that shows three types of echoes. The echoes represent types of bottom sediments. The echo type 1 shows no penetration of the acoustic signal that was associated to a sandy bottom. The echo type 2 presents sub bottom reflectors and it was related to a muddy bottom. The echo type 3 represents a rocky bottom that presents irregular morphology and no penetration of signal. The records are applicable to interpret the types of sediments and bottom morphology in estuary.
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Comportamento da Radiação Solar observado no período de Agosto/2004 a Março/2005 no Observatório Espacial do Sul
Authors M. Guedes, M.P. Pes, L.A. Biazi, S.L. Mantelli Neto, R.A. Guarnieri, E. Pereira and N.J. SchuchReliable environmental and climatic data are necessary to evaluate the solar and aeolic energy availability. Such evaluation will make possible the development of the sector of renewable energy resource assessment. The objective of this work is to study the behavior of the incident solar radiation in the central part of Rio Grande do Sul state - Brazil.
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Redes complexas de correlação espaço-temporal da pluviometria do semi-árido nordestino
Authors C.N. de Santana, J.G.V. Miranda and R.F.S. AndradeThis work uses the theory of complex networks to analyze the dynamics of rainfall in Northeast Brazil. Using time sequence records of 201 rainfall stations in Northeast Brazil, we generate a set of networks representing the relationships among them.
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Levantamentos geoelétricos no planalto de Campos do Jordão, São Paulo, Brasil
More LessGeoelectrical methods were used to define depth of the weathering mantle and topography of the basal surface in each of the four step-like topographical levels recognized in the Campos de Jordão Plateu between Morro do Itapeva and Vila Capivari, São Paulo state, Brazil. After the geophysical survey, drillings were carried out aimed at comparing the results and to sample the weathering profile material. Despite the initial apparent discrepancy between the SEVs and drillings results, it was possible to calibrate the interpretation of the geoelectrical results and to define the togography of the basal weathering surface (bedrock surface) in the different compartments.
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The use of FDEM–GCM method in environmental investigation: coastal aquifer case studies
By J.P.R. LimaThis work presents the results of a research project that it had as motivation to obtain a better knowledge of the seawater intrusion contamination problem of the coastal aquifers in Canoa Quebrada city at coastal zone. The water supply to the coastal zones comes mainly from the coastal aquifers that are represented in the Ceará State by a system composed of dunes/Barreiras Formation/ crystalline. Due to intensive use of these groundwater reserves in the last years as a consequence of accelerated population growth along the coast, these systems are beginning to present signs of exhaustion that are characterized by salt contamination.
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Simulation of climatic anomalies at the beginning of 21st century in the areas of Salvador and Porto Alegre cities on the basis of the physical-statistical heat-balance model of the “ocean – atmosphere” system.
Authors S.V. Khorozov, V.I. Budovy, V.A. Medvedev, V.S. Belogolov and I.M. MartinThere is made a simulation of semi-annual sea-surface temperature (SST) and semi-annual total of precipitation in Salvador and Porto Alegre cities on the basis of physical-statistical heat-balance model of the “ocean - atmosphere” system that was constructed with taking into account of solar activity. Also there is represented a longterm forecast of anomalies of semi-annual totals of precipitation in these regions.
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Inferência de mudanças climáticas a partir de fonte de dados geotermais na região de Manaus, AM, Brasil
More LessRecent studies had showed that the heat flux across the land surface into the subsurface and it is manifested at a later time by a perturbation to the background temperature field. We have analyzed temperature versus depth profiles measured in 11 sites distributed in Manaus City, Brazil and show that the temperature mean of surface in Manaus have warmed about 3,23oC ± 0,07 oC in the last 250 and 300 years.
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Estimativa de balanço de energia na região do Curaçá
Authors A.T. Vidal, A.B. Novaes and L.C. PereiraRadiation fluxes over a surface close to Sobradinho Dam, were measured on clear day. The Bowen ratio method for calculating latent heat and sensible heat fluxes density was used by measuring temperature and water vapour at two heights. Each of energy fluxes density was computed from the Bowen ratio and net radiation minus soil heat fluxes density. The site of interest, under drought conditions, the Bowen ratio was usually in the range 1 – 3, and the latent heat flux accounted for only 15% of the net radiation.
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Echo-location of whales using seismic records
By J.D. PrietoA pioneer methodology, oriented to whale detection in the vicinity of operating seismic vessels is proposed and discussed.
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Construção de Blocos Transportáveis para Calibração de Detectores Gama Aerotransportados e Terrestres
Authors D.U. Carlos and F.B. RibeiroThe construction of transportable radioactive concrete sources for portable and airborne gamma-ray spectrometers calibration is described in some detail. The eight concrete sources were constructed following the model adopted by the Geological Survey of Canada and have the dimensions of 1 m x 1 m x 0,3 m.
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Aplicação de geofísica rasa sobre a Caverna dos Ecos, Cocalzinho-GO
Authors L.G. da Silva, A.L.M. Cadamuro, J.E.P. Soares and C.T.C. NascimentoGeophysical methods have proven to be an invaluable tool in geosciences, and its use to help solve environmental problems has become more frequent in recent years.
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Composição Isotópica do Hidrogênio em Precipitações de Salvador (BA)
The stable hydrogen isotope composition (δD) of precipitation water from Salvador (BA) were measured monthy from October 2003 to February 2004. Deuterium composition varied from -60 e +7‰ (VSMOW). For the most part the monthly sample varied in a much smaller range of -18 to +7‰.
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Aplicações do Sonar de Varredura Lateral para planejamento ambiental em áreas recifais: o exemplo do Banco dos Abrolhos, BA
Authors L.A. Pereira de Souza and R.L. de MouraThe Abrolhos Bank is a 200 km enlargement of the Brazilian continental platform, with about 46,000km2, in which there are extensive mangroves, seagrass and algae bottoms, submerged and emergent coral reefs, and a group of small volcanic islands. Located off the Bahia State coast, the region encompasses the most extensive and richest coral reefs in the entire South Atlantic. Besides holding a representative assemblage of the Brazilian-endemic coral reef fauna, Abrolhos’ reefs present unique morphological attributes, growing as mushroom-shaped pinnacles that are locally known as “chapeirões”.
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Detalhamento elétrico da contaminação ácida no aqüífero Caraíba usando um sistema eletromagnético Sirotem Mk3
Authors E.S.M. dos Santos, O.A.L. de Lima and H.K. SatoThis work discuss the use of the transient EM method SIROTEM, for the underground monitoring of the Caraíba Metais Metallurgic industry, located in the northwestern corner of the Camaçari Petrochemical Complex (COPEC), Dias D' Ávila county, Bahia. Its main goal was to delineate a sulfuric acid plume that is invading a portion of the Caraíba aquifer block bellow that industrial unit.
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Métodos Elétrico e Eletromagnético Aplicados ao Delineamento de Zonas Contaminadas por Resíduos de um Curtume
Authors F. Huber, S.J. da Silva Fachin, S. Shiraiwa and W.R. BorgesThis work presents some results obtained with the Ground Penetrating Radar (GPR), electric and inductive electromagnetic (EM34) methods applied to determinate and localize areas of potentially contamination with industrial waste of a tanning industry. The area is located in city of Várzea Grande, Mato Grosso state, and actually abandoned.
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Reconhecimento de solos por meio de gamaespectrometria
Authors C.T.C. Nascimento, E.M. Guimarães and A.C.B. PiresThe purpose of this work is to present a procedure for survey of soils, based on gamma-ray spectrometry. The study area has 5 km2 and is located at Jardim Botânico de Brasília, an environmental protection area. Gammaray spectrometry survey was carried out in this area, in September 2000.
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Projeto aerogeofísico São Timóteo (província uranífera de Lagoa Real – Ba): grandezas dosimétricas e estimativa das concentrações de U e Th.
Authors E.F.S. Santos, F.F.L. Simões Filho and J.M. FlexorUranium and thorium concentrations (ppm eU and ppm eTh) obtained from the gamma-ray spectrometry airborne survey of the São Timóteo Project (uraniferous province of Lagoa Real - Bahia, Brazil, CNEN, 1979) has been compared with terrestrial data concentrations measured by the "Environmental Monitoring Program (EMP)" carried out during the years 1998-2003 in the same area.
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Análise da Velocidade Média dos Ventos na Região do Observatório Espacial do Sul: estudo preliminar
Authors M.P. Pes, L.A. Biazi, M. Guedes, S.L. Mantelli Neto, R.A. Guarnieri, E.B. Pereira and N.J. SchuchThe economy growth in developing countries, like Brazil, is related to the increase in energy demand. The use of fossil fuels should be avoided because it elevates the CO2 emission rates to the atmosphere. Besides, such resources are limited and they don't contribute to a sustained development. Therefore, the most promising scenario should contemplate the use of clean and renewable energies.
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Mapeamento geológico das rochas encaixantes às ocorrências de veios de quartzo aurífero da Seqüência Campestre, por meio da avaliação estatística de dados aerogeofísicos (gamaespectrometria) na Região de São Sepé, RS, Brasil
Authors M. de Souza Soares, J.C. Koppe, J.F.C. Leite Costa and S.B. Alves RolimDe acordo com o IAEA (2003), a gamaespectrometria é amplamente utilizada no mapeamento geológico, na pesquisa de solos, na exploração mineral e nos estudos de regolitos. Seu uso, como mapeamento, requer um entendimento da geoquímica dos radioelementos nas rochas e nos solos bem como dos processos que afetam sua distribuição e mobilidade. No primeiro momento, deve ser feito um mapeamento das unidades litológicas principais para então, realçar padrões de radioelementos dentro das unidades individuais. Adicionalmente, estudos geoquímicos, petrológicos e mineralógicos das rochas e solos podem corroborar com a interpretação dos estudos gamaespectrométricos da área em estudo.
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A multi-azimuth VSP experiment for fracture orientation detection in HMD field Algeria
Authors F. Chegrouche and F. BabaiaNatural micro-fractures are very important in the control of production in the hydrocarbon reservoirs. The presence of the vertical fractures in the rock mass causes the split of the incident shear wave into two approximately orthogonal components with different velocities. Shear wave splitting analysis permits the estimation of fracture orientation.
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Análise cinemática da Falha de Baixa Grande a partir de dados de sísmica de reflexão 3D, fase rifte da Bacia Potiguar, nordeste do Brasil
Authors R.M. Pontes and R.M.D. de MatosIn spite of significant study and exploration of the Potiguar
Basin, easternmost Brazilian equatorial margin, by the oil
industry, its still provides an interesting discussion about
its origin and the mechanisms of hydrocarbon trapping.
The mapping and interpretation of 3D seismic data, rift
phase of the basin, suggests that dip changes in the
Baixa Grande Fault plane are responsible for generating
regional synclinal folds, which provides powerful
information about its kinematics.
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Geração de mapas litogeofísicos como instrumento para a cartografia geológica: o exemplo do Cinturão Mineiro, MG
Authors J.C. Ferreira Uchoa, A.M. Silva and C.L. Benfica ToledoThe Mineiro Belt (MB) in the southern portion of the São Francisco Craton (SFC), Minas Gerais, Brazil, is a important Paleoproterozoic segment and shows plutonic, volcanic and sedimentary rocks, of Archean to Mesoproterozoic age, reworked by later thermo-tectonic events.
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Realce e Interpretação de dados aerogeofísicos como ferramenta para o mapeamento geológico em regiões intemperizadas: o caso da Serra de Cláudio, Porção Sul do Cráton São Francisco, M.G.
Authors A.C. Ruy, A.M. Silva and C.L. Benfica ToledoThis paper presents an integrated approach to geological mapping by the use of high-resolution airborne geophysical data and geological information in weathered regions. Innovations in the data processing allowed the elaboration of several products, applied on spatial evaluation of geological units and structural lineaments.
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A Expressão Magnética do Enxame de Diques nas regiões de Itapecerica e Cláudio e sua correlação com o magmatismo fissural do Quadrilátero Ferrífero e Espinhaço Meridional, MG
Authors E. Zacchi, A.C. Ruy, A.M. Silva and C.L. Benfica ToledoThe present paper intends to study the expression of mafic dyke swarms situated in southern portion of the São Francisco Craton (SFC). Our main purpose is the characterization of basic rock formation pulses that occur in this region, through aeromagnetic data and field relations. We mapped the magnetic expression of these bodies, mainly to understand their importance and correlation with the main geological unities.
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A expressão magnética e gamaespectrométrica das anomalias elípticas da região de Itapecerica, MG
Authors E. Zacchi, A.M. Silva and C.L. Benfica ToledoThe southern portion of the São Francisco Craton (SFC), Minas Gerais, Brazil, including rocks ranging from the early Archean up to the late Neoproterozoic. However, the lack of rock exposures and connections among rock formations at surface poses problems for regional geologic mapping and interpretation. In this paper, an attempt was made to map three elliptical anomalies in the southernmost part of the SFC, using aerogeophysical (magnetics and gamma ray) data, with the aim to understanding both regional rock domains and structure.
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3D Seismic Interpretation of the Praia Grande Impact Structure – Upper Cretaceous of Santos Basin, Offshore Brazil
Authors G.A. Correia, J.R. Corrêa de Menezes, G.V. Bueno and E.J.J. MarquesThis work presents the Praia Grande impact structure, located in the Santos Basin, approximately 200 km southeast from the coastline of São Paulo State, Brazil. The identification of this structure is based on the interpretation of three-dimensional seismic data, acquired and processed in 2004 for petroleum exploration in a Petrobras concession block in the Santos Basin.
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Análise geofísica-geológica da porção emersa da Bacia de Campos através de uma metodologia integrada - resultados finais
Authors G.F.S. Pavie and A.A.G. CarrasquillaThis work consists in the interpretation of geophysical data of the continental portion of Campos Basin. A crust model of this region was constructed based in gravity, magnetic and magnetotelluric data interpretation, which was correlated with existent geological information. In this form, these results permitted us the visualization of the continuous transference zones on the continental portion of Campos Basin, which were enhanced by the map analysis. On the other hand, with the modelled physical
properties, several maps were generated and geology associations were proposed. Finally, a three-dimensional visualization of mantle and basement surface, as a product of the modelling, provided us with a better understanding of the structural framework of this part of the basin, including the morphology of the bedrock and the thickness of sedimentary deposits.
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Gênese e contribuições da tectônica diastrófica e da deformação adiastrófica na migração e acumulação de hidrocarbonetos na Bacia de Jequitinhonha, Sul do Estado da Bahia
Authors A.F. de Brito and M.K. KaramBased on seismic data interpretation three differents stages of faulting could be observed in the Jequitinhonha Basin. The first stage, diastrophic, was related with rift origin and is represented by normal faults and horst and graben structures. The second stage was associated with late tectonic reativation of rift faults and was the trigger for the first halokinesis movement, causing the faulting and folding of the carbonate rocks from Barra Nova Group.
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Utilização da técnica de raio imagem na conversão em profundidade para melhorar o posicionamento de falhas
Authors G. Waisman and J.N. HounieThe correct imaging of subsurface layers, as others structural features, like faults, is one of the main challenges of the seismic method. This problem becomes more critical when an extension or a development program is taking place in highly faulted and tilted
reservoirs. In the studied area these characteristics are presents, due to the intense salt tectonics.
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Evidências sísmicas de zonas de colapso na porção basal da seqüência carbonática do Albiano da Bacia de Santos. Um modelo genético
More LessAnomalous seismic features in the lowest portion of the Albian carbonate sequence (Guaruja Fm.) of the Santos basin are identified and characterized by using of post stack seismic attributes (RMS amplitude, coherency) and analysis of the high frequency seismic volume.
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Integração de métodos geofísicos na caracterização de um limite entre as Bacias de Sergipe-Alagoas e Jacuípe
By R.C. CampeloThe present paper discusses the existence of a geological limit between Sergipe-Alagoas and Jacuípe Basins. Potencial field data and seismic reflection data are integrated to provide a larger understanding about the area. From the structural point of view, the Vaza-Barris System Fault (VBSF) seems to be the only candidate, since there is no other structure of the same trend and weigth in the area that could be suggested as a limit
between these basins.
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Processamento e interpretação de dados gamaespectrométricos aéreos do projeto Itabira-Ferros, MG
The area covered by the Itabira-Ferros Project is located in the State of Minas Gerais Iron Quadrangle and is known for its emerald occurrences and deposits.
The present study apply geophysical characteristics, using airborne gamma-ray spectrometric data and their integration with geology, to determine probable zones of emerald mineralization.
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Processamento e interpretação dos dados magnetrométricos aéreos do projeto Itabira-Ferros, MG
The area covered by the Itabira-Ferros Project is located in the State of Minas Gerais Iron Quadrangle and is known for its emerald occurrences and deposits.
The area is characterized by green stone belts (Guanhães Complex and Rio das Velhas Supergroup) and paleoproterozoic iron sequences belonging to Minas Series, inserted in granitic bodies (Granite Borrachudos). The development of emerald deposits is attributed to the interaction of pegmatitic fluids with mafic-ultramafic rocks of Rio das Velhas Supergroup.
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3D SRME Practice for Better Imaging
Authors D. Lin, J. Young, W.-J. Lin, M. Griffiths and M. HartmannProper parameter selection is key to the success of 3D SRME. The major parameters include surface grid size and crossline aperture. We show that SRME crossline gathers can be used to determine both parameters. We also use a data example from Gulf of Mexico (GOM) to demonstrate the benefits of 3D SRME.
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