Estratigrafia das seqüências deposicionais do grupo Guatá, borda leste da Bacia do Paraná

Pós-graduação em Geologia Regional - IGCE

Treatment of geophysical data as a non-stationary process

ABSTRACT: The Kalman-Bucy method is here analized and applied to the solution of a specific filtering problem to increase the signal message/noise ratio. The method is a time domain treatment of a geophysical process classified as stochastic non-stationary. The derivation of the estimator is based on the relationship between the Kalman-Bucy and Wiener approaches for linear systems. In the present work we emphasize the criterion used, the model with apriori information, the algorithm, and the quality as related to the results. The examples are for the ideal well-log response, and the results indicate that this method can be used on a variety of geophysical data treatments, and its study clearly offers a proper insight into modeling and processing of geophysical problems.

Determinação automática da porosidade e zoneamento de perfis através da rede neural artificial competitiva

Duas das mais importantes atividades da interpretação de perfis para avaliação de reservatórios de hidrocarbonetos são o zoneamento do perfil (log zonation) e o cálculo da porosidade efetiva das rochas atravessadas pelo poço. O zoneamento é a interpretação visual do perfil para identificação das camadas reservatório e, consequentemente, dos seus limites verticais, ou seja, é a separação formal do perfil em rochas reservatório e rochas selante. Todo procedimento de zoneamento é realizado de forma manual, valendo-se do conhecimento geológico-geofísico e da experiência do intérprete, na avaliação visual dos padrões (características da curva do perfil representativa de um evento geológico) correspondentes a cada tipo litológico específico. O cálculo da porosidade efetiva combina tanto uma atividade visual, na identificação dos pontos representativos de uma particular rocha reservatório no perfil, como a escolha adequada da equação petrofísica que relaciona as propriedades físicas mensuradas da rocha com sua porosidade. A partir do conhecimento da porosidade, será estabelecido o volume eventualmente ocupado por hidrocarboneto. Esta atividade, essencial para a qualificação de reservatórios, requer muito do conhecimento e da experiência do intérprete de perfil para a efetiva avaliação da porosidade efetiva, ou seja, a porosidade da rocha reservatório, isenta do efeito da argila sobre a medida das propriedades físicas da mesma. Uma forma eficiente de automatizar estes procedimentos e auxiliar o geofísico de poço nestas atividades, que particularmente demandam grande dispêndio de tempo, é apresentado nesta dissertação, na forma de um novo perfil, derivado dos perfis tradicionais de porosidade, que apresenta diretamente o zoneamento. Pode-se destacar neste novo perfil as profundidades do topo e da base das rochas reservatório e das rochas selante, escalonado na forma de porosidade efetiva, denominado perfil de porosidade efetiva zoneado. A obtenção do perfil de porosidade efetiva zoneado é baseado no projeto e execução de várias arquiteturas de rede neural artificial, do tipo direta, com treinamento não supervisionado e contendo uma camada de neurônios artificiais, do tipo competitivo. Estas arquiteturas são projetadas de modo a simular o comportamento do intérprete de perfil, quando da utilização do gráfico densidade-neutrônico, para as situações de aplicabilidade do modelo arenito-folhelho. A aplicabilidade e limitações desta metodologia são avaliadas diretamente sobre dados reais, oriundos da bacia do Lago Maracaibo (Venezuela).

Estudo geofísico regional sobre águas subterrâneas na Ilha do Marajó-Pará-Brasil

Nos últimos dez anos foram realizadas na parte leste da Ilha de Marajó (região dos campos naturais) pelo IDESP e NCGG, mais de 800 SEVs para fins hidrogeológicos. Na época, grande parte dessas SEVs não foram totalmente interpretadas em forma quantitativa, devido à falta de recursos técnicos para fazê-lo de forma eficiente. Agora, usando meios mais modernos para interpretação automática de SEVs, voltou-se a interpretá-las com a finalidade de apresentar uma visão regional dos principais aquíferos da área, agrupar as SEVs em famílias características, testar até que ponto essa interpretação é confiável e propor o modelamento bidimensional como técnica alternativa para interpretar as SEVs realizadas em certos locais da área em questão. Como resultado dessa interpretação, com base na teoria convencional dos meios estratificados, foram definidos três tipos de sistemas de aquíferos. 1. O primeiro, denominado de aquífero profundo, situado a profundidades maiores que 50m, estende-se por toda a região prospectada, estando provavelmente associada às camadas superiores da Formação Marajó ou às litologias altamente resistivas das camadas mais profundas do Grupo Pará. 2. O segundo, denominado de aquífero raso e de média profundidade, localiza-se na parte sul e sudeste da região a profundidades compreendidas entre 10 a 50m, e está associado às lentes arenosas do Grupo Pará. 3. O terceiro, é constituído pelos paleocanais e estruturas similares, distribuídos aleatoriamente na região a pouca profundidade. A partir do estudo detalhado das SEVs, decidiu-se classificá-las em 3 famílias características com seus respectivos tipos e apresentar mapas de localização e da espessura dos aquíferos, bem como mapas de condutância longitudinal total e resistividade média da área. Estes últimos, permitem que se divida a região dos campos da Ilha de Marajó em três zonas principais: 1. Uma, altamente resistiva, situada ao sul e sudeste, a qual coincide com os terrenos aflorantes do Grupo Pará. 2. Outra, altamente condutiva, está localizada no centro e norte, onde se encontram aleatoriamente distribuídos os paleocanais e coincide com os terrenos topograficamente mais baixos, geralmente argilosos e embebidos de água salgada, que são procedentes da erosão dos terrenos circundantes topograficamente mais altos. 3. A última é medianamente resistiva e está relacionada com os terrenos vizinhos à cidade de Chaves (noroeste da região dos campos), os quais apresentam semelhanças com os do sul e sudeste da área. Usando-se a técnica de inversão na interpretação de uma SEV característica de cada família, testou-se, através do seu tratamento estatístico, até que ponto os modelos usados na interpretação dessas SEVs (teoria convencional dos meios estratificados) seriam confiáveis. Conclui-se, então, que a alta correlação existente entre os parâmetros dos modelos assumidos (camadas horizontais, isotrópicas e homogêneas) pode-se dever à utilização de modelos geofísicos muito simples para interpretar a complexa geologia de Marajó. Tendo-se verificado que nem sempre é possível aplicar a teoria das SEVs em meios horizontalmente estratificados para interpretar SEVs obtidas em certos locais de Marajó, os quais muitas vezes apresentam bruscas variações laterais de resistividade, passou-se a demonstrar que estas variações laterais afetam profundamente os dados das SEVs, utilizando-se para isto a técnica dos elementos finitos, a qual leva em conta essa variação bidimensional das propriedades físicas do meio. Foi também possível com esta técnica, modelar uma estrutura rasa, semelhante a um paleocanal, concluindo-se que estes resultados sugerem o emprego, duma forma mais profunda, deste tipo de tratamento para os dados obtidos na região dos campos da Ilha de Marajó.

Métodos geofísicos aplicados a prospecção mineral na região do Igarapé Chega Tudo, Maranhão - Brasil

O presente trabalho de prospecção geofísica abrange o levantamento de uma faixa de direção NW-SE, desde o local denomina do Chatão, à margem direita do rio Gurupi, até 5 km além de Chega Tudo, no estado de Maranhão. Esse levantamento foi feito em travessas perpendiculares àquela faixa, a qual constitui uma extensa zona de falha. Os trabalhos de geofísica de campo, envolvendo os métodos magnético (campo total), cintilómétrico, eletro-resistivo (Schlumberger, Wenner e Half-Schlumberger) e E.M. (Slingram), foram realizados em duas etapas: a) levantamento de reconhecimento em uma área de 22 km², onde foram aplicados magnetometria e cintilometria e b) levantamento de detalhe em uma área de 3,50 km², onde foram aplicados eletro-resistividade e E.M. Os objetivos principais deste trabalho foram determinar e localizar as principais feições estruturais e geo-elétricas associadas às zonas mineralizadas, e selecionar, entre os métodos geofísicos empregados, qual o de melhor poder resolutivo na indicação de veios de quartzo em sub-superfície, possivelmente associados à mineração de ouro. O método magnético indicou uma anomalia principal no lado NE da área de reconhecimento, enquanto que o cintilométrico apresentou somente o valor do "background" da região. Por isso o método cintilométrico não será discutido nesse trabalho. Com os métodos eletro-resistivo e E.M. foram observadas várias anomalias ao longo de toda a área de detalhe. A interpretação dos dados de magnetometria e de eletro-resistividade foi realizada com técnicas computacionais, enquanto que para a dos dados eletromagnéticos foram empregados diagramas de fase. Os resultados apresentam uma estreita correlação das anomalias magnéticas e eletro-resistivas com a zona mineralizada. O método E.M. não apresentou nenhum poder resolutivo, uma vez que detectou anomalias semelhantes dentro e fora das áreas mais promissoras. Todas as anomalias foram confirmadas com furos de sondagem. Considerando-se que a área prospectada apresenta, devido ao difícil acesso, o mesmo grau de dificuldade para realização da pesquisa por métodos diretos (perfuração, poços ou trincheiras), como qualquer outra área similar na região amazônica, os resultados aqui apresentados confirmaram que os métodos magnético e eletro-resistivo podem ser utilizados com sucesso como ferramenta indireta na localização de zonas promissoras à exploração de ouro dentro da zona de falha de Chega Tudo ou em outros ambientes geológicos de semelhantes características.

Geological and geophysical data integration for delimitation of mineralized areas in a supergene manganese deposits

Geophysical methods are widely used in mineral exploration. This paper discusses the results of geological and geophysical studies in supergene manganese deposits of southern Brazil. Mineralized zones as described in geological surveys were characterized as of low resistivity (20 Omega.m) and high chargeability (30ms), pattern found also in oxides and sulfite mineral deposits. Pseudo-3D modeling of geophysical data allowed mapping at several depths. A relationship between high chargeability and low resistivity may define a pattern for high grade gonditic manganese ore. Large areas of high chargeability and high resistivity may result in accumulation of manganese and iron hydroxides, due to weathering of the gonditic ore, dissolution, percolation and precipitation.

Modelo petrofísico 3D do Arenito Namorado no Campo de Namorado - Bacia de Campos, RJ

The Namorado Oil Field represents the beginning of the oil exploration in Brazil, in the 70s, and it is still a subject of researches because the importance of this turbidite sandstone in the brazilian oil production. The Namorado’s production level was denominated “Namorado sandstone”, it is composed by turbidite sandstone deposited during the Albian-Cenomanian. In order to define the structural geometry of the main reservoir, geological and geophysical tools like RECON and Geographix (Prizm – Seisvision) softwares were used, and its application was focused on geological facies analysis, for that propose well logs, seismic interpretation and petrophysical calculations were applied. Along this work 15 vertical wells were used and the facies reservoirs were mapped of along the oil field; it is important to mentioned that the all the facies were calibrated by the correlation rock vs log profile, and 12 reservoir-levels (NA-1, NA-2, NA-3, NA-4, NA-5, NA-6, NA-7, NA-8, NA-9, NA-10, NA-11 e NA-12) were recognized and interpreted. Stratigraphic sections (NE-SW and NW-SE) were also built based on stratigraphic well correlation of each interpreted level, and seismic interpretation (pseudo-3D seismic data) on the southeastern portion of the oil field. As results it was interpreted on two- and three-dimensional maps that the deposition reservoir’s levels are hight controlled by normal faults systems. This research also shows attribute maps interpretation and its relationship with the selection of the reservoir attribute represented on it. Finally the data integration of stratigraphic, geophysical and petrophysical calculations lets us the possibility of obtain a detail geological/petrophysical 3D model of the main reservoir levels of “Namorado sandstone” inside the oil/gás field

Evolução tectonossedimentar dos principais reservatórios de hidrocarbonetos do Campo de Golfinho (Bacia do Espírito Santo)

The Golfinho Field is located in the offshore region of the Espírito Santo Basin. Its importance is linked to the current average production about 19,000 barrels of oil per day, in turbidite reservoirs , giving it the nineteenth placement among the largest oil fields producing of Brazil. By interpretation and correlation’s methods based on 2D seismic sections and geophysical well logs, the study of tectonic-sedimentary evolution of major Golfinho Field’s reservoirs, which are located in Maastrichtian , aims understand and characterize the geological model of the area for the purpose of identify the main structures and types of reservoirs, improving the geological understanding of the area and using this knowledge at similar sets, that may present exploratory success in similar cases. By structural contour maps and geological cross-sections generated since time-depth conversion , the results defined for the geological model of the area , two distinct tectonic styles: a distensinal tectonics style , characterized by grabens and horsts , which belongs to rift phase, and a salt tectonics style, characterized by salt domes , listric faults and folds rolllover folds type, which belongs to marine phase . The interpretation of seismic sections and subsequent analysis of the main deformations present in the Maastrichtian reservoirs rocks ( turbidites ) showed that the northern region of the field is the most affected by salt tectonics . As for reservoirs, it was concluded to be associated to tectonics formed by rollover folds type, being older than listric faults

Interpreting histopathology in the epididymis

While most of this Special Issue is devoted to the testis (which is where most drug and chemically induced toxicity of the male reproductive tract is identified), being able to recognize and understand the potential effects of toxicants on the epididymis is immensely important and an area that is often overlooked. The epididymis is the organ where the post-testicular sperm differentiation occurs, through a complex and still not completely understood sperm maturation process, allowing them to fertilize the oocyte. Also in the epididymis, sperm are stored until ejaculation, while being protected from immunogenic reaction by a blood-epididymis barrier. From a toxicologic perspective the epididymis is inherently complicated as its structure and function can be altered both indirectly and directly. In this review we will discuss the factors that must be considered when attempting to distinguish between indirect and direct epididymal toxicity and highlight what is currently known about mechanisms of epididymal toxicants, using the rat as a reference model. We identify 2 distinguishable signature lesions - one representing androgen deprivation (secondary to Leydig cell toxicity in the testis) and another representing a direct acting toxicant. Other commonly observed alterations will also be shown and discussed. Finally, we point out that many of the key functions of the epididymis can be altered in the absence of a detectable change in tissue structure. Collectively, we hope this will provide pathologists with increased confidence in identification of epididymal toxicity and enable more informed guidance as mechanism of action is considered.

DETERMINATION OF THE E/G RATIO OF WOOD LOGS USING TRANSVERSE VIBRATION

The Bernoulli's model for vibration of beams is often used to make predictions of bending modulus of elasticity when using dynamic tests. However this model ignores the rotary inertia and shear. Such effects can be added to the solution of Bernoulli's equation by means of the correction proposed by Goens (1931) or by Timoshenko (1953). But to apply these corrections it is necessary to know the E/G ratio of the material. The objective of this paper is the determination of the E/G ratio of wood logs by adjusting the analytical solution of the Timoshenko beam model to the dynamic testing data of 20 Eucalyptus citriodora logs. The dynamic testing was performed with the logs in free-free suspension. To find the stiffness properties of the logs, the residue minimization was carried out using the Genetic Algorithm (GA). From the result analysis one can reasonably assume E/G = 20 for wood logs.

Insights into the morphology of the Serra da Cangalha impact structure from geophysical modeling

Forward modeling is commonly applied to gravity field data of impact structures to determine the main gravity anomaly sources. In this context, we have developed 2.5-D gravity models of the Serra da Cangalha impact structure for the purpose of investigating geological bodies/structures underneath the crater. Interpretation of the models was supported by ground magnetic data acquired along profiles, as well as by high resolution aeromagnetic data. Ground magnetic data reveal the presence of short-wavelength anomalies probably related to shallow magnetic sources that could have been emplaced during the cratering process. Aeromagnetic data show that the basement underneath the crater occurs at an average depth of about 1.9 km, whereas in the region beneath the central uplift it is raised to 0.51 km below the current surface. These depths are also supported by 2.5-D gravity models showing a gentle relief for the basement beneath the central uplift area. Geophysical data were used to provide further constraints for numeral modeling of crater formation that provided important information on the structural modification that affected the rocks underneath the crater, as well as on shock-induced modifications of target rocks. The results showed that the morphology is consistent with the current observations of the crater and that Serra da Cangalha was formed by a meteorite of approximately 1.4 km diameter striking at 12 km s-1.

Evidence-based guidelines for interpreting change scores for the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30

Aim: To use published literature and experts' opinion to investigate the clinical meaning and magnitude of changes in the Quality of Life (QOL) of groups of patients measured with the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). Methods: An innovative method combining systematic review of published studies, expert opinions and meta-analysis was used to estimate large, medium, and small mean changes over time for QLQ-C30 scores. Results: Nine hundred and eleven papers were identified, leading to 118 relevant papers. One thousand two hundred and thirty two mean changes in QOL over time were combined in the meta-analysis, with timescales ranging from four days to five years. Guidelines were produced for trivial, small, and medium size classes, for each subscale and for improving and declining scores separately. Estimates for improvements were smaller than respective estimates for declines. Conclusions: These guidelines can be used to aid sample size calculations and interpretation of mean changes over time from groups of patients. Observed mean changes in the QLQ-C30 scores are generally small in most clinical situations, possibly due to response shift. Careful consideration is needed when planning studies where QOL changes over time are of primary interest; the timing of follow up, sample attrition, direction of QOL changes, and subscales of primary interest are key considerations. (C) 2012 Elsevier Ltd. All rights reserved.

Variability in light absorption and scattering of phytoplankton in Patagonian waters: Role of community size structure and pigment composition

Intense phytoplankton blooms were observed along the Patagonian shelf-break with satellite ocean color data, but few in situ optical observations were made in that region. We examine the variability of phytoplankton absorption and particulate scattering coefficients during such blooms on the basis of field data. The chlorophyll-a concentration, [Chla], ranged from 0.1 to 22.3 mg m−3 in surface waters. The size fractionation of [Chla] showed that 80% of samples were dominated by nanophytoplankton (N-group) and 20% by microphytoplankton (M-group). Chlorophyll-specific phytoplankton absorption coefficients at 440 and 676 nm, a*ph(440) and a*ph(676), and particulate scattering coefficient at 660 nm, b*p(660), ranged from 0.018 to 0.173, 0.009 to 0.046, and 0.031 to 2.37 m2 (mg Chla)−1, respectively. Both a*ph(440) and a*ph(676) were statistically higher for the N-group than M-group and also considerably higher than expected from global trends as a function of [Chla]. This result suggests that size of phytoplankton cells in Patagonian waters tends to be smaller than in other regions at similar [Chla]. The phytoplankton cell size parameter, Sf, derived from phytoplankton absorption spectra, proved to be useful for interpreting the variability in the data around the general inverse dependence of a*ph(440), a*ph(676), and b*p(660) on [Chla]. Sf also showed a pattern along the increasing trend of a*ph(440) and a*ph(676) as a function of the ratios of some accessory pigments to [Chla]. Our results suggest that the variability in phytoplankton absorption and scattering coefficients in Patagonian waters is caused primarily by changes in the dominant phytoplankton cell size accompanied by covariation in the concentrations of accessory pigments.

The secrets of publishing your article in Journal of Geophysical Research (Oceans)

[EN] The editorial and review processes along the road to publication are described in general terms. The construction of a well-prepared article and the manner in which authors may maximise the chances of success at each stage of the process towards final publication are explored. The most common errors and ways of avoiding them are outlined. Typical problems facing an author writing in English as a second language, including the need for grammatical precision and appropriate style, are discussed. Additionally, the meaning of plagiarism, self-plagiarism and duplicate publication is explored. Critical steps in manuscript preparation and response to reviews are examined. Finally, the relation between writing and reviewing is outlined, and it is shown how becoming a good reviewer helps in becoming a successful author

Multiresolution spherical wavelet analysis in global seismic tomography

Every seismic event produces seismic waves which travel throughout the Earth. Seismology is the science of interpreting measurements to derive information about the structure of the Earth. Seismic tomography is the most powerful tool for determination of 3D structure of deep Earth's interiors. Tomographic models obtained at the global and regional scales are an underlying tool for determination of geodynamical state of the Earth, showing evident correlation with other geophysical and geological characteristics. The global tomographic images of the Earth can be written as a linear combinations of basis functions from a specifically chosen set, defining the model parameterization. A number of different parameterizations are commonly seen in literature: seismic velocities in the Earth have been expressed, for example, as combinations of spherical harmonics or by means of the simpler characteristic functions of discrete cells. With this work we are interested to focus our attention on this aspect, evaluating a new type of parameterization, performed by means of wavelet functions. It is known from the classical Fourier theory that a signal can be expressed as the sum of a, possibly infinite, series of sines and cosines. This sum is often referred as a Fourier expansion. The big disadvantage of a Fourier expansion is that it has only frequency resolution and no time resolution. The Wavelet Analysis (or Wavelet Transform) is probably the most recent solution to overcome the shortcomings of Fourier analysis. The fundamental idea behind this innovative analysis is to study signal according to scale. Wavelets, in fact, are mathematical functions that cut up data into different frequency components, and then study each component with resolution matched to its scale, so they are especially useful in the analysis of non stationary process that contains multi-scale features, discontinuities and sharp strike. Wavelets are essentially used in two ways when they are applied in geophysical process or signals studies: 1) as a basis for representation or characterization of process; 2) as an integration kernel for analysis to extract information about the process. These two types of applications of wavelets in geophysical field, are object of study of this work. At the beginning we use the wavelets as basis to represent and resolve the Tomographic Inverse Problem. After a briefly introduction to seismic tomography theory, we assess the power of wavelet analysis in the representation of two different type of synthetic models; then we apply it to real data, obtaining surface wave phase velocity maps and evaluating its abilities by means of comparison with an other type of parametrization (i.e., block parametrization). For the second type of wavelet application we analyze the ability of Continuous Wavelet Transform in the spectral analysis, starting again with some synthetic tests to evaluate its sensibility and capability and then apply the same analysis to real data to obtain Local Correlation Maps between different model at same depth or between different profiles of the same model.