Downstream emissions of CH4 and CO2 from hydroelectric reservoirs (Tucuruí, Samuel, and Curuá-Una) in the Amazon basin.

Carbon dioxide (CO2) and methane (CH4) generated in reservoirs are released downstream of dams, and few studies have considered these downstream emissions. Fluxes downstream of 3 Amazon hydroelectric reservoirs (Tucuruí, Samuel, and Curuá-Una) are reported here. Degassing through turbines was calculated as the difference between intake and outflow concentrations. Additional releases along the Tocantins, Jamari, and Curuá rivers were measured at were liberated at the turbine outflow. The total downstream emissions are sufficiently large to require consideration in assessments of greenhouse gas emissions from hydroelectric reservoirs.

Análise da descarga sólida em suspensão na Bacia do Riacho Fundo, Brasília - DF

Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, 2015.

Homegardens e dinâmicas da paisagem. Estudo de cariz etnobotânico e paisagístico em Santa Susana, Alentejo

Mestrado em Arquitectura Paisagista - Instituto Superior de Agronomia - UL

A (re)fundação do Aqueduto da Água da Prata, em Évora 1533-37: Novos dados arqueológicos

INTRODUÇÃO: O AQUEDUTO DA ÁGUA DA PRATA, do alto do seu estatuto de monumento nacional e de maior projeto de aparato público do Renascimento português, tem exercido ao longo dos séculos um considerável fascínio sobre os que estimam o património histórico da cidade de Évora. E muitas são as razões que justificam um tal sentimento. Além das duas evocadas, talvez valha a pena arrolar a mais pueril de todas: a de que o velho aqueduto quinhentista, resistindo às vicissitudes do tempo, ainda hoje continua a cumprir a sua função original- o abastecimento de água potável e perene a Évora. E não se julgue que este aqueduto se limita à imagem iconográfica do arcaria agigantando-se à passagem da muralha medieval: uma complexa rede de nascentes e sistemas de adução, a montante, e um notável património urbano constituído, sobretudo, por fontes e chafarizes, a jusante, dão corpo a uma vasta estrutura hidráulica de captação, transporte e distribuição de água com mais de 19 km de extensão. E, este sim, é o verdadeiro monumento, tão utilitário quanto grandioso, que os antigos documentos designam, apropriadamente, por Cano Real da Agua da Prata. Naturalmente, nem todo este cano real resistiu ao tempo, sobretudo o troço rural entre S. Bento de Cástris e as nascentes do Divor, onde a estrutura hidráulica original foi edificada com evidente simplicidade de recursos. O seu avançado estado de ruína, obrigou, inclusivamente, a uma profunda reforma iniciada em 1873, de que resultou a catual configuração do Aqueduto, visível, sobretudo, entre a estrada de Arraiolos (monte das Pinas) e Metrogos. Esta reforma foi ampliada em sucessivas campanhas de beneficiação até cerca de 1930, época em que se iniciou a rede de distribuição domiciliária de água com a construção dos reservatórios de chegada, a central elevatória e o depósito elevado, marcas arquitetónicas ainda hoje bem visíveis na cidade, algumas das quais oportunamente integradas num itinerário expositivo municipal. Neste contexto, é natural que a relação afetiva comungada pela generalidade dos eborenses com este património monumental também se insinue na escrita familiar e sincera dos "eborógrafos". E muitos foram - entre nomes de diferentes épocas e desigual dimensão biográfica - os que lhe dedicaram generosas páginas de divulgação histórica4 , contributos científicos diversos, projetos de investigação arquitetónica e arqueológica, estudos de recuperação e valorização patrimonial, e até, como nos assegura Diogo Barbosa Machado, um "Tratado do Aqueducto Real da Fonte da agua da prata dedicado ao Senado da Cidade de Évora, em cujo Cartorio fe guarda" (MACHADO, 1741: 72), obra assinada pelo vereador (1605-1606) e Provedor do Cano, Agostinho de Moura Peçanha, e da qual parece não restar memória nos nossos arquivos. Diga-se, a propósito, que este acentuado interesse público pelo aqueduto de Évora, em especial nos últimos anos, tem sublinhado a importância da dinamização e rentabilização do seu enorme potencial turístico, lúdico e cultural, sendo bom exemplo a recente criação do "Percurso Ambiental da Água da Prata", por iniciativa camarária. Em muitos destes aspetos nos revemos tributários, quando não devedores. Talvez por isso nos sentimos tentados, desde há vários anos, a avançar no estudo e salvaguarda deste importante património local. Vontade adiada, diga-se, sobretudo pela manifesta falta de disponibilidade para levar a cabo um projeto de investigação, coerente e consequente, no mínimo tocado por algum ensaio de novidade. Contudo, em 2007, circunstâncias várias levaram-nos a interessar definitivamente pelo tema. Uma das que mais terá pesado resultou da leitura do um artigo publicado na revista Monumentos com o título "o sistema hidráulico quinhentista da cidade de Évora". Nele, os seus reputados autores sentenciavam a inexistência de um aqueduto romano anterior à obra quinhentista por mera impossibilidade técnica, afirmando-o com tal segurança que nem sentiram necessidade de esboçar a mais leve argumentação topográfica em defesa da sua tese. Dito assim, ficámos a imaginar se valeria o esforço tentar reabilitar alguma vez o tema do aqueduto romano. Em boa hora o decidimos fazer. E partimos do princípio de que a interpretação dos factos devia ser feita por cuidadosa recolha de prova que a diligência (não raras vezes a ventura) permitisse carrear com sucesso. E sendo correta esta premissa, a sua oportunidade ganhou mais força com a materialização de resultados concretos a compulsar toda a bibliografia para confronto de dúvidas e incoerências; a recolher indícios de estruturas e materiais arqueológicos; a esmiuçar a toponímia e a cartografia; a rever os locais-chave uma e outra vez; a seguir pistas abandonadas; a filtrar informação variada no mesmo crivo da dúvida; a entusiasmar gente da historiografia local a acreditar na viabilidade de hipóteses. Foi, justamente, esta a metodologia adotada ao decidirmo-nos pelo tema do Aqueduto. E, ao segui-la, julgamos ter logrado alcançar, além de um lastro de legitimidade científica, as bases conceptuais de um projeto de investigação consistente e coerente onde muito ajudou a imediata estudaram a hidráulica em Évora. ...

Escherichia coli : host interactions in the pathogenesis of canine pyometra

Tese de Doutoramento em Ciências Veterinárias na Especialidade de Ciências Biológicas e Biomédicas

Aditivação de pastas geopoliméricas com tetraborato de sódio e látex não iônico para cimentação de Poços de Petróleo

The development of activities in the oil and gas sector has been promoting the search for materials more adequate to oilwell cementing operation. In the state of Rio Grande do Norte, the cement sheath integrity tend to fail during steam injection operation which is necessary to increase oil recovery in reservoir with heavy oil. Geopolymer is a material that can be used as alternative cement. It has been used in manufacturing of fireproof compounds, construction of structures and for controlling of toxic or radioactive waste. Latex is widely used in Portland cement slurries and its characteristic is the increase of compressive strength of cement slurries. Sodium Tetraborate is used in dental cement as a retarder. The addition of this additive aim to improve the geopolymeric slurries properties for oilwell cementing operation. The slurries studied are constituted of metakaolinite, potassium silicate, potassium hydroxide, non-ionic latex and sodium tetraborate. The properties evaluated were: viscosity, compressive strength, thickening time, density, fluid loss control, at ambient temperature (27 ºC) and at cement specification temperature. The tests were carried out in accordance to the practical recommendations of the norm API RP 10B. The slurries with sodium tetraborate did not change either their rheological properties or their mechanical properties or their density in relation the slurry with no additive. The increase of the concentration of sodium tetraborate increased the water loss at both temperatures studied. The best result obtained with the addition of sodium tetraborate was thickening time, which was tripled. The addition of latex in the slurries studied diminished their rheological properties and their density, however, at ambient temperature, it increased their compressive strength and it functioned as an accelerator. The increase of latex concentration increased the presence of water and then diminished the density of the slurries and increased the water loss. From the results obtained, it was concluded that sodium tetraborate and non-ionic latex are promising additives for geopolymer slurries to be used in oilwell cementing operation

Influência das tensões tectônicas na permeabilidade da formação Açu - Bacia Potiguar

The behavior of the fluid flux in oil fields is influenced by different factors and it has a big impact on the recovery of hydrocarbons. There is a need of evaluating and adapting the actual technology to the worldwide reservoirs reality, not only on the exploration (reservoir discovers) but also on the development of those that were already discovered, however not yet produced. The in situ combustion (ISC) is a suitable technique for these recovery of hydrocarbons, although it remains complex to be implemented. The main objective of this research was to study the application of the ISC as an advanced oil recovery technique through a parametric analysis of the process using vertical wells within a semi synthetic reservoir that had the characteristics from the brazilian northwest, in order to determine which of those parameters could influence the process, verifying the technical and economical viability of the method on the oil industry. For that analysis, a commercial reservoir simulation program for thermal processes was used, called steam thermal and advanced processes reservoir simulator (STARS) from the computer modeling group (CMG). This study aims, through the numerical analysis, find results that help improve mainly the interpretation and comprehension of the main problems related to the ISC method, which are not yet dominated. From the results obtained, it was proved that the mediation promoted by the thermal process ISC over the oil recovery is very important, with rates and cumulated production positively influenced by the method application. It was seen that the application of the method improves the oil mobility as a function of the heating when the combustion front forms inside the reservoir. Among all the analyzed parameters, the activation energy presented the bigger influence, it means, the lower the activation energy the bigger the fraction of recovered oil, as a function of the chemical reactions speed rise. It was also verified that the higher the enthalpy of the reaction, the bigger the fraction of recovered oil, due to a bigger amount of released energy inside the system, helping the ISC. The reservoir parameters: porosity and permeability showed to have lower influence on the ISC. Among the operational parameters that were analyzed, the injection rate was the one that showed a stronger influence on the ISC method, because, the higher the value of the injection rate, the higher was the result obtained, mainly due to maintaining the combustion front. In connection with the oxygen concentration, an increase of the percentage of this parameter translates into a higher fraction of recovered oil, because the quantity of fuel, helping the advance and the maintenance of the combustion front for a longer period of time. About the economic analysis, the ISC method showed to be economically feasible when evaluated through the net present value (NPV), considering the injection rates: the higher the injection rate, the higher the financial incomes of the final project

Estudo paramétrico da segregação gravitacional na injeção contínua de vapor

Steam injection is the most used method of additional recovery for the extraction of heavy oil. In this type procedure is common to happen gravitational segregation and this phenomenon can affect the production of oil and therefore, it shoulds be considered in the projects of continuous steam injection. For many years, the gravitational segregation was not adequately considered in the calculation procedures in Reservoir Engineering. The effect of the gravity causes the segregation of fluids inside the porous media according to their densities. The results of simulation arising from reservoirs could provide the ability to deal with the gravity, and it became apparent that the effects of the gravity could significantly affect the performance of the reservoir. It know that the gravitational segregation can happen in almost every case where there is injection of light fluid, specially the steam, and occurs with greater intensity for viscous oil reservoirs. This work discusses the influence of some parameters of the rock-reservoir in segregation as viscosity, permeability, thickness, cover gas, porosity. From a model that shows the phenomenon with greater intensity, optimized some operational parameters as the rate flow rate steam, distance between the wells injector-producer, and interval of completion which contributed to the reduction in gravity override, thus increasing the oil recovery. It was shown a greater technical-economic viability for the model of distance between the wells 100 m. The analysis was performed using the simulator of CMG (Computer Modeling Group-Stars 2007.11, in which was observed by iterating between studied variables in heavy oil reservoirs with similar characteristics to Brazilian Northeast

Cinemática de partículas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo: avaliação durante paradas operacionais

The new oil reservoirs discoveries in onshore and ultra deep water offshore fields and complex trajectories require the optimization of procedures to reduce the stops operation during the well drilling, especially because the platforms and equipment high cost, and risks which are inherent to the operation. Among the most important aspects stands out the drilling fluids project and their behavior against different situations that may occur during the process. By means of sedimentation experiments, a correlation has been validated to determe the sedimentation particles velocity in variable viscosity fluids over time, applying the correction due to effective viscosity that is a shear rate and time function. The viscosity evolution over time was obtained by carrying out rheologic tests using a fixed shear rate, small enough to not interfere in the fluid gelling process. With the sedimentation particles velocity and the fluid viscosity over time equations an iterative procedure was proposed to determine the particles displacement over time. These equations were implemented in a case study to simulate the cuttings sedimentation generated in the oil well drilling during stops operation, especially in the connections and tripping, allowing the drilling fluid project in order to maintain the cuttings in suspension, avoiding risks, such as stuck pipe and in more drastic conditions, the loss of the well

Análise de modelos geológicos utilizando percolação dinâmica

In the present study we elaborated algorithms by using concepts from percolation theory which analyze the connectivity conditions in geological models of petroleum reservoirs. From the petrophysical parameters such as permeability, porosity, transmittivity and others, which may be generated by any statistical process, it is possible to determine the portion of the model with more connected cells, what the interconnected wells are, and the critical path between injector and source wells. This allows to classify the reservoir according to the modeled petrophysical parameters. This also make it possible to determine the percentage of the reservoir to which each well is connected. Generally, the connected regions and the respective minima and/or maxima in the occurrence of the petrophysical parameters studied constitute a good manner to characterize a reservoir volumetrically. Therefore, the algorithms allow to optimize the positioning of wells, offering a preview of the general conditions of the given model s connectivity. The intent is not to evaluate geological models, but to show how to interpret the deposits, how their petrophysical characteristics are spatially distributed, and how the connections between the several parts of the system are resolved, showing their critical paths and backbones. The execution of these algorithms allows us to know the properties of the model s connectivity before the work on reservoir flux simulation is started

Estudo comparativo da utilização do nitrogênio como fluido alternativo após a injeção de vapor

Currently, due to part of world is focalized to petroleum, many researches with this theme have been advanced to make possible the production into reservoirs which were classified as unviable. Because of geological and operational challenges presented to oil recovery, more and more efficient methods which are economically successful have been searched. In this background, steam flood is in evidence mainly when it is combined with other procedures to purpose low costs and high recovery factors. This work utilized nitrogen as an alternative fluid after steam flood to adjust the best combination of alternation between these fluids in terms of time and rate injection. To describe the simplified economic profile, many analysis based on liquid cumulative production were performed. The completion interval and injection fluid rates were fixed and the oil viscosity was ranged at 300 cP, 1.000 cP and 3.000 cP. The results defined, for each viscosity, one specific model indicating the best period to stop the introduction of steam and insertion of nitrogen, when the first injected fluid reached its economic limit. Simulations in physics model defined from one-eighth nine-spot inverted were realized using the commercial simulator Steam, Thermal and Advanced Processes Reservoir Simulator STARS of Computer Modelling Group CMG

Estudo da segregação gravitacional do processo de injeção de vapor em reservátórios heterogêneos

Due to reservoirs complexity and significantly large reserves, heavy oil recovery has become one of the major oil industry challenges. Thus, thermal methods have been widely used as a strategic method to improve heavy oil recovery. These methods improve oil displacement through viscosity reduction, enabling oil production in fields which are not considered commercial by conventional recovery methods. Among the thermal processes, steam flooding is the most used today. One consequence in this process is gravity segregation, given by difference between reservoir and injected fluids density. This phenomenon may be influenced by the presence of reservoir heterogeneities. Since most of the studies are carried out in homogeneous reservoirs, more detailed studies of heterogeneities effects in the reservoirs during steam flooding are necessary, since most oil reservoirs are heterogeneous. This paper presents a study of reservoir heterogeneities and their influence in gravity segregation during steam flooding process. In this study some heterogeneous reservoirs with physical characteristics similar those found in the Brazilian Northeast Basin were analyzed. To carry out the simulations, it was used the commercial simulator STARS by CMG (Computer Modeling Group) - version 2007.11. Heterogeneities were modeled with lower permeability layers. Results showed that the presence of low permeability barriers can improve the oil recovery, and reduce the effects of gravity segregation, depending on the location of heterogeneities. The presence of these barriers have also increased the recovered fraction even with the reduction of injected steam rate

O papel das estruturas lineares, artificiais e naturais, como locais de refúgio de micromamíferos

Avaliámos a importância das bermas das estradas como áreas de refúgio para pequenos mamíferos, em paisagens Mediterrânicas intensivamente pastoreadas, e comparámos esta possível função das estradas como refúgio com o papel fundamental das galerias ripícolas como reservatórios de diversidade biológica. Para esse efeito, foram realizadas capturas de micromamíferos em dois segmentos de estrada e em duas ribeiras da região de Évora. Foram capturados 457 indivíduos de cinco espécies diferentes. Mus spretus foi a espécie mais capturada, seguida de Crocidura russula e Apodemus sylvaticus. M. spretus apresentou uma maior abundância nas bermas de estrada do que na vegetação ripicola, enquanto que a abundância de C. russula e A. sylvaticus era semelhante para ambos os habitats. O número de capturas das três espécies foi bastante superior dentro dos habitats lineares do que na matriz circundante. Os indivíduos de M. spretus eram maiores nas ribeiras, mas significativamente menores fora dos habitats lineares, e os indivíduos de C. russula apresentavam uma melhor condição corporal nas bermas das estradas. Tanto as estradas como as ribeiras exerceram um forte efeito de barreira aos movimentos dos micromamíferos. Concluímos então que as bermas das estradas actuam como habitat de refúgio em áreas sub-óptimas das paisagens Mediterrânicas. ABSTRACT: We assessed the importance of road verges as refuge areas for small mammals, in highly intensified grazed pastures on a Mediterranean landscape, and compared road function as refuge with the fundamental role of riparian galleries as reservoirs of biological diversity. For this purpose, a small mammal trapping study was undertaken on road verges and on small stream sides. We sampled two road segments and two streams in the vicinity of Évora, Portugal. We captured a total of 457 individuals of five different species. Mus spretus was the most common species captured, followed by Crocidura russula and Apodemus sylvaticus. M. spretus was more abundant on road verges than on riparian strips, whilst the abundance of C. russula and A. sylvaticus were similar in the two habitats. Captures of the three species were much higher inside both linear habitats than on the surrounding matrix. M. spretus were bigger on stream sites but significantly smaller outside the linear habitats and C. russula had better body conditions on roads. 8oth roads and streams exerted a strong barrier effect to small mammals' movements. We conclude that roadside verges act as refuge habitat in sub-optimal Mediterranean landscapes.

Uma aplicação da apredizagem por reforço na otimização da produção em um campo de petróleo

The objective of reservoir engineering is to manage fields of oil production in order to maximize the production of hydrocarbons according to economic and physical restrictions. The deciding of a production strategy is a complex activity involving several variables in the process. Thus, a smart system, which assists in the optimization of the options for developing of the field, is very useful in day-to-day of reservoir engineers. This paper proposes the development of an intelligent system to aid decision making, regarding the optimization of strategies of production in oil fields. The intelligence of this system will be implemented through the use of the technique of reinforcement learning, which is presented as a powerful tool in problems of multi-stage decision. The proposed system will allow the specialist to obtain, in time, a great alternative (or near-optimal) for the development of an oil field known

Estudo paramétrico da recuperação de petróleo pesado por aquecimento eletromagnético resistivo

Electrical resistive heating (ERH) is a thermal method used to improve oil recovery. It can increase oil rate and oil recovery due to temperature increase caused by electrical current passage through oil zone. ERH has some advantage compared with well-known thermal methods such as continuous steam flood, presenting low-water production. This method can be applied to reservoirs with different characteristics and initial reservoir conditions. Commercial software was used to test several cases using a semi-synthetic homogeneous reservoir with some characteristics as found in northeast Brazilian basins. It was realized a sensitivity analysis of some reservoir parameters, such as: oil zone, aquifer presence, gas cap presence and oil saturation on oil recovery and energy consumption. Then it was tested several cases studying the electrical variables considered more important in the process, such as: voltage, electrical configurations and electrodes positions. Energy optimization by electrodes voltage levels changes and electrical settings modify the intensity and the electrical current distribution in oil zone and, consequently, their influences in reservoir temperature reached at some regions. Results show which reservoir parameters were significant in order to improve oil recovery and energy requirement in for each reservoir. Most significant parameters on oil recovery and electrical energy delivered were oil thickness, presence of aquifer, presence of gas cap, voltage, electrical configuration and electrodes positions. Factors such as: connate water, water salinity and relative permeability to water at irreducible oil saturation had low influence on oil recovery but had some influence in energy requirements. It was possible to optimize energy consumption and oil recovery by electrical variables. Energy requirements can decrease by changing electrodes voltages during the process. This application can be extended to heavy oil reservoirs of high depth, such as offshore fields, where nowadays it is not applicable any conventional thermal process such as steam flooding