Protótipo de um microgerador termoelétrico de estado sólido: cogeração a gás

The thermoelectric energy conversion can be performed directly on generators without moving parts, using the principle of SEEBECK effect, obtained in junctions of drivers' thermocouples and most recently in semiconductor junctions type p-n which have increased efficiency of conversion. When termogenerators are exposed to the temperature difference (thermal gradient) eletromotriz a force is generated inducing the appearance of an electric current in the circuit. Thus, it is possible to convert the heat of combustion of a gas through a burner in power, being a thermoelectric generator. The development of infrared burners, using porous ceramic plate, is possible to improve the efficiency of heating, and reduce harmful emissions such as CO, CO2, NOx, etc.. In recent years the meliorate of thermoelectric modules semiconductor (TEG's) has stimulated the development of devices generating and recovery of thermal irreversibility of thermal machines and processes, improving energy efficiency and exergy these systems, especially processes that enable the cogeneration of energy. This work is based on the construction and evaluation of a prototype in a pilot scale, for energy generation to specific applications. The unit uses a fuel gas (LPG) as a primary energy source. The prototype consists of a porous plate burner infrared, an adapter to the module generator, a set of semiconductor modules purchased from Hi-Z Inc. and a heat exchanger to be used as cold source. The prototype was mounted on a test bench, using a system of acquisition of temperature, a system of application of load and instrumentation to assess its functioning and performance. The prototype had an efficiency of chemical conversion of 0.31% for electrical and heat recovery for cogeneration of about 33.2%, resulting in an overall efficiency of 33.51%. The efficiency of energy exergy next shows that the use of primary energy to useful fuel was satisfactory, although the proposed mechanism has also has a low performance due to underuse of the area heated by the small number of modules, as well as a thermal gradient below the ideal informed by the manufacturer, and other factors. The test methodology adopted proved to be suitable for evaluating the prototype

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

Análise paramétrica da simulação composicional do processo de Drenagem Gravitacional Assistida por Gás (GAGD)

In Brazil and around the world, oil companies are looking for, and expected development of new technologies and processes that can increase the oil recovery factor in mature reservoirs, in a simple and inexpensive way. So, the latest research has developed a new process called Gas Assisted Gravity Drainage (GAGD) which was classified as a gas injection IOR. The process, which is undergoing pilot testing in the field, is being extensively studied through physical scale models and core-floods laboratory, due to high oil recoveries in relation to other gas injection IOR. This process consists of injecting gas at the top of a reservoir through horizontal or vertical injector wells and displacing the oil, taking advantage of natural gravity segregation of fluids, to a horizontal producer well placed at the bottom of the reservoir. To study this process it was modeled a homogeneous reservoir and a model of multi-component fluid with characteristics similar to light oil Brazilian fields through a compositional simulator, to optimize the operational parameters. The model of the process was simulated in GEM (CMG, 2009.10). The operational parameters studied were the gas injection rate, the type of gas injection, the location of the injector and production well. We also studied the presence of water drive in the process. The results showed that the maximum vertical spacing between the two wells, caused the maximum recovery of oil in GAGD. Also, it was found that the largest flow injection, it obtained the largest recovery factors. This parameter controls the speed of the front of the gas injected and determined if the gravitational force dominates or not the process in the recovery of oil. Natural gas had better performance than CO2 and that the presence of aquifer in the reservoir was less influential in the process. In economic analysis found that by injecting natural gas is obtained more economically beneficial than CO2

Estudo do comportamento de pastas compósitas cimento/sílica/poliuretana para poços de petróleo HPHT

Os poços HPHT atravessam zonas anormalmente pressurizadas e com altos gradientes de temperatura. Esses poços apresentam elevadas concentrações de tensões produzidas pelas operações de perfuração e fraturamento hidráulico, flutuações da pressão e temperatura, forças dinâmicas geradas durante a perfuração, formações inconsolidadas, entre outros aspectos, podendo resultar em falhas mecânicas na bainha de cimento. Tais falhas comprometem a estabilidade mecânica do poço e o isolamento das zonas produtoras de óleos e/ou gás. Para que operações corretivas não se façam necessárias, é preciso adequar as pastas às condições de cada poço. Sistemas de pastas de cimento para poços HPHT requerem um bom controle de suas propriedades termo-mecânicas. Visto que a temperaturas superiores a 110 oC (230 oF) o cimento, após alcançar um valor máximo de resistência, inicia um processo de perda de resistência (retrogressão). Para prevenir esse efeito substitui-se parcialmente o cimento Portland por sílica com objetivo de incrementar a reação pozolânica. Esta reação modifica a trajetória do processo natural de hidratação do cimento, o gel de silicato de cálcio hidratado (C-S-H) se converte em várias outras fases com maior resistência. Polímeros também são adicionados para proporcionar maior flexibilidade e agir como barreira à propagação de trincas desenvolvidas sob tensão. O presente trabalho teve como objetivo estudar o comportamento do sistema cimento/sílica/polímero quando submetido às condições de alta temperatura e alta pressão. Foram formuladas pastas de cimento puro, pastas contendo 40 % BWOC de sílica flour e pastas com diferentes concentrações de poliuretana (5 % a 25 %) e 40 % BWOC de sílica flour. O peso específico das pastas foi fixado em 1,87 g/cm3 (15,6 lb/gal). Os resultados demonstram que as resistências da pasta contendo 40% de sílica e das com adição de polímero foram muito superiores a da pasta de cimento puro, não ocorrendo o efeito da retrogressão. As pastas com polímero apresentaram um crescente aumento da tenacidade com o aumento da concentração da mesma, sendo assim capaz de suportar as tensões. Além de se manterem estáveis termicamente acima de 180 ºC. O sistema também apresentou excelentes resultados de filtrado, reologia, água livre, estabilidade e permeabilidade. Sendo assim, o mesmo mostrou ser aplicável a poços HPHT

Análise comparativa entre simuladores de linha de fluxo e diferenças finitas para um reservatório de petróleo submetido a injeção de água

Water injection is the most widely used method for supplementary recovery in many oil fields due to various reasons, like the fact that water is an effective displacing agent of low viscosity oils, the water injection projects are relatively simple to establish and the water availability at a relatively low cost. For design of water injection projects is necessary to do reservoir studies in order to define the various parameters needed to increase the effectiveness of the method. For this kind of study can be used several mathematical models classified into two general categories: analytical or numerical. The present work aims to do a comparative analysis between the results presented by flow lines simulator and conventional finite differences simulator; both types of simulators are based on numerical methods designed to model light oil reservoirs subjected to water injection. Therefore, it was defined two reservoir models: the first one was a heterogeneous model whose petrophysical properties vary along the reservoir and the other one was created using average petrophysical properties obtained from the first model. Comparisons were done considering that the results of these two models were always in the same operational conditions. Then some rock and fluid parameters have been changed in both models and again the results were compared. From the factorial design, that was done to study the sensitivity analysis of reservoir parameters, a few cases were chosen to study the role of water injection rate and the vertical position of wells perforations in production forecast. It was observed that the results from the two simulators are quite similar in most of the cases; differences were found only in those cases where there was an increase in gas solubility ratio of the model. Thus, it was concluded that in flow simulation of reservoirs analogous of those now studied, mainly when the gas solubility ratio is low, the conventional finite differences simulator may be replaced by flow lines simulator the production forecast is compatible but the computational processing time is lower.

Análise paramétrica do método de injeção alternada de água e CO2(WAG) em reservatórios de petróleo

After the decline of production from natural energy of the reservoir, the methods of enhanced oil recovery, which methods result from the application of special processes such as chemical injection, miscible gases, thermal and others can be applied. The advanced recovery method with alternating - CO2 injection WAG uses the injection of water and gas, normally miscible that will come in contact with the stock oil. In Brazil with the discovery of pre-salt layer that gas gained prominence. The amount of CO2 present in the oil produced in the pre-salt layer, as well as some reservoirs is one of the challenges to be overcome in relation to sustainable production once this gas needs to be processed in some way. Many targets for CO2 are proposed by researchers to describe some alternatives to the use of CO2 gas produced such as enhanced recovery, storage depleted fields, salt caverns storage and marketing of CO2 even in plants. The largest oil discoveries in Brazil have recently been made by Petrobras in the pre -salt layer located between the states of Santa Catarina and Espírito Santo, where he met large volumes of light oil with a density of approximately 28 ° API, low acidity and low sulfur content. This oil that has a large amount of dissolved CO2 and thus a pioneering solution for the fate of this gas comes with an advanced recovery. The objective of this research is to analyze which parameters had the greatest influence on the enhanced recovery process. The simulations were performed using the "GEM" module of the Computer Modelling Group, with the aim of studying the advanced recovery method in question. For this work, semi - synthetic models were used with reservoir and fluid data that can be extrapolated to practical situations in the Brazilian Northeast. The results showed the influence of the alternating injection of water and gas on the recovery factor and flow rate of oil production process, when compared to primary recovery and continuous water injection or continuous gas injection

Análise da recuperação em reservatório de gás com baixa permeabilidade (TIGHT GAS) através do fraturamento hidráulico

With the increasing of energetic consumption in the worldwile, conventional reservoirs, known by their easy exploration and exploitation, are not being enough to satisfy this demand, what has made necessary exploring unconventional reservoirs. This kind of exploration demands developing more advanced technologies to make possible to exploit those hydrocarbons. Tight gas is an example of this kind of unconventional reservoir. It refers to sandstone fields with low porosity, around 8%, and permeabilities between 0.1 and 0.0001 mD, which accumulates considerable amounts of natural gas. That natural gas can only be extracted by applying hydraulic fracturing, aiming at stimulating the reservoir, by creating a preferential way through the reservoir to the well, changing and making easier the flow of fluids, thus increasing the productivity of those reservoirs. Therefore, the objective of this thesis is analyzing the recovery factor of a reservoir by applying hydraulic fracturing. All the studies were performed through simulations using the IMEX software, by CMG (Computer Modelling Group), in it 2012.10 version

Metodologia para avaliação de cinemática de partículas gasosas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo

Many challenges have been presented in petroleum industry. One of them is the preventing of fluids influx during drilling and cementing. Gas migration can occur as result of pressure imbalance inside the well when well pressure becomes lower than gas zone pressure and in cementing operation this occurs during cement slurry transition period (solid to fluid). In this work it was developed a methodology to evaluate gas migration during drilling and cementing operations. It was considered gel strength concept and through experimental tests determined gas migration initial time. A mechanistic model was developed to obtain equation that evaluates bubble displacement through the fluid while it gels. Being a time-dependant behavior, dynamic rheological measurements were made to evaluate viscosity along the time. For drilling fluids analyzed it was verified that it is desirable fast and non-progressive gelation in order to reduce gas migration without affect operational window (difference between pore and fracture pressure). For cement slurries analyzed, the most appropriate is that remains fluid for more time below critical gel strength, maintaining hydrostatic pressure above gas zone pressure, and after that gels quickly, reducing gas migration. The model developed simulates previously operational conditions and allow changes in operational and fluids design to obtain a safer condition for well construction

La redefinición de la agenda socialdemócrata entre la crisis del petróleo y el fin del socialismo real (1973-1992)

Resumen: El objetivo de este artículo es mostrar las estrategias de las organizaciones socialdemócratas frente a los nuevos desafíos que surgieron con la crisis del petróleo y la aparición de los llamados “valores posmateriales”. Se profundizará en una de las principales: el aumento de la actividad política trasnacional y la creación de comisiones que trabajaron aspectos relacionados con el desarrollo, la seguridad, el armamentismo nuclear y el medio ambiente. Estas comisiones no solo constituyeron un importante cambio frente a las tradiciones precedentes, también influyeron significativamente los desarrollos posteriores en dichas materias

Petróleo

Coletânea sobre os antecedentes da Política Nacional do Petróleo e das atribuições do Conselho Nacional do Petróleo; incluindo legislação, discursos parlamentares, estudos especializados, memoriais, investigações oficiosas e particulares que permitem uma visão da história econômica do petróleo brasileiro. Reúne projetos, requerimentos e outros documentos parlamentares, do período de 1824 a 1957, que precederam ao projeto da Petrobrás, da tramitação na Câmara dos Deputados e no Senado Federal até à reunião do Congresso para decidir sobre o veto. Inclui inquéritos da comissão especializada sobre a Petrobrás em atividade.

Constitucionalidade da Lei do petróleo e da adoção de novos regimes de contratação

Consultoria Legislativa - Área XII - Recursos Minerais, Hídricos e Energéticos.

A compensação financeira pela exploração de petróleo e de recursos minerais

Consultoria Legislativa - Área XII - Recursos Minerais, Hídricos e Energéticos.

Gás natural : uma importante alternativa energética para o Brasil

Consultoria Legislativa - Área XII - Recursos Minerias, Hídricos e Energéticos.