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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

[en] VISUALIZATION OF TWO PHASE FLOW IN POROUS MEDIA BY X-RAY MICROTOMOGRAPHY / [pt] MICROTOMOGRAFIA DE RAIOS-X APLICADA À VISUALIZAÇÃO DO ESCOAMENTO BIFÁSICO EM MEIOS POROSOS

RODRIGO CID LOUREIRO ASSAF 07 January 2019 (has links)
[pt] Na indústria do petróleo estudam-se os chamados métodos de recuperação melhorada de óleo, que visam melhorar a varredura macroscópica do reservatório e reduzir a saturação de óleo residual nas regiões varridas pela injeção da fase aquosa. Este trabalho apresenta um estudo fundamental do processo de injeção de emulsões óleo-água como método de recuperação melhorada. O meio poroso utilizado nos estudos foi um empacotamento de esferas de vidro. O meio poroso foi inicialmente saturado com óleo. O deslocamento de óleo foi realizado através da injeção sequencial de água, emulsão e água. Microtomografia de raios-X foi utilizada para determinar a distribuição das fases aquosas e oleosas ao final de cada etapa do processo de injeção. Processamento das imagens 3D obtidas permitiram a quantificação do efeito da injeção de emulsão no desvio do caminho preferencial da fase aquosa e na distribuição e tamanho de gânglios de óleo residual, gerando recuperações incrementais com relação a injeção de água. / [en] In the oil industry, the so-called enhanced oil recovery methods are studied, which aim to improve the macroscopic scanning of the reservoir and reduce the residual oil saturation in the regions swept by the injection of the aqueous phase. This work presents a fundamental study of the process of injection of oil-water emulsions as an improved recovery method. The porous medium used in the studies was a glass bead packaging. The porous medium was initially saturated with oil. The oil displacement was performed through the sequential injection of water, emulsion and water. X-ray microtomography was used to determine the distribution of the aqueous and oily phases at the end of each step of the injection process. Processing of the 3D images obtained allowed the quantification of the effect of emulsion injection on the deviation of the preferred path of the aqueous phase and the distribution and size of residual oil ganglia, generating incremental recoveries in relation to a water injection.
12

[pt] ANÁLISE DE SENSIBILIDADE NA MODELAGEM 2D DA CONTENÇÃO DE FRATURAS HIDRÁULICAS / [en] SENSITIVITY ANALYSIS IN 2D MODELING OF HYDRAULIC FRACTURE CONTAINMENT

RAFAEL FONSECA DE MESQUITA 29 December 2021 (has links)
[pt] Este trabalho faz uma análise da variação dos parâmetros que têm importância na propagação de fraturas hidráulicas e da influência desses parâmetros na conten-ção do fraturamento. Os experimentos numéricos foram feitos em um modelo 2D utilizando um simulador de elementos finitos com acoplamento sequencial hidro-dinâmico, tendo como premissa o comportamento dos processos envolvidos em es-tado estacionário. Inicialmente foram feitos testes de validação das soluções numé-ricas empregadas neste trabalho a partir de casos cujas soluções são bem conheci-das. Então, efeitos de variações de poropressão, de estado de tensões, propriedades das rochas, intervalos de início da fratura hidráulica, efeitos térmicos e o dano à permeabilidade da formação permoporosa foram utilizados para avaliar a contenção da fratura hidráulica. Primeiramente os efeitos foram avaliados separadamente e, em seguida, foram combinados aos pares, por meio de sorteio, e então avaliados. Os estudos levaram à conclusão de que o fator de maior influência para o início da propagação da fratura hidráulica na rocha capeadora (primeiros metros) é o valor da tensão mínima de confinamento do reservatório e a continuidade da propagação vertical na rocha selante é dominada pelo contraste de tensões entre rochas reserva-tório e capeadora. Entretanto, os demais parâmetros exercem influência na conten-ção do fraturamento hidráulico e devem ser levados em consideração neste tipo de estudo, principalmente os que servirão de insumo para a tomada de decisões. / [en] This master thesis analyzes the parameter s variation on the hydraulic frac-ture s propagation importance and the influence of these parameters on fracture containment. The numerical experiments were performed in a 2D model using a finite element simulator with sequential hydrodynamic coupling, having the sta-tionary behavior of the processes involved as premise. Validation tests were ini-tially performed for the numerical solutions used in this thesis from cases which solutions are well known. Then, effects of pore pressure variations, stress state, rock properties, hydraulic fracture opening intervals, thermal effects, and damage to the permoporous formation were used to evaluate the hydraulic fracture containment. At first, the effects were evaluated separately, then sorted for pair combinations, so they could be analyzed. These analyzes led to the conclusion that the most influen-tial factor for the hydraulic fracture initial propagation in the cap rock (first meters) is the reservoir’s minimum confinement stress value, and the vertical propagation continuity in the sealing rock is dominated by the stress contrast between reservoir and cap rocks. However, other parameters influence the hydraulic fracturing con-tainment and should be considered for this type of study, especially those that will serve as input for decision-making.
13

[en] HEXAVALENT CHROMIUM REMEDIATION USING CALCIUM POLYSULFIDE: STUDY CASE: RIO DE JANEIRO / [pt] REMEDIAÇÃO DE CROMO HEXAVALENTE UTILIZANDO POLISSULFETO DE CÁLCIO: ESTUDO DE CASO: RIO DE JANEIRO

RAFAEL FERREIRA GODOY 10 August 2015 (has links)
[pt] Esta dissertação apresenta os resultados obtidos no processo de remediação de uma área contaminada por cromo hexavalente por meio da técnica de remediação química in situ (ISCR). A área de estudo localiza-se na cidade do Rio de Janeiro e foi ocupada por uma fábrica de vidros por cerca de quarenta anos e comprada para construção de condomínios residenciais. A área de estudo passou um processo de gerenciamento ambiental que contemplou diversos estudos ambientais para aquisição de dados e delimitar a contaminação, horizontal e verticalmente. O teste de bancada realizado com o reagente químico polissulfeto de cálcio demonstrou ser eficiente para reduzir as concentrações de cromo hexavalente em solo e água subterrânea. Com base nos dados adquiridos neste teste foi possível calcular a dose de injeção do polissulfeto de cálcio. Foram realizados setenta pontos de sondagem, pela técnica direct push, para injetar duzentos e cinquenta e dois mil e trinta litros de solução de polissulfeto de cálcio e água, sendo aproximadamente três mil e quinhentos litros por ponto de injeção. Os resultados após a injeção demonstraram que o polissulfeto de cálcio conseguiu remover o cromo hexavalente que estava adsorvido ao solo e reduziu a concentração de cromo hexavalente na água subterrânea entre quarenta e seis e sessenta e sete e noventa e nove e noventa e cinco por cento , após dezenove meses da injeção. Dessa forma, comprovou a eficiência deste reagente químico para remediação de áreas contaminadas por cromo hexavalente, assim como foi observado nos artigos técnicos de estudos de casos nos Estados Unidos e Europa. / [en] This dissertation presents the results obtained in the remediation process remediation of a contaminated area by hexavalent chromium applying the technology in situ chemical remediation (ISCR). The study area is located in the Rio de Janeiro city and was occupied by a glass factory for forty years and purchased for construction of residential condominiums. This dissertation presents the results obtained in the remediation process remediation of a contaminated area by hexavalent chromium applying the technology in situ chemical remediation (ISCR). The study area is located in the Rio de Janeiro city and was occupied by a glass factory for forty years and purchased for construction of residential condominiums. Chromium is an important metal for the industry and is used in various products and processes, such as electroplating, leather treatment, pulp, wood preservation, and refractory manufacturing. The trivalent chromium is essential from a nutritional point of view, non-toxic and poorly absorbed in the body, acting in the maintenance of some functions. Cr(III) is the most common being found and occurs naturally, since the element Cr(VI) can occur naturally, but in low concentrations, if the groundwater has geochemical conditions the Cr (III) can be oxidize to Cr (VI). The hexavalent chromium is the most dangerous valence state and, according to ATSDR (two thousand and twelve), have greater mobility in the groundwater, being carcinogenic by inhalation of high doses of soluble chromate salts. The mobility of hexavalent chromium is high in soil and groundwater because it is not adsorbed by the soil in that valence state, on the other hand when it is in trivalent form is strongly adsorbed by the soil, forming insoluble precipitates, having low mobility in soil and groundwater. The hexavalent chromium remediation by in situ chemical reduction using calcium polysulfide has been the subject of several field studies documented in the literature, both for soil and groundwater from the Chromite Ore Processing Residue (COPR) (Storch, et al., two thousand and two; Graham, et al., two thousand and six ; Charboneau, et al., two thousand and six ; Wazne, et al., two thousand seven a; Wazne, et al., two thousand seven b; Chrysochoou, et al., two thousand and ten ; Chrysochoou & Ting, two thousand and eleven ; Pakzadeh & Batista, two thousand and eleven ; Chrysochoou, et al., two thousand and twelve ). Calcium polysulfide is a fertilizer to soil and commercially available and has been used in some remediation studies cases for reducing hexavalent chromium in soil and groundwater. Being commercially available and used as fertilizer, it is a relatively cheap chemical reagent in comparison with other chemical compounds exclusively developed for this purpose. The stoichiometric demand and the chemical kinetics of the reduction of Cr (VI) by the calcium polysulfide in aqueous solution was studied by Graham et al. (two thousand and six) from the chromite ore processing residue (COPR). With this study it was reported that a molar ratio of a point sixty-six is required (close to the theoretical value of one point five) and a first-order kinetics with an initial concentration of twenty-six eight point mg/L and pH of the CPS solution around eleven point five, with the presence of oxygen. Thus, the hexavalent chromium is reduced to chromium hydroxide, slightly water soluble compound which is precipitated to the soil. The trivalent chromium has low solubility, toxicity, mobility, reactivity and is considered stable. There are various application techniques of chemical reagents in the underground environment, and choosing the most appropriate method for each area depends on the type of contaminant, geological environment, groundwater and surface interference, depth, thickness and size of the contaminated area. As described by Suthersan (mil novecentos ninety-six), the injection of chemical reagents has to achieve two objectives: (one) creating and maintaining an ideal redox environment and other parameters such as pH, presence or absence of dissolved oxygen, etc.; and (two) the delivery and distribution of the necessary reagents for a homogeneous way throughout the injection area, both horizontally and vertically. Thus, it is essential that the conceptual model of the study area is very detailed, so there is no doubt in the choice of chemical reagent application methodology. Although there are numerous laboratory studies on hexavalent chromium remediation using calcium polysulfide, there are few reports in the literature on the field application, especially case studies in Brazil, therefore, this case study becomes a demonstration applying calcium polysulfide as a remediation technique for hexavalent chrome, with geochemical data, which are important for monitoring chemical reduction. This case study shows the effectiveness, dosage and concentration of the study area, and may apply to other hexavalent chromium remediation projects. Materials and Methods A former glass factory (the Site ) operated in the North Zone of Rio de Janeiro / RJ, Brazil from the mid-thousand nine hundred and fifty s to two thousand and five. A portion of the facility was used to store raw material to produce glass, including arsenic oxide, and another portion of the Site was used to conduct industrial plating using hexavalent chromium (Cr(VI)) in the glass molds. In two thousand and nine, the Site was purchased for mixed use redevelopment, demanding an environmental assessment and subsequent remediation. Between two thousand and nine and two thousand and twelve several phases of site investigation was conducted. The results of the investigation indicated that Cr(VI) was present in soil at concentrations up to approximately twenty one mg/kg and in groundwater at concentrations up to approximately thirty mg/L. These concentrations exceeded regulatory criteria of three hundred mg/Kg for soil and zero point zero five mg/L for groundwater. A phased remedial approach was developed consisting of the following: (a) excavation and off-site disposal of two and four hundred ton of Cr(VI) impacted soil from the source area, performed in the unsaturated and saturated zone soils in the Cr(VI) source area; (b) post-excavation monitoring of the groundwater conditions; and (c) groundwater treatment following the excavation program. Hexavalent chromium concentrations in groundwater decreased significantly following the excavation, however, additional reduction of concentrations of Cr(VI) contaminant in groundwater was required. Then was designed and implemented a set of bench-scale treatability tests in order to evaluate groundwater remediation alternatives. Several proprietary and non-proprietary reductants for co-treatment of Cr(VI) were evaluated. Calcium polysulfide were selected to treat Cr(VI). To reduce residual Cr(VI) concentrations in the groundwater plume located downgradient of the former excavated source area, dois e seven hundred cubic meters were targeted for active treatment. The groundwater remediation approach consisted of the injection of thirty liters of CPS (twenty nine percent) diluted in two hundred and twenty liters of water, yielding a total of two hundred and fifty liters of solution injected using direct push technology into seventy two locations. Groundwater Monitoring As part of chemical reagent injection stage was performed the baseline monitoring with collection of soil and groundwater samples. The soil sampling was performed by direct push technique using PVC liner with two inches in diameter, to analyze the total and hexavalent chromium concentrations. Six months after the injection were installed sixteen monitoring wells, eight shallow wells (five meters) and eight deep wells (nine meters) spread upstream, side, middle and downstream of the injection area. Groundwater geochemical parameters (i.e., temperature, total solids dissolved, specific conductance, pH, oxidation-reduction potential, and temperature) were measured at the time groundwater samples were collected. Groundwater samples were collected and analyzed for total and dissolved chromium, hexavalent chromium, iron, arsenic, manganese, calcium, sulfate, and sulfide. Samples were field-filtered with disposable zero point forty-five μm polyethylene filter capsules prior to collecting samples for dissolved metals. Results and Discussion Dose calculations for the reduction of hexavalent chromium have been performed with the data obtained in the bench-scale treatability test and resulted in a stoichiometric demand of four mlCPS/kg soil to the treatment of the study area. Therefore thirty liters of solution was used containing twenty-nine percent calcium polysulfide and approximately two hundred and twenty two liters to perform their mixture, totaling two hundred and fifty-two thousand and thirty liters of solution. For solution injection were performed seventy two soil borings with eight point five meters deep, and the product was injected range between two point five and eightpoint five meters. The depth of injection was from two point five mbgl covered any change in water level due to seasonal variation. In each soil boring was injected chemical reagent solution comprised four hundred and seventeen liters of calcium polysulfide diluted in tree and eighty-three liters of water for a total volume of tree and a half liters of solution injected per point. The comparative analysis results of the third monitoring campaign ( eighteen months post-injection) with the baseline campaign (september/two thousand and twelve) indicated reduction of hexavalent chromium concentrations between forty-six point sixty-seven and ninety-nine and ninety-five percent. Regarding the second monitoring campaign (twelve months post-injection), the hexavalent chromium concentrations reduced between twenty-three point ninety-nine and ninety nine point seventy-nine percent in five of the fifteen monitoring wells that were sampled. In three of the fifteen monitoring wells the hexavalent chromium concentrations remained below the quantitation limit used by the analytical laboratory method. There was no increase in hexavalent chromium concentration, compared the results of the third and second monitoring campaign. The evaluation of the Eh and pH values measured in the monitoring campaigns showed that the pH value was in the acidic range (about four ) and after removal of contaminated soil with hexavalent chromium pH raised to between five and six, after the chemical reagent injection pH increased to the basic range (above seven point five). In the second and third campaign the pH reduced to acid range (below six point five), which can be regarded as the pH value of the area background. The Eh has inversely proportional behavior, increasing between the first and third campaign, and in the third campaign the measured values are in the ranges considered as moderately reducing (hundred to four hundred mV) and oxidizer (> four hundred mV). The pH variation also showed a relationship between increased concentrations of calcium, iron, manganese and sulfate (in some monitoring wells). There were also reductions in hexavalent chromium concentrations in monitoring wells. Conclusion This case study indicates that the use of different remediation techniques when applied together (excavation and chemical reduction), reducing the time required for remediation of a contaminated site without impacting the final cost of remediation. The chemical reduction of hexavalent chromium using calcium polysulfide was effective to reduce the concentration to less than the quantification limit of the analytical method used. Therefore, as presented it is necessary to carry out several studies to detail the hexavalent chromium concentration in the site, as well as understand the geochemistry of groundwater and performing bench-scale tests to evaluate the effectiveness of the chemical reagent in the site study hydrogeological environment and calculate the required dose. The treatability test with calcium polysulfide demonstrated the feasibility of using this chemical reagent by In Situ Chemical Reduction (ISCR) to reduce the hexavalent chrome concentration in soil and groundwater. The test resulted in a stoichiometric demand of four mlCPS /kg soil to the treatment of the study area. Soil samples collected six months after injection showed that the calcium polysulfide could desorb hexavalent chromium from the soil, since, contaminant concentrations were not detected in the samples. neteen months after the injection of the chemical reagent the groundwater concentrations of hexavalent chromium reduced from forty-six point sixty-seven to ninety-nine and ninety-five percent in relation to baseline campaign. And, of the fifteen monitoring wells in just three wells hexavalent chromium concentrations were detected. This demonstrates the effectiveness of using calcium polysulfide to remediate hexavalent chromium in soil and groundwater, confirming the studies by Storch et al. (two thousand and two), Graham et al (two thousand and six), Charboneau et al. ( two thousand and six), Wazne et al. (two thousand and seven a), Wazne et al. (two thousand and seven b), Chrysochoou et al. (two thousand and ten), Chrysochoou & Ting (two thousand and eleven), Pakzadeh & Batista (two thousand and eleven), Chrysochoou et al (2012) in several areas in United States and Europe.
14

[pt] ESTUDO EXPERIMENTAL DA INJEÇÃO DE SOLUÇÃO POLIMÉRICA EM ARENITOS / [en] EXPERIMENTAL STUDY OF POLYMERIC SOLUTION INJECTION IN SANDSTONES

ADEMIR FREIRE DE MEDEIROS 31 January 2022 (has links)
[pt] Após uma jazida de petróleo ser encontrada, a produção de óleo ou gás é feita através de um poço produtor que é perfurado até atingir as camadas de rocha onde os hidrocarbonetos estão alojados. Com a constante produção, a pressão de reservatório decresce até atingir um nível que é insuficiente para o aproveitamento econômico. Geralmente, utiliza-se a injeção de água para manter o nível de pressão do reservatório. Nos estudos de um reservatório de petróleo é fundamental o conhecimento de propriedades básicas da rocha e dos fluidos nela contidos. São essas propriedades que determinam as quantidades de fluidos existentes no meio poroso, a sua distribuição, a capacidade desses fluidos se moverem e, mais importante, a quantidade de fluidos que pode ser extraída. Através do método convencional de injeção de água objetiva-se a manutenção da pressão do reservatório e o deslocamento de óleo em direção aos poços produtores. A água (fluido deslocante) tende a ocupar gradualmente o espaço antes ocupado pelo óleo (fluido deslocado), contudo, por efeitos capilares, uma parcela do óleo não é retirada do meio poroso configurando o que chamamos óleo residual. Em função da razão de mobilidade da água e do óleo, a frente de deslocamento não é uniforme, e um grande volume do reservatório não é atingido pela água de injeção. A adição de polímero à água de injeção visa o aumento da viscosidade da água, e assim, melhorar a razão de mobilidade água-óleo, aumentando a eficiência de varrido uma vez que uniformiza a frente de avanço, reduzindo a formação de caminhos preferenciais no reservatório. Além de diminuir a razão de mobilidade, soluções poliméricas podem contribuir para um melhor deslocamento de óleo em escala de poro, a partir de seu efeito elástico, reduzindo, portanto, a saturação de óleo residual. Contudo, tal mecanismo em micro-escala, ou seja, em escala de poro não é totalmente compreendido. O presente trabalho preocupa-se principalmente em analisar o fator de recuperação do óleo e saturação de óleo residual após processo de deslocamento de óleo por água salgada, solução polimérica de poliacrilamida parcialmente hidrolisada (HPAM) e solução de glicerina em testemunhos de Arenito Bentheimer. Um porta-testemunho especial foi utilizado para a realização dos testes de deslocamento, sendo monitoradas a variação de pressão ao longo da amostra, além dos volumes de injeção e produção de fluidos em função do tempo. / [en] After an oil deposit is found, oil or gas is produced through a production well that is drilled until it reaches the rock layers where the hydrocarbons are housed. With constant oil production, the reservoir pressure decreases until it reaches a level that is insufficient for economic use. Water injection is generally used to maintain the reservoir pressure level. It is essential to know the basic rock and fluid properties to study an oil reservoir. These properties determine the volume of fluids in the porous medium, their distribution, the ability of these fluids to move, and most importantly, the volume of fluids that can be extracted. The conventional water injection method aims to maintain the reservoir pressure and the oil displacement towards the producing wells. Water (displacing fluid) tends to gradually occupy the space previously occupied by oil (displaced fluid), however, due to capillary effects, an oil portion is not removed from the porous medium, configuring what we call residual oil. Because of the water-oil mobility ratio, the displacement front is not uniform and a large volume of the reservoir is not reached by the injection water. Polymer addition in the injection water aims at increasing water viscosity, and thus, improving the water-oil mobility ratio, increasing the sweeping efficiency since it unifies the advance front, reducing the formation of preferential paths in the reservoir. Besides reducing the mobility ratio, polymeric solutions can contribute to a better oil displacement in pore-scale, based on its elastic effect, reducing residual oil saturation. However, this mechanism is not fully understood in the micro-scale. The present work is concerned with analyzing oil recovery factor and residual oil saturation after the oil displacement process by saltwater, polymeric solution of partially hydrolyzed polyacrylamide (HPAM), and glycerin solution in sandstone Bentheimer samples. A special core holder was used to displacement tests, the injection differential pressure on the sample was monitored, in addition to the injection volumes and production volume as a function of time.
15

[en] EFFECT OF REPROCESSING ON THE MECHANICAL PROPERTIES OF A HDPE/LDPE BLEND / [pt] EFEITO DO REPROCESSAMENTO NAS PROPRIEDADES MECÂNICAS EM UMA BLENDA DE PEBD/PEAD

WILLIAM BUSCHLE ROMARIZ INACIO 31 August 2018 (has links)
[pt] Os termoplásticos representam a grande maioria dos polímeros empregados hoje em dia e a grande vantagem de sua aplicação é que podem ser reaquecidos e moldados repetidamente. Com a crise do petróleo em 1973, os custos para transformar o petróleo em materiais plásticos se tornaram mais atrativos do que transformá-lo em materiais mais tradicionais. Com isso, os investimentos nas indústrias de transformação cresceram, ao mesmo tempo que a preocupação com o meio ambiente. Devido a facilidade de reprocessar esses materiais a temperaturas moderadas, muitas empresas passaram a reutilizar seus resíduos dentro de seus próprios processos. Neste escopo, esse trabalho tem como objetivo estudar o comportamento mecânico do polietileno de baixa densidade (PEBD) e de uma mistura física formada por polietileno de baixa densidade (PEAD) e polietileno de alta densidade, com uma proporção de 80/20, ao serem submetidos a diversos ciclos de processamento. Os materiais estudados foram preparados e doados pela Companhia de Canetas Compactor. Para este estudo, o material sofreu dez etapas de injeção/extrusão. A partir de ensaios de tração foram determinadas as tensões e cargas máximas suportadas, calculando-se em seguida o módulo de elasticidade, alongamento e tenacidade de cada material. A adição do PEAD é responsável por aumentar a resistência e a dureza do material. Do ponto de vista prático, o material reprocessado não apresentou mudanças significativas de performance. Análises por infravermelho mostraram que não há degradação por oxidação ao longo do processo de reciclagem. / [en] Thermoplastics are the most used polymers nowadays on account of being easily reprocessable with high temperatures. During the oil crisis in 1973 the costs of transforming oil into plastic materials became more attractive than turning them into more traditional materials. Furthermore, the investments in transformation industries grew alongside the concern for the environment. Due to the ease of reprocessing these materials a lot of companies started recycling them within their process. In this context, the present study aims to analyze the mechanical behavior of a low density polyethylene (LDPE) and high density polyethylene (HDPE) blend and pure LDPE after 10 cycles of reprocessing. The polymers were donated by Companhia de Canetas Compactor. The materials suffered up to 10 cycles of injection moulding/extrusion. Tensile tests were made to determine the maximum yield stress and maximum load allowed. Afterwards, calculations were made to determine elongation, Young modulus and toughness. The HDPE addition was responsible to raise the materials yield stress and hardness. From a practical point of view the reprocessing didn t affect significantly the materials performance. FTIR analyses didn t detect oxidation through the process.
16

[en] NUMERICAL STUDY OF LOSS OF INJECTIVITY IN ROCK / [pt] ESTUDO NUMÉRICO DE DECLÍNIO DE INJETIVIDADE EM ROCHA

FLAVIO ALCHAAR BARBOSA 24 February 2003 (has links)
[pt] Esta dissertação apresenta um estudo numérico, utilizando o método dos elementos finitos, para simular o entupimento de rochas provocado pela injeção de água contendo partículas sólidas. Dentre os diferentes parâmetros que afetam o declínio de injetividade, quatro foram analisados, considerando-se a situação de fluxo unidimensional: fator de dano, concentração de partículas sólidas presentes no fluido de injeção, coeficiente de filtragem e taxa de injeção. Um estudo paramétrico ressaltando a influência destes fatores na perda de injetividade é também apresentado neste trabalho, concluindo-se que os resultados numéricos obtidos concordam satisfatoriamente com as observações experimentais disponíveis e soluções analíticas publicadas na literatura. O trabalho estuda também numericamente a simulação do entupimento dos poros da rocha considerando dois modelos de redução de permeabilidade e recupera valores do coeficiente de filtragem (Lambda ) e do fator de dano ( Beta ) através de análises inversa pelo método dos elementos finitos. / [en] This dissertation presents a numerical study, based on the finite element method, to simulate rock pore plugging caused by the injection of water containing solid particles in suspension. Amongst the parameters that affect rock injectivity decline, the following four were analyzed, considering undimensional flow: damage coefficient, solid particle concentration present in the injection fluid, filtration coefficient and injection rate. A parametric study standing out the influence of the these factors in the loss of injectivity is also presented in this work, concluding that the numerical results agree satisfactorily with the available experimental data and analytical solutions published in the literature. This work also numerically investigates the process of rock pore plugging considering two different permeability reduction models and recovers values of the filtration coefficient (Lambda ) and the damage factor ( Beta ) through inverse analyses carried outn by the finite element method.
17

[en] FLEXIBLE COMPOSITION FOR C PLUS PLUS 11 / [pt] COMPOSIÇÃO FLEXIVEL EM C MAIS MAIS 11

MAXIMILIEN PHILIPPE M A DE BAYSER 01 February 2017 (has links)
[pt] Injeção de dependências, uma forma de inversão de controle, é uma forma de estruturar a configuração e composição de componentes de software que traz vários benefícios como um acoplamento reduzido entre componentes. No entanto, um framework genérico de injeção de dependências requer instrospecção em tempo de execução, o que explica por que injeção de dependências é popular em Java mas praticamente inexistente em C Mais Mais. Neste trabalho apresentamos um sistema de introspecção para C Mais Mais 11 e mostramos como ele pode ser usado para melhorar uma implementação de Service Component Architecture (SCA) para C Mais Mais. Usamos vários novas funcionalidades de C Mais Mais 11 como perfect forwarding, variadic templates e lvalue references para melhorar a usabilidade da API de reflexão e minimizar o overhead de execução. / [en] Dependency injection, a form of inversion of control, is a way of structuring the configuration and composition of software components that brings many benefits such as a loose coupling of components. However, a generic dependency injection framework requires runtime type introspection and this is why dependency injection is popular in Java and almost non-existent in C plus plus. In this work we present a introspection system for C plus plus 11 and show how to use it to improve an implementation of the Service Component Architecture (SCA) for C plus plus. It uses several features of C plus plus 11 such as perfect forwarding, variadic templates and lvalue references to improve usability and minimize overhead.
18

[pt] DEGRADAÇÃO MECÂNICA DE SOLUÇÕES POLIMÉRICAS EM FLUXO LAMINAR EXTENSIONAL / [en] MECHANICAL DEGRADATION OF POLYMER SOLUTIONS IN EXTENSIONAL LAMINAR FLOW

LUA SELENE DA SILVA ALMEIDA 28 June 2021 (has links)
[pt] Devido ao seu comportamento físico-químico, os polímeros solúveis em água são utilizados em várias fases de perfuração, completação, e produção de poços de petróleo. Portanto, é fundamental prever e controlar o comportamento em meio poroso para entender o desempenho do polímero. Experimentos foram conduzidos para estudar a degradação de uma solução aquosa semi-diluída de PEO, usando dois capilares com diâmetros de entrada diferentes (100 micrômetros e 200 micrômetros) ambos com constrição de 50 micrômetros, criando fluxos transientes rápidos em seu centro. Diferentes vazões foram impostas a fim de observar diferentes taxas de cisalhamento e de alongamento no sistema. O efluente do fluxo foi coletado e reinjetado, e suas propriedades reológicas foram utilizadas como proxies para a degradação. Observamos que, para a contração mais abrupta, a vazão mínima necessária para degradar a solução é menor. Este resultado, analisado apenas sob a perspectiva da taxa de cisalhamento, não é razoável, já que a taxa de cisalhamento na constrição a que o polímero é submetido é igual em ambos os capilares. Portanto, inferimos que a brusquidão da contração desempenha um papel na degradação, o que significa que a taxa de alongamento pode ser responsável pela menor taxa de fluxo crítico. Também foi observado um padrão de como ocorre a degradação com as injeções subsequentes. Podemos inferir que injeções subsequentes causam degradação incremental antes de se aproximar de um patamar de estabilização e que vazões mais altas geram patamares de degradação mais baixos. / [en] Due to their physical-chemical behavior, water-soluble polymers are used extensively in various phases of drilling, completion, workover, and production of oil and gas wells. Therefore, it is fundamental to predict and to control in-situ porous medium behavior in order to understand polymer performance. Experiments were conducted to study the degradation of a semi diluted (2000 ppm) aqueous solution of PEO, using two capillaries with different entrance diameter (100 micrometers and 200 micrometers) both with 50 micrometers radius constriction, creating Fast-Transient Flows in their center. Different injection rates were imposed in order to observe different shear and extensional rates in the system. The effluent of the flow was collected, and reinjected, and rheological properties of the fluids were used as proxies for the degradation of the solution. We observed that for the more abrupt contraction, the minimum flow rate needed for degrading the polymer solution is lower. This result, when analyzed purely under shear rate perspective, is not reasonable, since the constriction shear rates to which the polymer is subjected are equal at both capillaries. Therefore, we inferred that the abruptness of the contraction plays a role in the degradation, which means elongational rate may be responsible for the lower critical flow rate. It was also observed a pattern for how the degradation occurs with subsequent injections. We could infer that subsequent injections cause incremental degradation before approaching a stabilization plateau and that higher flow rates generated lower degradation plateaus.
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[pt] CATALOGANDO ANTIPADRÕES DE INJEÇÃO DE DEPENDÊNCIA EM SISTEMAS DE SOFTWARE / [en] CATALOGING DEPENDENCY INJECTION ANTI-PATTERNS IN SOFTWARE SYSTEMS

RODRIGO NUNES LAIGNER 19 June 2020 (has links)
[pt] Contexto Injeção de Dependência (DI) é um mecanismo comumente aplicado para desacoplar classes de suas dependências com o objetivo de prover uma melhor modularização do software. No contexto de Java, a existência de uma especificação de DI e frameworks populares, como o Spring, facilitam o emprego de DI em projetos de software. Entretanto, más práticas de implementação de DI podem trazer más consequências, como maior acoplamento, dificultando alcançar o principal objetivo de DI. Apesar de a literatura sugerir a existência de anti-padrões de DI, não há uma documentação detalhada de tais más práticas. Em adição, não há evidência da ocorrência e da percepção de utilidade dos mesmos do ponto de vista de desenvovedores. Objetivos Nosso objetivo é revisar os anti-padrões de DI reportados com o objetivo de analisar sua completude e propor um novo catálogo de anti-padrões de DI para Java. Método Nós propomos um catálogo contendo 12 anti-padrões de DI para Java. Nós selecionamos 4 projetos open-source e 2 projetos closed-source que adotam um framework de DI e desenvolvemos uma ferramenta que analisa estaticamente a ocorrência dos anti-padrões de DI candidatos no código fonte das aplicações. Em adição, nós conduzimos uma pesquisa por meio de entrevistas face a face com três desenvolvedores experientes que regularmente aplicam DI em seus projetos. Nós estendemos a pesquisa com o objetivo de obter a percepção de um conjunto de 15 desenvolvedores experientes e novatos por meio de um questionário online Resultados Ao menos 9 anti-padrões de DI apareceram frequentemente nos projetos de software analisados. Em adição, a avaliação recebida dos desenvolvedores confirmaram a relevância do catálogo. Por fim, os respondentes expressaram o desejo de refatorar as instâncias de antipadrões de DI propostas. Conclusões O catálogo contém anti-padrões de DI que ocorrem na prática e são úteis. Compartilhar com praticantes da indústria os permitirá evitar a introdução de anti-padrões em seus projetos de software. / [en] Background Dependency Injection (DI) is a commonly applied mechanism to decouple classes from their dependencies in order to provide better modularization of software. In the context of Java, the availability of a DI specification and popular frameworks, such as Spring, facilitate DI usage in software projects. However, bad DI implementation practices can have negative consequences, such as increasing coupling, hindering the achievement of DI s main goal. Even though the literature suggests the existence of DI anti-patterns, there is no detailed documentation of such bad practices. Moreover, there is no evidence on their occurrence and perceived usefulness from the developer s point of view. Aims Our goal is to review the reported DI anti-patterns in order to analyze their completeness and to propose and evaluate a novel catalog of Java DI anti-patterns. Method We propose a catalog containing 12 Java DI anti-patterns. We selected 4 opensource and 2 closed-source software projects that adopt a DI framework and developed a tool to statically analyze the occurrence of the candidate DI anti-patterns within their source code. Also, we conducted a survey through face to face interviews with three experienced developers that regularly apply DI. We extended the survey in order to gather the perception of a set of 15 expert and novice developers through an online questionnaire. Results At least 9 different DI anti-patterns appeared frequently in the analyzed projects. In addition, the feedback received from the developers confirmed the relevance of the catalog. Besides, the respondents expressed their willingness to refactor instances of anti-patterns from source code. Conclusions The catalog contains Java DI anti-patterns that occur in practice and are useful. Sharing it with practitioners may help them to avoid such anti-patterns.

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