Orientador: Antonio Carlos Bannwart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-04T02:30:45Z (GMT). No. of bitstreams: 1 Silva_RosivaniadaPaixao_M.pdf: 2594655 bytes, checksum: b6c2b50ec1aafc9b617cd07d018c8efc (MD5) Previous issue date: 2004 / Resumo: O processamento primário dos fluidos na produção do petróleo consiste na separação entre o óleo, gás, água e as impurezas em suspensão, no condicionamento dos hidrocarbonetos para que possam ser transferidos para as refinarias, e no tratamento da água para reutilização ou descarte apropriado. Com a crescente importância de campos de óleos pesados, cuja densidade é mais próxima da água e a viscosidade é da ordem de centenas de vezes a da água, a produção deste óleo e o processamento primário dos fluidos produzidos com as tecnologias usuais tornam-se pouco atraente e muitas vezes inviável. Este trabalho investiga o comportamento da dispersão de água em óleo pesado que pode se transformar em emulsão. Portanto, o estudo sobre o conceito e a classificação das emulsões de água em óleo e de óleo em água e a revisão das principais técnicas para sua geração e separação, visam definir estratégias para a separação eficaz desses fluidos. A partir disso, investiga-se os critérios de projeto de vasos separadores gravitacionais trifásicos, tais como o tempo de retenção, tamanho e velocidade terminal das partículas, enfatizando-se os aspectos físicos da separação. Utilizou-se o software Mathematica??para a modelagem das equações que governam o dimensionamento de vasos separadores horizontais, permitindo-se observar a influência de diversas variáveis nas dimensões do vaso separador / Abstract: The primary processing of the produced fluids from an oil field consists in the separation of oil, gas, water and solids suspensions, in the conditioning of the hydrocarbons for transporting to the refinery, and in the water treatment for reuse or proper disposal. For heavy oils, whose densities are almost the same as water and viscosities about two hundred times higher than water, the production and primary processing with the usual technologies is not attractive and many times unfeasible. This work investigates the behavior of the water dispersion in a heavy oil, that can become an emulsion. The scope of the study of water-in-oil and oil-in-water emulsions and the review of the principal techniques for its generation, leads to strategies to efficiently separate these liquids. Considering the presence of a free gas phase, design criteria for three-phase separator, such as retention time, size and terminal velocity of the particles, emphasizing the physical aspects of separation, are investigated. Mathematica??software was used for solving the equations that rule the design of horizontal separators vases, allowing observation of the influence of several parameters on the separator dimensions / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

The scope of the present thesis is the development of a Computational Fluid Dynamics model to describe the multiphase flow inside a structured packing absorber for postcombustion carbon capture. The work focuses mainly on two flow characteristics: the interface tracking and the reactive mass transfer between the gas and the liquid. The interface tracking brings the possibility of studying the liquid maldistribution phenomenon, which strongly affects the mass transfer performance. The development of a user-defined function to account for the reactive mass transfer between phases constitutes the second major concept considered in this thesis. Numerical models found in the literature are divided into three scales due to the current computational capacity: small-, meso- and large-scale. Small-scale has usually dealt with interface tracking in 2D computational domains. Meso-scale has usually been considered to assess the dry pressure drop performance of the packing (considering only the gas phase). Large-scale studies the liquid distribution over the whole column assuming that the structured packing behaves as a porous medium. This thesis focuses on small- and meso-scale. The novelty of this work lies in expanding the capabilities of the aforementioned scales. At small-scale, the interfacial tracking is implemented in a 3D domain, instead of 2D. The user-defined function that describes the reactive mass transfer of CO2 into the aqueous MEA solution is also included to assess the influence of the liquid maldistribution on the mass transfer performance. At the meso-scale, the Volume of Fluid method for interface tracking is included (instead of only the gas phase) to describe flow characteristics such as the liquid hold-up, the interfacial area and the mass transfer. At the theoretical level, this model presents the particularity of including both a mass and a momentum source term in the conservation equations. A comprehensive mathematical development shows the influence of the mass source terms on the momentum equation.

Cette thèse est centrée sur le développement d’outils expérimentaux permettant de mieux caractériser l’étude du couplage entre l’évaporation de gouttelettes et un écoulement turbulent gazeux environnant. Dans notre étude on cherche à se placer dans un régime de couplage fort entre les gouttelettes évaporantes et la turbulence. Dans ce régime peu renseigné dans la littérature, les gouttelettes se trouvent dans un régime intermédiaire entre le régime de traceur et le régime inertiel. Dans un premier temps nous présentons un dispositif expérimental capable de générer une turbulence homogène isotrope avec de fortes fluctuations de vitesse, ainsi que la réalisation de l’injection de gouttelettes initialement monodisperses. Puis, l’instrumentation Lagrangienne développée (en collaboration avec le laboratoire Hubert Curien de St Etienne) : l’holographie numérique en ligne, est ensuite testée et validée pour un fluide non évaporant. Une méthode de tracking des gouttelettes a été mise au point afin de reconstruire les trajectoires des gouttelettes dans le volume turbulent homogène isotrope. La précision obtenue sur les diamètres (2% pour des gouttes de 60 μm) vient complètement valider cette métrologie pour l’étude de l’évaporation. Les premiers résultats obtenus avec des gouttelettes évaporantes de fréon R114 font apparaître la visualisation, à notre connaissance inédite, des sillages évaporants. Une première reconstruction de trajectoire avec l’évolution du diamètre de la goutte au cours du temps est enfin présentée. / This experimental thesis is based on the developpement of experimental tools in order to better understand the coupling between evaporation process and turbulent flow. Our studies focuses on evaporating droplets with strong interaction with turbulent flow, i.e. droplets between fluid particles behaviour and inertial behaviour. This pecular situation is hardly studied regarding to scientific litterature. We first present experimental set up generating homogeneous isotropic turbulence with high Reynolds number and strong fluctuations. Then we present injection process of initially monodisperse droplets in the turbulent flow. Lagrangian instrumentation consists of the use of digital in-line holography (in collaboration with Laboratoire Hubert Curien à St Etienne). This metrology is definitely validated regarding to the accuracy on the droplet diameter measurements. Tracking algorithm is then proposed in order to reconstruct Lagrangian droplet trajectories. First results obtained with evaporating droplets are finally presented like evaporating trails, and time evolution of the diameter of a freon droplet.

Dans cette thèse, nous avons développé un code de simulation numérique directe pour l’étude des écoulements particulaires. Le schéma numérique est basé sur une technique de domaines fictifs. Le code est validé sur de nombreux cas test puis nous l’avons utilisé pour étudier la sédimentation de particules bidimensionnelles en milieu confiné. Trois cas ont été analysés : sédimentation d’une particule unique, d’un doublet de particules et d’un grand nombre de particules. Dans le premier cas nous retrouvons le phénomène de survitesse qui apparaît pour une particule excentrée à bas nombre de Reynolds. Nous montrons que cette survitesse est très sensible à l’inertie du fluide : elle diminue lorsqu’on augmente le nombre de Reynolds. Cet effet est retardé par le confinement. Dans le cas d’un doublet de particules, nous retrouvons les comportements complexes observés dans la littérature (hystérésis, cascade sous-harmonique et chaos). Nous montrons qu’une nouvelle série de bifurcations et un nouvel attracteur apparaissent pour des particules plus pesantes. Il s’agit là d’une transition vers le chaos par la voie de la quasi-périodicité. Nous donnons le diagramme de bifurcation étendu. La nouvelle branche correspond à une structure horizontale qui conduit à une sédimentation lente. Dans le cas d’un grand nombre de particules, nous montrons que la vitesse de chute de l’interface fluide-particules suit une loi de type Richardson-Zaki, mais avec un exposant d’environ 4. Comme pour des sphères, la valeur de cet exposant dépend du confinement. Enfin, nous observons un phénomène de blocage, inattendu pour des particules non-cohésives, dû au caractère bidimensionnel de la suspension / In the present thesis, a fully-resolved numerical code has been developed for the analysis of particle-laden flows. A fictitious domain method is used. First, this numerical tool has been validated by using classical benchmarks. It has then been used to simulate the complex sedimentation of particles in three generic two-dimensional configurations: a single particle, a particle pair and a large number of particles in a confined domain. In the first case, the peak-velocity of an off-centred inclusion is recovered at low-Reynolds number. It is shown that this peak-velocity is very sensitive to fluid inertia: the peak-velocity decreases when the Reynolds number increases. This effect is delayed by the confinement. The very complex dynamics of a pair of particles sedimenting in a confined domain, observed in the litterature, is recovered (hysteresis, period-doubling cascade and chaos). It is shown that a new series of bifurcations, leading to a new attractor, emerges when the non-dimensional particle weight is increased. This new transition corresponds to a quasi-periodic route. The extended bifurcation diagram is given. The new branch discovered in this work corresponds to a nearly horizontal particle doublet, with a slow settling velocity. In the case of the settling of large number of particles, a RZ-like law is recovered for the sedimentation velocity of the fluid-particle interface. The exponent is close to 4, in contrast with the case of spheres. Finally, the sedimentation velocity at the end of the settling process is observed to be significantly reduced, like for cohesive sediments. This unexpected behaviour is related to the two-dimensionality of the suspension

Gas-liquid annular two phase flow in pipes is important in the oil and gas, nuclear and the process industries. It has been identified as one of the most frequently encountered flow regimes and many models (empirical and theoretical) for the film flow and droplet behaviour for example have been developed since the 1950s. However, the behaviour in large pipes (those with diameter greater than 100 mm) has not been fully explored. As a result, the two- phase flow characteristics, data, and models specifically for such pipes are scarce or non-existent such that those from smaller pipes are extrapolated for use in design and operation. Many authors have cautioned against this approach since multiphase pipe flow behaviour is different between small and large pipes. For instance the typical slug flows seem not to occur in vertical upwards flows when the pipe diameter exceeds 100 mm. It is therefore imperative that theoretical models and empirical correlations for such large diameter pipes are specifically developed.

[pt] O escoamento de bolhas de gás em fluidos não-newtonianos é muito importante em diversas aplicações, tais como biorreatores, processamento de alimentos e operações de perfuração e cimentação de poços de petróleo, contudo poucos estudos abordam este tema. No presente trabalho é analisado o escoamento ascendente de bolhas de gás em fluido viscoplástico, modelado aqui como fluido Herschel-Bulkley. Utilizou-se uma abordagem bidimensional, aproximada por placas paralela. O escoamento multifásico foi numericamente simulado fazendo uso do método de volumes finitos VOF (volume of fluid), o qual resolve as equações de conservação de massa e momento aclopado a uma equação para a fração volumétrica dos fluidos. A influência de fatores tais como tensão limite de escoamento, dimensão da bolha, número de bolhas e distância entre as bolhas escoando em um fluido viscoplástico foram investigadas. Os resultados indicaram que a tensão limite de escoamento tem grande impacto na velocidade de deslocamento da bolha. No caso de mais de uma bolha escoando foi também observado que o deslocamento de uma bolha altera a velocidade de ascenção das outras, fazendo com que elas se unam, e a medida em que a distância entre as bolhas aumenta a interferência é eliminada e as mesmas escoam como bolhas individuais. Além disso, foi verificado que, dependendo do tamanho da bolha escoando, a parede interfere na sua velocidade de ascenção. Por fim foi analisada a mudança no formato da bolha, podendo-se observar que em número de Reynolds menores a mesma apresenta um formato esférico e a medida em que este parâmetro aumenta, a bolha vai se deformando e adquire uma forma elipsoidal. Os resultados qualitativos do presente estudo numérico foram comparados com alguns trabalhos experimentais encontrados na literatura e corresponderam relativamente bem. / [en] The gas bubble displacement in non-Newtonian fluids is important in many applications, including bioreactors, food processing and drilling and cementing of oil wells however a few studies have investigated this issue. The motion of gas bubbles in a viscoplastic fluid, modeled as a Herschel-Bulkley fluid, is analysed in the present work. A bidimensional approach was used, approximated by parallel plates. The multiphase flow was numerically simulated using the finite volume technique VOF (volume of fluid), which solves the conservation equations of mass and momentum coupled to an equation for the volume fraction of the fluids. Is was investigated the influence of factors such as fluid yield stress, bubble size, number of bubbles rising in the viscoplastic fluid and also the distance between them. The results indicated that the yield stress has great impact on the bubble rising velocity. In the case of multiple bubbles flowing it was also observed that the displacement of one bubble influences the rising velocity of the others, causing them to join together. As the distance between the bubbles increase the interference is eliminated and the bubbles flow separately. Furthermore, it was found that there was an wall interference depending on the size of the bubble. Lastly, it was analysed the change in the shape of the bubble. It could be observed that for lower Reynolds number the bubbles presented an spherical shape and as this parameter increases it turns into an elipsoidal shape. The qualitative results of the present study agreed relatively well with experimental works found in the literature.

In der vorliegenden Arbeit werden verschiedene Simulationsansätze angewandt um die Hydrodynamik in einem neu entwickelten Wirbelschichtvergaser zu untersuchen. Die Ansätze umfassen a) entdimensionalisierter Ähnlichkeitskennzahlen und empirischer Gleichungen, b) 1D Simulationen mittels ASPEN Plus®, c) 3D CFD Simulationen mittels Ansys Fluent® zur detaillierten Abbildung der zu erwartenden Hydrodynamik. Vor- und Nachteile der jeweiligen Ansätze sowie Klassen von ermittelbaren Simulationsdaten werden diskutiert. Ein Schwerpunkt der Arbeit liegt in der Identifizierung geeigneter Experimente aus der Literatur, auf Basis von Ähnlichkeitskennzahlen, um die Simulationen zu validieren. Die Vergasersimulationen zeigen, dass sich erwartungsgemäß ein aus hydrodynamischer Sicht gestufter Prozess ausbildet. Die entstehenden Zonen lassen sich als Festbett, blasenbildende Wirbelschicht, Jet-Wirbelschicht mit Rezirkulationszelle und strähnenbildende, zirkulierende Wirbelschicht identifizieren und entsprechen demnach dem Verfahrensanspruch.

La compréhension des écoulements multiphasiques en milieu poreux revêt une importance capitale dans de nombreuses applications industrielles et environnementales, à des échelles spatiales et temporelles variées. Par conséquent, la présente étude propose une modélisation des écoulements multiphasiques en milieu poreux par le biais de la méthode Volume de Fluide, et présente des simulations de digitations de Saffman-Taylor, motivées par l'analyse d'expériences de balayage dans des blocs de grès de Bentheimer quasi bidimensionnels initialement saturés en huile extra-lourde par de l'eau. Le code Gerris, permettant des calculs parallèles efficaces à l'aide d'un maillage de type octree, est utilisé. Des tests de précision et de rapidité de calcul sont réalisés à l'aide de divers niveaux de raffinement, ainsi qu'une comparaison avec des simulations de référence dans la littérature. Des simulations 3D dans des milieux réels numérisés sont réalisés avec des résultats encourageants. Même s'il n'est pas encore possible d'atteindre des nombres capillaires réalistes, des écoulements dans des domaines cubiques de 1 mm de côté sont simulés, avec un temps de calcul raisonnable. Des simulations 2D de digitations visqueuses avec injection centrale ou latérale sont également présentées, basées sur la loi de Darcy. L'aspect fractal des digitations est étudié aussi bien à l'aide de la dimension fractale que de la variation de l'aire des motifs obtenus par rapport à leur périmètre. Enfin, des balayages à l'aide de polymères suivant des balayages à l'eau dans un processus en deux temps sont simulés à partir d'une modélisation darcéenne. / Understanding multiphase flow in porous media is of tremendous importance for many industrial and environmental applications at various spatial and temporal scales. The present study consequently focuses on modelling multiphase flows by the Volume-of-Fluid method in porous media and shows simulations of Saffman-Taylor fingering motivated by the analysis of waterflooding experiments of extra-heavy oils in quasi-2D square slab geometries of Bentheimer sandstone. The Gerris code which allows efficient parallel computations with octree mesh refinement is used. It is tested for accuracy and computational speed using several levels of refinement and comparing to reference simulations in the literature. Simulations of real rocks are realised in three dimensions with very promising results. Though it is not yet possible to attain realistic capillary numbers, it is possible to simulate flows in domains of physical size up to 1 mm3 in reasonable CPU time. 2D simulations of viscous fingering with both central and lateral injection are also presented in this study, based on Darcy's law. The fractal aspect of this fingering is studied by considering both its fractal dimension and the variation of the area of the resulting pattern with respect to its arclength. Finally, polymer flooding following waterflooding in a two-step process is simulated with Darcy modelling.

The presence of subseismic scale faulting within high porosity sandstone reservoirs and aquifers represents a significant source of uncertainty for activities such as hydrocarbon production and the geologic sequestration of carbon dioxide. The inability to resolve geometrical properties of these smaller scale faults, such as size, connectivity and intensity, using conventional subsurface datasets (i.e. seismic reflection tomography, wireline log and core), leads to ambiguous representations within reservoir models and simulators. In addition, more fundamental questions still remain over the role of cataclastic faults in the trapping and transfer of mobile geofluids within the subsurface, particularly when two or more immiscible fluid phases are present, as is the case during hydrocarbon accumulation, waterflood operations and CO2 injection. By harnessing recent developments in 3D digital surface and volume imaging, this study addresses uncertainties pertaining to the geometrical and petrophysical properties of subseismic scale faults within porous sandstone reservoirs. A novel structural feature extraction and modelling framework is developed, which facilitates the restoration of fault and fracture architecture from digital rock surface models. This framework has been used to derive volumetric fault abundance and connectivity from a normal sense array of cataclastic shear bands developed within high porosity sandstones of the Vale of Eden Basin, UK. These spatially resolved measures of discontinuity abundance provide the basis for the geostatistical extrapolation of fracture/fault intensity into reservoir modelling grids, which promises the introduction of a much higher degree of geological realism into discrete fracture network models than can currently be achieved through purely stochastic methods. Moreover, by establishing spatial correspondences between volumetric faulting intensity and larger scale features of deformation observed at the study area (cataclastic shear zones), the work demonstrates the potential to relate reservoir equivalent measures of fault or fracture abundance obtained from outcrop to seismically resolvable structures within the subsurface, aiding the prediction of reservoir structure from oilfield datasets. In addition to the derivation of continuum scale properties of sub-seismic scale fault networks, a further investigation into the pore-scale controls which govern the transfer of fluids within cataclised sandstones has been conducted. Through X-ray tomographic imaging of experimental core flood (scCO2-brine primary drainage) through a cataclastic shear band bearing sandstone, insights into the influence that variations in fault structure exert over the intra-fault drainage pathway of an invading non-wetting fluid have been gained. Drainage across the fault occurs as a highly non-uniform and non-linear process, which calls into question the practice of using continuum methods to model cross fault flow. This work has also provided an improved understanding of the role that high capillary entry pressure cataclised regions play in modifying pore-fluid displacement processes within the surrounding matrix continuum. In particular, the high sweep efficiency and enhanced non-wetting phase pore-wall contact relating to elevated phase pressure observed during drainage points towards favourable conditions for wettability alteration within cataclised sandstones. This is likely to negatively impact upon the effectiveness of oil recovery and CO2 sequestration operations within equivalent reservoir and aquifer settings.

Orientador: Antonio Carlos Bannwart / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-22T09:34:42Z (GMT). No. of bitstreams: 1 Gaspari_EduardoFerreira_D.pdf: 3211545 bytes, checksum: 80820e359cf9df0a39b228d34978524f (MD5) Previous issue date: 2013 / Resumo: Utilizando um método numérico especializado em problemas hiperbólicos chamado Riemann Solver, é feito um estudo para avaliar o processo de evolução de roll waves em canais fechados. Todo o estudo se baseia em fenômenos de propagação de ondas hiperbólicas do tipo ondas de gravidade. Foi utilizado um modelo unidimensional para representar a dinâmica das roll waves. Inicialmente foi feita uma análise das velocidades características envolvidas, a qual indicou, para o arranjo estratificado, um fraco acoplamento entre os fenômenos de propagação de onda mais relacionados com a compressibilidade dos fluidos e os fenômenos de propagação de ondas mais relacionados com a variação hidrostática na seção transversal do canal. Os resultados desta análise foram utilizados para justificar uma modelagem de roll wave considerando os fluidos como incompressíveis. Testes numéricos também foram feitos, demonstrando que a hipótese de fluidos incompressíveis não leva a uma perda de qualidade na modelagem de ondas de gravidade em canais fechados. Foi observada a fragilidade da hipótese de perfil hidrostático de pressão nos modelos de dois fluidos e é proposta uma modificação para este perfil de pressão considerando os efeitos dinâmicos devido à forma rugosa da interface em um escoamento estratificado instável. São feitas comparações com resultados experimentais de literatura para o filme de líquido em regime laminar e foram feitos experimentos para o filme de líquido em regime turbulento. As comparações entre as simulações e os resultados experimentais demonstrando que o modelo proposto é consistente / Abstract: Using a Riemann Solver numerical method, a study to evaluate the process of evolution of roll waves in closed channels was implemented. The whole study is based on the phenomena of hyperbolic gravity waves propagation. It was used a one-dimensional model to represent the dynamics of roll waves. Initially an analysis of the propagation wave velocities involved on to the stratified flow was done, a weak coupling between the wave propagation phenomena more closely related to fluid compressibility and wave propagation phenomena more closely related to the change in the void fraction, due the gravity waves, was verified. The results of this analysis were used to justify a roll wave modeling considering the fluids as incompressible. Numerical tests were also performed, showing that the hypothesis of incompressible fluids does not lead to a loss of quality in the modeling of gravity waves in closed channels. It was observed a fragility of the hydrostatic pressure profile assumption to modeling unstable stratified flow. It was proposed a modification to this pressure profile, considering the dynamic effects of the roughness interface. Comparisons were made with experimental results from the literature for the liquid film in laminar and experiments made for the film of liquid in turbulent flow. This comparison between simulations and experimental results demonstrate that the proposed model is consistent / Doutorado / Explotação / Doutor em Ciências e Engenharia de Petróleo