Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-29Bitstream added on 2014-06-13T20:49:12Z : No. of bitstreams: 1 brandt_is_me_ilha.pdf: 996540 bytes, checksum: 97a4b2aa127103d8e81ea086dc41e70e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Entre tantas tecnologias alternativas desenvolvidas ao longo das últimas décadas, procurando aumentar a eficácia das técnicas convencionais ou propondo novas técnicas não convencionais na transmissão da energia elétrica a longas distâncias e lugares de difícil acesso, o estudo proposto apresenta alguns conceitos e características para sistemas de transmissão constituídos por quatro fases genéricas. O sistema de transmissão tetrafásico tem sido tema de diversos estudos e aplicações em alguns países da Europa e Ásia, apresentando algumas vantagens quando comparado ao sistema de transmissão trifásico convencional. Esse sistema pode ser facilmente integrado ao sistema trifásico por meio de transformadores, amplamente abordado por diversas referências bibliográficas. Nesse estudo foi realizado uma análise comparativa das possíveis sobretensões ocorridas nos domínios da frequência e do tempo entre os sistemas de transmissão trifásico e tetrafásico, avaliando as características elétricas e as respostas transitórias eletromagnética e impulsiva, mostrando novas vantagens sobre esta tecnologia, fornecendo uma avaliação completa sobre o tema / Among the many alternative technologies developed over the past decades, seeking to increase the effectiveness of conventional techniques or proposing new non-conventional techniques in the transmission of electricity over long distances and places of difficult access, the proposed study presents some concepts and features to transmission systems that are constituted of four generic phases. The four-phase transmission system has been subject of numerous studies and applications in some countries in Europe and Asia, presenting some advantages compared to the conventional three-phase transmission system. This system can be easily integrated into the three-phase system through transformers, thoroughly approached by several bibliographical references. In this study was made a comparative analysis of the possible overvoltages that occurred in the areas of frequency and time between the transmission systems of three-phase and four-phase, evaluating the electrical characteristics and the transient answers, electromagnetic and impulsive, showing new advantages over this technology, providing a complete evaluation of this issue

Orientador: Sérgio Kurokawa / Banca: Jean Marcos de Souza Ribeiro / Banca: Edson Guedes da Costa / Resumo: Entre tantas tecnologias alternativas desenvolvidas ao longo das últimas décadas, procurando aumentar a eficácia das técnicas convencionais ou propondo novas técnicas não convencionais na transmissão da energia elétrica a longas distâncias e lugares de difícil acesso, o estudo proposto apresenta alguns conceitos e características para sistemas de transmissão constituídos por quatro fases genéricas. O sistema de transmissão tetrafásico tem sido tema de diversos estudos e aplicações em alguns países da Europa e Ásia, apresentando algumas vantagens quando comparado ao sistema de transmissão trifásico convencional. Esse sistema pode ser facilmente integrado ao sistema trifásico por meio de transformadores, amplamente abordado por diversas referências bibliográficas. Nesse estudo foi realizado uma análise comparativa das possíveis sobretensões ocorridas nos domínios da frequência e do tempo entre os sistemas de transmissão trifásico e tetrafásico, avaliando as características elétricas e as respostas transitórias eletromagnética e impulsiva, mostrando novas vantagens sobre esta tecnologia, fornecendo uma avaliação completa sobre o tema / Abstract: Among the many alternative technologies developed over the past decades, seeking to increase the effectiveness of conventional techniques or proposing new non-conventional techniques in the transmission of electricity over long distances and places of difficult access, the proposed study presents some concepts and features to transmission systems that are constituted of four generic phases. The four-phase transmission system has been subject of numerous studies and applications in some countries in Europe and Asia, presenting some advantages compared to the conventional three-phase transmission system. This system can be easily integrated into the three-phase system through transformers, thoroughly approached by several bibliographical references. In this study was made a comparative analysis of the possible overvoltages that occurred in the areas of frequency and time between the transmission systems of three-phase and four-phase, evaluating the electrical characteristics and the transient answers, electromagnetic and impulsive, showing new advantages over this technology, providing a complete evaluation of this issue / Mestre

The aim of this Master Thesis Frameworks for automatic testing is to compare frameworks of five most popular programming languages of today. The comparison is divided into two parts. The first one deals with comparing by using the test patterns and the second part deals with measuring of exact values while working with tools. The outcome of this thesis are criteria that can be used for comparison of other frameworks for automatic testing other than used in this work.

Thermal and chemical recovery processes are important EOR methods used often by the oil and gas industry to improve recovery of heavy oil and high viscous oil reservoirs. Knowledge of underlying mechanisms and their modeling in numerical simulation are crucial for a comprehensive study as well as for an evaluation of field treatment. EOS-compositional, thermal, and blackoil reservoir simulators can handle gas (or steam)/oil/water equilibrium for a compressible multiphase flow. Also, a few three-phase chemical flooding reservoir simulators that have been recently developed can model the oil/water/microemulsion equilibrium state. However, an accurate phase behavior and fluid flow formulations are absent in the literature for the thermal chemical processes to capture four-phase equilibrium. On the other hand, numerical simulation of such four-phase model with complex phase behavior in the equilibrium condition between coexisting phases (oil/water/microemulsion/gas or steam) is challenging. Inter-phase mass transfer between coexisting phases and adsorption of components on rock should properly be modeled at the different pressure and temperature to conserve volume balance (e.g. vaporization), mass balance (e.g. condensation), and energy balance (e.g. latent heat). Therefore, efforts to study and understand the performance of these EOR processes using numerical simulation treatments are quite necessary and of utmost importance in the petroleum industry. This research focuses on the development of a robust four-phase reservoir simulator with coupled phase behaviors and modeling of different mechanisms pertaining to thermal and chemical recovery methods. Development and implementation of a four-phase thermal-chemical reservoir simulator is quite important in the study as well as the evaluation of an individual or hybrid EOR methods. In this dissertation, a mathematical formulation of multi (pseudo) component, four-phase fluid flow in porous media is developed for mass conservation equation. Subsequently, a new volume balance equation is obtained for pressure of compressible real mixtures. Hence, the pressure equation is derived by extending a black oil model to a pseudo-compositional model for a wide range of components (water, oil, surfactant, polymer, anion, cation, alcohol, and gas). Mass balance equations are then solved for each component in order to compute volumetric concentrations. In this formulation, we consider interphase mass transfer between oil and gas (steam and water) as well as microemulsion and gas (microemulsion and steam). These formulations are derived at reservoir conditions. These new formulations are a set of coupled, nonlinear partial differential equations. The equations are approximated by finite difference methods implemented in a chemical flooding reservoir simulator (UTCHEM), which was a three-phase slightly compressible simulator, using an implicit pressure and an explicit concentration method. In our flow model, a comprehensive phase behavior is required for considering interphase mass transfer and phase tracking. Therefore, a four-phase behavior model is developed for gas (or steam)/ oil/water /microemulsion coexisting at equilibrium. This model represents coupling of the solution gas or steam table methods with Hand’s rule. Hand’s rule is used to capture the equilibrium between surfactant, oil, and water components as a function of salinity and concentrations for oil/water/microemulsion phases. Therefore, interphase mass transfer between gas/oil or steam/water in the presence of the microemulsion phase and the equilibrium between phases are calculated accurately. In this research, the conservation of energy equation is derived from the first law of thermodynamics based on a few assumptions and simplifications for a four-phase fluid flow model. This energy balance equation considers latent heat effect in solving for temperature due to phase change between water and steam. Accordingly, this equation is linearized and then a sequential implicit scheme is used for calculation of temperature. We also implemented the electrical Joule-heating process, where a heavy oil reservoir is heated in-situ by dissipation of electrical energy to reduce the viscosity of oil. In order to model the electrical Joule-heating in the presence of a four-phase fluid flow, Maxwell classical electromagnetism equations are used in this development. The equations are simplified and assumed for low frequency electric field to obtain the conservation of electrical current equation and the Ohm's law. The conservation of electrical current and the Ohm's law are implemented using a finite difference method in a four-phase chemical flooding reservoir simulator (UTCHEM). The Joule heating rate due to dissipation of electrical energy is calculated and added to the energy equation as a source term. Finally, we applied the developed model for solving different case studies. Our simulation results reveal that our models can accurately and successfully model the hybrid thermal chemical processes in comparison to existing models and simulators. / text

Hybrid gas/chemical Enhanced Oil Recovery (EOR) methods are such novel techniques to increase oil production and oil recovery efficiency. Gas flooding using carbon dioxide, nitrogen, flue gas, and enriched natural gas produce more oil from the reservoirs by channeling gas into previously by-passed areas. Surfactant flooding can recover trapped oil by reducing the interfacial tension between oil and water phases. Hybrid gas/chemical EOR methods benefit from using both chemical and gas flooding. In hybrid gas/chemical EOR processes, surfactant solution is injected with gas during low-tension-gas or foam flooding. Polymer solution can also be injected alternatively with gas to improve the gas volumetric sweep efficiency. Most fundamentally, wide applications of hybrid gas/chemical processes are limited due to uncertainties in reservoir characterization and heterogeneity, due to the lack of understanding of the process and consequently lack of a predictive reservoir simulator to mechanistically model the process. Without a reliable simulator, built on mechanisms determined in the laboratory, promising field candidates cannot be identified in advance nor can process performance be optimized. In this research, UTCHEM was modified to model four-phase water, oil, microemulsion, and gas phases to simulate and interpret chemical EOR processes including free and/or solution gas. We coupled the black-oil model for water/oil/gas equilibrium with microemulsion phase behavior model through a new approach. Four-phase fluid properties, relative permeability, and capillary pressure were developed and implemented. The mass conservation equation was solved for total volumetric concentration of each component at standard conditions and pressure equation was derived for both saturated and undersaturated PVT conditions. To model foam flow in porous media, comprehensive research was performed comparing capabilities and limitations of implicit texture (IT) and population-balance (PB) foam models. Dimensionless foam bubble density was defined in IT models to derive explicitly the foam-coalescence-rate function in these models. Results showed that each of the IT models examined was equivalent to the LE formulation of a population-balance model with a lamella-destruction function that increased abruptly in the vicinity of the limiting capillary pressure, as in current population-balance models. Foam models were incorporated in UTCHEM to model low-tension-gas and foam flow processes in laboratory and field scales. The modified UTCEM reservoir simulator was used to history match published low-tension-gas and foam coreflood experiments. The simulations were also extended to model and evaluate hybrid gas/chemical EOR methods in field scales. Simulation results indicated a well-designed low-tension-gas flooding has the potential to recover the trapped oil where foam provides mobility control during surfactant and surfactant-alkaline flooding in reservoirs with very low permeability. / text

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