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Investigation of Two-phase Microchannel Flow and Phase Equilibria in Micro Cells for Applications to Enhanced Oil RecoveryForoughi, Hooman 21 August 2012 (has links)
The viscous oil-water hydrodynamics in a microchannel and phase equilibria of heavy oil and carbon dioxide gas have been investigated in connection with the enhanced recovery of heavy oil from petroleum reservoirs.
The oil-water flow was studied in a circular microchannel made of fused silica with an I.D. of 250 µm. The viscosity of the silicone oil (863 mPa.sec) was close to that of the gas-saturated heavy oil in reservoirs. The channel was always initially filled with the oil. Two different sets of experiments were conducted: continuous oil-water flow and immiscible displacement of oil by water. For the case of continuous water and oil injection, different types of liquid-liquid flow patterns were identified and a flow pattern map was developed based on Reynolds, Capillary and Weber numbers. Also, a simple correlation for pressure drop of the two phase system was developed.
In the immiscible displacement experiments, the water initially formed a core-annular flow pattern, i.e. a water core surrounded by a viscous oil film. The initially symmetric flow became asymmetric with time as the water core shifted off centre and also the waves at the oil-water interface became asymmetric. A linear stability analysis for core-annular flow was also performed. A characteristic equation which predicts the growth rate of perturbations as a function of the core radius, Reynolds number, and viscosity and density ratios of the two phases was developed.
Also, two micro cells for gas solubility measurements in oils were designed and constructed. The blind cell had an internal volume of less than 2 ml and the micro glass cell had a volume less than 100 µl. By minimizing the cell volume, measurements could be made more quickly. The CO2 solubility was determined in bitumen and ashphaltene-free bitumen samples to show that ashphaltene has a negligible effect on CO2 solubility.
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Investigation of Two-phase Microchannel Flow and Phase Equilibria in Micro Cells for Applications to Enhanced Oil RecoveryForoughi, Hooman 21 August 2012 (has links)
The viscous oil-water hydrodynamics in a microchannel and phase equilibria of heavy oil and carbon dioxide gas have been investigated in connection with the enhanced recovery of heavy oil from petroleum reservoirs.
The oil-water flow was studied in a circular microchannel made of fused silica with an I.D. of 250 µm. The viscosity of the silicone oil (863 mPa.sec) was close to that of the gas-saturated heavy oil in reservoirs. The channel was always initially filled with the oil. Two different sets of experiments were conducted: continuous oil-water flow and immiscible displacement of oil by water. For the case of continuous water and oil injection, different types of liquid-liquid flow patterns were identified and a flow pattern map was developed based on Reynolds, Capillary and Weber numbers. Also, a simple correlation for pressure drop of the two phase system was developed.
In the immiscible displacement experiments, the water initially formed a core-annular flow pattern, i.e. a water core surrounded by a viscous oil film. The initially symmetric flow became asymmetric with time as the water core shifted off centre and also the waves at the oil-water interface became asymmetric. A linear stability analysis for core-annular flow was also performed. A characteristic equation which predicts the growth rate of perturbations as a function of the core radius, Reynolds number, and viscosity and density ratios of the two phases was developed.
Also, two micro cells for gas solubility measurements in oils were designed and constructed. The blind cell had an internal volume of less than 2 ml and the micro glass cell had a volume less than 100 µl. By minimizing the cell volume, measurements could be made more quickly. The CO2 solubility was determined in bitumen and ashphaltene-free bitumen samples to show that ashphaltene has a negligible effect on CO2 solubility.
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[en] RADIO RESEARCH MANAGEMENT TECHNIQUES FOR HIERARCHICAL CELL SYSTEMS / [pt] ESTUDO DE TÉCNICAS DE GERÊNCIA DE RECURSOS DE RÁDIO PARA SISTEMAS CELULARES HIERARQUIZADOSTIAGO TRAVASSOS VIEIRA VINHOZA 30 January 2004 (has links)
[pt] Sistemas de celulares de múltiplas camadas
(hierarquizados) são úteis para acomodar densidade alta de
tráfego mantendo a qualidade de serviço. Estes sistemas
procuram agregar as vantagens dos sistemas micro e
macrocelulares que são respectivamente: o aumento da
capacidade do sistema e a carga de sinalização da rede.
Neste trabalho são analisados aspectos de projeto e
desempenho de estruturas hierarquizadas como:
compartilhamento do espectro entre as camadas de micro-
células e macro-células bem como o desempenho de diferentes
estratégias de handoff entre essas camadas. Um outro
objetivo do trabalho foi o desenvolvimento de uma
ferramenta simples de simulação capaz de testar as diversas
estratégias de handoff e o desempenho do sistema para
diferentes soluções para a distribuição dos recursos de
rádio entre camadas. / [en] Multilayer cell systems are useful to accommodate high
traffic densities while still satisfying the QoS
requirements. These systems combine the advantages of
microcellular and macrocellular systems which are: the
increase of system capacity and the reduction of the number
of handoffs, hence decreasing the signaling load. This work
address design aspects such as spectrum sharing between the
macrocell and microcell layers and the performance of
different handoff strategies considering both layers.
Another goal of this work was the development of a simple,
but realistic, simulation tool which will allow obtaining
the radio resources management results here presented.
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[en] DEVELOPMENT, VALIDATION AND APPLICATION OF A FLEXIBLE TOOL FOR THE SIMULATION OF CELLULAR MOBILE SYSTEMS / [pt] DESENVOLVIMENTO, VALIDAÇÃO E APLICAÇÃO DE UMA FERRAMENTA FLEXÍVEL PARA A SIMULAÇÃO DE SISTEMAS MÓVEIS CELULARESILDELANO FERREIRA E SILVA 12 June 2002 (has links)
[pt] Este trabalho descreve uma ferramenta de simulação
esenvolvida para analisar o gerenciamento dos recursos de
rádio e parâmetros de QoS (Quality of Service) dos sistemas
móveis celulares. Pela natureza de um sistema real de
telefonia celular, é extremamente difícil que as variáveis
de saída de um simulador sejam derivadas de um conjunto
real de funções. Isso se deve à grande quantidade de
parâmetros que devem ser considerados no comportamento da
mobilidade, nas condições de tráfego, nas características
geográficas e morfológicas da região, na modelagem complexa
do canal rádio propagação móvel, entre outras. Visando a
desenvolver uma ferramenta de simulação próxima da
realidade, adotam-se modelos de propagação, de mobilidade e
de tráfego que sejam satisfatoriamente adequados ao caso
real. A contribuição deste trabalho é oferecer uma
ferramenta de simulação flexível, aqui adequada ao sistema
norte-americano TDMA (IS-136), que possibilite ao usuário,
além de analisar a capacidade do sistema,também avaliar
novos algoritmos de controle de potência, novas estratégias
de handoff, novos esquemas de alocação de canal e modelos
de propagação. A ferramenta será validada seguindo o
processo de um projeto real de telefonia celular e ao
final, será aplicada a um sistema celular com sobreposição
macro-células/micro-células, analisando-se algumas
estratégias de handoff dedicadas a esses sistemas. / [en] This work describes a simulation tool, which was developed
to analyze the radio resources and QoS (Quality of Service)
parameters in mobile systems. Because of the complex
characteristics of an actual cellular network, it is
extremely difficult having the outputs of the simulator
being derived from a real set of functions, due to the large
amount of parameters that have to be considered such as the
mobility behavior, the traffic conditions, the geographic
and morphologic characteristics of the region, the complex
modeling of mobile radio propagation channel, and so on. In
order to develop a simulation tool as near as possible to
the reality, models that are satisfactorily adequate to
the real case have been considered. So, propagation,
mobility and traffic models were adapted from the IS-136
American system. The contribution of this work is to offer
a flexible simulation tool that allows the user, in
addition to analyzing the capacity of the system, to
evaluate new algorithms of power control, handoff
strategies, channel allocation schemes and propagation
models. The tool will be validated following the process of
a real project of cellular telephony and at the end, it will
be applied to a cellular system with overlapped macro-
cells/micro-cells, and some handoff strategies dedicated to
those systems will be analyzed.
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