Orientadores: Denis Jose Schiozer, Martin Julian Blunt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-13T09:49:42Z (GMT). No. of bitstreams: 1 Beraldo_ValcirTadeu_D.pdf: 9605890 bytes, checksum: 4a102164c597164e50bd6a9d11c41c7c (MD5) Previous issue date: 2008 / Resumo: A variação espacial da composição inicial do óleo é um fenômeno que aparece em alguns reservatórios e que deve ser considerada nas simulações. O objetivo desta tese é implementar uma formulação que considera essa variação em simuladores por linhas de corrente. Esse tipo de simulação pode, em muitas situações, ser mais rápido que os simuladores por diferenças finitas. Uma das limitações importantes da simulação por linhas de corrente é o tratamento de compressibilidades de rocha e fluido. Por isso, foi também implementada uma formulação que considera compressibilidade com variação da qualidade do óleo. Inicialmente um simulador bifásico por linhas de corrente para sistema incompressível foi alterado para trabalhar com dois componentes na fase óleo, permitindo assim considerar a variação das propriedades desta fase. Em seguida, o simulador foi modificado, incorporando a formulação para sistemas compressíveis com variação de qualidade de óleo. Foi necessário criar, nesta fase, alguns procedimentos para tornar o programa estável nas diversas situações testadas. As implementações foram validadas através de comparações com simuladores comerciais por diferenças finitas em uma série de modelos que representam situações normalmente encontradas. Os testes mostraram que, em ambas formulações, foi possível a reprodução satisfatória dos resultados, utilizando os simuladores por linha de corrente. Na formulação para sistema compressível, foi feita uma análise de sensibilidade do tempo de execução e da qualidade da solução a alguns parâmetros de controle numérico que foram definidos no código computacional. Em modelos de sistemas compressíveis com variação nas propriedades de óleo, heterogêneos e refinados, os resultados mostraram que a combinação adequada de parâmetros permite a simulação por linhas de corrente em tempos sensivelmente menores que a simulação por diferenças finitas, mantendo-se a qualidade dos resultados. / Abstract: Spatial oil composition variation can be found in some reservoirs and it has to be considered in simulations. The goal of this thesis is to implement a formulation that considers this variation in streamline simulators, which can be, in many situations, faster than finite difference simulators. One of the important restraints of streamline simulations is the treatment of rock and fluid compressibility. Therefore, a formulation that considers oil quality variation with compressibility has also been implemented. At first, a two phase streamline simulator for incompressible system was modified to work with two components in the oleic phase, allowing consideration of property variations on this phase. Then, the simulator was modified in order to incorporate the formulation for compressible system with oil quality variation. The implementations have been validated by comparisons with a finite difference commercial simulator in several compressible reservoir models, showing good results. Using the formulation for compressible systems, it has been done a sensitivity analysis of execution time and quality of solution with the variation of some numerical parameters that have been defined in the computational code. In models of heterogeneous and very refined reservoirs with oil property variation, the results showed that the appropriate combination of numerical parameters allows running the streamline simulation much faster than finite difference simulation, while keeping the quality of the results. / Doutorado / Reservatórios e Gestão / Doutor em Ciências e Engenharia de Petróleo

The commercial polycrystalline superalloy RR1000 developed for turbine disc applications contains a large number of alloying elements. This complex alloy chemistry is required in order to produce appropriate microstructures and the required mechanical properties, such that the most important strengthener γʹ displays complex alloy chemistry. The broad aim of this project is to develop an approach to measuring the composition of γʹ precipitates at a broad range of length scales from nanometres to hundreds of nanometres, and subsequently develop a better understanding of the role of thermodynamics and diffusion kinetics on γʹ phase separation and precipitate growth. A solution of the absorption-corrected EDX spectroscopy to spherical particles was developed in our work, therefore enabling the quantitative analysis of precipitates' composition using an absorption-corrected Cliff-Lorimer approach. By performing this quantification, size-dependent precipitate compositional variations were obtained. Examination of this quantitative approach was compared to thermodynamic calculations of primary γ' precipitates possessing equilibrium compositions. Given the development of semi-quantitative compositional measurements for spherical γʹ precipitates and that cooling is one of the most common and critical regimes in physical metallurgy of Ni-based superalloys, this approach was then applied to study the local compositional variations that are induced in γ' precipitates when the alloy RR1000 undergoes different cooling rates. These measured compositions have been compared to detailed thermodynamic calculations and provide new experimental evidence of the importance of the dominant role of aluminium antisite diffusion in determining the low-temperature growth kinetics of fine-scale γ' precipitates. We have applied a similar analysis approach to study the compositional variations of γʹ cores within the class of secondary precipitates upon cyclic coarsening and reversal coarsening. It was shown that supersaturated Co in secondary γʹ exhibits an overall trend towards the equilibrium but Co content can significantly increase as γʹ coarsens. It was demonstrated that the limited elemental diffusivity in γ and γʹ compared to the observed coarsening rate in the coarsening regime results in the long-lasting Co supersaturation in γʹ and builds up elemental enhancements or depletions. These inhomogeneous elemental distributions produce compressive elastic constraints on large-scale secondary γʹ, therefore inducing morphological instability of these γʹ and causing the reversal coarsening. These results enable us to better understand the role that both thermodynamics and limited diffusion kinetics plays in controlling the complex microstructures of γ' precipitates.