Métodos de elementos finitos híbridos aplicados a escoamentos miscíveis em meios porosos heterogêneos

• Autor(a) principal: Rodriguez Nunez, Yoisell
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do LNCC
• Texto Completo: https://tede.lncc.br/handle/tede/203
• topic: Método dos elementos finitos; Escoamento em meios porosos; Simulação numérica de reservatórios; Finite element method; Flow in porous media; Numerical simulation of reservoirs; CIÊNCIAS EXATAS E DA TERRA::MATEMÁTICA::MATEMÁTICA APLICADA::ANÁLISE NUMÉRICA

The numerical simulation of incompressible miscible displacements in porous media has obtained significant progress in the last decades being an useful tool in several areas of interest. In particular, in the oil industry the use of numerical simulation allows to obtain qualitative and quantitative data that may provide a better understanding of the physical and chemical processes that occur, for example, in petroleum reservoirs. The system of partial differential equations governing miscible displacement consists of an elliptic subsystem stemming from conservation of mass, Darcy’s law and a transport equation expressing the conservation of the injected fluid (concentration). Although the concentration is the variable of greatest interest, the calculation of the velocity field requires special attention since it is responsible for transporting the mixture and, therefore, its production. Besides, it has a strong influence on the stability and accuracy of the transport equation when we are dealing with adverse mobility ratios, that is, the solvent is less viscous than the resident oil. These facts motivate us to seek for an efficient and accurate numerical method for the calculation of the velocity field (Darcy’s system) in order to reduce inaccuracies in calculating the concentration. In this thesis we propose a Stabilized Dual Hybrid Mixed (SDHM) method to approximate the Darcy subsystem. It is shown that this methodology is stable with usual finite element approximations, such as Lagrangian polynomial approximations, where all variables can be interpolated by equal-order functions. Furthermore, the SDHM method is conservative with appropriate parameters choices, and more accurate and robust when compared to the Galerkin method and postprocessing techniques. In order to verify the efficiency of the SDHM method, computer simulations are presented for the recovery processes of reservoirs for patterns flow problems in homogeneous and heterogeneous porous media, such as tracer injection and continuous injection. The SDHM method is employed together with a combination of the SUPG method in the spatial discretization, and an implicit finite difference scheme in the time for the concentration approximation of the transport equation. To verify the proposed methodology a semi-analytical approach is also employed which combines the SDHM approximation for velocity field with the concentration calculated analytically by the streamline method. The results obtained with the proposed formulation showed to be efficient, accurate and free of spurious oscillations even for highly heterogeneous scenarios, where we consider random permeability and adverse mobility ratios.