Banca de QUALIFICAÇÃO: JOSE CICERO ARAUJO DOS SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSE CICERO ARAUJO DOS SANTOS
DATE: 28/07/2022
LOCAL: Pos Graduação Engenharia Civil
TITLE:

Multiscale and Multilevel Methods with Non-Uniform Level Adaptation using segregated and coupled formulations

KEY WORDS:

Multiscale Finite Volume Method, Non-Uniform Levels, Coupled Formulation, Control of Non-Physical Terms in Multiscale Methods

PAGES: 54
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

Currently, geocellular models of oil reservoirs can have sizes of the order of up to 10⁹ control volumes and, in general, the flow and transport simulation in these models presents impediments related to the time and memory needed for simulation. In general, scale transfer techniques such as Upscaling are applied to define less refined models, which can be treated with available resources in a reasonable time. These techniques consist in the homogenization of fine-scale properties, which implies loss of information, particularly in highly heterogeneous media. Recently, Multiscale Finite Volume (MSFV) methods have been developed to minimize these losses. These techniques use algebraic operators (restriction and extension) to transfer information between scales and provide more accurate solutions than those obtained with the a (Upscaling) techniques. In addition, they present reduced computational cost, compared to the simulation performed directly on the fine scale. However, classical multiscale methods can produce highly oscillatory pressure solutions in media with high permeability contrasts. This can generate spurious solutions for the pressure field, leading, for example, to the appearance of the gas phase along the reservoir where the pressure erroneously drops below the bubble point. This can substantially increase the computational cost to solve the problem due to the need to apply iterative procedures to improve the solution. In this context, we proposed two procedures to control the generation of oscillatory solutions. The adaptation of basis functions in a local pre-processing step, called A-AMS (Adaptive - Algebraic Multiscale Solver) and the dynamic adaptation of non-uniform levels, called NU-ADM (Non-Uniform Algebraic Dynamic Multilevel and Multiscale). ) throughout the simulation. Both procedures use algebraic parameters to control oscillations and are based on non-physical terms that appear in the less refined scale transmissibilities matrix (coarse), and which correspond to negative transmissibilities in this matrix. In the discretization of the fine scale transport problem, the first order upwind method was used. We apply the NU-ADM method in two ways, the first using a segregated strategy like IM-PES (Implicit Pressure Explicit Saturation), and the second using a coupled strategy called FIM (Fully Implicit Method). In the IMPES strategy, the flow problem (pressure-velocity) was solved using the NU-ADM method, while the transport problem was solved, after a local step of reconstruction of the velocity field, explicitly in the fine scale. In the FIM strategy, the flow problem and the transport problem were discretized using the NU-ADM method. In both cases, the fine-scale discretization of the problem was performed by applying the finite volume method with flows on the faces approximated by TPFA (Two Point Flux Approximation) for the flow problem and first-order upwind for the problem of transport.

BANKING MEMBERS:
Externo ao Programa - 2332238 - ALESSANDRO ROMARIO ECHEVARRIA ANTUNES
Externo ao Programa - 1288023 - FABIO SANTANA MAGNANI
Presidente - 1218780 - PAULO ROBERTO MACIEL LYRA