(246b) New Research Simulation Framework for Flow Modeling of Complex Physical System

A novel simulation framework for simulating flow in porous media for mixtures having an arbitrary number of phases will be presented. In this framework we manage to keep a unified computational structure for different compositional formulations and complex physical models. That includes generic phase appearance/disappearance treatment, efficient linear solver typical for mixed types of unknowns, finite volume discretization using flexible spatial stencil etc. The behavior of components in any phase is computed using mixed phase equilibrium assumptions. This type of simulation is very important for modeling of natural and industrial processes, such as development of natural hydrocarbon resources, including gas-hydrates, CO2 injection into hydrocarbon reservoirs and saline aquifers, and for modeling of thermal processes. We use a Fully Implicit (FI) time approximation with general extension to the Adaptive Implicit Method (AIM) using flexible algebraic reduction. The framework is built on top of an Automatic Differentiation with Expression Templates Library (ADETL) which generates the corresponding derivatives for any nonlinear relation and helps to construct Jacobian matrix for the nonlinear solver. Phase behavior for the new framework is calculated using standard multiphase flash with initial conditions (stability analysis) based on Compositional Space Parameterization (CSP), which helps to improve both efficiency and robustness of the standard Equation of State (EoS) computations. Within the framework, the nonlinear behavior of different variable sets, including both natural and mass-type variables is investigated. The general extension of two-phase variable substitution is used to handle the phase appearance and disappearance for systems with arbitrary numbers of phases. Examples will be presented including different types of CO2 injection in a hydrocarbon reservoir, such as miscible and immiscible two-phase CO2 injection, thermal injection of CO2+steam (three-phase), and cold CO2 injection (three phase with the second liquid CO2-rich phase).