Fully implicit compositional thermal simulator using rigorous multiphase calculations

Simulation of the in-situ combustion process is one of the most complex simulations amongst other reservoir flow simulations. Accurate simulation of the process is critical to obtain a successful implementation of the in-situ combustion process. Several factors impact performance of the simulation of this process. First are all the numerical models used for different sub-processes, such as reactions, fluid phase behavior, heat loss to surrounding formations and fluid physical properties. In the previous numerical models of the in-situ combustion process, very simplified models were used for the phase behavior of the fluid. Recent studies show that the fluid phase behavior model has a great effect on the results of the simulation. In this work, a novel simulator is presented, which uses a rigorous phase equilibrium model for fluid phase behavior calculations. The numerical model is developed in such a way that different models for the phenomena mentioned above can be replaced easily. The other affecting parameter is the solution scheme of the simulator. Previous studies indicated that the more implicit the solution scheme, the better the performance of the simulator. The presented simulator uses a full implicit solution scheme to solve the equations. The applicability of this method is examined through two synthetic reservoirs.