Numerical Simulation of In-situ Combustion in a Fracture-Porous Medium System

In this work, the numerical simulation of in-situ combustion in a fracture-porous medium system at laboratory scale, was done. The simulations were developed in a commercial reservoir simulator designed to evaluate oil recovery by thermal methods. The simulator involves the mass, momentum (Darcy law) and energy balance equations for multiphase and multicomponent flows. The main aim of this work was to study the effect of the airflow rate and oil saturation on the in-situ combustion behaviour. In the first stage of this study, the in-situ combustion was simulated in a homogeneous porous medium and the simulation was validated using experimental data. In a second stage, such simulation was modified in order to incorporate fractures in the porous medium. It was found that the oxygen diffusion from fractures to porous medium controls the in-situ combustion in fractured systems. Moreover, it is necessary to restrict the injected air flow rate due to the breakthrough phenomenon and because the oil recovery is not substantially increased for larger flow rates.