Oxygen transport under combustion conditions in a fracture-porous medium system

Abstract

In this work the oxygen transport was modeled numerically, at pore scale, in a matrix-fracture system saturated by nitrogen. This system appears when the in-situ combustion (ISC) method is applied for oil recovery in fractured reservoirs. The main aim was to study the effect of oxygen flow rate and the fracture width on the oxygen transport from the fracture to the porous matrix due to this controls the combustion front propagation. The porous matrix microstructure was modeled as a medium composed by circular particles in a periodic arrangement. In order to simulate the combustion reaction that occurs in an in-situ combustion process, the coke-oxygen reaction was taken into account on the particles surface. The gas, coke and oxygen mass balances as well as the gas momentum balance were resolved using a software that involves the finite element technique. The oxygen distribution was studied in the matrix-fracture system as a function of: (1) the oxygen flow rate, and (2) the fracture width. It was found that increasing such parameters stimulate the coke consumption. Moreover, they increase the oxygen transport from the fracture to the matrix.