Improved Mobility Reduction of Non Dense Gas Foam in Presence of High Residual Oil Saturation

Enhanced Oil Recovery by injection of non dense gases attracts a renewed interest in various oil producing regions. However, most gas injection operations suffer from early gas breakthrough and oil production can be limited by gas recycling capabilities. In that context, use of gas foam appears as a flexible and inexpensive method for improving gas conformance and reducing gas-oil ratio (GOR) during oil production. Foam effect on GOR is known to be temporary, which calls for repeated treatment of offending zones during the lifetime of an oil well. The reasons for this limited effect are linked to many factors including surfactant adsorption during foam propagation, foam dry-out and impact of oil. Effect of the latter can be dramatic and result in inefficient treatment. Here, using a new oil-resistant formulation, we present petrophysics results for non-dense gas foams formed by co-injection in presence of various oil saturations. We obtain high mobility reduction factors at oil saturations up to 35%, significantly above results from the literature. We compare this new formulation to a benchmark formulation both in bulk tests and in porous media. Based on these data, we try to find correlations between bulk and porous media foaming behaviours.