Scale-Up Evaluations and Simulations of Mobility Control Foams for Improved Oil Recovery

Abstract

Foam experiments were duplicated in both short (20 cm) and long (2 m) Berea cores to ascertain how to scale-up foam performance. Gas mobility reduction factors were measured at pseudo-steady state as a function of foam quality, and foam velocity in oil free cores and at residual oil saturation, at room temperature and at 7000 kPa system pressure. The experimental results indicate that different water fractional flows, for particular frontal advance rates, are needed to generate strong foams. This effect is much more pronounced in the presence of oil, i.e. higher fractional flow of water was needed to establish significant mobility reduction factors when residual oil was present. Foams generated in the presence of residual oil produced consistently lower mobility reduction factors than foams generated in cores without oil. When no oil was present, the scale-up work experiments show good correspondence between the short and long core lengths. The increased pressures experienced in the upstream section of the long core, during foam flow, do however affect the mobility reduction capacity of the foam and need to be taken into consideration. Injecting foam steadily into a short core at waterflood residual oil lowered the oil saturation significantly and subsequently allowed for strong foams to be established. Repeating this flooding sequence on the long core caused a blocking emulsion (gas/surfactant solution/oil) to be formed in-situ, which completely blocked the long core.