Exploring a mechanistic approach for characterizing transient and steady state foam flow in porous media

Foam model parameters are often derived from laboratory coreflood data at a steady state foam flow regime, which makes them unsuitable for simulating transient foam flow. Since significant foam trapping occurs during transient flow regime, foam trapping process is inadequately covered in most models. In this study, a core-flooding procedure is presented that allows for estimation of multiple foam model parameters in both transient and steady state foam regimes. Surfactant alternating gas (SAG) method of foam injection was modified such that at the end of each SAG cycle, mobile and trapped foams saturations were measured using a coreflood apparatus equipped with in-situ saturation measuring tool. Multiple SAG cycles were then conducted to generate a dataset as a function of water saturation and capillary pressure. The dataset includes trapped and mobile foam saturation, gas mobility reduction factor, flow rate of mobile foam, limiting capillary pressure, critical water saturation below which foam ruptures, and minimum pressure drop to propagate foam across a porous media, all in a single coreflood experiment. This dataset allowed both capillary pressure and initial-residual gas saturation curves to be generated for foam flow in a representative rock sample. Such curves, which are generated for the first time for foam transport, allow the physics of foam flow in the transient and steady state flow to be captured. The behavior of the curves is also dependent on the properties of the foam and porous medium. The possible application of such curves for modelling and planning CO2 sequestration is also discussed. The method is promising for upscaling to field scale in the sense that the test may be conducted in an actual well in the field. More insight on foam transport in porous media as revealed by this method are discussed in details.