Analytical Modeling of Emulsion Flow at the Edge of Steam Chamber During SAGD Process

Different models have been proposed to describe two- and three-phase flow at the edge of a steam chamber developed during a SAGD process. However, two-dimensional scaled SAGD experiments and recent micro model visualizations demonstrate that steam-condensate is primarily in the form of microbubbles dispersed in the oil phase (water-in-oil emulsion). Therefore, the challenging question is: Can multiphase Darcy equation be used to describe the transport of water as a discontinuous phase? Furthermore, the physical impact of water as a continuous phase or as microbubbles on oil flow can be different. Water microbubbles increase the apparent oil viscosity, while a continuous water phase decreases the oil relative permeability. Investigating the impact of these two phenomena on oil mobility at the steam chamber edge and on overall oil production rate during a SAGD process requires development of relevant mathematical models that is the focus of this thesis. In this thesis, we develop an analytical model for lateral expansion of steam chamber that accounts for formation and transport of water-in-oil emulsion both in single and two phase flow. It is assumed that emulsion is generated due to condensation of steam, which is penetrated into the heated bitumen. The emulsion concentration decreases from a maximum value at the chamber interface to zero far from the interface. The oil viscosity is affected by both temperature gradient due to heat conduction and microbubble concentration gradient due to emulsification. We conduct a sensitivity analysis by using the measured data from scaled SAGD experiments. The sensitivity analysis shows that by increasing the value of m (temperature viscosity parameter), the effect of emulsification on oil flow rate decreases. It also shows that the effect of temperature on oil mobility is much stronger than that of emulsion. We also compare the model predictions with field production data from several SAGD operations. Butler’s model overestimates oil production rate due to single-phase assumption, while the proposed model presents more accurate oil flow rate supporting the fact that emulsification effect should be included in the SAGD analysis.