| Emulsions constitute an important part of all EOR methods, yet the mathematical modelling of emulsions is still largely empirical. This is due to the lack of physical as well as mathematical descriptions of emulsion flow. This research addresses both aspects of this problem. Experimental work was first carried out to observe the physical mechanisms that occur when a stable emulsion flows in a porous medium. More comprehensive work was done on emulsion rheology and droplet capture for different kinds of emulsion flow in two types of porous media, especially for the system of comparable drop and pore sizes. The results show that the change in emulsion rheology in a porous medium has an overall trend similar to that in a viscometer for the shear rates of interest. Furthermore, the emulsion droplets were found to be captured according to a filtration process. These mechanisms were then represented mathematically and incorporated into a one-dimensional, three-phase (oleic, aqueous, and emulsion) model which accounts for interaction of a surfactant, oil, water, and the rock matrix. The developed model was used to simulate linear core floods of stable emulsions. Simulated and experimental production histories were compared. It was found that a multiphase, non-Newtonian rheological model of an emulsion with interfacial tension-dependent relative permeabilities and time-dependent capture gave the best predictions of the simulations of the experimental core floods. |
