A method for quantitative evaluation of emulsion stability using Critical
Electric Field (CEF) determinations over a range of conditions, such as a
range of temperatures, demulsifier compositions, or demulsifier
concentrations. The method includes determining the CEF for a series of
emulsions that differ substantially only in their internal phase volume
ratio. A plot of CEF values as a function of the inverse of the internal
phase volume ratio is characterized by a linear slope. Using the slope, a
theoretical CEF value can be determined by extrapolating to where the
inverse of the internal phase volume ratio is about one. The slope for a
given emulsion series is associated with the relative energy barrier to
flocculation and the theoretical critical electric field for a given
emulsion series is associated with the relative energy barrier to
coalescence. Comparative studies are performed using this method.