Dynamic Displacement Measurements of Three-Phase Relative Permeabilities Using Three Immiscible Liquids

Abstract

ABSTRACT The main difficulties to overcome in dynamic displacement relative permeability measurements are capillary end effects and viscous fingering. The latter problem is particularly severe in three-phase systems which include gas. Both of these problems are greatly mitigated in the three liquid system presented here. Water, benzyl alcohol, and decane are the three immiscible liquids which play the role of water, oil, and gas in the conventional three-phase system. The interfacial tensions in this system are about a factor of ten smaller than the comparable tensions for the conventional system, so the capillary end effect is less. Furthermore, viscosity contrasts are diminished, thus lowering the chance of fingering. An extension of the Welge-JBN method to three phases is derived. Each displacement experiment follows a saturation trajectory across the ternary diagram. The method is used to calculate three-phase relative permeabilities along each trajectory. Finally, the data from all trajectories are combined to provide isoperms over a large portion of the ternary diagram. Also included are the two sets of two-phase relative permeabilities needed to apply the interpolative three-phase relative permeability model of Stone. The measured isoperms indicate the model over-predict the relative permeability to oil: oil flows at lower rates than predicted.