MODELING NONWETTING-PHASE RELATIVE PERMEABILITY ACCOUNTING FOR A DISCONTINUOUS NONWETTING PHASE

A model Par the wetting and nonwetting-phase constitutive relationship s is presented. The nonwetting-phase relative permeability in the mode l is a function of the degree of continuous nonwetting-phase saturatio n. Different formulations of the continuous nonwetting-phase model wer e evaluated by comparison of calculated anti measured air permeabiliti es as well as discontinuous air saturations, A Brooks and Corey-Burdin e type formulation of tile nonwetting phase relative permeability was more accurate than the corresponding van Genuchten-Mualem equation. Es timated discontinuous air saturations were higher for drying than for wetting, thus reflecting hysteresis in the water-retention smd relativ e air permeability functions. The continuous nonwetting-phase model pr ovided a much better prediction of relative air permeabilities than a formulation that neglects tile presence of a discontinuous nonwetting phase. Three emergence point model for the nonwetting-phase relative p ermeability provided a good approximation of the continuous nonwetting -phase model.