Loss of Real Characteristics for Models of Three-Phase Flow in a Porous Medium.

摘要

The paper examines the generalized Buckley-Leverett equations governing three-phase immiscible, incompressible flow in a porous medium, in the absence of gravitational and diffusive/dispersive effects. We consider the effect of the relative permeability models on the characteristic speeds in the one-dimensional flow. Using a simple idea from projective geometry, we show that under reasonable assumptions on the relative permeabilities there must be at least one point in the saturation triangle at which the characteristic speeds are equal. In general, there is a small region in the saturation triangle where the characteristic speeds are complex. This is demonstrated with the numerical results at the end of this reprint. Reprints. (kr)