Uniqueness conditions in a hyperbolic model for oil recovery by steamdrive

In this paper we study a one-dimensional model for oil recovery by steamdri ve. This model consists of two parts: a (global) interface model and a (loc al) steam condensation/capillary diffusion model. In the interface model a steam condensation front (SCF) is present as an internal boundary between t he hot steam zone (containing water, oil and steam) and the cold liquid zon e (containing only water and oil). Disregarding capillary pressure away fro m the SCF, a 2 x 2 hyperbolic system arises for the water and steam saturat ion. This system cannot be solved uniquely without additional conditions at the SCF. To find such conditions we blow up the SCF and consider a parabol ic transition model, including capillary diffusion. We study in detail the existence conditions for traveling wave solutions. These conditions provide the missing matching conditions at the SCF in the hyperbolic limit. We sho w that different transition models yield different matching conditions, and thus different solutions of the interface model. We also give a relatively straightforward approximation and investigate its validity for certain ran ges of model parameters.