ABSTRACT
In this paper we examine factors influencing the characteristics of slightly sub-miscible gas displacement of oil in a heterogeneous system. 2D fine grid compositional solutions are obtained using a fast simulator, MORE, on a Cray YMP computer for a stochastically generated heterogeneity distribution. It is shown that only four pseudo-components are needed to represent the phase behavior adequately and that although fairly low interfacial tensions are obtained, there is not a discernible need to modify the immiscible relative permeabilities. Comparisons are made with heterogeneous results based on the simpler first contact miscible assumptions often used in two-component high resolution simulations of viscous fingering. The fully compositional flow is less unstable than its miscible counterpart, but it is found that the latter can be made to reproduce a compositional solution through reducing the mobility ratio from M = 20 to M = 5. A method for determining this effective mobility ratio is described. Cases with gravity give moderate agreement using M = 5, provided an ad hoc adjustment is also made to the gravity number.
