This report summarizes progress in a research effort to quantify the effects of nonuniform flow on displacement performance in CO/sub 2/ floods. Results are reported in three areas: (1) effect of phase behavior in one-dimensional flow; (2) interaction of viscous instability and flow in heterogeneous porous media; and (3) detection and representation of reservoir heterogeneity. 94 refs., 83 figs., 8 tabs.