Good progress has been made on all aspects of the carbon dioxide (CO/sub 2/) research program at the New Mexico Petroleum Recovery Research Center. Construction of high pressure experimental equipment for measurements of CO/sub 2/ displacement efficiency in cores and slim tubes has been completed. A sophisticated apparatus for measurements of phase behavior and fluid properties of mixtures of CO/sub 2/ and crude oils has been designed and built. The experimental setup permits a variety of multiple contact phase behavior experiments which explore mixture compositions which realistically model displacement processes at temperatures and pressures of interest. Gas chromatography techniques previously used to characterize crude oils have been extended to allow analyses of mixtures containing CO/sub 2/ and hydrocarbons ranging from methane to molecules as heavy as tetracontane (C/sub 40/). A series of displacements with alcohol-oil-water mixtures, which are analogue systems with useful similarities to CO/sub 2/-hydrocarbon systems have been completed. A one-dimensional CO/sub 2/ flooding simulator has been developed which gives excellent agreement between simulated and experimental results for the analogue alcohol-oil-water displacements. Finally, a qualitative analysis is given for the complex phase behavior observed for mixtures of CO/sub 2/ and crude oils at temperatures below 50/sup 0/C and the effects of phase behavior on expected displacement efficiency are calculated. The results indicate that relatively small changes in pressure can be expected to have a strong influence on the efficiency of CO/sub 2/ displacements of crude oils.