This report describes progress in a comprehensive research program on fundamental aspects of carbon dioxide flooding. The research is designed to permit more accurate prediction of the outcome of CO/sub 2/ floods and to produce information needed to improve process performance. The research effort is divided into three parts: (1) measurements and analysis of phase behavior and fluid properties of CO/sub 2/-crude oil mixtures, (2) displacement experiments to study mixing of CO/sub 2/ and oil in reservoir rocks, and (3) development of mobility control methods for CO/sub 2/ floods. In the first area, a viscometer based on an oscillating quartz crystal is being developed for installation in a continuous flow apparatus to study compositions and densities of phases in equilibrium. Simultaneous measurements of phase compositions, densities and viscosities will allow testing of the accuracy of viscosity correlations for CO/sub 2/-crude oil mixtures and quantitative assessments of the driving force for viscous instability. Component partitioning data obtained in the same apparatus for mixtures of CO/sub 2/ with well-characterized hydrocarbon mixtures and crude oils are being used to develop an improved correlation for minimum miscibility pressure which accounts for differences in oil and injected fluid composition. In the second area, miscible displacement experiments with fluids of matched densities and viscosities in reservoir cores are used to measure within the pore space on mixing of oil and CO/sub 2/. The third area, concerned with mobility control, is itself divided into two parts. The displacement behavior of CO/sub 2/ foams (dispersions of dense CO/sub 2/ in water) and the synthesis of polymeric materials soluble directly in CO/sub 2/ are being explored as means for thickening CO/sub 2/ to improve reservoir sweep efficiency. Improved experimental techniques for rapid evaluation of mobility control additives are also being developed. 26 references, 24 figures, 8 tables.