The ultimate objective of this project is to improve the efficiency of carbon dioxide flooding as an enhanced oil recovery process. This aim is to be pursued by the development of techniques and/or additives for mobility control. Suggested methods will control those non-uniformities in frontal displacement which are due to or aggravated by the unfavorable mobility ratios between the carbon dioxide containing displacing fluid and the displaced oil and water. Because many other researchers and engineers have worked on these problems, Phase 1 of this project has been to collect, study and assess information about their former and continuing efforts. Much of these investigators'work has been reported in the petroleum engineering and other technical literature. Relevant articles referred to have ranged from fundamental studies of the mechanisms of. fluid displacement and frontal stability in porous media to accounts of field operations in ongoing CO2 flooding projects. The Phase 1 activity of this project has contributed to the planning of the laboratory work that is to be accomplished in its continuing phases, making possible more detailed decisions concerning the nature of the projected experimental tasks. To this date, most Phase 2 activity has consisted of the planning and design of laboratory work. This effort has been directed to a dual purpose. The first of these is to prepare a series of experiments which will supply information on mobility control in CO2 floods, that can be used to improve their efficiency. Secondly, however, these tests must also be sufficiently convincing to the engineering staffs of operating oil companies to have an impact on the practice of future Enhanced Oil Recovery activity in the field. The first of these purposes is addressed by the plans documented below. The second purpose will be kept in view during these planning and preliminary reporting stages, and must become the primary objective of the later reporting phases of the project. In case the outcome of the tests carried out in Phase 2 are sufficiently promising, a Phase 3 follow-up on the design of mobility-controlled CO 2 . floods would be warranted. Such work would entail the presentation of specific operating and reservoir engineering design rules, based both on the laboratory measurements and comparisons performed in Phase 2, and on further analysis along lines which have been suggested in the literature.