How the U. S. can produce more oil

Production by conventional methods--which, on average, has recovered only about one third of the oil in U.S. reservoirs--is declining to a low rate. Then enhanced oil recovery processes must be applied if additional oil is to be produced. Of various enhanced oil recovery processes studied by the petroleum industry, three types have shown promise--thermal methods, in which steam is injected into reservoirs; chemical flooding, in which polymers mixed with water are used; and carbon dioxide miscible flooding, in which carbon dioxide is used together with water. Only thermal methods are making a significant contribution to production now, and experimental work is still being done. Chemical and carbon dioxide miscible processes are still largely experimental. Reservoir characteristics--geology, fluid properties, rock properties--determine which process can best be applied to a given reservoir. As a rough guide, chemical flooding appears best for low viscosity oils, which flow more easily than other oils, and thermal methods work best for high viscosity oils. Price and environmental barriers are discussed. (MCW)