Practical considerations in steamflooding

During the last few years, continuous or intermittent injection of steam into a reservoir has established itself as a technically feasible and often profitable oil recovery method. On the basis of very limited data it would seem that the overall ratio of barrels of oil recovered to the barrels of water injected as steam may range from 0.3 to 0.6. Among the unknowns involved in a steam-flood, is the value of the steam-flood residual oil saturation. This must be known, or estimated by other means. Another important quantity which is not known is sweep efficiency. Gravity segregation may lead to the passage of steam through the upper portion of the reservoir. This may lead to poor conformance in a high permeability, isotropic formation. Presence of high permeability streaks can lead to the failure of the project, since steam break-through would occur very early in the life of the project, and thereafter most of the injected heat energy would go unused. (18 refs.)