NITROGEN-DRIVEN CO2 SLUGS REDUCE COSTS.

Use of carbon dioxide slugs rather than pure CO//2 from beginning to end of a tertiary recovery run would permit a stretching of available CO//2 supplies and a reduction in the process cost. Permian Basin fields contain 3 to 5 billion bbl of oil that could conceivably be recovered by tertiary methods. This article describes research work at Texas A&M University, which has involved injection of both carbon dioxide and nitrogen to increase oil recovery. Nitrogen costs about half as much as CO//2 on Mcf basis.