Coinjection of steam and nitrogen, carbon dioxide, or air at low pressures (400 psi) (2760 kPa) into Utah tar sands was studied. Slight enhancement of steam drive was observed with all three (if no combustion occurred with the air) and significant improvement occurred when the tar spontaneously ignited during air injection. Little difference in recovery between simultaneous and alternating modes of injection was observed.

You can access this article if you purchase or spend a download.