Enhanced Oil Recovery Through Oxygen-Enriched In-Situ Combustion: Test Results From the Forest Hill Field in Texas

This paper presents selected results from the first known field test in which oxygen-enriched air was successfully used in an in-situ combustion process for the enhanced recovery of crude oil. The advantages of using pure oxygen instead of air for in-situ combustion are discussed, and a comparison of the relative economics of oxygen and air injection is presented. Safety issues, which mainly concern the increased flammability of metals in oxygen and the oxygen compatibility of oil-field materials, are also discussed. Oxygen-enriched air was injected into a single well in the Forest Hill field in Wood County, TX. Over the course of the 2-year test, the injection rate varied from 200 to 300 Mscf/D (5.7 X 10/sup 3/ to 8.6 X 10/sup 3/ std m/sup 3//d), the injection pressure varied from 1,750 to 2,500 psig (12.1 to 17.2 MPa), and the oxygen concentration in the injected gas ranged from 21 to 90 vol%. Air also was injected into four other wells in the field during the time that oxygen-enriched air injection took place. Oil-production rates are presented for the oxygen and air patterns. Although rigorous comparisons are difficult, there are indications that the use of oxygenenriched air permits production rate advantages.