| 摘要 |
The sweep efficiency of a steam flooding process is improved by injecting steam into the lower portion of the formation through an injection well until steam channeling or steam overriding has occurred, after which steam injection is terminated and an oxygen-containing gas such as air, oxygen-enriched air, or oxygen is injected into the formation to oxidize the residual oil in the portion of the formation where steam override or channeling has occurred. This forms an asphaltic material that decreases the permeability of that zone. Thereafter, steam injection is resumed and as a consequence of the oxidized asphaltic material plug, the steam moves into portions of the formation to mobilize viscous oil not swept by the initial injection of steam. During injection of the oxygen-containing gas production of oil may be terminated or continued. Multiple cycles of steam and oxygen-containing gas injection may be applied to a formation to better control sweep efficiency.
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