| 摘要 |
A process for recovering hydrocarbons from an in situ formation. The process includes the steps of injecting steam though an injection well into an underground extraction chamber having a hydrocarbon extraction interface, warming the hydrocarbons at the extraction interface to cause the hydrocarbons to flow downwardly by gravity drainage and to release dissolved hydrocarbon gases and moving the hydrocarbon gases from the extraction interface to improve heat transfer from said steam to said interface. The last step is to recover liquids such as hydrocarbons and water through a production well. The invention provides adding a buoyancy modifying agent to the steam to cause the hydrocarbon gases to accumulate in the well in a preferred location. The preferred location is at the top of the chamber where the gases protect the top of the chamber from being extracted to the point of breakthrough.
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