| 摘要 |
Viscous petroleum may be recovered from viscous petroleum-containing formations including tar sand deposits by injecting into the formation a gaseous mixture of a carrier gas and a solvent which is liquid at reservoir conditions, such as pentane, hexane, heptane, octane, carbon disulfide, etc., and mixtures thereof. The gaseous mixture is formed by contacting a normally liquid solvent with a carrier gas such as nitrogen and introducing the carrier gas having solvent vaporized therein into the formation. Recovery of petroleum and solvent may be from the same well as is used for injection or from a remotely located well. The carrier gas and/or solvent may be heated prior to injection to increase solvency rate and vapor pressure. In throughput operations, the gaseous solvent mixture may be followed by water, hot water or steam to displace the residual solvent from the formation.
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