Abstract The recovery of heavy crude oils and tars from subterranean oil bearing formations is enhanced by the injection of pressurized and heated hydrocarbon vapor into a single well drilled into the formation. Condensation of the hydrocarbon vapor heats the heavy oil and tars entrapped in the formation and dilutes the oil so as to decrease its viscosity and enhance its flow into a lower portion of the well. The oil and solvent collected are removed to the surface by pumping. The preferred hydrocarbon vapor is a low boiling fraction derived by distillation of the oil recovered from the formation, however, some stable externally-produced aromatic hydrocarbon vapors of high solvent power such as benzene or toluene or mixtures thereof may also be used and reclaimed from the oil by distillation.
A method for recovery of heavy hydrocarbon material such as heavy crude oils and tars from subterranean oil-bearing formation, comprising the steps of: (a) providing a well hole through overburden into the oil bearing formation and installing casing in at least the overburden portion of the hole; (b) providing a pressurized heated hydrocarbon solvent vapor and injecting it into the well and into said formation to condense and dissolve and reduce the viscosity of the heavy oil therein and facilitate its flow into the well; (c) allowing the reduced viscosity oil and condensed solvent liquid mixture to drain into the bottom portion of the well; (d) pumping the recovered liquids from the well to above ground; (e) partially distilling the recovered liquid to reclaim at least a portion of the hydrocarbon solvent vapor for reinjection into the well; and (f) using a portion of the recovered oil as fuel to fire and heat distillation step (e).