IN SITU OIL EXTRACTION FROM UNDERGROUND FORMATIONS USING HOT SOLVENT VAPOR INJECTIONS

摘要

ABSTRACT OF THE DISCLOSUREHeavy oil or bitumen extracted and removed fromunderground oil bearing formations having low permeabilitysuch as tar sands by injection of hot hydrocarbon solventvapor into a single well hole at a pressure not substantiallyexceeding the pressure in the formation to effectively heatand extract the bitumen. The hot solvent vapor is passeddownwardly through an annular passage of concentric pipingplace in the well bore and is injected out through upperperforations in the casing and into the formation The hotsolvent vapor condenses in the formation and drains alongwith recovered oil through lower perforations back into thebottom end of the inner pipe, from which the product oil andsolvent mixture is pumped to above ground. The solvent ispartially reclaimed from the oil product by distillation meansand the solvent fraction is reheated and reinjected into thewell bore for further use.The solvent used should be matched to the characteristicsof the bitumen in the tar sands formation for most effectiverecovery of bitumen, and contains substantially aromatic-23-