METHOD OF RECOVERING OIL USING CONTINUOUS STEAM FLOOD FROM A SINGLE VERTICAL WELLBORE

摘要

A method for recovery of oil from a subterranean, viscousoil-containing formation penetrated by one or more wells each ofwhich is provided with at least two separate flow paths, thefirst flow path in fluid communication with the bottom of theformation from adjacent or below the formation and the secondflow path in fluid communication with substantially the fullvertical thickness of the formation. Steam is injected into theformation via the second flow path and fluids including oil arerecovered from adjacent or below the bottom of the formation viathe first flow path at a predetermined rate which issubstantially less than the injection rate of steam so as toincrease the formation pressure to a desired level. Formationpressure is maintained at the desired level while continuinginjection of steam and production of fluids including oil untilthe fluids recovered contain an unfavorable amount of water. Ina preferred embodiment, the tubing providing the first flow pathmay be progressively withdrawn or lowered into the wellbore toobtain improved steam-oil ratios and/or higher oil productionrates. This method provides maximum gravity drive displacementof oil from the formation.