Patent ID: 7841404

Claim:
An in-situ combustion process for recovering liquefied or gasified hydrocarbon from an underground hydrocarbon reservoir without withdrawing combustion product from a region proximate a ceiling of the reservoir via a separate bleed well, comprising the steps of: (a) providing at least one production well having a substantially horizontal leg positioned relatively low in said reservoir, said horizontal leg having at one end thereof a heel portion and at an opposite end thereof a toe portion, said horizontal leg adapted to permit inflow of liquefied hydrocarbon into an interior of said horizontal leg, said production well having a substantially vertical section connected to said horizontal leg proximate said heel portion thereof; (b) providing production tubing inside said production well extending within said vertical section and within at least a portion of said horizontal portion to collect said liquefied hydrocarbon which flows into said horizontal leg; (c) injecting a medium into the production well, wherein said medium is selected from the group of mediums consisting of a non-oxidizing gas, steam, water, carbon dioxide, or mixtures thereof; (d) supplying an oxidizing gas to said underground reservoir, at least initially at a location of, or proximate, said vertical section of said production well; (e) igniting hydrocarbon within said hydrocarbon reservoir proximate said vertical section of said production well, so as to cause combustion of a portion of said hydrocarbon in said hydrocarbon reservoir proximate said vertical section and thereby create a combustion front which advances outwardly and away from said vertical section of said production well in at least a direction along said horizontal leg and towards said toe portion thereof; (f) causing heated liquefied hydrocarbon from said reservoir to drain from upper regions thereof and collect in said horizontal leg; and (g) removing from the production well, via said production tubing, said hydrocarbon which has flowed into said horizontal leg.