Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
214 words
A method for recovering viscous oil from a subterranean, permeable, viscous oil-containing formation, said formation being penetrated by at least two wells, one injection well and one production well, said wells being in fluid communication with a substantial portion of the oil formation, comprising: (a) injecting steam into the injection well and recovering fluid including oil from the formation by the production well until the fluid being recovered from the production well comprises an unfavorable amount of steam or water; (b) thereafter closing off the fluid communication between the production well and at least a portion of the upper part of the oil formation while maintaining fluid communication with the lower portion of the formation; (c) thereafter injecting a predetermined volume of a solvent into the formation via the fluid communication between the production well and the lower portion of the formation while simultaneously continuing injection of steam into the injection well; (d) recovering fluids including solvent and oil from the lower portion of the formation through the production well until the fluid being recovered from the production well comprises a predetermined amount of solvent; and (e) repeating steps (c) and (d) for a plurality of cycles until the fluid being recovered from the production well comprises an unfavorable amount of steam or water.
Claim 2
Independent Claim
214 words
A method for recovering viscous oil from a subterranean, permeable, viscous oil-containing formation, said formation being penetrated by at least two wells, one injection well and one production well, said wells being in fluid communication with a substantial portion of the oil formation, comprising: (a) injecting steam into the injection well and recovering fluid including oil from the formation by the production well until the fluid being recovered from the production well comprises an unfavorable amount of steam or water; (b) thereafter closing off the fluid communication between the production well and at least a portion of the upper part of the oil formation while maintaining fluid communication with the lower portion of the formation; (c) thereafter injecting a predetermined volume of a solvent into the formation via the fluid communication between the production well and the lower portion of the formation while simultaneously continuing injection of steam into the injection well; (d) recovering fluids including solvent and oil from the lower portion of the formation through the production well until the fluid being recovered from the production well comprises a predetermined amount of solvent; and (e) repeating steps (c) and (d) for a plurality of cycles until the fluid being recovered from the production well comprises an unfavorable amount of steam or water.
Claim 3
Dependent Claim
46 words
A method as recited in claim 1 wherein the solvent of step (c) is a light hydrocarbon selected from the group consisting of C 4 to C 10 aliphatic hydrocarbons, natural gasoline, naphtha, light crude oil, partially refined tar generally known as syncrude and mixtures thereof.
Claim 4
Dependent Claim
39 words
A method as recited in claim 1 wherein fluid production from the production well during step (d) is continued until the amount of solvent in the produced fluids has decreased to a value less than 12 percent by volume.
Claim 5
Dependent Claim
40 words
A method as recited in claim 1 wherein the volume of solvent injected during step (c) is from 10 to 50 barrels per foot of formation thickness with which the lower portion of the production well is in fluid communication.
Claim 6
Dependent Claim
40 words
A method as recited in claim 1 wherein the volume of solvent injected during step (c) is from 10 to 20 barrels per foot of formation thickness with which the lower portion of the production well is in fluid communication.
Claim 7
Dependent Claim
22 words
A method as recited in claim 1 wherein said injection well is in fluid communication with the lower portion of the formation.