Patent ID: 8287050

Claim:
A method for extracting hydrocarbons, comprising: (a) providing a first underground excavation in proximity to a hydrocarbon-containing deposit; and (b) forming, from the first underground excavation, a second underground excavation, the second underground excavation being designed to at least partially cave in to increase a permeability of at least one of the hydrocarbon-containing deposit and an adjacent hydrocarbon-barren deposit, wherein the forming step (b) comprises the following sub-step: forming, in the second underground excavation a liner, the liner defining interior and exterior portions of the second underground excavation, the exterior portion being located exteriorly of the liner, being a free volume, and being positioned between the liner and an interior surface of the second excavation, at a selected location an area of the exterior portion being at least about 2% of an area of the second underground excavation, wherein the exterior portion is maintained substantially free of a backfill material before subsidence of surrounding rock, wherein the hydrocarbon-containing formation is oil sands, wherein the area ranges from about 2 to about 22% of the area of the second underground excavation, wherein after subsidence of the rock into the exterior portion a zone of disturbance has a diameter that is at least about 200% of the diameter of the second excavation, wherein the second underground excavation is formed by a tunnel boring machine, the tunnel boring machine comprising a rotating cutter head having a first diameter and shield having a second diameter, wherein the liner is assembled under the shield, wherein the liner has a third diameter, wherein the second diameter is from about 25 to about 100 millimeters smaller than the first diameter, and wherein the third diameter is from about 50 to about 200 millimeters smaller than the second diameter, wherein the surrounding rock is part of at least one of the hydrocarbon-containing and a hydrocarbon-barren deposit.