Patent EA-004696-B1 (EA)
Title: In-situ combustion for oil recovery
Inventor: COLES JOHN MATTEW
IPC: E21B36/04
Filed: 2001-10-10
Abstract: 1. A system for transmitting heat into a hydrocarbon containing formation surrounding a heat injection well, the system comprising: an oxidizing fluid source; an oxidant supply conduit disposed in the wellbore of the heat injection well, wherein the conduit is configured to provide an oxidizing fluid from the oxidizing fluid source to a reaction zone in the formation during use, and wherein the oxidizing fluid is selected to oxidize at least a portion of the hydrocarbons in the formation in the vicinity of the wellbore zone during use such that heat is generated at the reaction zone; and a combustion gases exhaust conduit disposed in the wellbore of the heat injection well for transmitting combustion gases through the wellbore of the heat injection well away from the reaction zone. 2. The system of claim 1, wherein the system is configured to allow heat to transfer substantially by conduction from the reaction zone to a selected section of the formation during use. 3. The system of claim1, wherein the oxidant supply and combustion gases exhaust conduits are equipped with pressure regulation devices which control the pressure in the reaction zone such that at least a substantial part of the combustion gases generated at the reaction zone are vented to the earth surface through the combustion gases exhaust conduit. 4. The system of claim 1, wherein the oxidant injection conduit and the combustion gases exhaust conduit extend co-axially to each other from a wellhead of the heater well into the hydrocarbon bearing formation, the oxidant injection conduit protrudes from the lower end of the oxidant injection conduit through at least a substantial part of the hydrocarbon bearing formation and the protruding lower part of the oxidant injection conduit is equipped with an array of oxidant injection ports via which in us oxidant is injected into an annular space between the oxidant injection conduit and the reaction zone. 5. The system of claim 1, wherein the oxidant injection conduit is an air injection conduit and is provided with an air injection pump and the air injection conduit and combustion gases exhaust conduits are each provided with a pressure control valve for controlling the pressure in the annular space between the perforated lower part of the oxidant injection conduit and the reaction zone such that said pressure is substantially equal to a pore pressure in at least part the surrounding hydrocarbon containing formation and transfer of combustion gases into the formation is inhibited. 6. The system of any one of claims 1-5, wherein the heat injection well further comprises an electric heater for transmitting heat into the reaction zone. 7. The system of any one of claims 1-5, wherein the heater well further comprises a fuel injection conduit for injecting fuel into the reaction zone. 8. A method for transmitting heat into a hydrocarbon containing formation surrounding a heat injection well, the method comprising: injecting an oxidant through an oxidant supply conduit disposed in the wellbore of the heat injection well to a reaction zone in the formation, inducing the oxidizing fluid to oxidize at least a portion of the hydrocarbons in the formation in the vicinity of the wellbore such that heat and combustion gases are generated in the reaction zone; and removing at least part of the combustion gases through an exhaust conduit disposed in the wellbore of the heat injection well away from the reaction zone. 9. The method of claim 8, wherein the heat generated in the reaction zone is transferred substantially by conduction from the reaction zone to a pyrolysis zone in the hydrocarbon containing formation where hydrocarbons are pyrolysed. 10. The method of claim 9, wherein one or more production wells traverse the hydrocarbon containing formation at selected distances from the heat injection well, and the fluid pressures in the heat injection well and each production well are controlled such that pyrolysed hydrocarbons products are induced to flow from pyrolysis zone through the formation into the production well or wells and that transfer of combustion gases from the reaction zone into any production well is inhibited. 11. The method of claim 8, 9 or 10, wherein the hydrocarbon containing formation is a coal layer. 12. The method of claim 8, 9 or 10, wherein the hydrocarbon containing formation is an oil shale deposit or a tar sand. 13. The method of any one of claims 8-12, wherein the heat injection well is pre-heated by an electric heater before oxidant is injected into the heat injection well.