Patent EA-004979-B1 (EA)
Title: Enhanced oil recovery by in situ gasification
Inventor: DAVIDSON IAN DAVID FARQUHAR
IPC: E21B43/24
Filed: 2001-04-20
Abstract: 1. A process for recovery of oil and/or gas by downhole gasification of oil in a subterranean formation in the presence of water to generate the gases H2, CO and CO2 which comprises deploying upon a drill string a tool having a controllable gasification device therein, controllably launching the tool from a surface production facility down to the subterranean formation, determining the location of the tool in relation to its operational proximity to the oil in said subterranean formation, providing at least one riser tubing for the selective recovery of the oil, or gaseous or vaporized products from said oil, and activating the gasification device to cause at least one of the following reactions: C + H2O -> CO + H2 CO + H2O -> CO2 + H2 CpHq + H2O -> pCO + qH2 CO2 + C -> 2CO CH4 + H2O -> CO + 3H2 CH4 + CO2 -> CO2 + H2 thereby accumulating gas pressure over oil in the subterranean formation. 2. A process according to claim 1, wherein activating the gasification device causes all of said reactions. 3. A process according to any of claims 1,2, wherein a plurality of tools are deployed at selected positions. 4. A process according to claim 3, wherein several drill strings are used to deploy the tools in a selected pattern to achieve a controlled gasification front for driving oil toward a production facility. 5. A process according to any of claims 1-4, wherein oil is recovered by allowing accumulating gas pressure to drive the oil into the riser tubing. 6. A process according to any of claims 1-5, further comprising subsequently recovering the tool from the subterranean formation. 7. A process for downhole gasification of oil in a subterranean formation which comprises running a gasification tool having an electrically powered resistive heating element therein from a surface production facility down to the subterranean formation, bringing said tool into operational proximity with the oil in said subterranean formation, and activating the tool to initiate gasification in the presence of water within a predetermined temperature range to generate the gases H2, CO and CO2. 8. A process according to claims 7, wherein said oil is an oil other than heavy crude oil. 9. A process according to any of claims 7,8, wherein the gases generated by the gasification process are collected by providing a gas riser tubing between the production facility and the subterranean formation such that an end of said tubing enters accumulating gas in a head space above the oil to provide for gas recovery to the surface production facility. 10. A process according to any of claims 7-9, wherein the gases generated by the thermal gasification process are allowed to accumulate above the oil to build pressure, and the oil is collected by providing a production riser tubing between the surface production facility and the subterranean formation such that an end of said tubing penetrates the oil to a sufficient depth to permit oil recovery to the surface production facility. 11. A process according to any of claims 7-10, wherein oil recovered is subjected to a gasification process in a surface facility. 12. A process according to any of claims 7-11, wherein gas obtained from the gasification process in the surface facility is injected back into the formation to facilitate enhanced oil recovery. 13. A process according to any of claims 7-12, which comprises deploying the tool for gasification of oil from a surface production facility down to the subterranean formation, determining the location of the tool in relation to its operational proximity to the oil in said subterranean formation, and providing at least one riser tubing for the selective recovery of the mineral oil, or gaseous products from said oil, and activating the gasification device to cause at least one of the following reactions: C + H2O -> CO + H2 CO + H2O -> CO2 + H2 CpHq + H2O -> pCO + qH2 CO2 + C -> 2CO CH4 + H2O -> CO + 3H2 CH4 + CO2 -> CO2 + H2 thereby accumulating gas pressure over oil in the subterranean formation. 14. A process according to any of claims 13, wherein activating the gasification device causes all of said reactions. 15. A process according to claim 14, wherein the gasification tool is deployed upon a drill string. 16. A process according to claim 14, wherein a plurality of gasification tools are deployed at selected positions upon a drill string. 17. A process according to any of claims 14, 16, wherein several drill strings are used to deploy the gasification tools in a selected pattern to achieve a controlled gasification front for driving oil toward a production facility. 18. A process according to any of claims 9-17, wherein oil is recovered by allowing accumulating gas pressure to drive the oil into the riser tubing.