Moving injection gravity drainage for heavy oil recovery

A method for in situ combustion (ISC) of a hydrocarbon material bearing subterranean formation, wherein the formation is intersected by at least one completed well-pair comprising a first generally horizontal well and a second generally horizontal well situated below the first well, and wherein the first and the second wells comprise a horizontal well liner that further comprises a plurality of perforations spaced along substantially a length of the well liner, and said method of recovering petroleum comprising:

• a. positioning a tubing string in the first well and in the second well wherein the tubing string is configured for multi-point injection at multiple points along a length of the tubing string;
• b. injecting steam via some of the multiple points along the length of the tubing string positioned in the first well and/or in the second well into the formation;
• c. withdrawing, from the second well, petroleum that moves downwardly in the formation and flows into the second well;
• d. replacing steam injection into the formation via the tubing string positioned in the first well with an oxidant injection, via some of the multiple points along a length of the tubing string, once the temperature of a region of the formation proximate the first well reaches the auto-ignition temperature of in-situ hydrocarbons, whereby auto-ignition of the in-situ hydrocarbon material commences and thereby forms one or more combustion zones;
• e. withdrawing, from the second well, petroleum that moves downwardly in the formation and flows into the second well;
• f. moving the tubing string positioned in the first well while maintaining the oxidant injection into the formation to maintain combustion of the in-situ hydrocarbon material, the moving comprising:
• changing the multiple points of the oxidant injection along the length of the tubing string from an initial location of multiple points of injection to a changed location of multiple points of injection, wherein some of the changed location of multiple points of injection overlap with some of the initial locations of multiple points of injection to ensure that one or more of the combustion zones are always supplied with an oxidant, and wherein some of the changed locations of multiple points of injection being positioned adjacent to the one or more of the combustion zones thereby allowing the injected oxidant to be exposed to uncombusted hydrocarbon material, and wherein over time, as the tubing string is moved along an axis of the first well, one or more of the combustion zones move through the hydrocarbon material;
• and
• g. continuing to withdraw, from the second well, petroleum that moves downwardly in the formation and flows into the second well.