System and method for the recovery of hydrocarbons by in-situ combustion

A method for recovering a hydrocarbon liquid from a subterranean reservoir containing hydrocarbons, the method comprising:

• (a) providing a primary liquid production wellbore having a substantially horizontal primary production length which extends through the reservoir, wherein the primary production length is positioned substantially within a vertical primary production plane;
• (b) providing at least one vent well in fluid communication with the reservoir at a venting position in the reservoir which is relatively higher in the reservoir than the primary production length;
• (c) providing an injector apparatus in fluid communication with the reservoir along an injection line in the reservoir which is substantially parallel with the primary production plane, wherein the injection line extends along at least a portion of the primary production length, wherein the injection line is relatively higher in the reservoir than the primary production length, and wherein the injection line is relatively lower in the reservoir than the venting position;
• (d) injecting an injection gas containing oxygen into the reservoir along the injection line in order to cause combustion of the hydrocarbons contained in the reservoir, thereby heating the reservoir so that the hydrocarbon liquid drains toward the primary liquid production wellbore;
• (e) producing the hydrocarbon liquid from the primary liquid production wellbore;
• and
• (f) venting, from the vent well, gases contained in the reservoir.