Patent ID: 8381810

Claim:
A method of conducting in situ combustion in an underground reservoir, comprising: a. forming at least one injection well disposed in the underground reservoir between first and third production wells, wherein the injection well is vertically deviated with a first horizontal injector well portion extending toward the first production well and a second horizontal injector well portion extending toward the third production well, wherein the first and second horizontal injector well portions can vary from 30° to 120° from vertical and thereby provide lateral area coverage that facilitates establishing communication with the first and third production wells for beginning the in situ combustion, wherein the distal ends of the first and second horizontal injector well portions include a toe portion, wherein the opposite ends of the first and second horizontal injector well portions include a heel portion, wherein the heel portions connect the first and second horizontal injector well portions to where the injection well is vertically deviated; b. forming the first production well having a first substantially horizontal producer portion and a first substantially vertical producer portion disposed in the underground reservoir, wherein the distal end of the horizontal producer portion includes a toe portion, wherein the opposite end of the horizontal portion includes a heel portion, wherein the heel portion connects the first horizontal producer portion to the first vertical portion of the first production well; c. forming a second production well having a second substantially horizontal producer portion and a second substantially vertical producer portion disposed in the underground reservoir, wherein the distal end of the horizontal producer portion includes a toe portion, wherein the opposite end of the horizontal portion includes a heel portion, wherein the heel portion connects the second horizontal producer portion to the second vertical portion of the second production well, wherein the second production well is located lower in the reservoir than the first production well; d. forming the third production well having a third substantially horizontal producer portion and a third substantially vertical producer portion disposed in the underground reservoir, wherein the distal end of the horizontal producer portion includes a toe portion, wherein the opposite end of the horizontal portion includes a heel portion, wherein the heel portion connects the third horizontal producer portion to the third vertical portion of the third production well; e. injecting an oxidant into the injection well to establish a combustion front of ignited hydrocarbons to propagate a combustion front through the reservoir; f. recovering hydrocarbons from the reservoir via the second production well due to gravity drainage; and g. recovering combustion gas from the reservoir via the first and third production wells.