US Patent 7909093 In situ combustion as adjacent formation heat source

Methods and apparatus relate to in situ combustion. Configurations of injection and production wells facilitate the in situ combustion. A first production well disposed in a first oil bearing reservoir is spaced from a second production well disposed in a second oil bearing reservoir separated from the first oil bearing reservoir by a stratum having lower permeability than the first and second oil bearing reservoirs. The stratum isolates one of the first and second production wells from one of the first and second oil bearing reservoirs. In situ combustion through the first oil bearing reservoir generates heat that irradiates into the second oil bearing reservoir to enable producing hydrocarbon with the second production well.