Hydrocarbon recovery facilitated by in situ combustion

Abstract

A process for hydrocarbon recovery performs a steam assisted gravity drainage (SAGD) operation by injecting steam in a steam injection well of a SAGD well pair and continuing to inject steam to establish fluid communication between the steam injection well and an oxidizing gas injection well that includes an oxidizing gas injection well segment that is spaced generally above the steam injection well segment, and producing hydrocarbons from a hydrocarbon production well of the SAGD well pair, the hydrocarbon production well including a generally horizontal production well segment disposed generally parallel to and vertically below a generally horizontal steam injection well segment of the steam injection well such that the steam injection well segment is disposed generally vertically between the production well segment and the oxidizing gas injection well segment. In response to determining that the steam injected in the steam injection well reaches the oxidizing gas injection well or is near a top of the oil sands reservoir, SAGD is discontinued and oxidizing gas is injected through an injection well. The oxidizing gas supports in situ combustion (ISC) in the reservoir. During ISC, combustion gases are produced through the steam injection well of the steam assisted gravity drainage well pair; and the mobilized hydrocarbons are recovered from the reservoir through the hydrocarbon production well of the steam assisted gravity drainage well pair.