Indirect downhole steam generator with carbon dioxide capture

摘要

Methods and systems for enhancing recovery of hydrocarbons below a permafrost layer are provided which use a downhole combustion device to inject a heated fluid into a subterranean formation to enhance hydrocarbon recovery through viscosity reduction. The system is configured to avoid adversely thermally affecting the permafrost, which is highly undesirable. One or more heat exchangers may be used in conjunction with the combustion device to enhance heat transfer of various streams. The heat exchanger(s) mitigate the adverse effects of various streams on the permafrost by lowering the return stream temperatures, which are transported through the wellbore. A carbon dioxide capture system may be provided to recover carbon dioxide from the combustion device exhaust. Certain optional embodiments allow the amount of carbon dioxide introduced into the formation to be independently controlled to further enhance the hydrocarbon recovery.

主权项

1. A method for enhancing heavy oil recovery from a subterranean formation comprising the steps of:
providing a first heat exchanger; providing a combustion device; providing a second heat exchanger; situating the first heat exchanger, the combustion device, and the second heat exchanger downhole in a wellbore in the subterranean formation at a depth below a permafrost zone wherein the depth is a sufficient distance from the permafrost zone to avoid substantially thermally affecting the permafrost zone; introducing water, a fuel, and an oxidant downhole to the combustion device; combusting the fuel with the oxidant in the combustion device to form an exhaust gas, the exhaust gas comprising carbon dioxide; introducing the exhaust gas and the water into the second heat exchanger; allowing the exhaust gas to heat the water in the second heat exchanger to form steam; allowing the exhaust gas to exit the second heat exchanger and to be introduced into the first heat exchanger; allowing additional quantities of the water, the fuel, and the oxidant to enter the first heat exchanger and allowing the additional quantities of the water, the fuel, and the oxidant to be preheated by the exhaust gas in the first heat exchanger; allowing the steam to exit the second heat exchanger into the subterranean formation to heat any in-situ heavy oil to form heated heavy oil; recovering the heated heavy oil from the subterranean formation; recovering the exhaust gas from the first exchanger to the surface without the exhaust gas being introduced into the subterranean formation and introducing the exhaust gas into a carbon dioxide capture system; separating a substantial portion of the carbon dioxide from the exhaust gas in the carbon dioxide capture system to form an enriched carbon dioxide stream and a CO2-depleted stream; and introducing a portion of the enriched carbon dioxide stream into the subterranean formation.