(267c) Reduction Of CO2 Emissions Arising From In-Situ Combustion Processes

In-Situ Combustion (ISC) is an enhanced oil recovery method where one injects compressed air into the subsurface and ignites it with the fuel in place. ISC is particularly beneficial in heavy oil reservoirs (a largely untapped resource) not only because it lowers viscosity and generates steam in-situ but it also selectively burns heavier, less desirable fractions of the oil, a so called ?in-situ upgrading process?. After initial heating, fuel in place at the injection well pyrolyzes, forming a coke. This coke combusts upon contact with the injected air, producing steam, CO₂, and heat. The heat generated from combustion reactions, in combination with continuing air injection, propagates a reaction front through the reservoir, displacing oil towards a production well. One side effect of the ISC process is that the reactions emit significant amounts of CO₂ at the production well. Using simulation, we show the potential of a hybrid ISC/CO₂ flood process to minimize CO₂ emission. We validate our hypothesis that after initial ignition, it is possible to sustain the ISC process even with a low O₂, high CO₂ injection stream. Ultimately, the goal is to circulate the maximum possible amount of hot, compressed CO₂ formed from the combustion back into the reservoir. The recycling of CO₂ produced during the ISC process provides for a less carbon intensive recovery method in addition to a reduced energy requirement for compression.