Improving oil recovery rates in THAI in situ combustion process using pure oxygen

In-situ-combustion-type processes such as the Toe-to-Heel Air Injection (THAI) process have been shown to have advantages over other thermal enhanced oil recovery processes. The THAI process uses in situ combustion to mobilise and upgrade bitumen or heavy oil within the reservoir. This study compares the effect of injecting pure oxygen instead of air on the performance of the THAI process. It is found that over the 833 days of the process time, an additional 3.85% of oil originally in place (OOIP) was recovered with injecting pure oxygen compared to with injecting air. It is found that as the combustion front advances, higher axial length fraction of the HP well is used for oil production. Observing the oil production rate distribution along the HP well, it is concluded that highest oil flow rate enters the HP well at the toe in both models. It has been shown that it is likely that gas production might have negatively affected the oil production when air is the injected fluid (i.e. in the air model).