Another Way To Extract Oil From Tar Sands Without Natural Gas

I've already written about one process for converting Canadian tar sands to usable crude oil without taking up valuable natural gas to cook the stuff; Green Car Congress has another one such, this time from Petrobank, which has a proprietary means for doing the extraction that involves pumping air into the tar sands, and burning part of it. This causes a large amount of heat, which in turn upgrades and loosens the oil, which is then pumped out. The company estimates that about 80% of the oil trapped in the sands can be removed this way; even more of the crude could be upgraded on the way out using catalytic means.

A thought a couple days later: I wonder, could something similar to this be used on tapped-out conventional oilfields? If two-thirds of the oil is left behind in a regular oilfield, that could be something like 50% more recovery, not too shabby, and without requiring a source of CO₂.