These aquifers are under bedrock. The Carbon dioxide when pumped down should go super-critical that is, a dense liquid nearly a solid. In theory at least, carbon would be absorbed into the bedrocks to eventually make oil again. Throughout it is in a form that can be metered and measured.
To collect carbon in sufficient quantity takes a coal burn or similar closed environment operation.
In North Dakota they are taking coal, putting it into a kiln type container, heating it and adding a bit of oxygen. In this new air mix a flash fire is ignited and takes care of all the other air components leaving behind pure carbon dioxide.
The continued clean burning of the coal is used to generate steam for use in electricity. What is left behind is super clean and consistent ash suitable for other applications.
In this case the pure CO2 taken off is piped to Saskatchewan who uses it as a solvent to scrub oil off shale. They do not know how much carbon dioxide stays down there or how much is absorbed into the oil. Effervescent oil is a possibility.
On the plus side Alberta's plan can be audited. However, anything to do with an audible quantity in this province will probably end up in a General Accounts of Carbon shell outs. Scary!
There is about 5.1 billion dollars coming in now on royalty. Of this the Government has said 2 billion was going to Carbon storage. If it works in my mind it is worth it.
There is nothing in this scenario that allows free carbon capture such as that pumped out of machines or is released from opening the ground.
I can however see an application where the facilities that the gas that is used to heat the water for their process could be enclosed and that the gas affluent carbon dioxide may, just may be captured.
In all there are more questions than answers and the oil companies and this Government's secrecy does not make any of it easier to understand. Mostly they are so accustomed to lying after 27 years of practice they just find it easiest to do.