Carbon dioxide (CO2) has been used in commercial manner for decades to increase recovery from oil fields in a process called "CO2-enhanced oil recovery" or CO2-EOR. Harnessing this practice to qualify as permanent storage of CO2 is possible, but requires a major paradigm shift from conventional EOR to "EOR+", including additional activities. These activities will drive additional cost.
However, analysis of a hypothetical, representative oil field demonstrates that EOR+ can under the right conditions be more profitable than traditional EOR. This, however, requires that, in addition to the benefit that comes from additional oil production, the EOR+ operator receives a benefit from storing CO2.
In aggregate, EOR+ offers a significant prize. Up to 375 Bbbl of additional oil could be produced from suitable fields across the globe. Between 60 and 240 gigatonnes of CO2 could be stored underground in the process.