It can be way worse than 100% if the reduced oil extraction costs (or greenwashed accounting from earning carbon credits for sequestration) results in more net oil being extracted, than there would have been without access to CO2.
Not to mention the energy costs of actually pulling carbon out of the air. Often, getting 1kg of CO2 out of the air ends up costing so much energy that you end up emitting more than 1kg of it.
If sequestration weren't a fairy tale that will keep us distracted for another few decades while we continue to ruin our environment, people would be doing it, not talk about doing it.
But yeah, it's quite underwhelming.
1 - Wild guess. But it's certainly less than 100%, and certainly not by a lot.