Slightly different because frack fluid is a liquid slurry at surface conditions and CO2 is gas that needs to be compressed into a supercritical state. Your poin

Slightly different because frack fluid is a liquid slurry at surface conditions and CO2 is gas that needs to be compressed into a supercritical state. Your point stands that oil and gas (and surrounding industry) engineers know what they're doing when dealing with the subsurface.