Most of that oil would've burned anyway, just a little bit at a time, inside a combustion chamber, after being refined and distributed somewhere.

When an oil pipeline or well catches fire, it burns in a spectacularly dirty way, but the net CO2 emissions in the atmosphere is actually reduced from shutting down that facility so that it can't process and export as much oil anymore. Meanwhile, the logistics and pricing effects probably destroy demand, so that the world as a whole burns less oil afterward.