If you read the opening chapter of Robert Baer’s book about Saudi Arabia, there is a scenario described in which a terrorist blows up the Saudi oil facilities at Abquaic. Due to the plumbing and geography of how the Saudi oil industry is set up, the attack cripples the whole ability of the country to export oil. I am guessing that that was what McCain was referring to.
Then McCain needs to learn the difference between a crude oil exporting facility and a refinery.
It's like the difference between a cattle ranch and a meat processing plant. They don't look much alike.