7 million barrels * $30 a barrel = 210 million just to take the oil. Plus $20 a barrel when you sell it brings you to $350,000,000 in revenue on a 7 million barrel tank. What am I missing, other than not being able to build the tank fast enough?
I mean, if you have a spare $300 million lying around, that sounds like a fantastic arbitrage opportunity, and (napkin math time) if you're holding the barrels for more than 10 months, that'd be the way to do it.