It's definitely a magic trick. He gets to say he's opened up all these new offshre sites without having to pay any price from his environmental supporters. The site has no impact if no one wants to drill there.
To play Devil's advocate for a moment...
Gas around me is at about $2.70 a gallon. It's that much for one reason and one reason only- that's what consumers are willing to pay for it. If the suppliers could get $8, they'd price it there. But when they inch it up, demand drops and the supply pipeline begins to back up. The price drops to remove the constraint. So will a new tax really affect prices at the pumps? A 15 cent increase in tax may get passed along to the consumer. But the consumer isn't tax sensitive. They're fuel price sensitive. So demand will drop, supplies will back up and prices will drop. The net effect being the oil company is now paying the tax.
To look at it more simply, if there was 15 cents to be had, the oil suppliers would be seeing it now.
Am I missing something?