If U.S. domestic supplies were tapped — and in particular the oil shales, the world price for oil could be kept at about $40/bbl for a long time.
By locking up the oil-shales, and other domestic supplies — the government (Obama, Pelosi, Reid — just to personalize things, according to Akinsky's Rules) has removed all protection from the U.S. consumer & guaranteed that the U.S. economy will bleed money, when the price of oil goes up.
The next step on the agenda appears to be shutting down the oil sands in Alberta. The greatest single source of imported oil for the U.S.
While Shell, and other big oil companies would develop the oil shales, if given the chance — they'll also be happy raking in billions of windfall profits from the wells they already have in production.
There's some more discussion about this here:
See here for the real goal.