I recently hear of a potential oil boom in the USA base on oil shales in the green river formation. Shell is trying to incorporate deep underground heat exchangers to convert the oil shales (kerogen) into crude oil and also reduce the viscosity of the synthetic crude oil formed.
Go back throughout history and there have been half a dozen other "potential oil shale booms". It was always "if the price of oil goes up just a few more dollars, then oil shale will flood the markets, etc". However, oil shale has a horrendous energy return on investment. Even the best areas of the Green River formation yield maybe a 2:1 ratio, while some of the worst conventional oil sources aren't that bad. Back in the '80's, Exxon spent a massive amount of money (billions?), but it proved to be too expensive. It was somewhere around a couple thousand dollars per barrel. If oil cost that much, then gas would be between $50 and $100 per gallon.
Besides, even if Shell (who's currently working on a new technique) do get it to work, the amount of oil will still be very small. I believe the numbers are something like a 1 GW nuclear plant to produce 100,000 bpd.