This article quotes a Rand study that there are 800 billion barrels of oil available in the oil shale around the 3-corners area of Colorado, Wyoming, and Utah. In that case, it's just a matter of economically getting it out, and trying not to destroy the environment. I don't understand the problem, though, since Canada has been getting oil from shale for years.
Anyway, this potential for us to continue to rely on oil is not good, in my opinion. We should get off oil dependency as soon as possible to a cleaner more environmentally friendly source.
There you can look at the oil sands of Alberta and see if that looks environmentally friendly or not.