And I thought the only way to get the oil was to cook it.
yep.
And I thought the only way to get the oil was to cook it.
Pretty much. It is locked in a near or at surface shale, too shallow to frac and with no overburden pressure to force it into a reservoir. Much of the Book Cliffs area has exposures of the Green River Shale.
As an aside, the US Govt. tried freeing the hydrocarbons a few decades back with a small nuclear device. That didn't produce the desired results. There was also a pilot project to cook the oil out of the mined shale at Parachute, CO, (UNOCAL, I think). It shud down in the '80s when the price of oil crashed, and would likely be EPA'd out of existence today.