On one small test plot about 20 feet by 35 feet, on land Shell owns, they started heating the rock in early 2004. "Product" - about one-third natural gas, two-thirds light crude - began to appear in September 2004. They turned the heaters off about a month ago, after harvesting about 1,500 barrels of oil.
While we were trying to do the math, O'Connor told us the answers. Upwards of a million barrels an acre, a billion barrels a square mile. And the oil shale formation in the Green River Basin, most of which is in Colorado, covers more than a thousand square miles - the largest fossil fuel deposits in the world.
They don't need subsidies; the process should be commercially feasible with world oil prices at $30 a barrel. The energy balance is favorable; under a conservative life-cycle analysis, it should yield 3.5 units of energy for every 1 unit used in production. The process recovers about 10 times as much oil as mining the rock and crushing and cooking it at the surface, and it's a more desirable grade. Reclamation is easier because the only thing that comes to the surface is the oil you want.
That would be one trillion barrels of oil.