Oil & Gas Journal
August 24, 2010, Nick Snow

An estimated 1.5 trillion bbl of oil in place lies in Western Colorado’s Piceance basin oil shale, the US Geological Survey said in the first comprehensive assessment published since 1989. ...

http://www.pennenergy.com/index/petroleum/display/3573486040/articles/oil-gas-journal/exploration-development-2/reserves/2010/08/piceance-basin_oil-shale.html