Colorado oil production typically accounts for about one percent of the annual U.S. total; most of this production occurs in the Denver and Piceance basins. As of the end of 2009, Colorado was 10th in the nation for both liquid petroleum reserves and production. Two of the nation's 100 largest oil fields by proved reserves are found in Colorado: Wattenberg (13th) and Rangely (74th). Colorado has two oil refineries in Commerce City north of Denver.
Colorado also has the world's largest resources of oil shale
which is neither oil, nor shale.
NIOBRARA SHALE OIL
The Colorado Geological Survey's RockTalk
Colorado's New Oil Boom - The Niobrara
Hydraulic fracturing in the Niobrara and its relation to fresh water aquifers:
The Niobrara Calculation Tool
Fact Sheet on hydraulic fracturing:
Association of American State Geologists: Hydraulic Fracturing
AAPG Rocky Mountain Section presentation on Niobrara production and value in Colorado:
Niobrara Tight Oil Success in Colorado: What do the Numbers Indicate?