The U.S. Geological Survey has approximated how much undiscovered onshore shale oil and gas resources are available for use in Alaska’s North Slope region. According to the U.S. Geological Survey (USGS), about zero up to two billion barrels of oil is available in the region. The USGS also estimated that there is zero up to 80 trillion cubic feet of natural gas. These resources represent recoverable assets, and are quantities of gas and oil that are obtainable with using modern and readily available technology. Production has never been attempted in this Alaskan region because of economic and infrastructure capabilities. The shales in this region span most of the area, but exclude the environmentally-sensitive Arctic National Wildlife Refuge.