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USGS Estimates 37.5 Tcf of Recoverable Gas on Alaska's Central North Slope

A new U.S. Geological Survey (USGS) assessment estimates that there is about 37.5 Tcf of undiscovered but technically recoverable natural gas resources, 478 million bbl of natural gas liquids and 4 billion bbl of oil in the central part of the Alaska North Slope and the adjacent state offshore area.

The central North Slope contains most of the commercial oil fields and virtually all of the petroleum-producing infrastructure and pipelines in northern Alaska, including the Trans-Alaska Pipeline System. Furthermore, the undiscovered resources would be in close proximity to the proposed Alaska natural gas pipeline system. To date, 15 billion bbl of oil have been produced from this area, and remaining reserves include 7 billion bbl of oil and 35 Tcf of gas.

Most undiscovered oil accumulations in the central North Slope assessment area are expected to be relatively small in comparison to those already discovered. There is estimated to be 37.5 Tcf of undiscovered natural gas in the central North Slope, with the majority located in the southern half of the assessment area in the foothills of the Brooks Range, USGS said.

This is about half of what has been estimated to occur (73 Tcf of natural gas) in National Petroleum Reserve in Alaska (NPRA) and significantly more than has been estimated to occur (9 Tcf of natural gas) in the Arctic National Wildlife Refuge (ANWR) 1002 area. Recent USGS estimates of undiscovered oil in adjacent areas include 10.6 bbl of oil in the NPRA and 10.4 billion bbl of oil in the ANWR 1002 area.

The central North Slope lies between the NPRA and ANWR, and extends from the Brooks Range northward to the state-federal offshore boundary. The assessment area consists mostly of state and native lands, covering about 23,000 square miles (about one-half the size of New York). The population in the area is limited to Prudhoe Bay and other oil production facilities.

The USGS said its assessment was based on a comprehensive review of all available geological, geophysical and geochemical evidence, including hydrocarbon source rocks, reservoir rocks and traps. For complete central North Slope energy information go to the USGS energy website at

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