What is the difference between assessed “resources” and “reserves”? Why doesn’t the USGS assess both?

RESERVES are quantities of oil and gas that are already discovered, recoverable, and commercial.

The USGS assesses UNDISCOVERED RESOURCES, which are those that are estimated to exist based on geologic knowledge and theory.

The USGS does not assess reserves because some of the data needed to make those calculations is not available to us. Much of that information is proprietary data that belongs to commercial oil companies.

Learn more: USGS Energy Resource Assessments

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Why is the USGS resource assessment for Marcellus Shale so low, compared to the Energy Information Administration and the petroleum industry’s assessments?

This question cannot be answered clearly because the methods used by those organizations to estimate resource volumes are not publically available to compare step-by-step. The USGS does not include previously discovered reserves in its estimates. It also does not include reserves that have already been produced. Nor does it include resources that...

When will the full USGS study of the Marcellus shale gas be available?

The USGS publishes its oil and gas resource assessments on the Energy Resources Program web site as soon as they are completed, peer reviewed by scientists knowledgeable about the subject, and formatted for publication. Two geological reports on the Marcellus shale have been released and are available on the site. The USGS has no plans to reassess...

What are the different columns on a USGS oil and gas resource assessment table?

The USGS uses a statistically-based process to calculate the likely range of its estimate. The range of values extends from a 5% or greater likelihood of occurrence (the F5 value, or largest estimated value) to less than 95% likelihood of occurrence (the F95 value, or smallest estimated value). The F50 column is the value that occurs when 50% of...

How much gas is in the Marcellus Shale?

According to the USGS assessment, the Marcellus Shale contains about 84 trillion cubic feet of undiscovered, technically recoverable natural gas and 3.4 billion barrels of undiscovered, technically recoverable natural gas liquids. Undiscovered resources are those that are estimated to exist based on geologic knowledge and theory, while technically...
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Date published: December 22, 2017

Re-Assessing Alaska's Energy Frontier

Less than 80 miles from Prudhoe Bay, home to the giant oil fields that feed the Trans-Alaska Pipeline, lies the site of USGS’ latest oil and gas assessment: the National Petroleum Reserve-Alaska and adjacent areas. Managed by the Bureau of Land Management, the NPR-A covers 22.8 million acres, more than the entire state of South Carolina.

Date published: October 5, 2017

Forecasting the World’s Energy Resources

It is difficult to overstate the importance of energy to the American economy.  Managing this vital sector depends on knowing how many energy resources we have, how many we use and need, and how these resources are transported.

Date published: November 15, 2016

USGS Estimates 20 Billion Barrels of Oil in Texas’ Wolfcamp Shale Formation

This is the largest estimate of continuous oil that USGS has ever assessed in the United States.

Date published: June 8, 2016

USGS Estimates 66 Trillion Cubic Feet of Natural Gas in Colorado’s Mancos Shale Formation

This is the second-largest assessment of potential shale & tight gas resources that the USGS has ever conducted.

Date published: December 17, 2015

USGS Estimates 53 Trillion Cubic Feet of Gas Resources in Barnett Shale

The Barnett Shale contains estimated mean volumes of 53 trillion cubic feet of shale natural gas, 172 million barrels of shale oil and 176 million barrels of natural gas liquids, according to an updated assessment by the U.S. Geological Survey. This estimate is for undiscovered, technically recoverable resources.

Date published: June 20, 2012

USGS Releases Unconventional Gas Estimates for Five East Coast Basins

Using a geology-based assessment method, the U.S. Geological Survey estimated a mean undiscovered natural gas resource of 3.9 trillion cubic feet and a mean undiscovered natural gas liquids resource of 135 million barrels in continuous accumulations within five East Coast Mesozoic basins, according to a new USGS report.  

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Image: Bakken Drill Rig
March 14, 2016

Bakken Drill Rig

A drill rig in the Bakken oil field in Stark County, western North Dakota. 

Attribution: Energy and Minerals
Image shows USGS scientists standing beside a drill rig in protective gear.
September 14, 2015

Drilling a Core for the Eagle Ford

USGS scientists drilling a research core near Waco, Texas. This core was drilled by USGS during field work for an oil and gas assessment for the Eagle Ford of the Gulf Coast Basins. Cores like these provide information on the various rock layers, such as their make-up, their age, etc.

The USGS assesses undiscovered, technically recoverable oil and gas resources for

Image: Bakken Oil Well
April 30, 2014

Bakken Oil Well

Oil-well pads dotting the landscape of typical badland topography. Thousands of new wells are drilled into the Bakken and Three Forks annually, making this one of the most productive plays in the Nation.

Attribution: Water Resources
Oil and Gas Resources of the Arctic Alaska Petroleum Province
December 31, 2006

Oil and Gas Resources of the Arctic Alaska Petroleum Province

Arctic Alaska Petroleum Province, showing locations of principal geologic features. AF, Alpine oil field; ANWR, Arctic National Wildlife Refuge; NPRA, National Petroleum Reserve in Alaska; PB, Prudhoe Bay oil field

Marcellus assessment units

Marcellus Shale Assessment Units

Map of the Appalachian Basin Province showing the three Marcellus Shale assessment units, which encompass the extent of the Middle Devonian from its zero isopach edge in the west to its erosional truncation within the Appalachian fold and thrust belt in the east.