United States Assessments of Undiscovered Oil and Gas Resources
Explore US Undiscovered Oil and Gas Assessment Provinces
Assessment results, publications, data and more are available
click here to launchAssessment Overview
The USGS assesses potential for undiscovered oil and gas resources in priority geologic provinces in the United States. This website highlights conventional and unconventional (continuous) oil and gas assessments.
Summary of Continuous Assessments
This applications shows maps and tables of all continuous assessments in the United States.
Click here to launchRecent Assessments
Below are the latest US Assessments:
2020 Mowry Shale, Wind River Basin
2021 Western North Slope, Alaska
2020 San Juan Basin Province -Lewis, Fruitland and Mancos-Menefee
2019 Ordovician Collingwood Formation & Utica Shale of Michigan Basin
Browse AssessmentsScience Center Objects
USGS Energy Resources Program provides periodic assessments of the oil and natural gas endowment of the United States and the World. This website provides access to new, prioritized, assessment results and supporting data for the United States, as part of the Energy Policy and Conservation Act (EPCA).
National Oil and Gas Assessment Methodology
The U.S. Geological Survey Energy Resources Program assesses the potential for undiscovered oil and gas resources in priority geologic provinces in the United States and around the world (click here for information about World Oil and Gas Assessments). Two methodologies are used by the USGS; one for assessing conventional oil and gas resources and one for assessing unconventional (continuous) oil and gas resources (such as shale gas and coalbed gas). USGS publications detailing and explaining the conventional and continuous assessment methodologies are provided below. These methodologies have been subjected to rigorous peer reviews by non federal panels, and the two panel reports are provided on this page.
Conventional Resources
USGS Reports
U.S. Geological Survey Assessment Concepts for Conventional Petroleum Accumulations
By James W. Schmoker and T.R. Klett
U.S. Geological Survey Input-Data Form and Operational Procedure for the Assessment of Conventional Petroleum Accumulations
By T.R. Klett, James W. Schmoker, and Ronald R. Charpentier
A Monte Carlo Simulation Method for the Assessment of Undiscovered, Conventional Oil and Gas
By Ronald R. Charpentier and T.R. Klett
Continuous Resources
USGS Reports
U.S. Geological Survey Assessment Concepts for Continuous Petroleum Accumulations
By James W. Schmoker
U.S. Geological Survey Input-Data Form and Operational Procedure for the Assessment Of Continuous Petroleum Accumulations, 2002
By T.R. Klett and James W. Schmoker
Analytic Resource Assessment Method for Continuous Petroleum Accumulations—The ACCESS Assessment Method
By Robert A. Crovelli
FORSPAN Model Users Guide
By T.R. Klett, and Ronald R. Charpentier
Methodology Revisions
Improved USGS methodology for assessing continuous petroleum resources.
Charpentier, R.R., and Cook, T.A.
Applying Probabilistic Well-Performance Parameters to Assessments of Shale-Gas Resources
By Ronald R. Charpentier and Troy Cook
Assembling Probabilistic Performance Parameters of Shale-Gas Wells
By Cook, Troy, and Charpentier, R.R.
USGS Methodology for Assessing Continuous Petroleum Resources
By Ronald R. Charpentier and Troy Cook
New U.S. Geological Survey Method for the Assessment of Reserve Growth
By Timothy R. Klett, Emil D. Attanasi, Ronald R. Charpentier, Troy A. Cook, Philip A. Freeman, Donald L. Gautier, Phuong A. Le, Robert T. Ryder, Christopher J. Schenk, Marilyn E. Tennyson, and Mahendra K. Verma (Reserve Growth Assessment Team)
Variability of Distributions of Well-Scale Estimated Ultimate Recovery for Continuous (Unconventional) Oil and Gas Resources in the United States
By U.S. Geological Survey Oil and Gas Assessment Team
Peer Review
Reserve Growth Methodology
USGS Reports
New U.S. Geological Survey Method for the Assessment of Reserve Growth
By Reserve Growth Assessment Team
Reserve Growth of Oil and Gas Fields - Investigations and Applications
By Troy Cook
Peer Review
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Date published: December 19, 2018Status: ActiveEastern Basins Oil and Gas Assessments
The USGS has conducted several assessments of undiscovered oil and gas in formations in the Blue Ridge Thrust Belt (5068), Piedmont Province (5069), Atlantic Coastal Plain Province (5070), and the New England Province (5072). These basins are generally east of the Appalachian Basin Province (5067).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveCincinnati Arch Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas resources of the Cincinnati Arch Province (5066) :
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveArkoma Basin Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas resources of the Arkoma Basin Province 5062.
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveSouthern Oklahoma Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered continuous oil and gas resources of the Southern Oklahoma Province (5061).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveSedgwick Basin Oil and Gas Assessments
Province Code: 5059
The Salina Basin Province (5059), covers an area of about 45,000 sq mi, consisting of the eastern half of Nebraska and the north-central portion of Kansas. The basin lies between the Cambridge Arch-Central Kansas Uplift Province (5053) on the west, the Nemaha Uplift Province (5055) to the east, the Sioux Arch Province (5032) to the north, and a...
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveOzark Uplift Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas potential of the Ozark Uplift Province (5057).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveNemaha Uplift Province Oil and Gas Assessment
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas potential of the Nemaha Uplift Province (5055).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ArchivedForest City Basin Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas potential of the Forest City Basin Province (5056).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveCambridge Arch-Central Kansas Uplift Oil and Gas Assessment
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas potential of the Cambridge Arch/Central Kansas Uplift Province (5053).
Contacts: Christopher J Schenk -
Date published: December 7, 2018Status: ActiveIowa Shelf Oil and Gas Assessments
The U.S. Geological Survey completed the following assessments of undiscovered oil and gas potential of the Iowa Shelf Province (5052).
Contacts: Christopher J Schenk
Assessment of undiscovered conventional oil and gas resources in the lower Paleozoic of the Williston Basin Province, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 83 million barrels of oil and 351 billion cubic feet of gas in lower Paleozoic strata of the Williston Basin Province, North Dakota, Montana, and South Dakota.
Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Ellis, Geoffrey S.; Finn, Thomas M.; Le, Phuong A.; Marra, Kristen R.; Leathers-Miller, Heidi M.; Drake, Ronald M.
Assessment of undiscovered conventional oil and gas resources of upper Paleozoic strata in the Williston Basin Province, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean oil and gas resources of 134 million barrels of oil and 81 billion cubic feet of gas in upper Paleozoic strata of the Williston Basin Province in North Dakota, Montana, and South Dakota.
Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Ellis, Geoffrey S.; Finn, Thomas M.; Le, Phuong A.; Marra, Kristen R.; Leathers-Miller, Heidi M.; Drake, Ronald M.
Assessment of undiscovered gas resources in the Williston Basin Province, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 2,438 billion (2.4 trillion) cubic feet of gas resources in the Williston Basin Province, in North Dakota, Montana, and South Dakota.
Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Ellis, Geoffrey S.; Finn, Thomas M.; Le, Phuong A.; Marra, Kristen R.; Leathers-Miller, Heidi M.; Drake, Ronald M.
Assessment of undiscovered oil and gas resources in the Pennsylvanian Tyler Formation of the Williston Basin Province, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 161 million barrels of oil and 93 billion cubic feet of gas in the Tyler Formation of the Williston Basin Province, North Dakota.
Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Finn, Thomas M.; Le, Phuong A.; Marra, Kristen R.; Ellis, Geoffrey S.; Leathers-Miller, Heidi M.; Drake, Ronald M.
Assessment of undiscovered gas resources in Upper Devonian to Lower Cretaceous strata of the western North Slope, Alaska, 2021
Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 1,407 billion (1.4 trillion) cubic feet of gas in conventional accumulations in Upper Devonian to Lower Cretaceous strata of the western North Slope, Alaska.
Houseknecht, David W.; Mercier, Tracey J.; Schenk, Christopher J.; Moore, Thomas E.; Rouse, William A.; Dumoulin, Julie A.; Craddock, William H.; Lease, Richard O.; Botterell, Palma J.; Sanders, Margaret M.; Smith, Rebecca A.; Connors, Christopher D.; Garrity, Christopher P.; Whidden, Katherine J.; Gooley, Jared T.; Counts, John W.; Long, Joshua H.; DeVera, Christina A.
Assessment of continuous gas resources in the Horn River Basin, Cordova Embayment, and Liard Basin, Canada, 2019
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 135.4 trillion cubic feet of continuous gas in Devonian–Mississippian shales in the Horn River Basin, Cordova Embayment, and Liard Basin of Canada.
Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Finn, Thomas M.; Le, Phuong A.; Brownfield, Michael E.; Marra, Kristen R.; Gaswirth, Stephanie B.; Leathers-Miller, Heidi M.; Pitman, Janet K.
Assessment of continuous oil and gas resources in the Mowry Shale, Wind River Basin Province, Wyoming, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 288 million barrels of oil and 2.6 trillion cubic feet of gas in the Mowry Shale in the Wind River Basin Province, Wyoming.
Finn, Thomas M.; Schenk, Christopher J.; Mercier, Tracey J.; Woodall, Cheryl A.; Tennyson, Marilyn E.; Marra, Kristen R.; Le, Phuong A.; Leathers-Miller, Heidi M.; Ellis, Geoffrey S.
Geologic assessment of undiscovered oil and gas resources in the Cherokee Platform area of Kansas, Oklahoma, and Missouri
In 2015, the U.S. Geological Survey completed a geology-based assessment to estimate the volumes of undiscovered, technically recoverable petroleum resources in the Cherokee Platform Province area of southeastern Kansas, northeastern Oklahoma, and southwestern Missouri. The U.S. Geological Survey identified four stratigraphic intervals that...
Drake, Ronald M.; Hatch, Joseph R.
Structure contour and isopach maps of the Wolfcamp shale and Bone Spring Formation of the Delaware Basin, Permian Basin Province, New Mexico and Texas
A series of structure contour and isopach maps for the Wolfcamp shale and the Bone Spring Formation of the Delaware Basin, Permian Basin Province, were generated in support of the U.S. Geological Survey 2018 assessment of undiscovered continuous oil and gas resources. The interpreted formation tops used to generate the maps are from the IHS Markit...
Gaswirth, Stephanie B.
Assessment of undiscovered oil and gas resources in the Upper Cretaceous Austin Chalk and Tokio and Eutaw Formations, U.S. Gulf Coast, 2019
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 6.9 billion barrels of oil and 41.5 trillion cubic feet of natural gas in conventional and continuous accumulations in the Upper Cretaceous Austin Chalk and Tokio and Eutaw Formations onshore and in State...
Pitman, Janet K.; Paxton, Stanley T.; Kinney, Scott A.; Whidden, Katherine J.; Haines, Seth S.; Varela, Brian A.; Mercier, Tracey J.; Woodall, Cheryl A.; Schenk, Christopher J.; Leathers-Miller, Heidi M.; Pearson, Ofori N.; Burke, Lauri A.; Le, Phuong A.; Birdwell, Justin E.; Gianoutsos, Nicholas J.; French, Katherine L.; Drake, Ronald M.; Finn, Thomas M.; Ellis, Geoffrey S.; Gaswirth, Stephanie B.; Marra, Kristen R.; Tennyson, Marilyn E.; Shorten, Chilisa M.
Assessment of undiscovered gas resources in the Lewis Shale Total Petroleum System of the San Juan Basin Province, New Mexico and Colorado, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 2.6 trillion cubic feet of gas in the Lewis Shale Total Petroleum System of the San Juan Basin Province, New Mexico and Colorado.
Marra, Kristen R.; Schenk, Christopher J.; Mercier, Tracey J.; Leathers-Miller, Heidi M.; Tennyson, Marilyn E.; Finn, Thomas M.; Woodall, Cheryl A.; Brownfield, Michael E.; Le, Phuong A.; Drake, Ronald M.
Assessment of undiscovered gas resources of the Fruitland Total Petroleum System, San Juan Basin Province, New Mexico and Colorado, 2020
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 39 trillion cubic feet of gas within continuous and conventional reservoirs of the Fruitland Total Petroleum System in the San Juan Basin Province, New Mexico and Colorado.
Marra, Kristen R.; Schenk, Christopher J.; Mercier, Tracey J.; Leathers-Miller, Heidi M.; Tennyson, Marilyn E.; Finn, Thomas M.; Woodall, Cheryl A.; Brownfield, Michael E.; Le, Phuong A.; Drake, Ronald M.
Downloadable Data for National Oil and Gas Assessments
GIS Data for the National Oil and Gas Assessments
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Date published: April 29, 2021USGS National and Global Oil and Gas Assessment Project - Williston Basin, Lower Paleozoic Conventional Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered oil and gas resources in the Lower Paleozoic of the Williston Basin province in Montana, North Dakota and South Dakota. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources.
Attribution: Central Energy Resources Science Center -
Date published: April 29, 2021
USGS National and Global Oil and Gas Assessment Project - Williston Basin, Tyler Formation Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered oil and gas resources in the Tyler formation of the Williston Basin province in Montana, North Dakota and South Dakota. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources.
Attribution: Central Energy Resources Science Center -
Date published: April 29, 2021
USGS National and Global Oil and Gas Assessment Project - Williston Basin, Gas Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered gas resources in the Williston Basin province in Montana, North Dakota and South Dakota. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources.
Attribution: Central Energy Resources Science Center -
Date published: April 29, 2021
USGS National and Global Oil and Gas Assessment Project - Williston Basin, Upper Paleozoic Conventional Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered oil and gas resources in the Upper Paleozoic of the Williston Basin province in Montana, North Dakota and South Dakota. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources.
Attribution: Central Energy Resources Science Center -
Date published: April 5, 2021
USGS National and Global Oil and Gas Assessment Project - Wind River Basin, Mowry Shale Formation Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered oil and gas resources in the Mowry formation of the Wind River Basin Province in Wyoming. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources.
Attribution: Central Energy Resources Science Center -
Date published: November 27, 2020
USGS National and Global Oil and Gas Assessment Project - San Juan Basin Province, Mancos-Menefee Composite Total Petroleum System and underlying Todilto Total Petroleum System Assessment Units and Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of Oil and Gas Resources in the Mancos-Menefee Composite and Underlying Todilto Total Petroleum Systems of New Mexico and Colorado. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is...
Attribution: Central Energy Resources Science Center -
Date published: November 27, 2020
USGS National and Global Oil and Gas Assessment Project - San Juan Basin Province, Fruitland Total Petroleum System Assessment Units and Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of gas resources in the Fruitland Total Petroleum System of New Mexico and Colorado. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is defined within the context of the higher-level...
Attribution: Central Energy Resources Science Center -
Date published: November 27, 2020
USGS National and Global Oil and Gas Assessment Project - San Juan Basin Province, Lewis Shale Total Petroleum System Assessment Units and Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of gas resources in the Lewis Shale Total Petroleum System of New Mexico and Colorado. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is defined within the context of the higher-level...
Attribution: Central Energy Resources Science Center -
Date published: October 28, 2020
USGS National and Global Oil and Gas Assessment Project-Gulf Coast Mesozoic Province, Upper Cretaceous Austin Chalk Group and Tokio and Eutaw Formations Assessment Units and Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of oil and gas resources in the Upper Cretaceous Austin Chalk Group and Tokio and Eutaw Formations in Texas, Louisiana, Mississippi, Alabama, Florida and Arkansas. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas
Attribution: Central Energy Resources Science Center -
Date published: September 9, 2020
USGS National and Global Oil and Gas Assessment Project - Sacramento Basin, Conventional and Continuous Assessment Unit Boundaries and Assessment Input Data Forms
This data release contains the boundaries of assessment units and input data for the assessment of undiscovered gas resources of the Sacramento Basin province in California. The Assessment Unit is the fundamental unit used in the National Assessment Project for the assessment of undiscovered oil and gas resources. The Assessment Unit is defined within the context of the higher-level Total...
Attribution: Central Energy Resources Science Center
Explore US Oil and Gas Assessments
This map shows the provinces assessed by the USGS for undiscovered oil and gas resources.
USGS Announces Largest Continuous Oil Assessment in Texas and New Mexico
Estimates Include 46.3 Billion Barrels of Oil, 281 Trillion Cubic feet of Natural Gas, and 20 Billion Barrels of Natural Gas Liquids in Texas and New Mexico’s Wolfcamp Shale and Bone Spring Formation.
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Date published: June 22, 2018USGS Estimates Oil and Gas in Texas’ Eagle Ford Group
The Eagle Ford Group of Texas contains estimated means of 8.5 billion barrels of oil, 66 trillion cubic feet of natural gas, and 1.9 billion barrels of natural gas liquids, according to a new assessment by the U.S. Geological Survey. This estimate consists of undiscovered, technically recoverable resources in continuous accumulations.
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Date published: April 10, 2008
3 to 4.3 Billion Barrels of Technically Recoverable Oil Assessed in North Dakota and Montana’s Bakken Formation—25 Times More Than 1995 Estimate—
North Dakota and Montana have an estimated 3.0 to 4.3 billion barrels of undiscovered, technically recoverable oil in an area known as the Bakken Formation.
Attribution: Region 5: Missouri Basin
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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... -
Why have some estimates of undiscovered technically recoverable oil or gas changed so much from previous estimates?
Petroleum geologists have long known that oil and gas resources were present in “tight” or impermeable formations such as shale. But there was no feasible way to extract that oil and gas, so they were not “technically recoverable” and were not included in USGS assessment results. Thanks to new technologies, oil and gas can now be extracted from “... -
Where in the United States is hydraulic fracturing being used for oil and gas extraction?
Hydraulic fracturing is used in many established oil and gas producing regions of the country as well as some areas new to the petroleum industry. Maps of major shale gas, tight gas, and tight oil basins are available from the U.S. Energy Information Administration, although not all of the shale basins shown currently have production. Learn more:... -
When did hydraulic fracturing become such a popular approach to oil and gas production?
Hydraulic fracturing in vertical wells has been used for over fifty years to improve the flow of oil and gas from conventional reservoirs. However, the current practice of horizontal drilling coupled with multiple applications of hydraulic fracturing in a single well was pioneered in the late 1980s and has continued to evolve. Since the final... -
Are other countries using hydraulic fracturing for oil and gas extraction?
Yes, hydraulic fracturing is being used extensively in Canada and is increasingly being used in countries in Asia, Europe, and South America. Learn more: Hydraulic Fracturing Induced Earthquakes -
What are "technically recoverable" oil and gas resources?
“Technically recoverable” means that the oil and/or gas can be produced using currently available technology and industry practices. This is regardless of any economic or accessibility considerations. For example, the technology required to produce oil from a location might exist, but it costs more than the oil is worth. The oil is still...