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
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).
Assessment 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.
Recent Assessments
Below are the latest US Assessments:
- 2025 Federal Lands of the Onshore United States
- 2024 Upper Cretaceous Niobrara Formation
- 2024 Mowry Composite Total Petroleum Systems
- 2024 Hosston and Travis Peak Formations
- 2023 Escondido, Olmos, and San Miguel Formations of the Western Gulf Basin Prov…
- 2023 Los Angeles Basin
- 2024 upper Paleozoic of the Wind River Basin, Bighorn Basin, and Powder River B…
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
Below are a list of recent assessment areas. You can also use the National Oil and Gas Assessment Map to browse these assessments.
Alaska Petroleum Systems
Appalachian Basin Oil and Gas Assessments
Permian Basin Oil and Gas Assessments
Montana Thrust Belt Oil and Gas Assessments
Raton Basin-Sierra Grande Uplift Oil and Gas Assessments
Southwestern Wyoming Oil and Gas Assessments
Powder River Basin Oil and Gas Assessments
Uinta-Piceance Basin Oil and Gas Assessments
Williston Basin Oil and Gas Assessments
Anadarko Basin Oil and Gas Assessments
Wind River Basin Oil and Gas Assessments
Eastern Basins Oil and Gas Assessments
Below are FAQ associated with this project.
What are the different columns on a USGS oil and gas resource assessment table? What are the different columns on a USGS oil and gas resource assessment table?
Oil and gas estimates always involve some amounts of uncertainty. To account for this, the USGS presents its assessments of oil and gas potential in the form of a range based on how certain we are that this amount of oil and gas exist. The USGS uses a statistically based process (or model) to calculate the likely range of its estimates. The range of values extends from a 5% or greater likelihood...
What are "technically recoverable" oil and gas resources? 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 technically recoverable. Learn more: USGS Energy Assessments
Why do the oil and gas resource numbers sometimes change when the USGS releases a new assessment of an oil and gas formation? Why do the oil and gas resource numbers sometimes change when the USGS releases a new assessment of an oil and gas formation?
Assessments regularly change based on our understanding of geology, as well as advances in technology. As more is learned about the geology of a given formation, both from USGS research and from industry activity, a clearer picture of the potential recoverable oil and gas resources can be created. In some cases, industry activity can show that a rock formation that was previous thought to have...
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).
Assessment 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.
Recent Assessments
Below are the latest US Assessments:
- 2025 Federal Lands of the Onshore United States
- 2024 Upper Cretaceous Niobrara Formation
- 2024 Mowry Composite Total Petroleum Systems
- 2024 Hosston and Travis Peak Formations
- 2023 Escondido, Olmos, and San Miguel Formations of the Western Gulf Basin Prov…
- 2023 Los Angeles Basin
- 2024 upper Paleozoic of the Wind River Basin, Bighorn Basin, and Powder River B…
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
Below are a list of recent assessment areas. You can also use the National Oil and Gas Assessment Map to browse these assessments.
Alaska Petroleum Systems
Appalachian Basin Oil and Gas Assessments
Permian Basin Oil and Gas Assessments
Montana Thrust Belt Oil and Gas Assessments
Raton Basin-Sierra Grande Uplift Oil and Gas Assessments
Southwestern Wyoming Oil and Gas Assessments
Powder River Basin Oil and Gas Assessments
Uinta-Piceance Basin Oil and Gas Assessments
Williston Basin Oil and Gas Assessments
Anadarko Basin Oil and Gas Assessments
Wind River Basin Oil and Gas Assessments
Eastern Basins Oil and Gas Assessments
Below are FAQ associated with this project.
What are the different columns on a USGS oil and gas resource assessment table? What are the different columns on a USGS oil and gas resource assessment table?
Oil and gas estimates always involve some amounts of uncertainty. To account for this, the USGS presents its assessments of oil and gas potential in the form of a range based on how certain we are that this amount of oil and gas exist. The USGS uses a statistically based process (or model) to calculate the likely range of its estimates. The range of values extends from a 5% or greater likelihood...
What are "technically recoverable" oil and gas resources? 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 technically recoverable. Learn more: USGS Energy Assessments
Why do the oil and gas resource numbers sometimes change when the USGS releases a new assessment of an oil and gas formation? Why do the oil and gas resource numbers sometimes change when the USGS releases a new assessment of an oil and gas formation?
Assessments regularly change based on our understanding of geology, as well as advances in technology. As more is learned about the geology of a given formation, both from USGS research and from industry activity, a clearer picture of the potential recoverable oil and gas resources can be created. In some cases, industry activity can show that a rock formation that was previous thought to have...