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United States Assessments of Undiscovered Oil and Gas Resources

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By Central Energy Resources Science Center August 6, 2024

Explore US Undiscovered Oil and Gas Assessment Provinces

Assessment results, publications, data and more are available

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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

Image shows a map of the assessment units of the 2018 Delaware Basin oil and gas assessment

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

Interactive map and chart highlighting USGS Domestic Continuous (Unconventional) Oil & Gas Assessments, 2000-Present

This applications shows maps and tables of all continuous assessments in the United States.

Click here to launch

Recent Assessments

Below are the latest US Assessments:

Browse Assessments

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

American Association of Petroleum Geologists Committee on Resource Evaluation (CORE) Subcommittee to review the United States Onshore Continuous (Unconventional) Gas Assessment Methodology Used by the USGS

 

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

American Association of Petroleum Geologists Committee on Resource Evaluation (CORE) Subcommittee to review the Growth-to-Known Reserves

 

Below are a list of recent assessment areas.  You can also use the National Oil and Gas Assessment Map to browse these assessments.

Filter Total Items: 59

Below are datasets related to the National Oil and Gas Assessments.  

Legacy downloadable data
Filter Total Items: 46
No Result Found

Below are publications associated with this project.

Filter Total Items: 98

Upper Devonian–Mississippian stratigraphic framework of the Arkoma Basin and distribution of potential source-rock facies in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems

Wireline logs were used to document the stratigraphic framework of Upper Devonian–Mississippian strata in the Arkoma Basin, and maps of high-gamma ray (HGR) log response were used to analyze the spatial distribution of potential source rocks in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems. The Woodford–Chattanooga shale is a transgressive deposit that accumulated on an arid co
Authors
David W. Houseknecht, William A. Rouse, Stanley T. Paxton, John C. Mars, Bryant R. Fulk
By
Energy Resources Program, Geology, Energy & Minerals Science Center

4D petroleum system model of the Mississippian System in the Anadarko Basin Province, Oklahoma, Kansas, Texas, and Colorado, U.S.A.

The Upper Devonian and Lower Mississippian Woodford Shale is an important petroleum source rock for Mississippian reservoirs in the Anadarko Basin Province of Oklahoma, Kansas, Texas, and Colorado, based on results from a 4D petroleum system model of the basin. The Woodford Shale underlies Mississippian strata over most of the Anadarko Basin portions of Oklahoma and northeastern Texas. The Kansas
Authors
Debra K. Higley
By
Energy Resources Program, Central Energy Resources Science Center

Assessment of undiscovered technically recoverable oil and gas resources of Puerto Rico and the Puerto Rico-U.S. Virgin Islands Exclusive Economic Zone, 2013

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 19 million barrels of undiscovered, technically recoverable oil and 244 billion cubic feet of undiscovered natural gas in the Puerto Rico–U.S. Virgin Islands Exclusive Economic Zone.
Authors
Christopher J. Schenk, Ronald R. Charpentier, Timothy R. Klett, Stephanie B. Gaswirth, Janet K. Pitman, Michael E. Brownfield, Tracey J. Mercier, Craig J. Wandrey, Jean N. Weaver
By
Energy Resources Program, Central Energy Resources Science Center

Petroleum system analysis of the Hunton Group in West Edmond field, Oklahoma

West Edmond field, located in central Oklahoma, is one of the largest oil accumulations in the Silurian–Devonian Hunton Group in this part of the Anadarko Basin. Production from all stratigraphic units in the field exceeds 170 million barrels of oil (MMBO) and 400 billion cubic feet of gas (BCFG), of which approximately 60 MMBO and 100 BCFG have been produced from the Hunton Group. Oil and gas are
Authors
Stephanie B. Gaswirth, Debra K. Higley
By
Energy Resources Program

Reserve growth of oil and gas fields—Investigations and applications

The reserve growth of fields has been a topic for ongoing discussion for over half a century and will continue to be studied well into the future. This is due to the expected size of the volumetric contribution of reserve growth to the future supply of oil and natural gas. Understanding past methods of estimating future volumes based on the data assembly methods that have been used can lead to a b
Authors
Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Procedure for calculating estimated ultimate recoveries of Bakken and Three Forks Formations horizontal wells in the Williston Basin

Estimated ultimate recoveries (EURs) are a key component in determining productivity of wells in continuous-type oil and gas reservoirs. EURs form the foundation of a well-performance-based assessment methodology initially developed by the U.S. Geological Survey (USGS; Schmoker, 1999). This methodology was formally reviewed by the American Association of Petroleum Geologists Committee on Resource
Authors
Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Assessment of undiscovered oil resources in the Bakken and Three Forks Formations, Williston Basin Province, Montana, North Dakota, and South Dakota, 2013

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered volumes of 7.4 billion barrels of oil, 6.7 trillion cubic feet of associated/dissolved natural gas, and 0.53 billion barrels of natural gas liquids in the Bakken and Three Forks Formations in the Williston Basin Province of Montana, North Dakota, and South Dakota.
Authors
Stephanie B. Gaswirth, Kristen R. Marra, Troy A. Cook, Ronald R. Charpentier, Donald L. Gautier, Debra K. Higley, Timothy R. Klett, Michael D. Lewan, Paul G. Lillis, Christopher J. Schenk, Marilyn E. Tennyson, Katherine J. Whidden
By
Energy Resources Program, Central Energy Resources Science Center

Input-form data for the U.S. Geological Survey assessment of the Devonian and Mississippian Bakken and Devonian Three Forks Formations of the U.S. Williston Basin Province, 2013

In 2013, the U.S. Geological Survey assessed the technically recoverable oil and gas resources of the Bakken and Three Forks Formations of the U.S. portion of the Williston Basin. The Bakken and Three Forks Formations were assessed as continuous and hypothetical conventional oil accumulations using a methodology similar to that used in the assessment of other continuous- and conventional-type asse
Authors
Stephanie B. Gaswirth, Kristen R. Marra, Troy A. Cook, Ronald R. Charpentier, Donald L. Gautier, Debra K. Higley, Timothy R. Klett, Michael D. Lewan, Paul G. Lillis, Christopher J. Schenk, Marilyn E. Tennyson, Katherine J. Whidden
By
Energy Resources Program, Central Energy Resources Science Center

Map of assessed shale gas in the United States, 2012

The U.S. Geological Survey has compiled a map of shale-gas assessments in the United States that were completed by 2012 as part of the National Assessment of Oil and Gas Project. Using a geology-based assessment methodology, the U.S. Geological Survey quantitatively estimated potential volumes of undiscovered gas within shale-gas assessment units. These shale-gas assessment units are mapped, and s
Authors
Laura R. H. Biewick
By
Energy Resources Program, Central Energy Resources Science Center

Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado

In 2002, the U.S. Geological Survey (USGS) estimated undiscovered oil and gas resources that have the potential for additions to reserves in the San Juan Basin Province, New Mexico and Colorado. Paleozoic rocks were not appraised. The last oil and gas assessment for the province was in 1995. There are several important differences between the 1995 and 2002 assessments. The area assessed is smaller
Authors
By
Energy Resources Program

Variability of oil and gas well productivities for continuous (unconventional) petroleum accumulations

Over the last decade, oil and gas well productivities were estimated using decline-curve analysis for thousands of wells as part of U.S. Geological Survey (USGS) studies of continuous (unconventional) oil and gas resources in the United States. The estimated ultimate recoveries (EURs) of these wells show great variability that was analyzed at three scales: within an assessment unit (AU), among AUs
Authors
Ronald R. Charpentier, Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Controls on the deposition and preservation of the Cretaceous Mowry Shale and Frontier Formation and equivalents, Rocky Mountain region, Colorado, Utah, and Wyoming

Regional variations in thickness and facies of clastic sediments are controlled by geographic location within a foreland basin. Preservation of facies is dependent on the original accommodation space available during deposition and ultimately by tectonic modification of the foreland in its postthrusting stages. The preservation of facies within the foreland basin and during the modification stage
Authors
Mark A. Kirschbaum, Tracey J. Mercier
By
Energy Resources Program, Central Energy Resources Science Center

Below are datasets related to the National Oil and Gas Assessments.  

Below are news stories associated with this project.

Below are FAQ associated with this project.

Below are partners associated with this project.

Bureau of Land Management (BLM)

Bureau of Ocean Energy Management (BOEM)

U.S. Department of Energy (DOE)

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

Image shows a map of the assessment units of the 2018 Delaware Basin oil and gas assessment

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

Interactive map and chart highlighting USGS Domestic Continuous (Unconventional) Oil & Gas Assessments, 2000-Present

This applications shows maps and tables of all continuous assessments in the United States.

Click here to launch

Recent Assessments

Below are the latest US Assessments:

Browse Assessments

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

American Association of Petroleum Geologists Committee on Resource Evaluation (CORE) Subcommittee to review the United States Onshore Continuous (Unconventional) Gas Assessment Methodology Used by the USGS

 

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

American Association of Petroleum Geologists Committee on Resource Evaluation (CORE) Subcommittee to review the Growth-to-Known Reserves

 

Below are a list of recent assessment areas.  You can also use the National Oil and Gas Assessment Map to browse these assessments.

Filter Total Items: 59

Below are datasets related to the National Oil and Gas Assessments.  

Legacy downloadable data
Filter Total Items: 46
No Result Found

Below are publications associated with this project.

Filter Total Items: 98

Upper Devonian–Mississippian stratigraphic framework of the Arkoma Basin and distribution of potential source-rock facies in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems

Wireline logs were used to document the stratigraphic framework of Upper Devonian–Mississippian strata in the Arkoma Basin, and maps of high-gamma ray (HGR) log response were used to analyze the spatial distribution of potential source rocks in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems. The Woodford–Chattanooga shale is a transgressive deposit that accumulated on an arid co
Authors
David W. Houseknecht, William A. Rouse, Stanley T. Paxton, John C. Mars, Bryant R. Fulk
By
Energy Resources Program, Geology, Energy & Minerals Science Center

4D petroleum system model of the Mississippian System in the Anadarko Basin Province, Oklahoma, Kansas, Texas, and Colorado, U.S.A.

The Upper Devonian and Lower Mississippian Woodford Shale is an important petroleum source rock for Mississippian reservoirs in the Anadarko Basin Province of Oklahoma, Kansas, Texas, and Colorado, based on results from a 4D petroleum system model of the basin. The Woodford Shale underlies Mississippian strata over most of the Anadarko Basin portions of Oklahoma and northeastern Texas. The Kansas
Authors
Debra K. Higley
By
Energy Resources Program, Central Energy Resources Science Center

Assessment of undiscovered technically recoverable oil and gas resources of Puerto Rico and the Puerto Rico-U.S. Virgin Islands Exclusive Economic Zone, 2013

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 19 million barrels of undiscovered, technically recoverable oil and 244 billion cubic feet of undiscovered natural gas in the Puerto Rico–U.S. Virgin Islands Exclusive Economic Zone.
Authors
Christopher J. Schenk, Ronald R. Charpentier, Timothy R. Klett, Stephanie B. Gaswirth, Janet K. Pitman, Michael E. Brownfield, Tracey J. Mercier, Craig J. Wandrey, Jean N. Weaver
By
Energy Resources Program, Central Energy Resources Science Center

Petroleum system analysis of the Hunton Group in West Edmond field, Oklahoma

West Edmond field, located in central Oklahoma, is one of the largest oil accumulations in the Silurian–Devonian Hunton Group in this part of the Anadarko Basin. Production from all stratigraphic units in the field exceeds 170 million barrels of oil (MMBO) and 400 billion cubic feet of gas (BCFG), of which approximately 60 MMBO and 100 BCFG have been produced from the Hunton Group. Oil and gas are
Authors
Stephanie B. Gaswirth, Debra K. Higley
By
Energy Resources Program

Reserve growth of oil and gas fields—Investigations and applications

The reserve growth of fields has been a topic for ongoing discussion for over half a century and will continue to be studied well into the future. This is due to the expected size of the volumetric contribution of reserve growth to the future supply of oil and natural gas. Understanding past methods of estimating future volumes based on the data assembly methods that have been used can lead to a b
Authors
Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Procedure for calculating estimated ultimate recoveries of Bakken and Three Forks Formations horizontal wells in the Williston Basin

Estimated ultimate recoveries (EURs) are a key component in determining productivity of wells in continuous-type oil and gas reservoirs. EURs form the foundation of a well-performance-based assessment methodology initially developed by the U.S. Geological Survey (USGS; Schmoker, 1999). This methodology was formally reviewed by the American Association of Petroleum Geologists Committee on Resource
Authors
Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Assessment of undiscovered oil resources in the Bakken and Three Forks Formations, Williston Basin Province, Montana, North Dakota, and South Dakota, 2013

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered volumes of 7.4 billion barrels of oil, 6.7 trillion cubic feet of associated/dissolved natural gas, and 0.53 billion barrels of natural gas liquids in the Bakken and Three Forks Formations in the Williston Basin Province of Montana, North Dakota, and South Dakota.
Authors
Stephanie B. Gaswirth, Kristen R. Marra, Troy A. Cook, Ronald R. Charpentier, Donald L. Gautier, Debra K. Higley, Timothy R. Klett, Michael D. Lewan, Paul G. Lillis, Christopher J. Schenk, Marilyn E. Tennyson, Katherine J. Whidden
By
Energy Resources Program, Central Energy Resources Science Center

Input-form data for the U.S. Geological Survey assessment of the Devonian and Mississippian Bakken and Devonian Three Forks Formations of the U.S. Williston Basin Province, 2013

In 2013, the U.S. Geological Survey assessed the technically recoverable oil and gas resources of the Bakken and Three Forks Formations of the U.S. portion of the Williston Basin. The Bakken and Three Forks Formations were assessed as continuous and hypothetical conventional oil accumulations using a methodology similar to that used in the assessment of other continuous- and conventional-type asse
Authors
Stephanie B. Gaswirth, Kristen R. Marra, Troy A. Cook, Ronald R. Charpentier, Donald L. Gautier, Debra K. Higley, Timothy R. Klett, Michael D. Lewan, Paul G. Lillis, Christopher J. Schenk, Marilyn E. Tennyson, Katherine J. Whidden
By
Energy Resources Program, Central Energy Resources Science Center

Map of assessed shale gas in the United States, 2012

The U.S. Geological Survey has compiled a map of shale-gas assessments in the United States that were completed by 2012 as part of the National Assessment of Oil and Gas Project. Using a geology-based assessment methodology, the U.S. Geological Survey quantitatively estimated potential volumes of undiscovered gas within shale-gas assessment units. These shale-gas assessment units are mapped, and s
Authors
Laura R. H. Biewick
By
Energy Resources Program, Central Energy Resources Science Center

Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado

In 2002, the U.S. Geological Survey (USGS) estimated undiscovered oil and gas resources that have the potential for additions to reserves in the San Juan Basin Province, New Mexico and Colorado. Paleozoic rocks were not appraised. The last oil and gas assessment for the province was in 1995. There are several important differences between the 1995 and 2002 assessments. The area assessed is smaller
Authors
By
Energy Resources Program

Variability of oil and gas well productivities for continuous (unconventional) petroleum accumulations

Over the last decade, oil and gas well productivities were estimated using decline-curve analysis for thousands of wells as part of U.S. Geological Survey (USGS) studies of continuous (unconventional) oil and gas resources in the United States. The estimated ultimate recoveries (EURs) of these wells show great variability that was analyzed at three scales: within an assessment unit (AU), among AUs
Authors
Ronald R. Charpentier, Troy A. Cook
By
Energy Resources Program, Central Energy Resources Science Center

Controls on the deposition and preservation of the Cretaceous Mowry Shale and Frontier Formation and equivalents, Rocky Mountain region, Colorado, Utah, and Wyoming

Regional variations in thickness and facies of clastic sediments are controlled by geographic location within a foreland basin. Preservation of facies is dependent on the original accommodation space available during deposition and ultimately by tectonic modification of the foreland in its postthrusting stages. The preservation of facies within the foreland basin and during the modification stage
Authors
Mark A. Kirschbaum, Tracey J. Mercier
By
Energy Resources Program, Central Energy Resources Science Center

Below are datasets related to the National Oil and Gas Assessments.  

Below are news stories associated with this project.

Below are FAQ associated with this project.

Below are partners associated with this project.

Bureau of Land Management (BLM)

Bureau of Ocean Energy Management (BOEM)

U.S. Department of Energy (DOE)

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