Detroit

Los Angeles

Chicago

Atlanta

Dallas

New York City

Boston

Houston

Washington

Miami

Philadelphia

Denver

San Jose

Seattle

Cleveland

Baltimore

Saint Louis

Tulsa

Phoenix San Diego

Pittsburgh

Kansas City

Portland

Indianapolis

Buffalo

Akron

Milwaukee

Camden Sacramento

Flint

Richmond

Memphis

Omaha

Oakland

Dayton

Nashville

MinneapolisSaint Paul

Cincinnati

San Antonio

Tampa

Rochester

Columbus

Wichita

Birmingham

Toledo

Fort

Worth

Tucson

Concord

Louisville

Norfolk

Hartford

Orlando

Spokane

Charlotte

Tacoma

Oklahoma

City

Eugene

Knoxville

Sarasota

Lansing

Jackson

Jacksonville

Marietta

Austin

Salt Lake City

Springfield

Providence

Clearwater

New Orleans

Las Vegas

Trenton

Pensacola

Albuquerque

Augusta

Winston-Salem

Roanoke

Baton Rouge

Mobile

Syracuse

Youngstown

Huntsville

Chattanooga

El Paso

Greenville

Fort Wayne

Fort LauderdaleWest Palm Beach

Grand

Rapids

Duluth

Vancouver

Covington

Little Rock

Newport NewsHampton

Cocoa

Beach

TEXAS

UTAH

MONTANA

NEVADA

CALIFORNIA

IDAHO

ARIZONA

OREGON

IOWA

KANSAS

WYOMING

NEW MEXICO

COLORADO

OHIO

MISSOURI

NEBRASKA

MINNESOTA

ILLINOIS

GEORGIA

FLORIDA

OKLAHOMA

ALABAMA

WISCONSIN

WASHINGTON

SOUTH DAKOTA

ARKANSAS

MAINE NORTH DAKOTA

NEW YORK

VIRGINIA

MISSISSIPPI

LOUISIANA

INDIANA

MICHIGAN

TENNESSEE

KENTUCKY

PENNSYLVANIA

NORTH CAROLINA

SOUTH CAROLINA

WEST

VIRGINIA

VERMONT

MASSACHUSETTS

MARYLAND

NEW JERSEY

NEW

HAMPSHIRE

CONNECTICUT

PUERTO RICO

DELAWARE

RHODE ISLAND

U.S. VIRGIN

ISLANDS

HAITI

THE

BAHAMAS

DOMINICAN

REPUBLIC

CUBA

Williston Basin Province

7.38 BBO

Appalachian Basin Province

0.94 BBO

Powder River Basin Province

0.42 BBO

Uinta-Piceance Basin Province

0.04 BBO

Gulf Coast Region

1.73 BBO

Montana Thrust Belt Province

0.03 BBO

Southwestern Wyoming Province

0.10 BBO

Paradox Basin Province

0.47 BBO

Anadarko Basin Province

0.39 BBO

Denver Basin Province

0.04 BBO

Bighorn Basin Province

0.005 BBO

Permian Basin Province

0.51 BBO

Hanna Basin

0.04 BBO

130° 125° 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 70°

50°

45°

40°

35°

30°

25°

20°

15°

10°

45°

40°

35°

30°

25°

20°

15°

10°

145° 140° 135° 130° 125° 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 70° 65° 60° 55°

Northern Alaska Province

0.94 BBO

155°

155° 140° 135°

145°

145°

150°

150°

160°

160°

165°

180° 175° 170° 165°

70°

70°

65°

65°

60°

60°

55°

55°

Fractured Niobrara Limestone

(Silo Field Area) AU

Niobrara-Codell

(Wattenberg Area) AU

Niobrara Continuous-Oil AU

Niobrara

Continuous-Oil AU

Mowry Fractured Shale

Continuous-Oil AU

Deep Uinta Overpressured

Continuous-Oil AU

Gothic, Chimney Rock,

Hovenweep Shale-Oil AU

Cane Creek

Shale-OIl AU

Shublik Continuous-Oil AU

Brookian Continuous-Oil AU

Kingak Continuous-Oil AU

Marias River Shale

Continuous-Oil AU

Niobrara Continuous-Oil AU

Mowry Continuous-Oil AU

Elm Coulee–Billings Nose

Continuous-Oil AU

Central Basin

Continuous-Oil AU

Nesson–Little Knife Continuous-Oil AU

Eastern Transitional

Continuous-Oil AU

Northwest Transitional

Continuous-Oil AU

Three Forks

Continuous-Oil AU

Utica Shale-Oil AU

Eagle Ford Shale-Oil AU

Austin Pearsall-Giddings Area Oil AU

Woodford Shale-Oil AU

Spraberry

Continuous-Oil AU

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 30 60 MILES

0 30 60 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

ALASKA

Anadarko Basin Province

Gulf Coast Region 

Appalachian Basin Province

Williston Basin Province

Powder River Basin Province

Montana Thrust Belt Province

Northern Alaska Province

Paradox Basin Province

Uinta-Piceance Basin Province

Southwestern Wyoming Province Hanna Basin Bighorn Basin Province

Denver Basin Province

Permian Basin Province

100 0 100 200 300 400 500 MILES

100 0 100 200 300 400 500 600 700 KILOMETERS

0 50 100 MILES

0 50 100 KILOMETERS

UNITED STATES

Abstract

The U.S. Geological Survey (USGS) conducts quantitative 

assessments of potential oil and gas resources of the 

onshore United States and associated coastal State waters. 

Since 2000, the USGS has completed assessments of 

continuous (unconventional) resources in the United States 

based on geologic studies and analysis of well-production 

data and has compiled digital maps of the assessment units 

classified into four categories: shale gas, tight gas, coalbed 

gas, and shale oil or tight oil (continuous oil). This is the 

fourth digital map product in a series of USGS 

unconventional oil and gas resource maps; its focus being 

shale-oil or tight-oil (continuous-oil) assessments. The map 

plate included in this report can be printed in hardcopy form 

or downloaded in a Geographic Information System (GIS) 

data package, which includes an ArcGIS ArcMap document 

(.mxd), geodatabase (.gdb), and a published map file (.pmf). 

Supporting geologic studies of total petroleum systems and 

assessment units, as well as studies of the methodology 

used in the assessment of continuous-oil resources in the 

United States, are listed with hyperlinks in table 1. 

Access to Report

This entire publication is available online at the USGS web site:

http:/pubs.usgs.gov/dds/dds-069/dds-069-jj/ or http://dx.doi.org/10.3133/ds69jj

and on CD-ROM by contacting:

eteamdisks@usgs.gov.

Access to Assessment Results

Comprehensive geologic studies, supporting data, and reports on the 

methodology used in assessing undiscovered oil and gas resources in the United 

States are available at the USGS Central Energy Resources Science Center website: 

http://energy.usgs.gov/OilGas/AssessmentsData/NationalOilGasAssessment.aspx

Project Chief: Christopher J. Schenk

Mean Continuous-Oil Resource Estimates—

Undiscovered, technically recoverable

billion barrels of oil (BBO)

7.5

5

2.5

1

0.5

0.1

0.05

0.01

Continuous (unconventional) Oil Assessment Units—

Merged on contiguous U.S. map. On inset maps,

outlined and labeled with green text in a light green

background.

Explanation

PACIFIC OCEAN

ATLANTIC OCEAN

Gulf of Mexico

MEXICO

CANADA

Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

By

U.S. Geological Survey National Assessment of Oil and Gas Resources Team, 

and Laura R.H. Biewick, compiler

2015

Shaded relief from U.S. Geological Survey, The National Map, published 2007 at http://nationalmap.gov/

Bathymetry from ETOPO1, NOAA Technical Memorandum

NESDIS NGDC–24 (Amante and Eakins, 2009)

Albers Equal Area Conic Projection, Central Meridian: -96.0

Standard Parallel 1: 29.5, Standard Parallel 2: 45.5

Latitude of origin: 23.0

Datum: North American Datum 1983

Any use of trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also contains 

copyrighted materials as noted in the text. Permission to reproduce copyrighted items must 

be secured from the copyright owner.

This database, identified as DDS 69–JJ, has been approved for release and publication by 

the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous 

review and is substantially complete, the USGS reserves the right to revise the data 

pursuant to further analysis and review. Furthermore, it is released on condition that neither 

the USGS nor the U.S. Government may be held liable for any damages resulting from its 

authorized or unauthorized use.

For more information concerning this publication, contact:

Center Director, USGS Central Energy Resources Science Center

Box 25046, Mail Stop 939

(303) 236-1647

Or visit the Central Energy Resources Science Center Web site at:

http://energy.usgs.gov/

Publishing support provided by: 

Denver Publishing Service Center

Edit and digital layout by L.J. Binder

Manuscript approved for publication Jamuary 15, 2015

To learn about the USGS and its information products visit

http://www.usgs.gov/ 

1-888-ASK-USGS

Suggested citation: U.S. Geological Survey National Assessment of Oil and 

Gas Resources Team, and Biewick, L.R.H., compiler, 2015, Map of assessed 

continuous (unconventional) oil resources in the United States, 2014: U.S. 

Geological Survey Digital Data Series 69–JJ, 12 p., 1 pl., GIS data package,

http://dx.doi.org/10.3133/ds69jj.

ISSN 2327-638X (online)

http://dx.doi.org/10.3133/ds69jj

Alaska Albers Equal Area Conic Projection

Central Meridian: -154.0

Standard Parallel 1: 55.0

Standard Parallel 2: 65.0

Latitude of origin: 50.0

Datum: North American Datum 1983

U.S. Department of the Interior

U.S. Geological Survey

Digital Data Series 69–JJ

Plate 1

U.S. Department of the Interior

U.S. Geological Survey

Digital Data Series 69–JJ

U.S. Geological Survey National Assessment of Oil and Gas Resources Project

Map of Assessed Continuous (Unconventional) 

Oil Resources in the United States, 2014
Cover. Basal Boquillas Limestone (Eagle Ford equivalent in west Texas), just above the contact with the Buda limestone, taken along US 90, 

approximately 4.1 miles north of the Pecos River US 90 Highway bridge. Photo by Jim Coleman (USGS).
Map of Assessed Continuous (Unconventional) 

Oil Resources in the United States, 2014

By U.S. Geological Survey National Assessment of Oil and Gas Resources Team, 

and Laura R.H. Biewick, compiler

U.S. Geological Survey National Assessment of Oil and Gas Resources Project

Digital Data Series 69–JJ

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

U.S. Geological Survey National Assessment of Oil and Gas Resources Team, and Biewick, L.R.H., compiler, 2015, 

Map of assessed continuous (unconventional) oil resources in the United States, 2014: U.S. Geological Survey Digital 

Data Series 69–JJ, 14 p., 1 pl., GIS data package, http://dx.doi.org/10.3133/ds069jj. 

ISSN 2327-638X (online)
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Synopsis of Continuous-Oil Assessments in the United States, 2013 .......................................................2

Williston Basin Province......................................................................................................................2

Gulf Coast Region..................................................................................................................................2

Northern Alaska Province...................................................................................................................3

Appalachian Basin Province ..............................................................................................................3

Permian Basin Province ......................................................................................................................3

Paradox Basin Province ......................................................................................................................4

Powder River Basin Province.............................................................................................................4

Anadarko Basin Province....................................................................................................................5

Southwestern Wyoming; Hanna, Laramie and Shirley Basins; and 

Denver Basin Provinces.........................................................................................................5

Uinta-Piceance Basin Province ........................................................................................................6

Montana Thrust Belt Province ...........................................................................................................6

Bighorn Basin Province.......................................................................................................................6

Digital Maps and Data...................................................................................................................................7

Summary..........................................................................................................................................................9

Acknowledgments.........................................................................................................................................9

References Cited............................................................................................................................................9

Figure

1. Map graphic links to the continuous-oil resources hardcopy map.....................................8

Table

1. Publication access table—Hyperlinks to USGS continuous-oil assessment

publications and web pages.................................................................................................. link

Plate

1. Map of assessed continuous (unconventional) oil resources in the

United States, 2014 .................................................................................................................. link
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

Area

square mile (mi2) 2.590 square kilometer (km2)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3)

barrel (bbl), petroleum,

1 barrel=42 gal.

0.1590 cubic meter (m3)

SI to Inch/Pound

Multiply By To obtain

Length

millimeter (mm) 0.3937 inch (in.)

Volume

cubic meter (m3) 35.31 cubic foot (ft3)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) +32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F–32)/ 1.8
Map of Assessed Continuous (Unconventional) 

Oil Resources in the United States, 2014

By U.S. Geological Survey National Assessment of Oil and Gas Resources Team, 

and Laura R.H. Biewick, compiler

Abstract

The U.S. Geological Survey (USGS) conducts 

quantitative assessments of potential oil and gas resources 

of the onshore United States and associated coastal State 

waters. Since 2000, the USGS has completed assessments of 

continuous (unconventional) resources in the United States 

based on geologic studies and analysis of well-production 

data and has compiled digital maps of the assessment units 

classified into four categories: shale gas, tight gas, coalbed 

gas, and shale oil or tight oil (continuous oil). This is the 

fourth digital map product in a series of USGS unconventional 

oil and gas resource maps; its focus being shale-oil or tight-oil 

(continuous-oil) assessments. The map plate included in this 

report can be printed in hardcopy form or downloaded in a 

Geographic Information System (GIS) data package, which 

includes an ArcGIS ArcMap document (.mxd), geodatabase 

(.gdb), and a published map file (.pmf). Supporting geologic 

studies of total petroleum systems and assessment units, as 

well as studies of the methodology used in the assessment of 

continuous-oil resources in the United States, are listed with 

hyperlinks in table 1. Assessment results and geologic reports 

are available at the USGS website http://energy.usgs.gov/

OilGas/AssessmentsData/NationalOilGasAssessment.aspx. 

Introduction

The U.S. Geological Survey (USGS) provides assessments of the oil and natural gas endowment of the United 

States (U.S.). Prioritized assessment results, as part of 

the Energy Policy and Conservation Act (EPCA) of 2000 

(Public Law 106-469, http://www.gpo.gov/fdsys/pkg/

PLAW-106publ469/html/PLAW-106publ469.htm) and the 

current National Oil and Gas Assessment, are available 

at the USGS Energy Resources Program website (U.S. 

Geological Survey, 2013). The assessments are based on the 

geologic elements and petroleum processes used to define 

a total petroleum system (TPS). An advantage of the total 

petroleum system approach is that by incorporating the 

assessment unit (AU) within a petroleum system, relations 

between elements and processes such as source rock, 

hydrocarbon generation, migration, and trapping units and 

mechanisms can be examined (Dubiel, 2003). Continuous-oil 

accumulations differ from conventional accumulations in 

that they are not significantly affected by hydrodynamics, 

there generally is no downdip oil/water contact, they are 

abnormally pressured, production is independent of structural 

closure, and conventional methods of assessing sizes and 

numbers of accumulations are not appropriate (Klett and 

others, 2000). The U.S. Geological Survey Oil and Gas 

Assessment Team (2012) describes estimated ultimate 

recovery (EUR) distributions that were calculated for each 

continuous (unconventional) AU, based on geologic studies 

and decline-curve analysis of well-production data from 

hundreds to thousands of wells per AU. Each AU was further 

subdivided into distributions of potential well-drainage areas. 

The EUR distribution used for each assessment calculation 

was specifically designed for undrilled well-drainage areas and 

for the productive capacities of those areas (U.S. Geological 

Survey Oil and Gas Assessment Team, 2012). Using this 

geologic and engineering framework, the USGS defined 

continuous-oil AUs in 14 geologic provinces that cover 

parts of 17 states. The provinces include: Northern Alaska; 

Uinta-Piceance Basin; Paradox Basin; Montana Thrust Belt; 

Hanna, Laramie and Shirley Basins; Williston Basin; Powder 

River Basin; Big Horn Basin; Southwestern Wyoming; 

Denver Basin; Permian Basin; Gulf Coast Basins; Anadarko 

Basin; and Appalachian Basin. The continuous-oil assessment 

units defined in these geologic provinces encompass parts of 

Alaska, Colorado, Utah, Arizona, New Mexico, Montana, 

Wyoming, North Dakota, Texas, Louisiana, Mississippi, 

Oklahoma, Kansas, Ohio, Pennsylvania, West Virginia, and 

New York (plate 1) and are described in detail by USGS 

investigators, as listed in table 1.
2 Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

Synopsis of Continuous-Oil Assessments

in the United States, 2013

The U.S. uses about 22 percent of total world petroleum consumption, at approximately 7.0 billion barrels 

(19.18 million barrels per day) of refined petroleum products 

and biofuels annually (Energy Information Administration, 

2012a). In 2012, the U.S. produced 11.1 million barrels 

per day (Energy Information Administration, 2012b). The 

Bakken region of North Dakota and Montana, in one of 

the largest oil-producing regions in the U.S., shows total 

wellhead output topping 1 million barrels of oil per day in 

January 2014 (Energy Information Administration, 2013). 

The following is a synopsis of geologic findings by the USGS 

scientists who assessed continuous-oil resources in the U.S. 

listed in descending order according to mean undiscovered, 

technically recoverable, continuous-oil resources. More 

detailed supporting geologic studies, referenced within, 

can be found at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Williston Basin Province (Gaswirth

and others, 2013)

Oil production from the Upper Devonian and Lower 

Mississippian Bakken Formation was discovered by Amerada 

Hess with the completion of the H.O. Bakken No.1 well in 

sec. 12, T. 157 N., R. 95 W., Williams County, North Dakota 

in 1951 (Nordquist, 1953; Johnson, 2001; Bottjer and others, 

2011). Robinson and others (2011) recognized that the ability 

to extract oil from the Bakken Formation at Elm Coulee field 

in eastern Montana as a transformative event. They explain 

that at Elm Coulee field a known oil resource was converted 

into reserves by the application of innovative horizontal 

drilling and completion technology (Robinson and others, 

2011). Within a few years, the discovery of the Parshall field at 

the eastern pinchout of the Bakken Formation in North Dakota 

took place, after which drilling expanded rapidly to the north 

and south and then to the west (Robinson and others, 2011). 

After more than 4,000 additional wells were drilled, providing 

significant geologic data about the Bakken and Three Forks 

Formations, Gaswirth and others (2013) updated and extended 

the 2008 USGS assessment of the Bakken Formation 

(Pollastro and others, 2008) and also assessed the Three Forks 

Formation. Four members of the Bakken Formation were 

described by Gaswirth and others (2013), including the upper 

and lower organic-rich black shales, which are the primary 

source rocks with present-day total organic carbon (TOC) 

values from <1 weight percent to 35 weight percent (Lillis, 

2013). The Three Forks Formation reaches a maximum thickness of 270 feet in the central portion of the basin (Bottjer and 

others, 2011) and is divided into lower and upper units, with 

variable oil saturations (Gaswirth and others, 2013). One of 

the most prolific onshore petroleum systems in the continental 

U.S., the Bakken and Three Forks Formations in the Williston 

Basin are the largest continuous oil accumulation assessed by 

the USGS to date (plate 1, and U.S. Geological Survey Oil and 

Gas Assessment Team, 2013). The Bakken petroleum system 

is a world-class petroleum resource representing the large 

upside to be gained by understanding unconventional petroleum systems (Stroud and Sonnenberg, 2011). In 2013, the 

USGS assessment of continuous-oil resources estimated mean 

undiscovered volumes of 7.38 billion barrels of oil (BBO), 

6.7 trillion cubic feet of associated natural gas (TCFG), and 

527 million barrels of natural gas liquids (MMBNGL) in the 

Bakken and Three Forks Formations in the Williston Basin 

Province of Montana and North Dakota (Gaswirth and others, 

2013). Supporting geologic studies of the Bakken and Three 

Forks Formations and the methodology used in the assessment are in progress, and can be found at the USGS Energy 

Resources Program website at http://energy.usgs.gov/OilGas/

AssessmentsData/NationalOilGasAssessment.aspx.

Gulf Coast Region (Dubiel and others, 2011)

One of the primary hydrocarbon-producing provinces 

of the U.S., and a major hydrocarbon-producing area of the 

world, is the Gulf of Mexico (Gulf Coast) region. Recent 

discoveries of continuous oil in the Gulf Coast region are 

some of the largest in the U.S. and have led to additional 

exploration throughout the onshore Gulf region. In 2010, the 

USGS completed an assessment of the undiscovered oil and 

gas resources in Jurassic and Cretaceous strata of the onshore 

areas and State waters of the Gulf Coast (Dubiel and others, 

2011). The USGS defined the Upper Jurassic−Cretaceous−

Tertiary Composite TPS and thirty-four defined AUs, with 

two AUs containing undiscovered, technically recoverable 

continuous oil in Upper Cretaceous strata. The continuous-oil 

resources reside in the Eagle Ford Shale and the Austin Chalk 

in Texas, and the marine shale of the Tuscaloosa Formation in 

Louisiana (Dubiel and others, 2012; Pearson, 2012). The Eagle 

Ford Shale is a dominant source rock in the onshore Gulf 

region, and Dubiel and others (2012) defined the continuous 

Eagle Ford Shale-Oil AU by thermal maturity values within 

the Eagle Ford Shale and the Tuscaloosa marine shale ranging 

from 0.6 to 1.2 percent vitrinite reflectance (Ro ). The Upper 

Cretaceous Austin Chalk is a historically well-known onshore 

oil and gas play that extends across south-central Texas into 

southern Louisiana. Pearson (2012) found that chalk of the 

Austin Pearsall–Giddings Area Oil AU produces oil and gas 

in a continuous reservoir, and traditional trap styles such as 

anticlines and faults are not essential for the accumulation 

and production of oil and gas. Pearson and others (2011) 

recognized that the underlying Upper Cretaceous Eagle Ford 

Shale is the principal source rock for Austin Chalk production. 

They noted that a continuous classification is common for 
Synopsis of Continuous-Oil Assessmentsin the United States, 2013 3

reservoirs like the Austin because the extremely low matrix 

porosity and permeability provide a means for trapping oil 

and gas accumulations that have diffuse boundaries and lack 

obvious traps and seals (Pearson, 2012). The USGS assessment of continuous-oil resources in Cretaceous strata of the 

Gulf Coast region estimated a mean of 1.73 BBO, 3 TCFG, 

and 140 MMBNGL (Dubiel and others, 2011; Pearson and 

others, 2011; Dubiel and others, 2012). Supporting geologic 

studies of the Gulf Coast region assessments are in progress, 

and 2010 assessment results of Jurassic and Cretaceous 

strata of the Gulf Coast are available at the USGS Energy 

Resources Program website at http://energy.usgs.gov/OilGas/

AssessmentsData/NationalOilGasAssessment.aspx.

Northern Alaska Province (Houseknecht 

and others, 2012)

The Northern Alaska Province encompasses the Alaska 

North Slope, which is one of the remaining petroleum exploration frontiers. It is geologically complex having evolved 

through the tectonic stages of passive margin, rift, foreland 

basin, and foreland fold and thrust belt (Schenk and others, 

2011). Houseknecht and others (2012) describe the potential 

for unconventional oil and gas resources in three North Slope 

source rocks including the: (1) informal Brookian shale 

(Cretaceous), (2) Kingak Shale (Jurassic and Cretaceous), 

and (3) Shublik Formation (Triassic). Houseknecht and 

others (2012) recognized that each of these stratigraphic 

units generated oil and gas that migrated into conventional 

accumulations, and that all three likely retained oil and gas. 

Houseknecht and others (2012) explain how the Alaska 

North Slope assessment represents an unexplored frontier for 

shale-oil and shale-gas resources, in that no attempt has been 

made to produce oil or gas directly from the source rocks. The 

presence of brittle lithologies in which natural fractures are 

common in both the Shublik and Brookian source rocks is an 

important consideration. The Kingak, however, is mostly clayrich shale. Because of the large range of uncertainty associated 

with estimating undiscovered, continuous-oil resources in 

these source rocks, Houseknecht and others (2012) used 

shale-oil and shale-gas formations in the lower 48 states as 

geologic and engineering analogs to define assessment units, 

and emphasized the 95- to 5-percent probability range in 

their estimates of shale-oil resources in northern Alaska. The 

USGS estimates of potential, technically recoverable shale-oil 

resources in northern Alaska range from zero to 2 BBO, 

from zero to 3.2 TCFG, and from zero to 83 MMBNGL 

(Houseknecht and others, 2012). Supporting reports on 

geology and methodology used in the Alaska North Slope 

assessment are in progress. Assessment results and related 

reports are available at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Appalachian Basin Province (Kirschbaum

and others, 2012)

The Utica–Lower Paleozoic TPS was identified in 

the 2002 USGS assessment of undiscovered, technically 

recoverable oil and gas resources in the Appalachian Basin 

province (Milici and others, 2003). The Utica Shale and 

equivalent units of thin black shale in the uppermost part of 

the Trenton Limestone (Group) are the primary source rocks 

in the Utica-Lower Paleozoic TPS (Ryder, 2008). In 2012, 

the USGS assessed unconventional oil and gas resources of 

the Middle and Upper Ordovician Utica Shale and adjacent 

units in the Appalachian Basin Province (Kirschbaum 

and others, 2012). Kirschbaum and others (2012) defined 

the Utica Shale-Oil AU as the area south of the United 

States–Canadian border where oil was generated and occupies 

matrix porosity and organic porosity in the Utica Shale and 

adjacent organic-rich shale. The thermal window for oil 

was based on a conodont alteration index (CAI) between 

1 and 2 (Repetski and others, 2008) and TOC content greater 

than 1 weight percent (Wallace and Roen, 1989; Ryder, 

2008) in the area north of where the shale changes facies 

into carbonates (Kirschbaum and others, 2012). The Utica 

has little history of production, therefore Kirschbaum and 

others (2012) supplemented production data with analog data 

from the Devonian Marcellus Shale, Cretaceous Eagle Ford 

Shale, and Cretaceous Niobrara Formation. The assessed 

undiscovered, technically recoverable continuous oil resources 

for the Utica Shale-Oil AU, which contains the Ordovician 

Utica Shale and black shales of the Point Pleasant Shale of the 

Appalachian Basin Province resulted in estimated volumes 

ranging from 0.6 to 1.39 BBO, with an estimated mean 

continuous oil resource of 0.94 BBO, a mean of 0.94 TCFG, 

and a mean of 9 MMBNGL; (see Kirschbaum and others, 

2012). Supporting geologic studies of the Utica Shale and 

assessment units, and reports on the assessment methodology 

used, can be found at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx. 

Permian Basin Province (Schenk

and others, 2008)

The Permian Basin is a large structural basin filled 

with Paleozoic and younger sediments encompassing about 

82,000 square miles (mi2) in west Texas and southeastern New 

Mexico (Robinson, 1988). It acquired its present structural 

form by Early Permian time and was further accentuated by 

tectonic activity and downwarping during the Permian and 

Triassic Periods (Robinson, 1988). Permian rocks account 

for a large percentage of the oil and gas found in the Permian 

Basin. Robinson (1988) states that the fractured siltstone in 

the Spraberry Formation of the Midland Basin has a very 
4 Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

low recovery factor, although the volume of oil in-place is 

the largest of any single Permian pool. Handford (1981) 

recognized that thin black shales are widely distributed in the 

Spraberry-Dean system, and generally contain 1 to 3 percent 

TOC. Technologies like hydraulic fracturing and horizontal 

drilling have ignited new exploration in older plays like the 

Spraberry. Schenk and others (2008) defined the Paleozoic 

Composite Total Petroleum System, and assessed the undiscovered oil and gas potential of the Permian Basin Province 

of west Texas and southeastern New Mexico. For the first 

time, the USGS defined continuous assessment units in the 

Permian Basin Province including the Spraberry Continuous 

Oil AU in the Midland Basin. For undiscovered continuous oil 

resources, the estimated mean is 0.51 BBO, 258 BCFG, and 

26 MMBNGL (Schenk and others, 2008). Supporting geologic 

studies of the composite total petroleum system and assessment units, as well as the methodology used in the Permian 

Basin Province assessment are in progress. Assessment 

results are available at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Paradox Basin Province (Whidden, 2012)

The Paradox Basin is a tectonic depression in southeastern Utah, southwestern Colorado, northwestern New 

Mexico, and northeastern Arizona that formed during the 

Pennsylvanian Period in response to large intraplate stresses 

that have been attributed to the collision of Gondwana and 

Laurentia (Barbeau, 2003; Kluth and DuChene, 2009). 

The basin is generally defined by the geographic extent of 

halite deposited within the Middle Pennsylvanian Paradox 

Formation (Dubiel and others, 1996). The Paradox Basin 

began to subside in the Middle Pennsylvanian and is 

associated with uplift of the Uncompahgre Highlands of 

the Ancestral Rocky Mountains (Dubiel and others, 1996). 

As much as 9,000 ft of Middle and Upper Pennsylvanian 

evaporites, shale, and limestone, and at least 6,000 ft of 

Permian marine and continental strata are present in the basin 

(Dubiel and others, 1996). Nuccio and Condon (1996) found 

that the Ismay–Desert Creek interval and Cane Creek cycle 

of the Alkali Gulch interval of the Paradox Formation contain 

excellent organic-rich source rocks having TOC ranging from 

0.5 to 11.0 weight percent. The source rocks in both intervals 

contain Types I, II, and III kerogen and are potential source 

rocks for both oil and gas (Nuccio and Condon, 1996). In 

2011, the USGS defined the Paradox Formation TPS as hydrocarbons sourced from Middle Pennsylvanian (Desmoinesian) 

black dolomitic shales of the Paradox Formation (Whidden 

and others, 2012). Whidden and others (2012) described the 

interbedded salt and black shales that were deposited close to 

the northern margin of the basin along with clastics shed off 

the Uncompahgre uplift. Whidden and others (2012) explained 

that penesaline and normal-marine carbonates developed along 

the gently-dipping southwest basin margin and interfingered 

with the salt and black shales. Two continuous-oil AUs: (1) the 

Cane Creek Shale-Oil AU, and (2) the Gothic, Chimney Rock, 

Hovenweep Shale-Oil AU were defined as part of the Paradox 

Formation TPS. The shale-oil AUs in the Paradox Basin 

were assessed to contain mean undiscovered, technologically 

recoverable resources of 0.47 BBO, 398 BCFG, and 

31 MMBNGL (Whidden and others, 2012). Supporting studies 

of the geologic models and the methodology used in the 

2011 Paradox Basin assessment are in progress. Assessment 

results are available at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Powder River Basin Province (Anna

and others, 2006)

The USGS completed an assessment of the undiscovered 

oil and gas potential of the Powder River Basin (PRB) in 

2006, during which the Upper Cretaceous Mowry Shale 

and Niobrara Formation were identified as the primary 

hydrocarbon sources for Cretaceous conventional and 

unconventional reservoirs in the basin. The PRB, located in 

northeastern Wyoming and southeastern Montana, is one of 

many Rocky Mountain foreland basins that developed during 

the Laramide orogeny. The basin is asymmetric with the axis 

on the west side, where as much as 17,000 ft of sedimentary 

rock overlies the Precambrian basement (Anna and others, 

2009). Anna and others (2009) identified numerous structures 

observed at the surface that originated as faults, shear 

zones, or zones of weakness in the basement rocks during 

Precambrian time. These structural features were rejuvenated 

during the Laramide orogeny, and by periodic recurrent 

movement throughout the Phanerozoic. Most structures are 

oriented northwest-southeast and northeast-southwest, trends 

that probably influenced local and regional sedimentation 

patterns (Anna, 1986a, b). The Mowry Shale and the Niobrara 

Formation are self-contained petroleum systems. Anna and 

others (2009) reported TOC values for the Mowry Shale 

ranging from 2 to 4 weight percent near the middle of the 

formation, with Type II and Type III kerogen. The Niobrara 

Formation averages more than 3 weight percent TOC of 

Type II kerogen (Anna and others, 2009). Burial-history 

modeling by Anna and Cook (2008) indicated that hydrocarbon generation for both the Mowry Shale and the Niobrara 

Formation started at about 0.60 percent Ro at depths of about 

8,000 feet. At maximum depths, Ro for the Mowry is about 

1.2 to 1.3 percent and about 0.80 percent for the Niobrara. 

Anna and Cook (2008) defined overpressuring caused by 

hydrocarbon generation at an upper depth limit of 8,000 ft. 

Current and historical production data from unconventional 

fractured shale reservoirs with vertical wells were used to 

determine the EUR distribution for untested cells. Anna and 

Cook (2008) contended that horizontal drilling, state-of-the-art 
Synopsis of Continuous-Oil Assessmentsin the United States, 2013 5

completion practices, and comprehensive fracture and fault 

analysis might increase the Mowry and Niobrara EUR 

distribution analogous to the Permian Spraberry Formation 

EURs in the Permian Basin, Texas. Mean estimates of undiscovered, technically recoverable, continuous-oil resources 

in the Powder River Basin are 0.42 BBO, 424 BCFG, and 

25 MMBNGL (Anna and others, 2006). Supporting geologic 

studies and reports on the assessment method used in the 

Powder River Basin Province are available at the USGS 

Energy Resources Program website at http://energy.usgs.gov/

OilGas/AssessmentsData/NationalOilGasAssessment.aspx.

Anadarko Basin Province (Higley

and others, 2011)

The Upper Devonian and Lower Mississippian Woodford 

Shale is an important oil and gas shale in Oklahoma, southern 

Kansas, and northeastern Texas. It contains mainly Type II 

kerogen with up to 25 weight percent TOC content (Comer, 

1992; Johnson and Cardott, 1992; Roberts and Mitterer, 

1992). In addition to its excellent hydrocarbon source rock 

potential, the marine Woodford Shale is quartz-rich, which 

may enhance its reservoir potential (Cardott, 2012). Higley 

and others (2011) defined the Woodford Shale-Oil AU and 

areas where production characteristics are relatively favorable 

(sweet spots) based primarily on: (1) extent and thickness of 

the formation, (2) filling of underlying Hunton Formation 

eroded channels, (3) historical and estimated ultimate recoverable production from existing wells, and (4) levels of thermal 

maturation based on 1D, 2D, and 3D petroleum system models 

and on Ro maps and data. Higley’s (2011) petroleum system 

model of the Anadarko Basin shows source rocks across 

Kansas and Colorado are mostly immature for oil generation; 

thermal maturity in the deeper parts in Oklahoma and Texas 

range from mature to overmature for hydrocarbon generation. 

Higley (2011) showed Woodford hydrous-pyrolysis transformation ratios of the onset of oil generation (0.1 percent) to 

completion of oil and the start of gas generation (99 percent) 

correlates to a range of about 0.65 to 1.2 percent Ro. Higley 

and others (2011) assessed a mean undiscovered, technically 

recoverable resource estimate for the Woodford Shale Oil 

AU of 0.39 BBO, 2 TCFG, and 59 MMBNGL (Higley, 

2011). Assessment results and geologic reports are available 

at the USGS website at http://energy.usgs.gov/OilGas/

AssessmentsData/NationalOilGasAssessment.aspx.

Southwestern Wyoming (Finn and Johnson, 

2005); Hanna, Laramie and Shirley Basins 

(Dyman and Condon, 2007); and Denver Basin 

Provinces (Higley and Cox, 2007)

Finn and Johnson (2005) defined the Niobrara TPS as 

a self-sourced system that produces oil and natural gas from 

fractured carbonate rock reservoirs in the Upper Cretaceous 

Niobrara Formation and equivalent rocks in the Southwestern 

Wyoming Province. Dyman and Condon (2007) modeled 

two small Niobrara oil fields on the south flank of the Hanna 

Basin after continuous Niobrara oil fields in the Southwestern 

Wyoming Province, resulting in a continuous assessment unit 

that was defined and quantitatively assessed for Niobrara 

oil (Dyman and others, 2006). In the Denver Basin, oil was 

assessed for: (1) the Fractured Niobrara Limestone AU in 

the Upper Cretaceous Fractured Niobrara TPS, and (2) the 

Niobrara, combined with the underlying Codell Sandstone 

Member of the Carlile Shale, as part of the Cretaceous 

Composite TPS (Higley and others, 2003). The Niobrara and 

equivalents were deposited during a major Late Cretaceous 

marine transgressive cycle that created conditions favorable 

for the deposition of fine-grained marine carbonate rocks 

and the preservation of organic matter (Finn and Johnson, 

2005). Black shales within the Niobrara Formation, some of 

which are rich in coccoliths and fecal pellets, are the major 

hydrocarbon source rocks; shaly beds that overlie the chalky 

or sandy reservoir intervals are seals (Longman and others, 

1998). In the Southwestern Wyoming Province, Finn and 

Johnson (2005) found the thickness of the Niobrara ranges 

from 900 to 1,800 ft and the lithology consists mainly 

of interbedded organic-rich shale, calcareous shale, and 

marl. Dyman and Condon (2007) describe the Niobrara 

as concretionary, containing ledge-forming coquina beds; 

the limestones and chalks in the Niobrara give off a strong 

petroliferous odor. Dyman and Condon (2007) support an 

interpretation of limited migration for Niobrara-derived oil 

and consider potential oil accumulations in the Niobrara to be 

continuous-type accumulations. The presence of oil, therefore, 

is based primarily on thermal maturity rather than on migration pathways (Dyman and Condon, 2007). Within the Western 

Interior Basin, Niobrara TOC ranges from 0.2 to 7.6 weight 

percent; the best values occur east of the Hanna, Laramie, and 

Shirley Basins Province in the area of Silo field in Laramie 

County, Wyoming, in the northern Denver Basin (Landon and 

others, 2001). Finn and Johnson (2005) found the majority of 

28 Niobrara samples in the Southwestern Wyoming Province 

contain Type II, oil-prone kerogen with some mixing from 

Type III, gas-prone kerogen, especially in the western part of 

the province. Landon and others (2001) recognized a general 

increase in siliciclastic material in the Niobrara in the western 

part of the Cretaceous Western Interior Seaway, and source 

rock quality decreases. For the 2002 USGS assessment in the 

Southwestern Wyoming Province, the mean estimate of undiscovered, technically recoverable oil resource for the Niobrara 

continuous-oil assessment unit is 0.10 BBO, 62.2 BCFG, and 

3.7 MMBNGL (Kirschbaum, Finn, and others, 2002). In the 

Denver Basin, the mean estimate of undiscovered, technically 

recoverable oil resource for Niobrara continuous oil assessment units was 0.04 BBO, 329.5 BCFG, and 33 MMBNGL 

(Higley and others, 2003). The Niobrara Continuous Oil AU 

assessment in the Hanna, Laramie, Shirley Basins Province, 
6 Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

Wyoming, resulted in an estimated mean of 0.04 BBO and 

19 BCFG (Dyman and others, 2006). Geologic studies of 

total petroleum systems and assessment units, as well as 

reports on the methodology used in assessing resources, 

for the Denver Basin; Southwestern Wyoming; and Hanna, 

Laramie, Shirley Basins Provinces of the Rocky Mountain 

region are available at the USGS Energy Resources Program 

Web site at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Uinta-Piceance Basin Province (Dubiel, 2003)

Dubiel (2003) reported the results of the 2002 geologic 

assessment of undiscovered oil and gas resources of the 

Green River TPS within the Uinta-Piceance Basin Province 

in northeastern Utah and northwestern Colorado. Dubiel 

(2003) described the Green River TPS as a prolific complex 

of entirely continental rocks that host gilsonite veins, oil 

shale, and tar sand all sourced from lacustrine rocks within 

the Paleocene and Eocene Green River Formation. The 

open-lacustrine facies averages about 6.0 weight percent 

total organic carbon, and locally has TOC contents as high 

as 60 weight percent. The kerogenous carbonate beds, 

referred to as oil shale, have hydrogen indices greater than 

500 milligrams of hydrocarbon per gram of rock (mg HC/g) 

TOC (see Dubiel, 2003). Oil shale in the Green River 

Formation—including the Piceance Basin of northwestern 

Colorado, the Uinta Basin of northeastern Utah, and the 

Greater Green River Basin of southwestern Wyoming—is 

the world’s largest known deposit of kerogen-rich rocks 

(Dyni, 2006). The total potential resource within these 

deposits, regardless of grade, is estimated in the most recent 

U.S. Geological Survey resource in-place assessment to be 

4.285 trillion barrels of oil (Johnson, Mercier, Brownfield, 

Pantea, and Self, 2010; Johnson, Mercier, Brownfield, and 

Self, 2010; Johnson and others, 2011; Birdwell and others, 

2012). Dubiel (2003) described minor oil and gas production 

from an illitic oil-shale lacustrine facies with high TOC values 

in the Cow Ridge Member of the Green River Formation 

in the Piceance Basin. Most of the lacustrine rocks were 

not buried deeply enough in the Piceance Basin to achieve 

the necessary thermal maturity to have generated abundant 

hydrocarbons. In the Uinta Basin, however, Dubiel (2003) 

found that the greater depth of burial of the Green River 

Formation produced sufficient thermal maturity to generate 

abundant hydrocarbons. Dubiel (2003) defined the Deep 

Uinta Overpressured Continuous-Oil Assessment Unit 

primarily by the occurrence of known overpressured source 

and reservoir rocks in the Green River Formation in the 

deepest part of the Uinta Basin. The USGS estimated a mean 

undiscovered, technically recoverable continuous-oil resource 

of 0.04 BBO, 64 BCFG, and 4.5 MMBNGL (Kirschbaum, 

Anna, and others, 2002). Supporting geologic studies and the 

methodology used in the Uinta-Piceance Province assessment 

are available at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.

Montana Thrust Belt Province (Schenk 

and others, 2002)

The calcareous Cone Member of the Upper Cretaceous 

Marias River Shale in the Montana Disturbed Belt has good 

potential as a source rock for oil because of the relatively high 

hydrogen index values and above average organic carbon 

values (Clayton and others, 1983). Perry (1995) felt that an 

excellent chance existed for considerable oil production from 

the fractured Cone Member, particularly if wells are drilled 

to encounter the maximum number of fractures. The USGS 

defined and estimated the Marias River Shale Continuous-Oil 

AU to contain a mean of about 0.03 BBO, 111 BCFG, and 

5.6 MMBNGL (Schenk and others, 2002). 

Bighorn Basin Province (Finn and others, 2010)

The Bighorn Basin developed primarily during the 

Laramide orogeny, a period of crustal instability that began 

during Late Cretaceous time and ended in early Eocene time 

(Gries, 1983; Love, 1988). Finn and others (2010) explain 

that many of the structures are the result of compressional 

deformation characterized by Precambrian basement-involved 

thrust faults (thick-skinned), wrench faults, and strongly 

folded and faulted anticlines and synclines. The basin covers 

approximately 10,400 mi2 in north-central Wyoming and a 

small part of south-central Montana. The Mowry Shale is one 

of the principal source rocks in the Bighorn Basin Province 

with TOC content ranging from 0.08 to 3.6 weight percent and 

hydrogen index (HI) values ranging from 10 to 634 units (Finn 

and others, 2010). Finn and others (2010) suggest that the 

Mowry Fractured Shale Continuous-Oil Assessment Unit has 

potential to produce oil from fractured siliceous marine shale 

and interbedded siltstones and thin sandstones. The AU occupies approximately 1,000 mi2

 in the eastern and southern parts 

of the Bighorn Basin, and extends to depths of 12,000 ft (Finn 

and others, 2010). The closest analog for the Mowry Fractured 

Shale Continuous-Oil AU is the Mowry Continuous-Oil AU in 

the Powder River Basin (Anna and Cook, 2008); however, the 

Mowry source rock there has higher TOC content and Type 

II kerogen (Burtner and Warner, 1984). The mean estimate 

for undiscovered, technically recoverable oil resources in the 

Mowry Fractured Shale Continuous-Oil AU has potential for 

additions to reserves of 0.005 BBO and 2 BCFG (Kirschbaum 

and others, 2008). Supporting geologic studies of total 

petroleum systems and assessment units, and reports on the 

methodology used in the Bighorn Basin Province assessment, are available at the USGS Energy Resources Program 

website at http://energy.usgs.gov/OilGas/AssessmentsData/

NationalOilGasAssessment.aspx.
Digital Maps and Data 7

Digital Maps and Data

This fourth digital map product in the series of USGS 

unconventional oil and gas resources maps represents the 

results of the 2000-series of USGS geologic assessments 

of the undiscovered continuous-oil resources in the U.S. 

For current and future reference, the USGS publishes 

the assessment data as a Geographic Information System 

(GIS) map and data package. The map is also available as 

a static Portable Document Format (.pdf) file. To access 

the hardcopy .pdf map, click on the map graphic shown in 

figure 1. Adobe Acrobat Reader software can be used to view 

the .pdf map and is available for download free-of-charge 

at http://get.adobe.com/reader/. The hardcopy .pdf map is 

designed to be printed on a 46×33 inch map sheet. 

The GIS map and data package is contained on CD–ROM

or can be downloaded at the USGS website http://pubs.usgs.gov/

dds/dds-069/dds-069-jj/ or http://dx.doi.org/10.3133/ds69jj. 

The ArcMap document contains an .mxd extension on the 

filename, is the main component of the GIS data package, and 

is used to analyze geospatial data, symbolize features, and 

create maps. Access to the .mxd file uses Esri’s ArcGIS 10 or 

newer versions of the desktop software (Esri, 2000). Using 

the published .mxd and the ArcGIS Publisher extension (Esri, 

2008a) in ArcMap, a special file called a published map file 

was created. Published map files contain a .pmf extension 

and can be accessed using any ArcGIS (Esri, 2000) desktop 

product, including the free-of-charge ArcReader (Esri, 2008b) 

application. ArcMap and ArcReader offer different ways 

to view a map in which one can perform map-based tasks. 

ArcReader provides basic tools for map viewing, printing 

and querying of geospatial data. More advanced geospatial 

processing requires the ArcGIS suite of geospatial processing 

programs, including ArcMap.

There are two ArcMap projects contained in

this report: (1) ContinuousOilMap2014.mxd, and

(2) ContinuousOilMap2014simplified.mxd. 

ContinuousOilMap2014.mxd is a complex ArcGIS 

project used to build, design, and export the .pdf map. 

Multiple data frames were used to enlarge and enhance 

each province area; upon initial launch, this file tends 

to be much slower than subsequent map starts. The 

ContinuousOilMap2014simplified.mxd is designed for the 

novice GIS user to easily navigate and utilize the data.

The digital map layout of both the .mxd and the .pmf, 

contains a map window with a series of layers in the table of 

contents frame on the left side of the navigation screen. Within 

the table of contents, select the box to the left of each layer 

or group of layers to display the features in map view. Click 

the “+” sign to the left of each layer, group, or data frame to 

display the symbology or the list of layers within that group or 

data frame. To deselect the entire group, ctrl-click the check 

box to the left of any one of the AU names. Ctrl-click again to 

toggle the check boxes on for the entire group.

By default, the map is displayed in Layout View, and the 

Contiguous U.S. (lower 48) is the active data frame. Layout 

View is designed to work with the map layout and graphic 

elements, such as titles, north arrows, and scale bars, along with 

the data frame, all of which are arranged on a page. Data View

is designed for exploring, displaying, and querying the data 

sets presented on your map, which is displayed in real-world 

coordinates (Esri, 2011). Navigation between Layout View

and Data View is available from the View drop-down menu.

Labels and annotation for the AUs are included as separate layers that can be toggled on and off, as deemed appropriate for a particular map display. In the simplified .mxd, the 

“Continuous-Oil AU Annotation” layer, when visible, shows 

all continuous-oil AU names. Users may zoom into a specific 

area of interest, in which case, individual province labels 

available within each province group can be toggled on and 

the AU annotation layer can be toggled off (made invisible). 

ArcMap projects (.mxd) and published map files (.pmf) 

can be enhanced by including auxiliary base map layers, 

many of which are available as ArcGIS services (for example, 

shaded relief, World imagery; Esri, 2010). Another important 

base layer, geologic units from the Geologic Map of North 

America (Reed and others, 2005; Garrity and Soller, 2009), 

is included for additional geologic context. Because many of 

these base layers are very large files, having them toggled on 

(visible in the map view) can adversely affect performance. 

Several base layers are visible upon opening the map project. 

Toggling these layers off can increase refresh and display 

performance while navigating the interactive map. Once an 

appropriate map graphic has been created, or area of interest 

has been isolated, the addition of one or more of the base 

layers can enhance the final map product or view.

All geospatial data are stored in file geodatabase (Esri, 

2012; ContinuousOil2014.gdb and BaseLayers.gdb) and 

shapefile format in a World Geodetic System (WGS) 1984 

projection, which is a standard projection for distributing 

geospatial data. 

The polygons in ContinuousOil2014.gdb represent 

continuous-oil assessment units (AUs) that have been defined 

and assessed by the USGS. An important aspect of this map 

product is that it does not require extensive GIS expertise or 

highly specialized equipment. 

The Metadata folder contains continuous-oil data 

documentation in XML, html, and text format. The base map 

layers have metadata incorporated from the published sources. 

Reference or base map layers from “The National Atlas of the 

United States of America” (U.S. Department of the Interior, 

2008) include: state and county boundaries, streams, water 

bodies, and urban areas in the U.S. For the ArcGIS.com web 

services (formerly ArcGIS Online; Esri, 2010), data descriptions, sources, and credits are stored as layer properties.
8 Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

Detroit

Los Angeles

Chicago

Atlanta

Dallas

New York City

Boston

Houston

Washington

Miami

Philadelphia

Denver

San Jose

Seattle

Cleveland

Baltimore

Saint Louis

Tulsa

Phoenix San Diego

Pittsburgh

Kansas City

Portland

Indianapolis

Buffalo

Akron

Milwaukee

Camden Sacramento

Flint

Richmond

Memphis

Omaha

Oakland

Dayton

Nashville

MinneapolisSaint Paul

Cincinnati

San Antonio

Tampa

Rochester

Columbus

Wichita

Birmingham

Toledo

Fort

Worth

Tucson

Concord

Louisville

Norfolk

Hartford

Orlando

Spokane

Charlotte

Tacoma

Oklahoma

City

Eugene

Knoxville

Sarasota

Lansing

Jackson

Jacksonville

Marietta

Austin

Salt Lake City

Springfield

Providence

Clearwater

New Orleans

Las Vegas

Trenton

Pensacola

Albuquerque

Augusta

Winston-Salem

Roanoke

Baton Rouge

Mobile

Syracuse

Youngstown

Huntsville

Chattanooga

El Paso

Greenville

Fort Wayne

Fort LauderdaleWest Palm Beach

Grand

Rapids

Duluth

Vancouver

Covington

Little Rock

Newport NewsHampton

Cocoa

Beach

TEXAS

UTAH

MONTANA

NEVADA

CALIFORNIA

IDAHO

ARIZONA

OREGON

IOWA

KANSAS

WYOMING

NEW MEXICO

COLORADO

OHIO

MISSOURI

NEBRASKA

MINNESOTA

ILLINOIS

GEORGIA

FLORIDA

OKLAHOMA

ALABAMA

WISCONSIN

WASHINGTON

SOUTH DAKOTA

ARKANSAS

MAINE

NORTH DAKOTA

NEW YORK

VIRGINIA

MISSISSIPPI

LOUISIANA

INDIANA

MICHIGAN

TENNESSEE

KENTUCKY

PENNSYLVANIA

NORTH CAROLINA

SOUTH CAROLINA

WEST

VIRGINIA

VERMONT

MASSACHUSETTS

MARYLAND

NEW JERSEY

NEW

HAMPSHIRE

CONNECTICUT

PUERTO RICO

DELAWARE

RHODE ISLAND

U.S. VIRGIN

ISLANDS

HAITI

THEBAHAMAS

DOMINICAN

REPUBLIC

CUBA

Williston Basin Province7.38 BBO

Appalachian Basin Province0.94 BBO

Powder River Basin Province0.42 BBO

Uinta-Piceance Basin Province

0.04 BBO

Gulf Coast Region1.73 BBO

Montana Thrust Belt Province0.03 BBO

Southwestern Wyoming Province

0.10 BBO

Paradox Basin Province

0.47 BBO

Anadarko Basin Province0.39 BBO

Denver Basin Province0.04 BBO

Bighorn Basin Province

0.005 BBO

Permian Basin Province

0.51 BBO

Hanna Basin0.04 BBO

130° 125° 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 70°

50°

45°

40°

35°

30°

25°

20°

15°

10°

45°

40°

35°

30°25°

20°

15°

10°

130° 135° 140° 145° 125° 120° 115° 110° 105° 100° 95° 90° 85° 80° 75° 70° 65° 60° 55°

Northern Alaska Province

0.94 BBO

155°

155° 135° 140°

145°

145°

150°

150°

160°

160°

165°

165° 170° 175° 180°

70°

70°

65°

65°

60°

60°

55°

55°

Fractured Niobrara Limestone

(Silo Field Area) AU

Niobrara-Codell

(Wattenberg Area) AU

Niobrara Continuous-Oil AU

Niobrara

Continuous-Oil AU

Mowry Fractured Shale

Continuous-Oil AU

Deep Uinta Overpressured

Continuous-Oil AU

Gothic, Chimney Rock,

Hovenweep Shale-Oil AU

Cane Creek

Shale-OIl AU

Shublik Continuous-Oil AU

Brookian Continuous-Oil AU

Kingak Continuous-Oil AU

Marias River Shale

Continuous-Oil AU

Niobrara Continuous-Oil AU

Mowry Continuous-Oil AU

Elm Coulee–Billings Nose

Continuous-Oil AU

Central Basin

Continuous-Oil AU

Nesson–Little Knife Continuous-Oil AU

Eastern Transitional

Continuous-Oil AU

Northwest Transitional

Continuous-Oil AU

Three Forks

Continuous-Oil AU

Utica Shale-Oil AU

Eagle Ford Shale-Oil AU

Austin Pearsall-Giddings Area Oil AU

Woodford Shale-Oil AU

Spraberry

Continuous-Oil AU

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 30 60 MILES

0 30 60 KILOMETERS

0 20 40 MILES

0 20 40 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

ALASKA

Anadarko Basin Province

Gulf Coast Region 

Appalachian Basin Province

Williston Basin Province

Powder River Basin Province

Montana Thrust Belt Province

Northern Alaska Province

Paradox Basin Province

Uinta-Piceance Basin Province

Bighorn Basin Province Hanna Basin Southwestern Wyoming Province

Denver Basin Province

Permian Basin Province

100 0 100 200 300 400 500 MILES

100 0 100 200 300 400 500 600 700 KILOMETERS

0 50 100 MILES

0 50 100 KILOMETERS

UNITED STATES

Abstract

The U.S. Geological Survey (USGS) conducts quantitative 

assessments of potential oil and gas resources of the onshore United States and associated coastal State waters. Since 2000, the USGS has completed assessments of continuous (unconventional) resources in the United States based on geologic studies and analysis of well-production data and has compiled digital maps of the assessment units classified into four categories: shale gas, tight gas, coalbed gas, and shale oil or tight oil (continuous oil). This is the fourth digital map product in a series of USGS unconventional oil and gas resource maps; its focus being shale-oil or tight-oil (continuous-oil) assessments. The map plate included in this report can be printed in hardcopy form or downloaded in a Geographic Information System (GIS) data package, which includes an ArcGIS ArcMap document (.mxd), geodatabase (.gdb), and a published map file (.pmf). Supporting geologic studies of total petroleum systems and assessment units, as well as studies of the methodology used in the assessment of continuous-oil resources in the United States, are listed with hyperlinks in table 1. 

Access to Report

This entire publication is available online at the USGS web site:http:/pubs.usgs.gov/dds/dds-069/dds-069-jj/ or http://dx.doi.org/10.3133/ds69jjand on CD-ROM by contacting:eteamdisks@usgs.gov.Access to Assessment Results

Comprehensive geologic studies, supporting data, and reports on the methodology used in assessing undiscovered oil and gas resources in the United 

States are available at the USGS Central Energy Resources Science Center website: http://energy.usgs.gov/OilGas/AssessmentsData/NationalOilGasAssessment.aspx

Project Chief: Christopher J. Schenk

Mean Continuous-Oil Resource Estimates—

Undiscovered, technically recoverable

billion barrels of oil (BBO)

7.5

5

2.5

1

0.10.5

0.010.05

Continuous (unconventional) Oil Assessment Units—

Explanation

Merged on contiguous U.S. map. On inset maps,outlined and labeled with green text in a light greenbackground.

PACIFIC OCEAN

ATLANTIC OCEAN

Gulf of Mexico

MEXICO

CANADA

Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014

ByU.S. Geological Survey National Assessment of Oil and Gas Resources Team, and Laura R.H. Biewick, compiler

2015

Shaded relief from U.S. Geological Survey, The National Map, published 2007 at http://nationalmap.gov/

Bathymetry from ETOPO1, NOAA Technical Memorandum

NESDIS NGDC–24 (Amante and Eakins, 2009)

Albers Equal Area Conic Projection, Central Meridian: -96.0

Standard Parallel 1: 29.5, Standard Parallel 2: 45.5

Latitude of origin: 23.0Datum: North American Datum 1983

Any use of trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items must 

be secured from the copyright owner.This database, identified as DDS 69–JJ, has been approved for release and publication by the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous 

review and is substantially complete, the USGS reserves the right to revise the data 

pursuant to further analysis and review. Furthermore, it is released on condition that neither 

the USGS nor the U.S. Government may be held liable for any damages resulting from its 

authorized or unauthorized use.

For more information concerning this publication, contact:Center Director, USGS Central Energy Resources Science Center

Box 25046, Mail Stop 939(303) 236-1647Or visit the Central Energy Resources Science Center Web site at:http://energy.usgs.gov/

Publishing support provided by: Denver Publishing Service CenterEdit and digital layout by L.J. BinderManuscript approved for publication Jamuary 15, 2015To learn about the USGS and its information products visithttp://www.usgs.gov/ 1-888-ASK-USGS

Suggested citation: U.S. Geological Survey National Assessment of Oil and 

Gas Resources Team, and Biewick, L.R.H., compiler, 2015, Map of assessed 

continuous (unconventional) oil resources in the United States, 2014: U.S. 

Geological Survey Digital Data Series 69–JJ, 12 p., 1 pl., GIS data package,

http://dx.doi.org/10.3133/ds69jj.

ISSN 2327-638X (online)http://dx.doi.org/10.3133/ds69jj

Alaska Albers Equal Area Conic Projection

Central Meridian: -154.0

Standard Parallel 1: 55.0

Standard Parallel 2: 65.0

Latitude of origin: 50.0Datum: North American Datum 1983

U.S. Department of the InteriorU.S. Geological Survey

Digital Data Series 69–JJ

Plate 1

Figure 1. Map graphic links to the continuous-oil resources hardcopy map.
References Cited 9

Summary

The USGS map of the principal continuous-oil resources 

in the U.S. displays the occurrence of this important resource 

in many regions of the country. Although the complexities 

of the geologic parameters that influence the success of a 

continuous-oil play in a given basin or setting are generally 

understood, estimates of the continuous-oil resource, especially the portion that is technically recoverable, are likely 

to change over time as our geologic understanding of the 

resource characteristics increases and with further advances 

in technology and recovery methods. New information can 

readily be added to this digital baseline, and the ability to 

visualize, display, and analyze geospatial data can enhance and 

(or) increase the understanding of continuous-oil resources 

and assessments in the future. 

Acknowledgments

This report is a compilation of work by many USGS 

geologists who presented the geologic evidence critical to 

defining and assessing the continuous-oil resource volumes 

across the U.S. The manuscript was improved by reviews from 

Christopher J. Schenk, Thomas Finn, and Dave Ferderer, and 

thanks are extended to them for their thoughtful evaluations 

and suggested revisions.

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Manuscript approved January 15, 2015

Prepared by the USGS Science Publishing Network

Publishing Service Centers (PSC)

Edit and cartographic layout by L.J. Binder, Denver PSC

Layout Caryl J. Wipperfurth, Raleigh PSC

For more information concerning this report, contact:

Center Director, USGS Central Energy Resources Science Center

Box 25046, Mail Stop 939

Denver, CO 80225

(303) 236-1647

Or visit the Central Energy Resources Science Center website at: 

http://energy.usgs.gov/
U.S. Geological Survey National Assessment of Oil and Gas Resources Team—Map of Assessed Continuous (Unconventional) Oil Resources in the United States, 2014—Digital Data Series 69–JJ

ISSN 2327-132X (online)

http://dx.doi.org/10.3133/dds69jj