National and Global Petroleum Assessment

Assessment of Undiscovered Continuous Gas Resources in Upper Devonian 

Shales of the Appalachian Basin Province, 2017

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2018–3018 

April 2018

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable continuous 

resources of 10.7 trillion cubic feet of natural gas in Upper Devonian shales of the Appalachian Basin Province.

Introduction

In 2017, the U.S. Geological Survey (USGS) 

completed a geology-based assessment of undiscovered, 

technically recoverable continuous (unconventional) 

natural gas resources in the Upper Devonian Cleveland 

and Huron Members of the Ohio Shale, Pipe Creek 

Shale Member of the Java Formation, Rhinestreet Shale 

Member of the West Falls Formation, and Middlesex 

Shale Member of the Sonyea Formation in the Appalachian Basin Province. The assessed area comprises parts 

of Kentucky, New York, Ohio, Pennsylvania, Tennessee, 

Virginia, and West Virginia (fig. 1). 

Geologic Model for Assessment

The assessment was based on the geologic elements 

of the Devonian Shale–Middle and Upper Paleozoic 

Total Petroleum System (TPS), including (1) hydrocarbon source rocks (source-rock richness and levels of 

thermal maturation and associated oil and gas generation 

and adsorption); (2) reservoir rock type (continuous), 

distribution, and properties (mineral composition, porosity, 

permeability, brittleness); and (3) types and distribution 

of reservoirs and seals and timing relative to petroleum 

generation. The assessed Upper Devonian shales primarily 

consist of organic-rich marine shales, and the contained 

hydrocarbon resources are considered self-sourced mostly 

on the basis of levels of thermal maturation in hydrocarbon productive areas.

Using this geologic framework, the USGS defined 

eight continuous assessment units (AUs) within the 

Devonian Shale–Middle and Upper Paleozoic TPS and 

quantitatively estimated undiscovered, technically recoverable natural gas and natural gas liquid (NGL) resources for 

three of the eight AUs (tables 1 and 2). Although historical 

oil production has been reported from the Ohio Shale and 

the Huron Member of the Ohio Shale, the assessment team 

concluded that future production likely will be dominated 

by natural gas and NGLs. The unassessed Pipe Creek 

Continuous Gas AU, Pipe Creek Continuous Oil AU, 

Rhinestreet Continuous Oil AU, Middlesex Continuous 

Gas AU, and Middlesex Continuous Oil AU are categorized as hypothetical because data were insufficient for 

quantitative resource assessment. Input data used to assess 

three continuous AUs are listed in table 1. 

The Cleveland Continuous Gas AU includes the 

areal extent of the Cleveland Member where the member 

is laterally contiguous with the correlative Chattanooga 

Shale AUs delineated in 2015 (Higley and others, 

2016), the area downdip of where the temperature of 

maximum release of hydrocarbons during Rock-Eval 

kerogen pyrolysis (Tmax) (Espitalie and others, 1985) 

of Cleveland samples is 435 degrees Celsius (°C) or more, and all areas of historical 

production from vertical and horizontal wells allocated to the Cleveland Member. The 

Huron Continuous Gas AU includes the areal extent of the Huron Member where the 

member is laterally contiguous with the correlative Chattanooga Shale AUs delineated 

in 2015 (Higley and others, 2016), the area downdip of where Tmax of Huron samples 

is 435 °C or more, and all areas of historical production from vertical and horizontal 

wells allocated to the Huron Member. The Rhinestreet Continuous Gas AU includes 

the areal extent of the Rhinestreet Shale Member where the member is downdip of 

the Devonian thermal maturity 1.2 percent vitrinite reflectance contour of East and 

others (2012) and all areas of historical production from vertical and horizontal wells 

allocated to the Rhinestreet Shale Member.

Figure 1. Map showing the boundaries of the three assessment units (AUs) that were 

quantitatively assessed in Upper Devonian shales of the Devonian Shale–Middle and 

Upper Paleozoic Total Petroleum System (TPS) in the Appalachian Basin Province. 

Huron Continuous

 Gas AU

Rhinestreet Continuous

 Gas AU

Devonian Shale–Middle

 and Upper Paleozoic TPS

OHIO

INDIANA

VIRGINIA

KENTUCKY

PENNSYLVANIA

NEW YORK

TENNESSEE

MICHIGAN

NORTH

CAROLINA

WEST

VIRGINIA

MARYLAND

NEW 

JERSEY

DELAWARE

ATLANTIC

OCEAN

LAKE

ERIE

ONTARIO

CANADA

−86° −84° −82° −80° −78° −76° −74°

42°

40°

38°

36°

Base map from U.S. Department of the Interior National Park Service

EXPLANATION

Cleveland Continuous

 Gas AU

0 100 200 KILOMETERS

0 100 200 MILES

IL

PA

NC

IN

NY

CAN

MI

ON

VA

TN

KY

OH

WI

WV

AL GA SC

VT

MD NJ

DE

NH

Map

area

CT

MA
Appalachian Basin Province Assessment Team

Catherine B. Enomoto, Michael H. Trippi, Debra K. Higley, William A. Rouse, Frank T. Dulong, Timothy R. Klett, Tracey J. Mercier,

Michael E. Brownfield, Heidi M. Leathers-Miller, Thomas M. Finn, Kristen R. Marra, Phuong A. Le, Cheryl A. Woodall, and Christopher J. Schenk

For More Information

Assessment results are also available at the USGS Energy Resources Program website at https://energy.usgs.gov.

ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20183018

Assessment input data—Continuous AUs

Cleveland Continuous Gas AU Huron Continuous Gas AU

Minimum Mode Maximum Calculated 

mean Minimum Mode Maximum Calculated mean

Potential production area of AU (acres) 4,360 555,000 11,000,000 3,853,120 77,900 2,601,285 30,918,306 11,199,164

Average drainage area of well (acres) 80 120 200 133.3 80 120 220 140

Untested area (%) 90 95 99 94.7 75 85 95 85

Success ratio (%) 30 55 95 60 65 80 95 80

Average EUR (BCFG) 0.04 0.1 0.5 0.12 0.04 0.1 0.7 0.13

AU probability 1.0 1.0

Assessment input data—Continuous AU

Rhinestreet Continuous Gas AU

Minimum Mode Maximum Calculated 

mean

Potential production area of AU (acres) 2,640 5,500,000 16,610,000 7,370,880

Average drainage area of well (acres) 80 120 240 146.7

Untested area (%) 95 97 99 97

Success ratio (%) 10 40 60 36.7

Average EUR (BCFG) 0.04 0.08 0.2 0.086

AU probability 1.0

Table 1. Key input data for three continuous assessment units in shales of the Cleveland, Huron, and Rhinestreet Members, Appalachian Basin Province. 

[AU, assessment unit; %, percent; EUR, estimated ultimate recovery per well; BCFG, billion cubic feet of gas. Well drainage area, success ratio, and EUR are from U.S. 

shale-gas and tight-gas analogs. The average EUR input is the minimum, median, maximum, and calculated mean. Shading indicates not applicable]

Total petroleum system and assessment 

units (AUs)

AU

probability

Accumulation

type

Total undiscovered resources

Oil (MMBO) Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

Devonian Shale–Middle and Upper Paleozoic Total Petroleum System

Cleveland Continuous Gas AU 1.0 Gas 214 1,466 5,592 1,991 5 33 136 47

Huron Continuous Gas AU 1.0 Gas 907 5,128 20,238 7,096 24 147 631 214

Rhinestreet Continuous Gas AU 1.0 Gas 351 1,357 3,522 1,570 4 15 44 18

Total undiscovered continuous resources 1,472 7,951 29,352 10,657 33 195 811 279

Table 2. Results for three assessment units in shales of the Cleveland, Huron, and Rhinestreet Members, Appalachian Basin Province. 

[MMBO, million barrels of oil; BCFG, billion cubic feet of gas; NGL, natural gas liquids; MMBNGL, million barrels of natural gas liquids. Results shown are fully 

risked estimates. For gas accumulations, all liquids are included in the NGL category. F95 represents a 95-percent chance of at least the amount tabulated; other fractiles 

are defined similarly. Fractiles are additive under the assumption of perfect positive correlation. Shading indicates not applicable]

References Cited

East, J.A., Swezey, C.S., Repetski, J.E., and Hayba, D.O., 2012, Thermal maturity map of Devonian shale in the Illinois, Michigan, and 

Appalachian basins of North America: U.S. Geological Survey Scientific Investigations Map 3214, 1 sheet, scale 1:24,000. [Also available at 

https://pubs.usgs.gov/sim/3214/.]

Espitalie, J., Deroo, G., and Marquis, F., 1985, Rock-Eval pyrolysis and its applications: Revue De L’Institut Francais Du Petrole, v. 40, p. 563–579.

Higley, D.K., Rouse, W.A., Enomoto, C.B., Trippi, M.H., Klett, T.R., Mercier, T.J., Brownfield, M.E., Tennyson, M.E., Drake, R.M., II, Finn, 

T.M., Gianoutsos, N.J., Pearson, O.N., Doolan, C., Le, P.A., and Schenk, C.J., 2016, Assessment of undiscovered oil and gas resources of the 

Mississippian Sunbury Shale and Devonian–Mississippian Chattanooga Shale in the Appalachian Basin Province, 2016: U.S. Geological Survey 

Fact Sheet 2016–3085, 2 p. [Also available at https://doi.org/10.3133/fs20163085.]

Undiscovered Resources Summary

The USGS quantitatively assessed undiscovered continuous gas and NGL resources in three AUs within the Devonian Shale–Middle and Upper 

Paleozoic TPS (table 2). For total undiscovered resources in all three AUs, the estimated means are 10,657 billion cubic feet of gas (BCFG), or 10.7 

trillion cubic feet of gas, with an F95–F5 (fractile value) range from 1,472 to 29,352 BCFG and 279 million barrels of natural gas liquids (MMBNGL) 

with an F95–F5 range from 33 to 811 MMBNGL. The estimated means for the Cleveland Continuous Gas AU are 1,991 BCFG with an F95–F5 range 

from 214 to 5,592 BCFG and 47 MMBNGL with an F95–F5 range from 5 to 136 MMBNGL. The estimated means for the Huron Continuous Gas 

AU are 7,096 BCFG with an F95–F5 range from 907 to 20,238 BCFG and 214 MMBNGL with an F95–F5 range from 24 to 631 MMBNGL. The 

estimated means for the Rhinestreet Continuous Gas AU are 1,570 BCFG with an F95–F5 range from 351 to 3,522 BCFG and 18 MMBNGL with an 

F95–F5 range from 4 to 44 MMBNGL.