U.S. Crude Oil, Natural Gas,

and Natural Gas Liquids Reserves

2007 Annual Report

DOE/EIA-0216(20

February 2009
DOE/EIA–0216(2007)

Distribution Category UC–950

U.S. Crude Oil, Natural Gas,

and Natural Gas Liquids Reserves

2007 Annual Report

February 2009

Energy Information Administration

Office of Oil and Gas

U.S. Department of Energy

Washington, DC 20585

This report was prepared by the Energy Information Administration, the independent statistical and analytical

agency within the U.S. Department of Energy. The information contained herein should be attributed to the

Energy Information Administration and should not be construed as advocating or reflecting any policy position

of the Department of Energy or any other organization.
Preface

The U.S. Crude Oil, Natural Gas, and Natural Gas

Liquids Reserves 2007 Annual Report is the 31st

prepared by the Energy Information Administration

(EIA) to fulfill its responsibility to gather and report

annual proved reserves estimates. The EIA annual

reserves report series is the only source of

comprehensive domestic proved reserves estimates.

This publication is used by the Congress, Federal

and State agencies, industry, and other interested

parties to obtain accurate estimates of the Nation's

proved reserves of crude oil, natural gas, and natural

gas liquids. These data are essential to the

development, implementation, and evaluation of

energy policy and legislation.

This report presents estimates of proved reserves of

crude oil, natural gas, and natural gas liquids as of

December 31, 2007, as well as production volumes

for the United States and producing States and State

subdivisions for the year 2007. Estimates are

presented for the following four categories of natural

gas: total gas (wet after lease separation),

nonassociated gas and associated–dissolved gas

(which are the two major types of wet natural gas),

and total dry gas (wet gas adjusted for the removal

of liquids at natural gas processing plants). In

addition, reserve estimates for two types of natural

gas liquids, lease condensate and natural gas plant

liquids, are presented. The estimates are based upon

data obtained from two annual EIA surveys: Form

EIA–23, “Annual Survey of Domestic Oil and Gas

Reserves” and Form EIA–64A, “Annual Report of the

Origin of Natural Gas Liquids Production.” Also

included is information on crude oil, natural gas, and

lease condensate reserves in nonproducing

reservoirs. A discussion of notable oil and gas

exploration and development activities during 2007

is provided.

The appendices contain data by operator production

size class for crude oil and natural gas reserves and

production; the top 100 U.S. fields ranked within an

oil or natural gas proved reserves group for 2007;

Table 1 converted to metric units; historical State

data; a summary of survey operations; a discussion

of statistical considerations; methods used to develop

the estimates provided in this report; maps of

selected State subdivisions; and examples of the

survey forms. A glossary of the terms used in this

report and in survey Forms EIA–23 and EIA–64A is

provided to assist readers in more fully

understanding the data.

This annual reserves report was prepared by the

Reserves and Production Division (located in Dallas,

Texas), Office of Oil and Gas, Energy Information

Administration. General information regarding

preparation of the report may be obtained from

Stephen Harvey, Director, Office of Oil and Gas and

John H. Wood, Director, Reserves and Production

Division (214.720.6160).

Authors were John H. Wood, Steven G. Grape, Rafi

Zeinalpour, and Rhonda S. Green. Technical

contributions were made by Jack Perrin, Toby

Engleman, Paul Chapman, and Gwen Preston.

Technical editing was provided by David F.

Morehouse.

Address questions on specific sections of the

publication to the following analyst/author:

Executive Summary and Appendices F and G

John H. Wood

Phone: 214.720.6160

E–mail: jwood@eia.doe.gov

Fax: 214.720.6155

Chapters 1, 2, 3, 4, 5

Steven G. Grape

Phone: 214.720.6174

E–mail: sgrape@eia.doe.gov

Fax: 214.720.6155

Appendices A, B, C, D, E, H, and I

Rhonda S. Green

Phone: 214.720.6161

E–mail: rgreen@eia.doe.gov

Fax 214.720.6155

Field-level Reserves Quality Assurance

Steven G. Grape

Phone: 214.720.6174

E–mail: sgrape@eia.doe.gov

Fax 214.720.6155

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report iii
Energy Information Administration

iv U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Internet Site Services

Visit the Energy Information Administration web site:

http://www.eia.doe.gov

The web site offers all EIA publications. Users can view or download selected

pages or entire reports, search for information, download EIA data and analysis

applications, and find out about new EIA information products and services.

COVER PHOTO:

Chesapeake Energy, 2007 Annual Report. Photo by Gary Wilson.

A drilling rig near downtown Fort Worth, Texas. Its target: natural gas from the

Barnett Shale.
Contents

Page

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

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

Background....................................................... 1

Survey Overview .................................................... 1

Form EIA-23 ..................................................... 1

New Form EIA-23 Element: Type Code ....................................... 2

Form EIA-64A .................................................... 2

Data Collection Operations ............................................. 2

2. Overview ......................................................... 3

National Summary ................................................... 3

Crude Oil ........................................................ 3

Natural Gas....................................................... 3

Natural Gas Liquids................................................... 7

Reserves Changes Since 1977............................................. 7

Economics and Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Mergers and Acquisitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Reserve-to-Production Ratios and Ultimate Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

R/P Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Proved Ultimate Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

International Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

International Reserves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Petroleum Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Dependence on Imports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

List of Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3. Crude Oil Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Discussion of Reserves Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Total Discoveries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

New Field Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

New Reservoir Discoveries in Old Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Sales and Acquisitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Areas of Note: Large Discoveries and Reserve Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

North Dakota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Other Gain Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Areas of Note: Large Declines in Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Gulf of Mexico Federal Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Kansas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Other Decline Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Reserves in Nonproducing Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4. Natural Gas Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Dry Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Discussion of Reserves Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Total Discoveries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

New Field Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

New Reservoir Discoveries in Old Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Sales and Acquisitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report v
Page

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Wet Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Nonassociated Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Total Discoveries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Associated-Dissolved Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Coalbed and Shale Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Areas of Note: Large Discoveries and Reserves Additions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Wyoming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Areas of Note: Large Declines in Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Gulf of Mexico Federal Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Reserves in Nonproducing Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5. Natural Gas Liquids Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Natural Gas Liquids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Total Discoveries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

New Field Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

New Reservoir Discoveries in Old Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Sales and Acquisitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Natural Gas Plant Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Lease Condensate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Reserves in Nonproducing Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Appendices

A. Operator Level Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

B. Top 100 Oil and Gas Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

C. Conversion to the Metric System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

D. Historical Reserves Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

E. Summary of Data Collection Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

F. Statistical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1

G. Estimation of Reserves and Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

H. Maps of Selected State Subdivisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-1

I. Annual Survey Forms for Domestic Oil and Gas Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1

Glossary

Tables

1. U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids, 1997-2007............ 4

2. Reserves Changes, 1977-2007........................................... 9

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vi U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
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3. U.S. Average Annual First Purchase Prices for Crude Oil, Domestic Wellhead Prices for Natural Gas, and the

Average Number of Active Rotary Drilling Rigs, 1977-2007 . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4. U.S. Exploratory and Development Well Completions, 1973-2007 . . . . . . . . . . . . . . . . . . . . . . . . . 12

5. International Oil and Natural Gas Reserves as of December 31, 2007. . . . . . . . . . . . . . . . . . . . . . . 18

6. Crude Oil Proved Reserves, Reserves Changes, and Production, 2007 . . . . . . . . . . . . . . . . . . . . . . 22

7. Reported Reserves in Nonproducing Status for Crude Oil, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . 27

8. Dry Natural Gas Proved Reserves, Reserves Changes, and Production, 2007 . . . . . . . . . . . . . . . . . . 30

9. Natural Gas Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

10. Nonassociated Natural Gas Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

11. Associated-Dissolved Natural Gas Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

12. Reported Unconventional Natural Gas Proved Reserves and Production, 2007 . . . . . . . . . . . . . . . . . . 39

13. Natural Gas Liquids Proved Reserves, Reserves Changes, and Production, 2007 . . . . . . . . . . . . . . . . 44

14. Natural Gas Plant Liquids Proved Reserves and Production, 2007 . . . . . . . . . . . . . . . . . . . . . . . . 45

15. Lease Condensate Proved Reserves and Production, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Figures

1. U.S. Crude Oil Proved Reserves, 1997-2007.................................... 5

2. Components of Reserves Changes for Crude Oil, 1997-2007 ........................... 5

3. U.S. Dry Natural Gas Proved Reserves, 1997-2007 ................................ 6

4. Components of Reserves Changes for Dry Natural Gas, 1997-2007........................ 6

5. U.S. Natural Gas Liquids Proved Reserves, 1997-2007 .............................. 8

6. Components of Reserves Changes for Natural Gas Liquids, 1997-2007 ...................... 8

7. U.S. Exploratory Well Completions, 1997-2007. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8. U.S. Development Well Completions, 1997-2007. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

9. U.S. Total Discoveries of Dry Natural Gas per Exploratory Gas Well Completion, 1977-2007 . . . . . . . . . . . 14

10. U.S. Total Discoveries of Crude Oil per Exploratory Oil Well Completion, 1977-2007 . . . . . . . . . . . . . . . 14

11. Reserves-to-Production Ratios for Crude Oil, 1945-2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

12. Reserves-to-Production Ratios for Wet Natural Gas, 1945-2007. . . . . . . . . . . . . . . . . . . . . . . . . . 16

13. Components of Proved Ultimate Recovery for Crude Oil and Lease Condensate, 1977-2007 . . . . . . . . . . . 17

14. Components of Proved Ultimate Recovery for Wet Natural Gas, 1977-2007 . . . . . . . . . . . . . . . . . . . . 17

15 Replacement of U.S. Crude Oil Production by Reserves Additions, 1997-2007 . . . . . . . . . . . . . . . . . . 21

16. Crude Oil Proved Reserves by Area, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

17. Changes in Crude Oil Proved Reserves by Area, 2006 to 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . 23

18. Replacement of U.S. Dry Natural Gas Production by Reserves Additions, 1997-2007. . . . . . . . . . . . . . . 29

19. Dry Natural Gas Proved Reserves by Area, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

20. Changes in Dry Natural Gas Proved Reserves by Area, 2006 to 2007. . . . . . . . . . . . . . . . . . . . . . . 31

21. Coalbed Natural Gas Proved Reserves, 1989-2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

22. Coalbed Natural Gas Production, 1989-2007. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

23. Coalbed and Shale Natural Gas Proved Reserves, 2006-2007 . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report vii

Executive Summary

In 2007, the U.S. recorded record-high additions to

dry natural gas proved reserves totaling 46.1 trillion

cubic feet (Tcf), more than double the 19.5 Tcf of dry

natural gas actually produced in the United States

during the year. The resulting 2007 year-end total

proved reserves of dry natural gas in the United

States rose 13 percent above 2006 levels to 237.7 Tcf,

the highest level in the 31 years EIA has published

annual reserves data. The record additions mostly

reflect the rapid development of unconventional gas

resources made up of coalbed methane and those

resources that use advanced technologies like

horizontal drilling with hydraulic fracturing

including shales and tight, low permeability

formations.

The United States also recorded more 2007 proved

reserves additions of crude oil than it produced, 2.0

billion barrels, or 0.3 billion barrels above production

of 1.7 billion barrels. Year-end proved reserves in

2007 stood at 21.3 billion barrels, nearly 2 percent

higher than at the end of 2006.

Proved reserves are the estimated quantities which

geological and engineering data demonstrate with

reasonable certainty to be recoverable in future years

from known reservoirs under existing economic and

operating conditions. Since 1977, EIA has published

comprehensive U.S. proved reserves data. U.S. Crude

Oil, Natural Gas, and Natural Gas Liquids Reserves 2007

Annual Report marks the thirty-first edition of this

EIA publication.

Natural Gas

In any given year, EIA's aggregate U.S. estimate of

proved reserves represents a snapshot of what can be

produced with reasonable certainty. Each year

estimates change as new discoveries and improving

technologies increase and changing prices alter

estimates of proved reserves. The result is

aggregated as proved reserves additions. If proved

reserves additions are greater than production,

reserves increase; if not, they decline.

Developments in 2007. Proved reserves of natural

gas increased by 26.6 Tcf in 2007, with 46.1 Tcf total

proved reserves additions and 19.5 Tcf of natural gas

production. It was the ninth consecutive year that

U.S. natural gas proved reserves rose, but the

increase was more than twice as great an increase as

in any other year since EIA began estimating this

data in 1977.

In 2007, natural gas proved reserves additions came

mostly from two broad categories, total discoveries

and net revisions.

Total Discoveries. Discoveries arise from drilling

exploratory wells. Total discoveries include extensions

to known fields, discovery of new fields, and the

discovery of new reservoirs in old fields.

In 2007, total discoveries accounted for 63 percent of

total natural gas proved reserves additions.

Exploratory gas well completions in 2007 rose by 32

percent from 2006. These exploration efforts led to 29

Tcf of total discoveries in 2007; 25 percent more than

in 2006 and 58 percent more than the prior 10-year

average (18.4 Tcf).

The different types of discoveries largely reflect

different stages of exploration. When an operator

discovers a new field or a new reservoir in an old

field, the proved reserves are often fairly low

compared to the eventual proved ultimate recovery.

The operator knows relatively little about the new

field or reservoir and can therefore be "reasonably

certain" of being able to produce only a small part of

the reserves that may be found and proved up at a

later stage of exploration. In 2007, new field and

reservoir discoveries accounted for about 7 percent

of total discoveries. New field discoveries were 0.8 Tcf,

95 percent more than in 2006, but 51 percent less

than the prior 10-year average (1.6 Tcf). New reservoir

discoveries in old fields were 1.2 Tcf, 3 percent more

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report ix

Changes to Proved Reserves, 2007:

Crude Oil (billion barrels)

Proved Reserves, 2006 21.0

Plus Proved Reserves Additions +2.0

Less 2007 Production -1.7

Proved Reserves, 2007 21.3 (+2%)

Dry Natural Gas (trillion cubic feet)

Proved Reserves, 2006 211.1

Plus Proved Reserves Additions +46.1

Less 2007 Production -19.5

Proved Reserves, 2007 237.7 (+13%)

Natural Gas Liquids (billion barrels)

Proved Reserves, 2006 8.47

Plus Proved Reserves Additions +1.50

Less 2007 Production -0.83

Proved Reserves, 2007 9.14 (+8%)
than in 2006, and 37 percent less than the prior

10-year average (1.9 Tcf).

After the initial discovery of a field or reservoir,

proved reserves (and production) often grow rapidly

as further exploration extends the original boundary.

The resulting proved reserves additions are recorded

as extensions of an existing field. Every year, most

natural gas total discoveries are extensions. In 2007,

27.1 Tcf, or the vast majority of total discoveries - and

almost 59 percent of all additions - were extensions to

existing gas fields. Extensions of dry gas proved

reserves in 2007 were 24 percent larger than in 2006

and 82 percent larger than the prior 10-year average

of 14.9 Tcf.

Net Revisions. Revisions occur primarily during the

development of already discovered reservoirs or

fields. Each year U.S. exploration and production

companies make positive and negative revisions. In

most years, net revisions are positive and sometimes

they are large, as in 2007. Most proved reserves

additions at this stage come from the ability to

produce a greater proportion of the original in-place

resources in the reservoir. Revisions can result from

greater experience with and understanding of the

geology and production characteristics of the field,

drilling on tighter spacing, installation of enhanced

recovery projects, improving technology, and

operator corrections to prior year reports. Changing

prices and price expectations lead to revisions, both

positive and negative, as well.

In 2007, net revisions accounted for 34 percent of total

natural gas reserves additions (15.5 Tcf). Over the

last 10 years, about 15 percent of proved reserves

additions have come from net revisions.

Sales and Acquisitions, and Adjustments. Three percent

of natural gas proved reserves additions came from a

small difference in the estimates of buyers and sellers

of reserves during the year and because of various

EIA adjustments made for statistical purposes.

Production. Natural gas production grew to 19.5 Tcf

in 2007, a 5-percent increase over 2006. With 46.1 Tcf

of gross proved reserves additions, net proved

reserves additions totaled 26.6 Tcf.

Prices. Natural gas prices at the wellhead in 2007

changed little from 2006, declining by only 3 cents to

an average of $6.39 per thousand cubic feet. Natural

gas prices had increased considerably between 2002

and 2005. Drilling for natural gas also increased in

2003 and has continued to increase each year

through 2007.

Long-term perspective. Dry natural gas proved

reserves declined between 1977 and 1993, but have

generally risen since then. Looking at the whole

31-year period from 1977 through 2007, gross proved

reserves additions totaled 601.4 Tcf, almost three

times the total proved reserves estimated in 1977 and

more than enough to replace the 571 Tcf of

production during that period.

Regional Natural Gas Proved Reserves Additions.

Regionally, Texas had the Nation's largest increase in

dry natural gas proved reserves in 2007, amounting

to a 17-percent gain (10.3 Tcf). Major net reserves

additions in the Rocky Mountain States included a

Energy Information Administration

x U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Natural Gas Proved Reserves Changes, 2007

Changes in Natural Gas Proved Reserves, 1977-2007
26-percent (6.2 Tcf) increase in Wyoming, a

27-percent (4.7 Tcf) increase in Colorado, and a

24-percent (1.2 Tcf) increase in Utah. Proved reserves

declined in two major gas-producing regions

including a 6-percent decline in the Gulf of Mexico

Federal Offshore (0.9 Tcf) and a 4-percent decline in

New Mexico (0.7 Tcf).

The additions in Texas were primarily due to

development of unconventional gas resources in

north and east Texas from shale in the Barnett Shale

and from tight sands in the Cotton Valley Formation,

supported by relatively high natural gas prices and

advancing technologies. The Newark East field in the

Texas Barnett Shale formation may soon become the

largest natural gas field in the country.

Unconventional Natural Gas Proved Reserves

Additions. Unconventional resources are playing an

increasingly important role in U.S. dry natural gas

reserves and production. For example, improved

technology now allows high economic returns for

development of reserves in shale reservoirs at the

prices seen in 2006 and 2007. As a result, proved

reserves of shale gas have been increasing rapidly.

EIA has collected data on proved natural gas

reserves from shale reservoirs for 2 years. The shale

gas proved reserves increased 50 percent in 2007 and

are now at about 9 percent of the U.S. total.

Proved reserves and production from coal reservoirs

increased rapidly from 1989 through 2002 before

stabilizing and even dropping slightly in 2006.

However, coalbed natural gas reserves saw an

11.5-percent increase in 2007. Coalbed proved

reserves now account for about 9 percent of U.S. dry

natural gas reserves. Coalbed natural gas production

decreased in 2007 but still accounted for about 9

percent of U.S. dry natural gas production.

Crude Oil

In 2007, U.S. crude oil proved reserves increased

nearly 2 percent as proved reserves additions

replaced 120 percent of production. Alaska saw the

largest increase in year-end crude oil proved

reserves, growing 7 percent over 2006 (284 million

barrels), followed closely by Texas with an increase

in year-end proved reserves of 5 percent (251 million

barrels). Alaska's increase included 45 million barrels

of new field discoveries. Due to rapid development

of unconventional oil resources associated with the

Bakken Formation, North Dakota had the third

largest increase in crude oil proved reserves, up 17

percent from 2006 (70 million barrels).

Developments in 2007. Total discoveries of crude oil

were 790 million barrels in 2007, 28 percent lower

than the prior 10-year average (1,100 million barrels)

and 37 percent greater than in 2006 (577 million

barrels). The majority of crude oil total discoveries in

2007 came from extensions to existing fields in Texas,

the Gulf of Mexico Federal Offshore, North Dakota,

New Mexico, and Alaska.

Total Discoveries. Operators discovered 29 percent

more extensions in 2007 than in 2006 (651 million

barrels) and 18 percent more than the prior 10-year

average (554 million barrels).

New field discoveries of crude oil reserves doubled in

2007 over 2006 (66 million barrels), though they were

only 16 percent of the prior 10-year average (407

million barrels). More than two-thirds of these

discoveries (45 of 66 million barrels) were in Alaska.

New reservoir discoveries in old fields were 70 percent

greater than 2006 (73 million barrels) but 48 percent

lower than the prior 10-year average (140 million

barrels).

Net Revisions. Crude oil net revisions totaled 1,200

million barrels in 2007.

Production. U.S. crude oil production increased for

the first time in 4 years, up 2 percent from estimated

2006 production. Alaska and the lower 48 States each

contributed about half of the U.S. total increase.

Other 2007 crude oil events of note:

• The annual average domestic first purchase

price for crude oil increased 11 percent from

$59.69 per barrel in 2006 to $66.52 per barrel.

• Exploratory oil well completions increased 17

percent from 2006.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report xi

Crude Oil Proved Reserves Changes, 2007
Long-term Perspective. Starting in 1977, EIA

estimated 32 billion barrels of crude oil proved

reserves. As with natural gas, this estimate proved

not to be a limit to future production, but an estimate

that was revised upward many times in the years

since. The United States produced 75 billion barrels

from 1977 through 2007, more than twice the proved

reserves estimated in 1977. Total proved reserves of

crude oil have declined by a third since 1977 as the

rate of production has outstripped proved reserves

additions (a total of 62 billion barrels over the

period). However, the rate of decline in total U.S.

crude oil reserves began to slow in 1994. Proved

reserves additions from revisions due to intensive

field development and enhanced oil recovery projects

have helped to sustain crude oil proved reserves by

providing more than half of all proved reserves

additions.

Natural Gas Liquids

Natural gas liquids reserves are associated with

natural gas production and include lease condensate

extracted at the well on the producing lease and

natural gas plant liquids reserves extracted at plants.

Large increases in natural gas proved reserves lead

to large increases in natural gas liquids proved

reserves, but the percent increases are not the same

because natural gas from different fields varies in

how much liquid is extractable. Overall, natural gas

liquids proved reserves increased 8 percent in 2007.

Operators replaced 181 percent of U.S. natural gas

liquids production with reserves additions.

Natural gas liquids represented 30 percent of total

liquid hydrocarbon proved reserves in 2007. Total

proved reserves of liquid hydrocarbons (crude oil

plus natural gas liquids) were 30.5 billion barrels in

2007, a 3-percent increase from the 2006 level.

Data

These estimates are based upon analysis of data from

Form EIA-23, "Annual Survey of Domestic Oil and

Gas Reserves", filed by 1,438 operators of oil and gas

wells, and Form EIA-64A, "Annual Report of the

Origin of Natural Gas Liquids Production", filed by

operators of 496 active natural gas processing plants.

The U.S. proved reserves estimates for crude oil and

natural gas are associated with sampling errors of

less than 1 percent.

EIA collects data on eight categories of proved

reserves changes in a survey at the field level. This

reported data represents a sample of the roughly

55,000 oil and gas fields that EIA has identified.

Companies report about 96 percent of the proved

reserve total. Adjustments cannot be attributed

directly to one of the other specific eight categories

because of the survey and statistical survey methods

employed.

Energy Information Administration

xii U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
1. Introduction

Background

The primary focus of EIA’s reserves program is

providing accurate annual estimates of U.S. proved

reserves of crude oil, natural gas, and natural gas

liquids. These estimates are essential to the

development, implementation, and evaluation of

national energy policy and legislation. In the past, the

Government and the public relied upon industry

estimates of proved reserves. However, the industry

ceased publication of reserve estimates after its 1979

report.

In response to a recognized need for credible annual

proved reserves estimates, Congress, in 1977, required

the Department of Energy to prepare such estimates.

To meet this requirement, the Energy Information

Administration (EIA) developed a program that

established a unified, verifiable, comprehensive, and

continuing annual statistical series for proved reserves

of crude oil and natural gas. It was expanded to include

proved reserves of natural gas liquids for the 1979 and

subsequent reports.

Survey Overview

EIA defines proved reserves, the major topic of this

report, as those volumes of oil and natural gas that

geological and engineering data demonstrate with

reasonable certainty to be recoverable in future years

from known reservoirs under existing economic and

operating conditions. There are other categories of

reserves, but by definition they are more speculative

and less precise than proved reserves. Readers who are

unfamiliar with the distinctions between types of

reserves or how reserves fit in the description of overall

oil and natural gas resources should see Appendix G.

This report provides proved reserves estimates for

calendar year 2007. It is based on data filed by large,

intermediate, and a select group of small operators of

oil and gas wells on Form EIA-23, “Annual Survey of

Domestic Oil and Gas Reserves,” and by operators of

all natural gas processing plants on Form EIA-64A,

“Annual Report of the Origin of Natural Gas Liquids

Production.” The U.S. crude oil and natural gas proved

reserves estimates are associated with sampling errors

of less than 1 percent at a 95-percent confidence level.

Form EIA-23

On Form EIA-23, an operator is defined as an

organization or person responsible for the

management and day-to-day operation of oil and/or

natural gas wells. This definition eliminates responses

from royalty owners, working interest owners (unless

they are also operators), and others not directly

responsible for oil and natural gas production

operations.

Operator size categories are based upon operator

annual production as indicated in various Federal,

State, and commercial records. Large operators are

those that produced at least 1.5 million barrels of crude

oil or 15 billion cubic feet of natural gas, or both, during

the report year. Intermediate operators produced less

than large operators, but more than 400,000 barrels of

crude oil or 2 billion cubic feet of natural gas, or both,

during the report year. Small operators are those that

produced less than intermediate operators. All data are

reported on a total operated basis, encompassing all

proved reserves and production associated with wells

operated by an individual operator within a field. This

concept is also called the “gross operated” or “8/8ths”

basis.

Large operators (Category I) and most intermediate

size operators (Category II) report reserves balance

data on Form EIA-23L to show how and why reserves

components changed during the year on a

field-by-field basis. Intermediate size operators who do

not keep reserves data are not asked to provide

estimates of reserves at the beginning of the year or

annual changes to proved reserves by component of

change; i.e., revisions, extensions, and new discoveries.

These volumes are instead estimated using statistical

calculations that preserve the relative relationships

between these items within each State or State

subdivision, as reported by large and intermediate

operators.

A sample selected from the large group of small

(Category III) operators are requested to provide

annual production and, if available, year ending

reserves volumes on Form EIA-23S. Details on the

selection of these operators and the determination of

the reserves volumes are found in Appendix F.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 1
The published reserve estimates include an additional

term, adjustments, calculated by the EIA, that

preserves an exact annual reserves balance of the form:

Adjustments are the annual changes in the published

reserve estimates that cannot be attributed to estimates

from other reserve change categories. They result from

the survey and statistical estimation methods

employed. For example, variations caused by changes

in the operator frame, different random samples,

different timing of reporting, incorrectly reported data,

or imputations for missing or unreported reserve

changes can contribute to adjustments.

Form EIA-23L Element: Type Code

The importance of unconventional resources of natural

gas and crude oil to domestic energy supply continues

to increase. EIA seeks to separately track the

development of these resources.

For the 2007 survey, respondents to the long form

version of Form EIA-23 were requested to assign a Type

Code to their field-level data. Type Code categorizes

proved reserves and production from a field as either

Conventional (C) or one of four types of Unconventional

reservoirs: Coal Bed (CB); Chalk (CH); Shale(SH); or other

Low Permeability (LP) reservoirs (permeability of 0.1

millidarcy or less). Sufficient responses were received

in the category of natural gas from Shale that a separate

table for Shale (Table 13) is included in this report.

Form EIA-64A

Form EIA-64A data were first collected for the 1979

survey year in order to develop estimates for total

natural gas liquids reserves. Data on liquids recovered

from natural gas, as reported by natural gas processing

plant operators, are combined with lease condensate

data collected on Form EIA-23 to provide the total

natural gas liquids reserves estimates.

Data Collection Operations

An intensive effort is made each year to maintain an

accurate and complete survey frame consisting of

operators of oil and gas wells and of natural gas

processing plants. The Form EIA-23 operator frame

contained 13,774 probable active operators and the

Form EIA-64A plant frame contained 496 probable

active natural gas processing plants in the United

States for 2007.

For more details on the survey process, see Appendix

E, Summary of Data Collection Operations.

The 2007 survey sample consisted of 1,438 operators.

EIA sampled 960 operators with certainty; 158

Category I operators, 510 Category II operators, and

292 smaller operators that were selected with certainty

because of their size in relation to the area or areas in

which they operated. EIA also chose 478 Noncertainty

operators in a systematic random sample of the

remaining operators. There were 17 Successor

operators in 2007. Seventy-five (75) respondents ceased

operating oil and/or gas properties (became

non-operator) during the survey year. For more details

on the survey response statistics, see Table E2 in

Appendix E.

EIA mailed EIA-64A forms to all known natural gas

processing plant operators as of February 1, 2007. The

100 percent response rate is detailed in Table E5 in

Appendix E.

National estimates of the production volumes for crude

oil, lease condensate, natural gas liquids, and dry

natural gas based on Form EIA-23 and Form EIA-64A

were compared with corresponding official production

volumes published by EIA, which are obtained from

non-survey based State sources. For report year 2007,

the Form EIA-23 National production estimates were 1

percent higher than the comparable Petroleum Supply

Annual (PSA) 2007 volumes for crude oil and lease

condensate combined and were 1 percent higher than

the comparable Natural Gas Monthly, October 2008

volume for 2007 dry natural gas.

Accuracy in reserves reporting is EIA’s first and

foremost goal for this report. Because of differences in

timing and data availability, the estimates of oil and

gas production presented in this report may differ from

those presented in other EIA reports.

Energy Information Administration

2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Published Proved Reserves at End of Previous Report Year

+ Adjustments

+ Revision Increases

- Revision Decreases

- Sales

+ Acquisitions

+ Extensions

+ New Field Discoveries

+ New Reservoir Discoveries in Old Fields

- Report Year Production

= Published Proved Reserves at End of Report Year
2. Overview

National Summary

The United States had the following proved reserves as

of December 31, 2007:

Crude Oil — 21,317 million barrels

Dry Natural Gas — 237,726 billion cubic feet

Natural Gas Liquids — 9,143 million barrels.

This Overview summarizes the 2007 proved reserves

balances of crude oil, dry natural gas, and natural gas

liquids on a national level and provides historical

comparisons between 2007 and prior years. Table 1

lists the estimated annual reserve balances since 1997

for crude oil, dry natural gas, and natural gas liquids.

Crude Oil

U.S. crude oil proved reserves increased 2 percent (345

million barrels) in 2007. Figure 1 shows the crude oil

proved reserves levels by major region and Figure 2

shows the components of reserves changes from 1997

through 2007.

As indicated in Figure 1, U.S. crude oil proved reserves

increased onshore in the lower 48 States and in Alaska,

but declined slightly in the Gulf of Mexico Federal

Offshore.

The components of reserves changes for crude oil are

shown in Figure 2. EIA tracks all components of

reserves changes: adjustments, revision increases,

revision decreases, sales, acquisitions, extensions, new

field discoveries, new reservoir discoveries in old

fields, and estimated production. These components

are discussed below.

Total discoveries are those reserves attributable to field

extensions, new field discoveries, and new reservoir

discoveries in old fields. They result from the drilling of

exploratory wells. Total discoveries of crude oil were

790 million barrels in 2007, 28 percent less than the

prior 10-year average (1,100 million barrels) and 37

percent more than 2006’s discoveries of 577 million

barrels.

The majority of crude oil total discoveries in 2007 came

from extensions to fields in Texas, the Gulf of Mexico,

North Dakota, New Mexico and Alaska. Operators

discovered 651 million barrels in extensions in 2007, 29

percent more than in 2006 and 18 percent more than the

prior 10-year average (554 million barrels).

New field discoveries accounted for 66 million barrels

of crude oil total discoveries. This was more than twice

the new field discoveries of 2006 (30 million barrels),

and only 16 percent of the prior 10-year average (407

million barrels). More than two-thirds of these

discoveries (45 of 66 million barrels) were in Alaska.

New reservoir discoveries in old fields were 73 million

barrels, 70 percent more than 2006 (43 million barrels)

but 48 percent lower than the prior 10-year average

(140 million barrels).

Crude oil net revisions totaled 1,200 million barrels in

2007. The net of sales and acquisitions of crude oil

proved reserves was a decline of 19 million barrels.

U.S. 2007 crude oil production was 1,691 million

barrels, up 2 percent from 2006's estimated production

(1,652 million barrels) and the first increase in 4 years.

Alaska and the lower 48 States each contributed about

half of the U.S. total increase. Reserves additions of

crude oil replaced 120 percent of 2007 crude oil

production.

Dry Natural Gas

Natural gas proved reserves increased by 26,641 billion

cubic feet in 2007. Figure 3 shows the dry natural gas

proved reserves levels by major region. It indicates that

additions of natural gas reserves in the Lower 48

onshore are raising the national total despite declining

Federal offshore natural gas reserves. Figure 4 shows

the components of reserves changes from 1997 through

2007.

Total discoveries of dry natural gas reserves, which is

the sum of field extensions, new field discoveries, and

new reservoir discoveries in old fields, were 29,091

billion cubic feet in 2007. This was 59 percent more than

the prior 10-year average (18,357 billion cubic feet) and

25 percent more than in 2006 (23,342 billion cubic feet).

The majority of natural gas total discoveries in 2007

were from extensions to existing fields. Field

extensions were 27,107 billion cubic feet, 25 percent

more than in 2006 (21,778 billion cubic feet) and 82

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 3
Energy Information Administration

4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table 1. Total U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids, 1997-2007

Revisionsa Net of Salesb New Reservoir Provedd Change

Net and and New Field Discoveries Total

c

 Estimated Reserves from

Adjustments Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

Crude Oil (million barrels of 42 U.S. gallons)

1997 520 914 1,434 NA 477 637 119 1,233 2,138 22,546 +529

1998 -638 518 -120 NA 327 152 120 599 1,991 21,034 -1,512

1999 139 1,819 1958 NA 259 321 145 725 1,952 21,765 +731

2000 143 746 889 -20 766 276 249 1,291 1,880 22,045 +280

2001 -4 -158 -162 -87 866 1,407 292 2,565 1,915 22,446 +401

2002 416 720 1,136 24 492 300 154 946 1,875 22,677 +231

2003 163 94 257 -398 426 705 101 1,232 1,877 21,891 -786

2004 74 420 494 23 617 33 132 782 1,819 21,371 -520

2005 221 569 790 278 805 205 41 1,051 1,733 21,757 +386

2006 94 2 96 194 504 30 43 577 1,652 20,972 -785

2007 65 1,200 1,265 -19 651 66 73 790 1,691 21,317 +345

Dry Natural Gas (billion cubic feet, 14.73 psia, 60° Fahrenheit)

1997 -590 4,902 4,312 NA 10,585 2,681 2,382 15,648 19,211 167,223 +749

1998 -1,635 5,740 4,105 NA 8,197 1,074 2,162 11,433 18,720 164,041 -3,182

1999 982 10,504 11,486 NA 7,043 1,568 2,196 10,807 18,928 167,406 +3,365

2000 -891 6,962 6,071 4,031 14,787 1,983 2,368 19,138 19,219 177,427 +10,021

2001 2,742 -2,318 424 2,630 16,380 3,578 2,800 22,758 19,779 183,460 +6,033

2002 3,727 937 4,664 380 14,769 1,332 1,694 17,795 19,353 186,946 +3,486

2003 2,841 -1,638 1,203 1,034 16,454 1,222 1,610 19,286 19,425 189,044 +2,098

2004 -114 744 630 1,844 18,198 759 1,206 20,163 19,168 192,513 +3,469

2005 1,887 2,699 4,586 2,544 21,050 942 1,208 23,200 18,458 204,385 +11,872

2006 743 -1,836 -1,093 2,996 21,778 409 1,155 23,342 18,545 211,085 +6,700

2007 1,147 15,461 16,608 408 27,107 796 1,188 29,091 19,466 237,726 +26,641

Natural Gas Liquids (million barrels of 42 U.S. gallons)

1997 -15 289 274 NA 535 114 90 739 864 7,973 +150

1998 -361 208 -153 NA 383 66 88 537 833 7,524 -449

1999 99 727 826 NA 313 51 88 452 896 7,906 +382

2000 -83 459 376 145 645 92 102 839 921 8,345 +439

2001 -429 -132 -561 102 717 138 142 997 890 7,993 -352

2002 62 31 93 54 612 48 78 738 884 7,994 +1

2003 -338 -161 -499 30 629 35 72 736 802 7,459 -535

2004 273 97 370 112 734 26 54 814 827 7,928 +469

2005 -89 21 -68 156 863 32 42 937 788 8,165 +237

2006 173 -165 8 117 924 16 53 993 811 8,472 +307

2007 -139 422 283 101 1,030 30 58 1,118 831 9,143 +671

aRevisions and adjustments = Col. 1 + Col. 2.

bNet of sales and acquisitions = acquisitions - sales.

c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

dProved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9.

NA=Not available.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves” and Form EIA-64A, “Annual Report of the Origin

of Natural Gas Liquids Production.” They may differ from the official EIA production data for crude oil, natural gas, and natural gas liquids for

2007 contained in the Petroleum Supply Annual 2007, DOE/EIA-0340(07) and the Natural Gas Annual 2007, DOE/EIA-0131(07).

Sources: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1996 through 2006 annual reports, DOE/EIA-0216.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 5

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1997-2006 annual reports, DOE/EIA-0216.{21-30}

Figure 1. U.S. Crude Oil Proved Reserves, 1997-2007

Figure 2. Components of Reserves Changes for Crude Oil, 1997-2007
Energy Information Administration

6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure 4. Components of Reserves Changes for Dry Natural Gas, 1997-2007

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1997-2006 annual reports, DOE/EIA-0216.{21-30}

Figure 3. U.S. Dry Natural Gas Proved Reserves, 1997-2007
percent more than the prior 10-year average (14,924

billion cubic feet).

New field discoveries were 796 billion cubic feet, 95

percent more than the volume discovered in 2006 (409

billion cubic feet) and 51 percent of the prior 10-year

average (1,555 billion cubic feet).

New reservoir discoveries in old fields were 1,188

billion cubic feet, 3 percent more than in 2006 (1,155

billion cubic feet) and 63 percent of the prior 10-year

average (1,878 billion cubic feet).

In 2007, net revisions (15,461 billion cubic feet)

accounted for 34 percent of total natural gas reserves

additions (46,107 billion cubic feet). Over the last 10

years, about 15 percent of proved reserves additions

have come from net revisions. The net of sales and

acquisitions of dry natural gas proved reserves was 408

billion cubic feet.

U.S. dry natural gas production grew to 19,466 billion

cubic feet in 2007, a 5-percent increase over 2006's dry

natural gas production (18,545 billion cubic feet).

Unconventional resources are playing an increasingly

important role in U.S. dry natural gas reserves and

production. For example, improved technology now

allows high economic returns for development of

reserves in shale reservoirs at the prices seen in 2006

and 2007. As a result, proved reserves of shale gas have

been increasing rapidly. EIA has collected data on

proved natural gas reserves from shale reservoirs for

two years. The shale gas proved reserves increased 50

percent in 2007 and are now at about 9 percent of the

U.S. total.

Proved reserves and production from coal reservoirs

increased rapidly from 1989 through 2002 before

stabilizing and even dropping slightly in 2006.

However, coalbed natural gas reserves saw an

11.5-percent increase in 2007. Coalbed proved reserves

now account for about 9 percent of U.S. dry natural gas

reserves. Coalbed natural gas production decreased in

2007 but still accounted for about 9 percent of U.S. dry

natural gas production.

Natural Gas Liquids

Natural gas liquids reserves are associated with

natural gas production and include lease condensate

extracted at the well on the producing lease and natural

gas plant liquids reserves extracted at plants. Large

increases in natural gas proved reserves lead to large

increases in natural gas liquids proved reserves, but the

percent increases are not the same because natural gas

from different fields varies in how much liquid is

extractable. Overall, natural gas liquids proved

reserves increased 8 percent in 2007. Operators

replaced 181 percent of U.S. natural gas liquids

production with reserves additions.

Natural gas liquids represented 30 percent of total

liquid hydrocarbon proved reserves in 2007. Total

proved reserves of liquid hydrocarbons (crude oil plus

natural gas liquids) were 30.5 billion barrels in 2007, a

3-percent increase from the 2006 level.

Reserves Changes Since 1977

EIA has collected oil and gas reserves estimates

annually since 1977. Table 2 lists the cumulative totals

of the components of reserves changes for crude oil and

dry natural gas from 1977 through 2007. The table has

two sections, one for the lower 48 States and another for

the U.S. total (which includes Alaska's contribution).

Annual averages for each component of reserves

changes are also listed, along with the percentage of

that particular component's impact on total U.S.

proved reserves. In this section, we compare these

averages to the 2007 proved reserves estimates as a

means of gauging the past year against history.

Crude Oil: Since 1977 U.S. operators have:

had average annual total discoveries of reserves

of 891 million barrels,

had average annual proved reserves additions

of 2,027 million barrels from total discoveries,

net revisions and adjustments, and net sales and

acquisitions, and

had an average annual proved reserves decline

of 393 million barrels nationwide, because

production exceeded proved reserves additions.

Since 1977, crude oil reserves have primarily been

sustained by proved ultimate recovery appreciation in

existing fields rather than by the discovery of new oil

fields. Only 11 percent of reserves additions since 1977

were booked as new field discoveries. Proved ultimate

recovery appreciation is the sum of net revisions,

adjustments, net sales and acquisitions, extensions, and

new reservoir discoveries in old fields (see the Proved

Ultimate Recovery section later in this chapter.) Since

1977, the 27,627 million barrels of total discoveries

accounted for 44 percent of reserves additions.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 7
Energy Information Administration

8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure 5. U.S. Natural Gas Liquids Proved Reserves, 1997-2007

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1997-2006 annual reports, DOE/EIA-0216.{21-30}

Figure 6. Components of Reserves Changes for Natural Gas Liquids, 1997-2007
Compared to the averages of reserves changes since

1977, 2007 was a down year for crude oil discoveries,

but an up year for net revisions, adjustments, and net

sales & acquisitions. Total discoveries of crude oil (790

million barrels) in 2007 were 11 percent less than the

post-1976 U.S. average (891 million barrels per year).

Looking at the components of total discoveries in 2007:

Extensions in 2007 (651 million barrels) were 23

percent more than the post-1976 average (529

million barrels),

2007’s new field discoveries (66 million barrels)

were 71 percent less than the post-1976 average

for crude oil (225 million barrels), and

New reservoir discoveries in old fields (73

million barrels) in 2007 were 47 percent less

than the post-1976 average (137 million barrels).

Revisions, Adjustments, Sales & Acquisitions were

1,246 million barrels in 2007. This was 10 percent more

than the post-1976 average of 1,136 million barrels per

year.

Dry Natural Gas: Since 1977 U.S. operators have:

had average annual new reserves discoveries of

14,521 billion cubic feet,

had average annual proved reserves additions

of 18,894 billion cubic feet from total

discoveries, net revisions and adjustments, and

net sales and acquisitions, and

had an average annual production of 17,477

billion cubic feet, increasing U.S. dry natural

gas reserves by an average 1,417 billion cubic

feet per year. In 2006 and prior years, this

average was negative.

Like crude oil reserves, natural gas reserves have

primarily been sustained by proved ultimate recovery

appreciation since 1977. For gas, extensions rather than

net revisions and adjustments are usually the largest

component. Extensions accounted for 55 percent of all

reserves additions since 1977 while net revisions,

adjustments, sales, and acquisitions accounted for only

23 percent.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 9

Table 2. Reserves Changes, 1977-2007

Lower 48 States U.S. Total

Average Percent Average Percent

per of Reserves per of Reserves

Components of Change Volume Year Additions Volume Year Additions

Crude Oil (million barrels of 42 U.S. gallons)

Proved Reserves as of 12/31/76 ...... 24,928 –– –– 33,502 –– ––

New Field Discoveries ........... 5,981 193 11.6 6,977 225 11.1

New Reservoir Discoveries in Old Fields . . 4,071 131 7.9 4,259 137 6.8

Extensions ................ 14,493 468 28.1 16,391 529 26.1

Total Discoveries ............. 24,545 792 47.5 27,627 891 44.0

Revisions, Adjustments, Sales & Acquisitionsa 27,081 874 52.5 35,218 1,136 56.0

Total Reserves Additions ......... 51,626 1,665 100.0 62,845 2,027 100.0

Production ................ 59,336 1,914 114.9 75,030 2,420 119.4

Net Reserves Change (since 1976)..... -7,710 -249 -14.9 -12,185 -393 -19.4

Dry Natural Gas (billion cubic feet at 14.73 psia and 60° Fahrenheit)

Proved Reserves as of 12/31/76 ...... 180,838 –– –– 213,278 –– ––

New Field Discoveries ........... 55,054 1,776 9.3 55,318 1,784 9.4

New Reservoir Discoveries in Old Fields . . 71,629 2,311 12.0 72,090 2,325 12.3

Extensions ................ 319,388 10,303 53.7 322,738 10,411 55.1

Total Discoveries ............. 446,071 14,389 75.0 450,146 14,521 76.9

Revisions, Adjustments, Sales & Acquisitionsa 148,557 4,792 25.0 135,570 4,373 23.1

Total Reserves Additions ......... 594,628 19,182 100.0 585,716 18,894 100.0

Production ................ 549,657 17,731 92.4 541,792 17,477 92.5

Net Reserves Change (since 1976)..... 44,971 1,451 7.6 43,924 1,417 7.5

a EIA did not separately collect data on sales and acquisitions of proved reserves until the year 2000.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 1977-2007 annual reports, DOE/EIA-0216.{1-30}
Energy Information Administration

10 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table 3. U.S. Average Annual Domestic First Purchase Prices for Crude Oil, Wellhead Prices for Natural

Gas, and the Average Number of Active Rotary Drilling Rigs, 1977-2007

Crude Oil Natural Gas

Year Current 2007 Constant Current 2007 Constant

(dollars per barrel) (dollars per thousand cubic feet) Number of Rigs

1977 8.57 24.02 0.79 2.21 2,001

1978 9.00 23.56 0.91 2.38 2,259

1979 12.64 30.56 1.18 2.85 2,177

1980 21.59 47.85 1.59 3.52 2,909

1981 31.77 64.38 1.98 4.01 3,970

1982 28.52 54.47 2.46 4.70 3,105

1983 26.19 48.12 2.59 4.76 2,232

1984 25.88 45.83 2.66 4.71 2,428

1985 24.09 41.40 2.51 4.31 1,980

1986 12.51 21.03 1.94 3.26 964

1987 15.40 25.21 1.67 2.73 936

1988 12.58 19.91 1.69 2.67 936

1989 15.86 24.19 1.69 2.58 869

1990 20.03 29.41 1.71 2.51 1,010

1991 16.54 23.47 1.64 2.33 860

1992 15.99 22.17 1.74 2.41 721

1993 14.25 19.32 2.04 2.77 754

1994 13.19 17.51 1.85 2.46 775

1995 14.62 19.02 1.55 2.02 723

1996 18.46 23.57 2.17 2.77 779

1997 17.23 21.64 2.32 2.91 943

1998 10.87 13.50 1.96 2.43 827

1999 15.56 19.05 2.19 2.68 625

2000 26.72 32.02 3.68 4.41 918

2001 21.84 25.55 4.00 4.68 1,156

2002 22.51 25.89 2.95 3.39 830

2003 27.56 31.03 4.88 5.49 1,032

2004 36.77 40.25 5.46 5.98 1,192

2005 50.28 53.30 7.33 7.77 1,381

2006 January 57.85 60.15 8.66 9.00 1,473

February 55.69 57.75 7.28 7.55 1,533

March 55.64 57.56 6.52 6.74 1,551

April 62.52 64.55 6.59 6.80 1,597

May 64.40 66.34 6.19 6.38 1,635

June 64.65 66.45 5.80 5.96 1,665

July 67.71 69.42 5.82 5.97 1,681

August 67.21 68.76 6.51 6.66 1,738

September 59.37 60.62 5.51 5.63 1,739

October 53.26 54.34 5.03 5.13 1,734

November 52.42 53.35 6.43 6.54 1,706

December 55.03 55.85 6.65 6.75 1,718

2006 Average 59.69 61.30 6.42 6.59 1,649

2007 January 49.32 49.82 5.92 5.98 1,714

February 52.94 53.32 6.66 6.71 1,736

March 54.95 55.23 6.56 6.59 1,749

April 58.2 58.43 6.84 6.87 1,750

May 58.9 59.04 6.98 7.00 1,748

June 62.35 62.41 6.86 6.87 1,771

July 69.23 69.26 6.19 6.19 1,777

August 67.77 67.68 5.90 5.89 1,804

September 73.27 73.03 5.61 5.59 1,783

October 79.32 78.84 6.25 6.21 1,762

November 87.16 86.43 6.37 6.32 1,798

December 85.28 84.38 6.53 6.46 1,811

2007 Average 66.52 66.52 6.39 6.39 1,768

Sources: Crude oil first purchase prices, natural gas wellhead prices, and number of rigs: Tables 9.1, 9.11, and 5.1, Monthly Energy

Review October 2008, DOE/EIA-0035(2008/10). 2007 constant dollars: U.S. Department of Commerce, Bureau of Economic Analysis,

Gross Domestic Product Implicit Price Deflators, August 2008.
Compared to the averages of reserves changes since

1977, 2007 was an up year for dry natural gas total

discoveries. Operators reported 29,091 billion cubic

feet of total discoveries of dry natural gas proved

reserves, twice as much as the post-1976 average

(14,521 billion cubic feet).

The net of revisions, adjustments, sales, and

acquisitions was 17,016 billion cubic feet in 2007,

almost quadruple the post-1976 U.S. average (4,373

billion cubic feet per year).

For the ninth year in a row (and 13 out of the last 14

years), the annual change to the national total of gas

reserves has been an increase. Consequently, the

average since 1977 is now a positive volume.

Economics and Drilling

Economics: Table 3 lists the average annual domestic

wellhead prices of crude oil and natural gas from 1977

to 2007.

In 2007, the U.S. crude oil first purchase price started at

a monthly average of $49.32 per barrel in January, rose

to a high of $87.16 in November, and ended the year at

$85.28 per barrel in December. The average annual U.S.

crude oil first purchase price increased from $59.69 in

2006 to $66.52 per barrel in 2007.

Oil prices vary by region. The average annual 2007

crude oil first purchase price ranged from a low of

$58.34 per barrel in Wyoming to a high of $71.63 per

barrel in Louisiana. {31}

The average annual wellhead natural gas price

decreased from $6.42 per thousand cubic feet in 2006 to

$6.39 in 2007. Monthly average natural gas prices

started at $5.92 per thousand cubic feet in January 2007,

rose to $6.98 in May, and ended the year at $6.53 per

thousand cubic feet in December 2007. {32}

Drilling: Also listed in Table 3 is the average number

of active rotary drilling rigs from 1977 to 2007. From

2006 to 2007, the annual average active rig count rose

from 1,649 to 1,768, a 7-percent increase.

Looking first at exploratory wells, there were 5,509

exploratory wells drilled in 2007 (Table 4). Of these, 14

percent were completed as oil wells, 60 percent were

completed as gas wells, and 26 percent were dry holes.

Exploratory oil and gas completions (excluding dry

holes) in 2007 were 29 percent more (Figure 7) than the

revised 2006 total.

The number of successful development wells

decreased for oil and natural gas in 2007 (Figure 8).

Including dry holes, there were an estimated 48,501

exploratory and development wells drilled in 2007.

This is 1 percent less than in 2006 and 49 percent more

than the average number of wells drilled annually in

the prior 10 years (32,495).

Figures 9 and 10 show the average volume of

discoveries per exploratory well for dry natural gas

and oil, respectively, since 1977. The 2007 average

volume of oil discoveries per exploratory well

increased 17 percent compared to 2006. The 2007

average volume of gas discoveries per exploratory well

decreased 5 percent compared to 2006.

For the fourteenth year in a row, the number of gas well

completions exceeded the number of oil well

completions in both the exploratory and development

categories.

Mergers and Acquisitions

The following large mergers and acquisitions were

announced in 2007 and are expected to have an impact

on the energy industry in the future:

On June 4, 2007, Dominion announced it would sell

most of its onshore natural gas and oil exploration and

production operations in two separate transactions for

a total of approximately $6.5 billion. This included 3.51

trillion cubic feet equivalent of natural gas and oil

reserves. Loews Corporation acquired Dominion's

operations in the Permian Basin, Michigan, and

Alabama. XTO Energy Inc. acquired operations in the

Rocky Mountains, Gulf Coast, San Juan Basin, and

south Louisiana. {33}

On July 18, 2007, Plains Exploration & Production

Company agreed to acquire Pogo Producing Company

for $3.42 billion in cash and stock. {34}

Reserve-to-Production Ratio

and Ultimate Recovery

R/P Ratios

The relationship between proved reserves and

production levels, expressed as the ratio of reserves to

production (R/P ratio), is often used in analyses. For a

mature producing area the R/P ratio tends to be

reasonably stable, so that the proved reserves at the end

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 11
Energy Information Administration

12 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table 4. U.S. Exploratory and Development Well Completionsa, 1973-2007

Exploratory Total Exploratory and Development

Year Oil Gas Dry Total Oil Gas Dry Total

1973 642 1,067 5,952 7,661 10,167 6,933 10,320 27,420

1974 859 1,190 6,833 8,882 13,647 7,138 12,116 32,901

1975 982 1,248 7,129 9,359 16,948 8,127 13,646 38,721

1976 1,086 1,346 6,772 9,204 17,688 9,409 13,758 40,855

1977 1,164 1,548 7,283 9,995 18,745 12,122 14,985 45,852

1978 1,171 1,771 7,965 10,907 19,181 14,413 16,551 50,145

1979 1,321 1,907 7,437 10,665 20,851 15,254 16,099 52,204

1980 1,777 2,099 9,081 12,957 32,959 17,461 20,785 71,205

1981 2,651 2,522 12,400 17,573 43,887 20,250 27,953 92,090

1982 2,437 2,133 11,307 15,877 39,459 19,076 26,379 84,914

1983 2,030 1,605 10,206 13,841 37,366 14,684 24,355 76,405

1984 2,209 1,528 11,321 15,058 42,906 17,338 25,884 86,128

1985 1,680 1,200 8,954 11,834 35,261 14,324 21,211 70,796

1986 1,084 797 5,567 7,448 19,213 8,599 12,799 40,611

1987 926 756 5,052 6,734 16,210 8,096 11,167 35,473

1988 855 747 4,711 6,313 13,646 8,578 10,119 32,343

1989 607 706 3,934 5,247 10,230 9,522 8,236 27,988

1990 664 693 3,793 5,150 12,445 11,126 8,496 32,067

1991 601 544 3,390 4,535 12,035 9,611 7,882 29,528

1992 498 427 2,550 3,475 9,019 8,305 6,284 23,608

1993 509 541 2,509 3,559 8,764 10,174 6,513 25,451

1994 579 740 2,465 3,784 7,001 9,739 5,515 22,255

1995 549 583 2,279 3,411 7,827 8,454 5,319 21,600

1996 496 591 2,246 3,333 8,760 9,539 5,587 23,886

1997 R 491 561 2,108 3,160 11,044 11,435 5,848 28,327

1998 R 327 566 1,585 2,478 7,556 11,510 4,745 23,811

1999 R 196 565 1,157 1,918 4,734 11,899 3,517 20,150

2000 R 288 657 1,333 2,278 7,986 16,935 4,117 29,038

2001 R 353 1,046 1,714 3,113 8,805 21,959 4,539 35,303

2002 R 255 843 1,271 2,369 6,724 17,225 3,706 27,655

2003 R 349 991 1,285 2,625 8,026 20,587 3,898 32,511

2004 R 386 1,652 1,331 3,370 8,676 23,728 3,975 36,379

2005 R 515 2,087 1,431 4,033 10,381 27,780 4,512 42,673

2006 R 637 2,498 1,400 4,535 12,693 31,597 4,812 49,101

2007 747 3,307 1,455 5,509 12,543 31,303 4,655 48,501

a

Excludes service wells and stratigraphic and core testing.

R = Revised Data.

Notes: Estimates include only the original drilling of a hole intended to discover of further develop already discovered oil or natural gas

resources. Other drilling activities, such as drilling an old well deeper, drilling of laterals from the original well, drilling of service and injec- tion wells, and drilling for resources other than oil and gas are excluded.

Source: Table 5.2, EIA Monthly Energy Review October 2008, DOE/EIA-0035(2008/10). These estimates are subject to continuous revi- sion as new data, some of which pertain to earlier months and years, become available.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 13

Source: Energy Information Administration, Office of Oil and Gas.

Figure 7. U.S. Exploratory Well Completions, 1997-2007

Figure 8. U.S. Development Well Completions, 1997-2007
Energy Information Administration

14 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Source: Energy Information Administration, Office of Oil and Gas.

Figure 9. U.S. Total Discoveries of Dry Natural Gas per Exploratory Gas Well Completion, 1977-2007

Figure 10. U.S. Total Discoveries of Crude Oil per Exploratory Oil Well Completion, 1977-2007
of a year serve as a rough guide to the production level

that can be maintained during the following year.

Operators report data which yield R/P ratios that vary

widely by area depending upon:

category of operator

geology and economics

number and size of new discoveries

amount of drilling that has occurred.

R/P ratios are a general indication of the state of

development in an area and, over time, the ratios

change. For example, when the Alaskan North Slope

oil reserves were booked in 1970, the U.S. R/P ratio for

crude oil increased because significant production

from these reserves did not begin until 7 years later due

to the need to build the Trans Alaska pipeline first. The

U.S. R/P ratio for crude oil decreased from 11.1-to-1 to

9.4-to-1 between 1977 and 1982 as Alaskan North Slope

reserves development and oil production reached high

levels.

In 2007 the national average R/P ratio decreased from

12.7 to 12.6, although both crude oil proved reserves

and production increased. Figure 11 shows the U.S.

R/P ratio trend for crude oil since 1945. After World

War II, increased drilling and discoveries led to a

greater R/P ratio. Later, when drilling found fewer

reserves than were produced, the ratio became smaller.

R/P ratios also vary geographically, because of

differences in development history and reservoir

conditions.

The areas with relatively high R/P ratios in 2007 were

the Permian Basin of Texas and New Mexico, and

California, where enhanced oil recovery techniques

such as carbon dioxide (CO2 ) injection and

steamflooding have improved the recoverability of oil

in old, mature fields. Areas that have the lowest R/P

ratios, like the Mid-Continent region, usually have

many older fields. There, new technologies such as

horizontal drilling are helping add new reserves

equivalent to the annual production, keeping the

regional reserves and R/P ratio for oil relatively stable.

Figure 12 shows the historical R/P ratio for wet natural

gas since 1945. Prior to 1945, R/P ratios were very high

since the interstate pipeline infrastructure was not yet

well developed. The market for natural gas grew

rapidly after World War II, lowering the R/P ratio.

From 2006 to 2007, the U.S. average R/P ratio for

natural gas increased from 11.4 to 12.2, since proved

reserves increased more than production increased.

Different marketing, transportation, and production

characteristics for gas are seen when looking at

regional average R/P ratios as compared to the 2007

U.S. average R/P ratio of about 12.2-to-1. Areas with a

higher range of R/P ratios than the national average

were the Pacific offshore and the Rockies. Several

major gas producing areas have R/P ratios below the

national average, particularly Texas, the Gulf of

Mexico Federal Offshore, and Oklahoma.

Proved Ultimate Recovery

Proved Ultimate Recovery is the sum of proved

reserves and cumulative production at a specified

point in time. It measures the maximum recoverable

volume known at that time and is a dynamic quantity

that is expected to change over time for any field, group

of fields, State, or country. In most instances, therefore,

an estimate of Proved Ultimate Recovery does not

represent the all-time maximum recoverable volume of

resources for a given field or area. In fact, the proved

ultimate recovery of a field, a group of fields, a State, a

region, or a country grows (appreciates) over time in

most instances.

Figures 13 and 14 show successive estimates of proved

ultimate recovery for the United States. The figures

show proved reserves and cumulative production over

the period 1977 through 2007 for crude oil plus lease

condensate and wet natural gas. They illustrate the

continued appreciation (growth) of proved ultimate

recovery over time.

In 1977, U.S. crude oil plus lease condensate proved

reserves were 33,615 million barrels. Cumulative

production of crude oil plus lease condensate for 1977

through 2007 was 77,346 million barrels. This

substantially exceeds the 1977 proved reserves, but at

the end of 2007 there were still 22,812 million barrels of

crude oil plus lease condensate proved reserves.

Therefore, the Nation’s estimated proved ultimate

recovery of crude oil primarily increased during this

period owing to the proved ultimate recovery appreciation

phenomenon that typically accompanies the continued

development of old fields. In fact, only 11 percent of

proved reserves additions of crude oil were booked as

new field discoveries from 1976 through 2007. The other

89 percent came from the proved reserves categories

related to the proved ultimate recovery appreciation

process.

Similarly, the 1977 wet natural gas proved reserves were

209,490 billion cubic feet, but 571 trillion cubic feet of

gas was produced from 1977 through 2007; there are

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 15
Energy Information Administration

16 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Sources: Annual reserves and production - American Petroleum Institute and American Gas Association (1945–1976) {35} and Energy

Information Administration, Office of Oil and Gas (1977–2006){1-30}. Cumulative production: U.S. Oil and Gas Reserves by Year of Field

Discovery (1977-1988).{36}

Figure 11. Reserves-to-Production Ratios for Crude Oil, 1945-2007

Figure 12. Reserves-to-Production Ratios for Wet Natural Gas, 1945-2007
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 17

Sources: Annual reserves and production - American Petroleum Institute and American Gas Association (1945–1976) {35} and Energy

Information Administration, Office of Oil and Gas (1977–2006){1-30}. Cumulative production: U.S. Oil and Gas Reserves by Year of Field

Discovery (1977-1988).{36}

Figure 13. Components of Proved Ultimate Recovery for Crude Oil and Lease Condensate, 1977-2007

Figure 14. Components of Proved Ultimate Recovery for Wet Natural Gas, 1977-2007
Ta ble 5. In ter na tional Oil and Natu ral Gas Re serves as of De cem ber 31, 2007

Oil

(mil lion bar rels)

Natu ral Gas

(bil lion cu bic feet)

Oil & Gas World Oil & Gas World 

Ranka Coun try Jour nal Oil Rankb Coun try Jour nal Oil

1 Saudia Arabiac.......

d

266,751 d264,825 1 Russia .............. 1,680,000 1,654,000

2 Iranc............... 138,400 137,000 2 Iranc................ 948,200 985,000

3 Iraqc............... 115,000 126,000 3 Qatarc.............. 905,300 905,450

4 Canadae............ 178,592 25,157 4 Saudia Arabiac........

d

253,107 d254,000

5 Kuwaitc.............

d

104,000 d99,425 5 United States ......... 211,085 217,500

6 Venezuelac.......... 87,035 81,000 6 United Arab Emiratesc. . 213,200 196,300

7 United Arab Emiratesc. 97,800 68,105 7 Nigeriac............. 183,990 184,500

8 Rus sia.............. 60,000 76,000 8 Algeriac............. 159,000 160,000

9 Libyac.............. 41,464 36,500 9 Venezuelac.......... 166,260 152,000

10 Nigeriac............ 36,220 37,200 10 Iraqc................ 111,940 91,000

Top 10 To tal.............. 1,125,262 951,212 Top 10 To tal .............. 4,832,082 4,799,750

11 Kazakhstan.......... 30,000 - 11 Kazakhstan .......... 100,000 -

12 United States ........ 20,972 21,000 12 Turkmenistan ......... 100,000 -

13 Qatarc.............. 15,207 20,000 13 Indonesiac........... 93,900 92,000

14 China .............. 16,000 18,052 14 Aus tra lia ............. 30,370 151,900

15 Brazil............... 12,182 12,539 15 Nor way.............. 79,130 81,683

16 Algeriac............. 12,200 11,900 16 China ............... 80,000 61,800

17 Mex ico ............. 11,650 11,061 17 Ma lay sia............. 83,000 88,010

18 An golac............. 9,035 9,500 18 Uzbekistan ........... 65,000 -

19 Azerbaijan........... 7,000 - 19 Egypt ............... 58,500 68,450

20 Nor way ............. 6,865 6,693 20 Kuwaitc..............

d

56,015 d66,300

21 Su dan .............. 5,000 6,700 21 Can ada ............. 58,200 58,256

22 Oman .............. 5,500 5,700 22 Libyac............... 50,100 52,800

23 In dia ............... 5,625 4,042 23 Neth er lands .......... 50,000 48,800

24 Malaysia ............ 4,000 5,458 24 Ukraine.............. 39,000 -

25 Ec ua dorc........... 4,517 4,780 25 In dia ................ 37,960 31,755

Top 25 To tal.............. 1,291,015 1,088,637 Top 25 To tal .............. 5,819,531 5,601,504

OPEC Total .............. 927,482 900,744 OPEC Total ............... 3,151,742 3,145,380

World To tal .............. 1,331,698 1,183,891 World To tal ............... 6,185,693 6,255,963

aRank is based on an av er age of oil re serves re ported by Oil & Gas Jour nal and World Oil.

bRank is based on an av er age of natu ral gas re serves re ported by Oil & Gas Jour nal and World Oil.

cMem ber of the Or gani za tion of Pe tro leum Ex port ing Coun tries (OPEC).

d

In cludes one-half of the re serves in the Neu tral Zone.

eOil and Gas Journal Canadian oil reserves include heavy (low gravity) oil.

Note: The En ergy In for ma tion Ad min istra tion does not cer tify these in ter na tional re serves data, but re pro duces the in for ma tion as a mat ter 

of con ven ience for the reader.

Sources: Penn Well Pub lish ing Com pany, Oil and Gas Jour nal, Vol. 105, No.48 (December 24, 2007). Gulf Pub lish ing Com pany, World

Oil, Vol.229, No. 9 (September, 2008).

Energy Information Administration

18 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
still 247,789 billion cubic feet of wet natural gas proved

reserves in 2007. Only 9 percent of proved reserves

additions of natural gas were booked as new field

discoveries from 1976 through 2007. The other 91

percent came from proved ultimate recovery

appreciation.

International Perspective

International Reserves

The EIA estimates domestic oil and gas reserves but

does not comprehensively estimate worldwide

reserves. As shown in Table 5, international reserves

estimates are presented in two widely circulated trade

publications. The world's total reserves are estimated

to be roughly 1.3 trillion barrels of oil and 6.2

quadrillion cubic feet of gas.

The United States ranked 12th in the world for proved

reserves of crude oil and 5th for natural gas in 2007. A

comparison of EIA's U.S. proved reserves estimates

with worldwide estimates obtained from other sources

shows that the United States had 2 percent of the

world's total crude oil proved reserves and 3 percent of

the world's total natural gas proved reserves at the end

of 2007. There are sometimes substantial differences

between the estimates from these sources. The Oil &

Gas Journal reported oil reserves for Canada at about

179 billion barrels. This is much higher than the World

Oil estimate of 25 billion. The Oil and Gas Journal

estimate includes a larger contribution of heavy oil

from Canadian tar sands. Another reason (among

many) for these differences is that condensate is often

included in foreign oil reserve estimates.

The Oil & Gas Journal {37} estimate for world oil

reserves increased 1 percent in 2007 owing to an

increase in Saudi Arabian and Iranian reserves. The

World Oil {38} estimate increased 3 percent in 2007 for

the same reasons. For world gas reserves in 2007, the

Oil & Gas Journal reported a slight (less than 0.5

percent) increase, while World Oil reported a 1-percent

decrease.

Several foreign countries have oil reserves

considerably larger than those of the United States.

Saudi Arabian oil reserves are the largest in the world,

dwarfing U.S. oil reserves. Iraqi oil reserves are more

than five times the U.S. reserves.

Petroleum Consumption

The United States is the world's largest energy

consumer. The EIA estimates energy consumption and

publishes it in its Annual Energy Review.{39} In 2007:

The U.S. consumed 101.6 quadrillion Btu of

energy. This was an increase of 1.74 quadrillion

Btu from the 2006 level of consumption. One

quadrillion Btu is equivalent to the amount of

energy in 45 million tons of coal, 170 million

barrels of crude oil, or one trillion cubic feet of

natural gas.

62 percent of U.S. energy consumption was

provided by petroleum and natural gas—crude

oil and natural gas liquids combined (39

percent), and natural gas (23 percent).

U.S. petroleum consumption was about 21

million barrels of oil and natural gas liquids

and 63 billion cubic feet of gas per day.

Dependence on Imports

The United States remains dependent on imported oil

and gas. In 2007, crude oil imports made up 66 percent

of the U.S. crude oil supply. Canada, Mexico, Saudi

Arabia, Venezuela, Nigeria, and Iraq were the primary

foreign suppliers of petroleum to the United States.{40}

Net natural gas imports increased slightly from the

2006 total of 3.5 trillion cubic feet to 3.8 trillion cubic

feet in 2007 (4.6 trillion imported; 0.8 trillion exported).

Imports satisfied approximately 20 percent of

consumption. Almost all of this gas was pipelined from

Canada. Some liquefied natural gas was imported from

Trinidad and Tobago, Egypt, Nigeria, and Algeria.

List of Appendices

Appendix A: Operator Level Data - How much of the

national total of proved reserves are operated by the

large oil and gas corporations? Appendix A separates

the large operators from the small and presents

reserves data according to operator production size

classes. Table A6 lists the top U.S. operators by

reported 2007 production.

Appendix B: Top 100 Oil and Gas Fields - What fields

have the most reserves and production in the United

States? The top 100 fields for oil and natural gas out of

the national inventory of more than 45,000 oil and gas

fields are listed in Appendix B. These fields hold 66

percent of U.S. crude oil proved reserves and 60

percent of U.S. natural gas proved reserves.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 19
Appendix C: Conversion to the Metric System - To

simplify international comparisons, a summary of U.S.

Crude Oil, Natural Gas, and Natural Gas Liquids

Reserves expressed in metric units is included as

Appendix C.

Appendix D: Historical Reserves Statistics -

Appendix D contains selected historical reserves data

presented at the national level. Readers interested in a

historical look at one specific State or region can review

these tables in an electronic data archive on the EIA

website. Table D9 contains the production and proved

reserves for 1997-2007 for the Gulf of Mexico Federal

Offshore region by water depths greater than 200

meters, and less than 200 meters. Table D10 contains

Nonproducing Reserves.

Appendix E: Summary of Data Collection Operations

- This report is based on two annual EIA surveys.

Proved reserves data is collected from U.S. oil and gas

field operators on Form EIA-23. Natural gas liquids

production data is collected annually from U.S. natural

gas plant operators on Form EIA-64A. Appendix E

describes the survey designs, response statistics,

reporting requirements, and sampling frame

maintenance.

Appendix F: Statistical Considerations - The EIA

strives to maintain or improve the accuracy of its

reports. Because a census of all oil and gas operators is

impractical, the EIA has adopted sound statistical

methods to impute data for those operators not

sampled and for those data elements that smaller

operators are not required to file. These methods are

described in Appendix F.

Appendix G: Estimation of Reserves and Resources -

Reserves are not directly measurable. They are

estimated on the basis of the best geological,

engineering, and economic data available to the

estimator. Appendix G describes reserve estimation

techniques commonly used by oil and gas field

operators and by EIA personnel who perform quality

assurance checks for selected fields. A discussion of the

relationship of reserves to overall U.S. oil and gas

resources is also included.

Appendix H: Maps of Selected State Subdivisions -

Certain large producing States have been subdivided

into smaller regions to allow more specific reporting of

reserves data. Maps of these States identifying the

smaller regions are provided in Appendix H.

Appendix I: Annual Survey Forms for Domestic Oil

and Gas Reserves - Samples of Form EIA-23 and Form

EIA-64A are presented in Appendix I.

Glossary - Provides definitions of the technical terms

used in this report.

Energy Information Administration

20 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
3. Crude Oil Statistics

Proved Reserves

The United States had 21,317 million barrels of crude

oil proved reserves as of December 31, 2007. This is 2

percent (345 million barrels) more than in 2006. The

principal factors contributing to the increase were large

positive net revisions and larger-than-average

extensions to existing oil fields.

Alaska had the largest increase in year-end crude oil

proved reserves, growing 7 percent over 2006 (284

million barrels), followed closely by Texas with an

increase in year-end proved reserves of 5 percent (251

million barrels). Alaska's increase included 45 million

barrels of new field discoveries. Due to rapid

development of unconventional oil resources

associated with the Bakken Formation, North Dakota

had the third largest volumetric increase in crude oil

proved reserves, up 17 percent from 2006 (70 million

barrels).

Reserves additions of crude oil in the U.S. replaced 120

percent of 2007 crude oil production (Figure 15).

Table 6 presents the U.S. proved reserves of crude oil

as of December 31, 2007, by selected States and State

subdivisions. Figure 16 maps 2007 crude oil proved

reserves by area.

The following four areas account for 76 percent of U.S.

crude oil proved reserves:

Percent of 2007

Area U.S. Oil Reserves

Texas 24

Alaska 20

Gulf of Mexico Federal Offshore 16

California 16

Area Subtotal 76

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 21

Figure 15. Replacement of U.S. Crude Oil Production by Reserves Additions, 1997-2007.

Source: Energy Information Administration, Office of Oil and Gas.

.
Energy Information Administration

22 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

aIncludes Arizona, Missouri, Nevada, New York, South Dakota, Tennessee, and Virginia.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves.” They may differ from the official Energy Information Administration production data for crude oil for 2007 contained in the

Petroleum Supply Annual 2007, DOE/EIA-0340(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska ..................... 3,879 0 487 34 9 16 40 45 0 261 4,163

Lower 48 States ............. 17,093 65 1,791 1,044 802 776 611 21 73 1,430 17,154

Alabama . . . . . . . . . . . . . . . . . . . 45 1 4 1 3 1 0 0 0 5 42

Arkansas . . . . . . . . . . . . . . . . . . . 37 -2 4 2 0 0 0 0 0 6 31

California ................... 3,389 -6 248 144 10 38 27 0 0 220 3,322

Coastal Region Onshore . . . . . 375 3 44 19 5 9 1 0 0 15 393

Los Angeles Basin Onshore . . 364 -8 24 16 0 21 1 0 0 17 369

San Joaquin Basin Onshore . . 2,448 -2 160 104 2 8 16 0 0 173 2,351

State Offshore . . . . . . . . . . . . . 202 1 20 5 3 0 9 0 0 15 209

Colorado . . . . . . . . . . . . . . . . . . . 274 1 38 14 1 1 24 0 0 19 304

Florida . . . . . . . . . . . . . . . . . . . . . 38 -1 21 0 37 14 0 0 0 3 32

Illinois . . . . . . . . . . . . . . . . . . . . . 89 -4 10 0 2 0 16 0 0 8 101

Indiana . . . . . . . . . . . . . . . . . . . . 12 5 3 1 0 0 0 0 0 2 17

Kansas . . . . . . . . . . . . . . . . . . . . 263 -32 30 27 0 0 4 0 4 36 206

Kentucky . . . . . . . . . . . . . . . . . . . 25 0 1 0 0 0 0 0 0 2 24

Louisiana. . . . . . . . . . . . . . . . . . . 428 47 59 48 29 41 13 0 1 54 458

North . . . . . . . . . . . . . . . . . . . . 68 21 6 5 11 6 0 0 0 9 76

South Onshore. . . . . . . . . . . . . 312 23 31 34 18 35 13 0 1 37 326

State Offshore . . . . . . . . . . . . . 48 3 22 9 0 0 0 0 0 8 56

Michigan . . . . . . . . . . . . . . . . . . . 63 2 2 6 5 3 1 0 0 5 55

Mississippi. . . . . . . . . . . . . . . . . . 186 9 24 9 1 6 6 0 1 22 200

Montana . . . . . . . . . . . . . . . . . . . 419 5 37 35 43 38 24 0 0 35 410

Nebraska. . . . . . . . . . . . . . . . . . . 14 -2 3 0 1 0 0 0 0 2 12

New Mexico. . . . . . . . . . . . . . . . . 705 24 76 62 38 43 41 0 0 54 735

East . . . . . . . . . . . . . . . . . . . . . 696 23 74 61 38 43 41 0 0 53 725

West . . . . . . . . . . . . . . . . . . . . 9 1 2 1 0 0 0 0 0 1 10

North Dakota . . . . . . . . . . . . . . . . 412 2 55 28 50 52 80 1 3 45 482

Ohio. . . . . . . . . . . . . . . . . . . . . . . 49 2 10 11 0 0 2 0 0 4 48

Oklahoma . . . . . . . . . . . . . . . . . . 569 -52 142 50 80 28 25 0 1 53 530

Pennsylvania . . . . . . . . . . . . . . . . 20 -5 2 4 0 0 1 0 0 2 12

Texas...................... 4,871 65 575 241 212 222 183 2 7 350 5,122

RRC District 1 . . . . . . . . . . . . . 76 3 15 2 1 1 2 0 0 10 84

RRC District 2 Onshore . . . . . . 65 1 5 2 2 2 0 0 0 7 62

RRC District 3 Onshore . . . . . . 180 8 25 27 15 46 8 0 1 26 200

RRC District 4 Onshore . . . . . . 30 4 6 4 6 2 1 0 1 4 30

RRC District 5 . . . . . . . . . . . . . 24 3 2 1 0 0 0 0 0 3 25

RRC District 6 . . . . . . . . . . . . . 157 0 33 7 15 3 2 0 1 14 160

RRC District 7B . . . . . . . . . . . . 89 3 15 1 6 2 0 0 0 9 93

RRC District 7C . . . . . . . . . . . . 288 16 21 16 25 33 29 0 1 21 326

RRC District 8 ............. 1,717 14 194 84 101 95 71 0 3 113 1,796

RRC District 8A ............ 2,093 9 226 89 31 28 65 2 0 124 2,179

RRC District 9 . . . . . . . . . . . . . 96 13 20 1 0 0 0 0 0 13 115

RRC District 10 . . . . . . . . . . . . 53 -8 12 6 10 10 5 0 0 6 50

State Offshore . . . . . . . . . . . . . 3 -1 1 1 0 0 0 0 0 0 2

Utah. . . . . . . . . . . . . . . . . . . . . . . 334 -8 25 3 0 1 23 0 0 17 355

West Virginia . . . . . . . . . . . . . . . . 23 0 7 0 0 0 0 0 0 2 28

Wyoming . . . . . . . . . . . . . . . . . . . 706 10 36 34 72 69 18 0 0 43 690

Federal Offshore ............. 4,096 3 372 324 218 219 122 18 56 439 3,905

Pacific (California) . . . . . . . . . . 441 2 14 8 3 20 0 0 0 25 441

Gulf of Mexico (Louisiana) .... 3,500 1 335 298 212 195 111 4 56 372 3,320

Gulf of Mexico (Texas). . . . . . . 155 0 23 18 3 4 11 14 0 42 144

Miscellaneousa . . . . . . . . . . . . . . 26 1 7 0 0 0 1 0 0 2 33

U.S. Total .................. 20,972 65 2,278 1,078 811 792 651 66 73 1,691 21,317

Table 6. Crude Oil Proved Reserves, Reserves Changes, and Production, 2007

(million barrels of 42 U.S. gallons)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 23

Figure 16. Crude Oil Proved Reserves by Area, 2007

Source: Energy Information Administration, Office of Oil and Gas.

Figure 17. Changes in Crude Oil Proved Reserves by Area, 2006 to 2007
Discussion of Reserves Changes

The following graphic portrays the beginning- and

end-of-year crude oil proved reserves, and the

components of crude oil proved reserves change

during 2007, at the same volumetric scale. Note that the

scale starts at 20 billion barrels rather than at zero.

Figure 17 maps the change in crude oil proved reserves

from 2006 to 2007 by area. The table below shows how

the top four areas fared compared to the total United

States:

Change in 2007

U.S. Oil Reserves

Area (million barrels)

Alaska +284

Texas +251

Gulf of Mexico Federal Offshore -191

California -67

Area Subtotal +277

U.S. Total +345

Figure 2 in Chapter 2 shows the components of the

changes in crude oil proved reserves for 2007 and the

preceding 10 years.

Total Discoveries

Total discoveries are those new reserves attributable to

extensions of existing fields, new field discoveries, and

new reservoir discoveries in old fields (see graph

below). They result from the drilling of exploratory

wells.

Total discoveries of crude oil were 790 million barrels

in 2007, 37 percent more than those of 2006 (577 million

barrels), but 28 percent less than the prior 10-year

average (1,100 million barrels).

Only five areas had total discoveries of 35 million

barrels or more in 2007:

Percent of 2007 U.S.

Area Oil Total Discoveries

Federal Offshore Gulf of Mexico 25

Texas 24

Alaska 11

North Dakota 11

New Mexico 5

Area Subtotal 76

Extensions

Operators reported 651 million barrels of extensions in

2007, 29 percent more than in 2006. The highest volume

of extensions was reported in Texas (183 million

barrels). The second highest volume of 2007 extensions

was 122 million barrels in the Gulf of Mexico Federal

Offshore, followed by 80 million barrels in North

Dakota.

In the prior 10 years, U.S. operators reported an

average of 554 million barrels of extensions per year.

The 2007 extensions were 18 percent above that

average.

New Field Discoveries

New field discoveries accounted for 66 million barrels

of crude oil reserves additions. This was more than

twice the new field discoveries of 2006 (30 million

Energy Information Administration

24 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Crude Oil Proved Reserves Changes, 2007
barrels). Sixty-eight percent of 2007 new field

discoveries (45 of 66 million barrels) were in Alaska.

In the prior 10 years, U.S. operators reported an annual

average of 407 million barrels of reserves additions

from new field discoveries. Reserves from new field

discoveries in 2007 were 16 percent of that average.

New Reservoir Discoveries in Old Fields

Operators reported 73 million barrels of crude oil

reserves additions from new reservoir discoveries in

old fields in 2007. This is 70 percent more than in 2006.

The majority of the new reservoir discoveries in old

fields (56 of 73 million barrels) came from the Gulf of

Mexico Federal Offshore.

In the prior 10 years, U.S. operators reported an annual

average of 140 million barrels of reserves from new

reservoir discoveries in old fields. Reserves from new

reservoir discoveries in old fields in 2007 were 52

percent of that average.

Revisions and Adjustments

Operators report thousands of positive and negative

revisions to proved reserves each year as development

wells are drilled, well performance is analyzed, new

technology is applied, or economic conditions change.

Adjustments are the annual changes in the published

reserve estimates that cannot be directly attributed to

the estimates for other reserve change categories. They

result instead from the survey and statistical estimation

methods employed.

There were 2,278 million barrels of revision increases,

1,078 million barrels of revision decreases, and 65

million barrels of adjustments in 2007. Combined, there

were 1,265 million barrels of net revisions and

adjustments for crude oil in 2007.

In the prior 10 years, net revisions and adjustments

added an annual average of 677 million barrels. The

2007 net revisions and adjustments were almost twice

that average.

Sales and Acquisitions

In the context of this report, Salesrepresents the volume

of crude oil proved reserves deducted from an

operator’s total reserves by sale or transfer of

operations of existing oil fields or properties to another

operator, instead of a volume of production “sold” at

the wellhead. Similarly, Acquisitions is that volume of

proved reserves added to an operator’s total reserves

through purchase or operations transfer of an existing

oil field or properties.

There are several reasons why sales and acquisitions

volumes are not equal for a given year. Since operators

have different engineering staffs and resources, or

different development plans or schedules, the estimate

of proved reserves for a field can change upon a change

in operatorship. Timing of the transfer of operations

can also impact these values.

In 2007, there were 811 million barrels of sales

transactions between operators and 792 million barrels

of acquisitions transactions yielding a net difference of

-19 million barrels.

Production

U.S. production of crude oil in 2007 was an estimated

1,691 million barrels. This volume, which does not

include lease condensate, was 2 percent higher than

2006’s production of 1,652 million barrels.

The Gulf of Mexico Federal Offshore remained the

largest oil producing area in the United States in 2007

with 24 percent of the national total (414 million barrels

of production). Texas and Alaska were second and

third, with 21 and 15 percent of the national production

total, respectively. California was fourth with 13

percent.

Alaskan oil production increased the most in 2007,

owing in part to repair work done in 2006 to the

Prudhoe Bay Field's oil pipeline gathering system. Its

production rose 19 million barrels, an 8-percent

increase. The Gulf of Mexico Federal Offshore had the

second largest production increase in 2007 (8 million

barrels, a 2-percent increase).

North Dakota had the third largest annual oil

production increase of any State (7 million barrels, an

18-percent increase) owing to continued development

of the unconventional Bakken Formation.

The 2007 Form EIA-23 national production estimates

(1,691 million barrels of crude oil and 181 million

barrels of lease condensate) are 1 percent higher than

the comparable Petroleum Supply Annual (PSA) 2007

volumes for crude oil and lease condensate production

combined (1,848 million barrels).

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 25
Areas of Note: Large Discoveries

and Reserves Additions

The following State and area discussions summarize

notable activities during 2007 concerning expected new

field reserves, development plans, and possible

production rates as reported in various trade

publications. The citations do not necessarily reflect

EIA’s concurrence, but are considered important

enough to be brought to the reader’s attention.

The following areas were the major success stories for

crude oil reserves and production for 2007.

Alaska

Alaska reported the largest increase (284 million

barrels) of proved oil reserves in 2007. The majority of

these reserves additions were reported as revision

increases. Alaska also had the largest volume of new

field discoveries in the Nation in 2007.

Nikaitchuq Field: One example of new

development in Alaska is the Nikaitchuq Field.

The operator, Eni Energy, reported that it

planned to drill approximately 80 wells, 32 from

onshore locations and the remaining 48 from an

artificial offshore island. The wells will then be

tied back to a production facility located at

Oliktok Point and may produce as much as

40,000 barrels per day. {41} (ENI Press Release,

April 11, 2007)

Texas

Texas reported a net increase of 251 million barrels of

crude oil proved reserves in 2007. As in Alaska, the

majority of the proved reserves additions in Texas

came from revisions. But 30 percent of total Texas

reserves additions (183 million barrels out of 601

million barrels) were extensions. This was the largest

volume of extensions in the Nation and primarily

occurred in west Texas.

Seminole Field: In May, Amerada Hess,

operator of the Seminole San Andres Unit

(SSAU), announced plans for an approximate

$300 million investment to expand its CO2

enhanced oil recovery project in this large,

mature field. A difficult-to-produce resource,

termed a Residual Oil Zone (ROZ), lies directly

underneath the field's main pay zone and

contains nearly one billion barrels of estimated

technically recoverable resources. However, the

chemistry of the oil within the ROZ prevents it

from moving without additional treatment.

Amerada Hess planned to deepen 47 production

wells into the ROZ, and then convert 29 wells

from production to carbon dioxide injection; the

injected carbon dioxide would then mobilize the

otherwise trapped oil and increase recovery.

Amerada Hess has successfully operated one

pilot program in the ROZ since 1994 and a

second pilot program since 2004, resulting in

this expansion. (Excerpted from Seminole

Sentinel, May 20, 2007)

North Dakota

North Dakota reported the Nation's third largest net

increase in proved crude oil reserves in 2007 -- 70

million barrels (17 percent over its 2006 total). These

increases come largely from the unconventional

Bakken Formation, a deep, predominantly shale

formation which produces light, sweet crude oil when

fractured. North Dakota's production increased from

38 million barrels in 2006 to 45 million barrels in 2007.

Bakken Formation (Parshall Field): EOG

Resources, Inc. reported successful drilling in

the unconventional Bakken Formation in North

Dakota where it had accumulated

approximately 320,000 net acres. During 2007,

EOG increased its estimated reserves in the

Bakken from 60 to approximately 80 million

barrels of oil, net. {42} (EOG Letter to

Stockholders, Annual Report 2007)

Other Gain Areas

Colorado, Louisiana, and New Mexico: Colorado,

Louisiana, and New Mexico all reported a net increase

of 30 million barrels of crude oil proved reserves in

2007.

Areas of Note:

Large Declines in Reserves

The following areas had large declines in crude oil

proved reserves due to downward revisions or

unreplaced production.

Gulf of Mexico Federal Offshore

The Gulf of Mexico Federal Offshore crude oil proved

reserves declined 5 percent (191 million barrels) in

2007. However, crude oil production increased 2

Energy Information Administration

26 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
percent from 405 million barrels in 2006 to 414 million

barrels in 2007.

California

California crude oil proved reserves declined 2 percent

(67 million barrels) in 2007. Production exceeded

reserves additions despite 27 million barrels of

extensions, positive net revisions, and net acquisitions

of crude oil proved reserves. California’s estimated

2007 production of 220 million barrels decreased 1

percent from the 2006 level (222 million barrels).

Kansas

There was a 22 percent decline (57 million barrels) in

Kansas' crude oil proved reserves in 2007. However,

Kansas crude oil production increased 3 percent from

its 2006 level.

Other Decline Areas

Discovery and development of new or existing oil

fields were also outpaced by crude oil production in

the following areas of the United States:

Oklahoma: Proved oil reserves decreased

by 7 percent (39 million barrels).

Wyoming: Proved oil reserves decreased

by 2 percent (16 million barrels).

Reserves in

Nonproducing Status

Not all proved reserves of crude oil reported in 2007

were producing. Operators reported 5,455 million

barrels of proved reserves in nonproducing status in

2007, 5 percent more than in 2006 (5,174 million

barrels). Nonproducing crude oil reserves (not

including lease condensate) are listed in Table 7.

Nonproducing reserves are those awaiting well

workovers, the drilling of extensions or additional

development wells, installation of production or

pipeline facilities, and depletion of other zones or

reservoirs before recompletion in reservoirs not

currently open to production.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 27
Energy Information Administration

28 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400

Lower 48 States ............................ 5,055

Alabama .................................. 0

Arkansas .................................. 0

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

Coastal Region Onshore . . . . . . . . . . . . . . . . . . . 42

Los Angeles Basin Onshore . . . . . . . . . . . . . . . . . 98

San Joaquin Basin Onshore. . . . . . . . . . . . . . . . . 168

State Offshore. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Kansas.................................... 9

Kentucky .................................. 0

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

North. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

South Onshore . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

State Offshore. . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Michigan .................................. 2

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Montana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

New Mexico. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

East . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

West . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Table 7. Reported Reserves in Nonproducing Status for Crude Oil, 2007a

(million barrels of 42 U.S. gallons)

Nonproducing Nonproducing Crude Oil Crude Oil

State and Subdivision Reserves State and Subdivision Reserves

Ohio...................................... 8

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Pennsylvania ............................... 0

Texas ..................................... 1,186

RRC District 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

RRC District 2 Onshore . . . . . . . . . . . . . . . . . . . . 16

RRC District 3 Onshore . . . . . . . . . . . . . . . . . . . . 22

RRC District 4 Onshore .................... 2

RRC District 5............................ 1

RRC District 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

RRC District 7B .......................... 1

RRC District 7C . . . . . . . . . . . . . . . . . . . . . . . . . . 137

RRC District 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . 454

RRC District 8A . . . . . . . . . . . . . . . . . . . . . . . . . . 484

RRC District 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

RRC District 10. . . . . . . . . . . . . . . . . . . . . . . . . . . 12

State Offshore............................ 0

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

Virginia.................................... 0

West Virginia ............................... 0

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Federal Offshore ............................ 2,304

Pacific (California) . . . . . . . . . . . . . . . . . . . . . . . . 20

Gulf of Mexico (Louisiana)c

.................. 2,231

Gulf of Mexico (Texas) . . . . . . . . . . . . . . . . . . . . . 53

Miscellaneousb ............................. 5

U.S. Total ................................. 5,455

a

Includes only those operators who produced 400,000 barrels of crude oil or 2 billion cubic feet of natural gas, or both, during the report

year (Category I or Category II operators). b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

c Includes Federal Offshore Alabama.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.
4. Natural Gas Statistics

Dry Natural Gas

Proved Reserves

The U.S. had record-high additions to dry natural gas

proved reserves in 2007, totaling 46.1 trillion cubic feet

(Tcf). This was more than twice the 19.5 Tcf of dry

natural gas produced in the United States during the

year. Year-end 2007 total proved reserves of dry

natural gas in the United States rose 13 percent above

the 2006 level to 237.7 Tcf, the highest year-end volume

in the 31 years EIA has published annual reserves

estimates.

The reserves additions record mostly reflects rapid

development of unconventional gas resources such as

coalbed methane and those resources that require

advanced technologies like horizontal drilling with

hydraulic fracturing, including shales and low

permeability (tight) formations. Total U.S. dry natural

gas reserves additions replaced 237 percent of 2007 dry

gas production (Figure 18).

The proved reserves of dry natural gas by State are

listed in Table 8 and shown on the map in Figure 19.

Eight areas accounted for 81 percent of the Nation’s dry

natural gas proved reserves:

Percent of 2007 U.S.

Area Dry Gas Reserves

Texas 30

Wyoming 12

Colorado 9

Oklahoma 8

New Mexico 7

Gulf of Mexico Federal Offshore 6

Alaska 5

Louisiana 4

Area Subtotal 81

Total U.S. natural gas production increased in 2007

mostly due to production increases in Texas

(particularly from the Barnett Shale), Colorado,

Wyoming, and Oklahoma.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 29

Figure 18. Replacement of U.S. Dry Natural Gas Production by Reserves Additions, 1997-2007

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

30 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

aIndicates the estimate is associated with a sampling error (95 percent confidence interval) that exceeds 20 percent of the estimated value.

b

Includes Federal offshore Alabama.

c

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves,” and Form EIA-64A, “Annual Report of the Origin of Natural Gas Liquids Production.” They may differ from the official Energy

Information Administration production data for natural gas for 2007 contained in the Natural Gas Annual 2007, DOE/EIA-0131(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska ..................... 10,245 1 2,147 112 10 6 28 0 0 388 11,917

Lower 48 States ............. 200,840 1,146 30,027 16,601 14,730 15,142 27,079 796 1,188 19,078 225,809

Alabama ................... 3,911 12 163 35 302 379 123 0 17 274 3,994

Arkansas ................... 2,269 -27 321 146 298 280 1,148 0 27 269 3,305

California ................... 2,794 33 355 273 164 231 16 0 1 253 2,740

Coastal Region Onshore . . . . . 206 3 32 26 4 6 0 0 0 12 205

Los Angeles Basin Onshore . . 153 0 15 16 0 0 0 0 0 8 144

San Joaquin Basin Onshore . . 2,345 31 296 217 158 225 13 0 1 227 2,309

State Offshore . . . . . . . . . . . . . 90 -1 12 14 2 0 3 0 0 6 82

Colorado ................... 17,149 136 3,924 582 750 450 2,812 15 23 1,326 21,851

Florida . . . . . . . . . . . . . . . . . . . . . 45 4 110 0 47 0 0 0 0 4 108

Kansas .................... 3,931 79 407 221 65 63 149 0 0 361 3,982

Kentucky ................... 2,227 37 62 152 4 6 373 0 0 80 2,469

Louisiana................... 10,474 192 1,011 1,104 2,303 1,651 1,247 0 134 1,257 10,045

North .................... 6,715 70 433 424 2,065 1,242 925 0 1 553 6,344

South Onshore............. 3,335 110 492 587 175 358 304 0 104 618 3,323

State Offshore . . . . . . . . . . . . . 424 12 86 93 63 51 18 0 29 86 378

Michigan ................... 3,065 -45 780 210 1,043 1,238 29 0 0 184 3,630

Mississippi. . . . . . . . . . . . . . . . . . 813 37 53 50 24 78 146 0 1 100 954

Montana ................... 1,057 9 92 74 41 39 81 0 1 112 1,052

New Mexico................. 17,934 136 2,534 2,431 570 376 585 20 10 1,349 17,245

East ..................... 3,914 82 488 413 289 218 426 20 10 462 3,994

West .................... 14,020 54 2,046 2,018 281 158 159 0 0 887 13,251

New York. . . . . . . . . . . . . . . . . . . 363 33 46 45 3 0 19 7 0 44 376

North Dakota . . . . . . . . . . . . . . . . 479 12 69 62 39 43 59 0 3 53 511

Ohio. . . . . . . . . . . . . . . . . . . . . . . 975 138 144 198 0 0 39 0 0 71 1,027

Oklahoma .................. 17,464 13 2,115 1,366 1,545 1,567 2,380 6 56 1,659 19,031

Pennsylvania ................ 3,050 181 326 418 4 41 358 7 3 183 3,361

Texas...................... 61,836 227 9,325 4,818 5,790 6,244 10,717 78 535 6,263 72,091

RRC District 1 ............. 1,063 -18 71 110 180 238 68 0 0 92 1,040

RRC District 2 Onshore ...... 2,060 -167 282 218 267 309 541 1 15 301 2,255

RRC District 3 Onshore ...... 3,050 56 470 518 606 577 277 42 68 512 2,904

RRC District 4 Onshore ...... 8,116 53 973 840 1,813 1,386 1,020 31 209 1,172 7,963

RRC District 5 ............. 12,593 97 3,223 952 23 151 3,243 0 3 1,130 17,205

RRC District 6 ............. 9,087 107 1,780 827 221 387 1,740 0 100 896 11,257

RRC District 7B ............ 1,471 -38 154 74 41 78 706 0 0 139 2,117

RRC District 7C ............ 5,126 -65 351 185 1,783 1,891 349 0 3 346 5,341

RRC District 8 ............. 6,070 111 690 558 320 321 664 0 120 538 6,560

RRC District 8A ............ 1,290 15 249 80 5 6 58 1 0 103 1,431

RRC District 9 ............. 6,218 162 536 118 45 6 1,219 0 17 519 7,476

RRC District 10 ............ 5,387 -61 532 315 486 894 809 3 0 482 6,281

State Offshore . . . . . . . . . . . . . 305 -25 14 23 0 0 23 0 0 33 261

Utah....................... 5,146 17 1,113 325 484 541 744 4 0 365 6,391

Virginia .................... 2,302 -25 108 36 0 27 262 0 0 109 2,529

West Virginia ................ 4,509 14 310 359 2 25 412 11 1 192 4,729

Wyoming ................... 23,549 -6 4,832 1,818 337 647 4,666 2 0 1,825 29,710

Federal Offshorea ............ 15,360 -62 1,815 1,864 897 1,185 657 608 368 2,731 14,439

Pacific (California) . . . . . . . . . . 811 -7 49 10 1 3 0 0 0 40 805

Gulf of Mexico (Louisiana)a . . . 11,824 -16 1,430 1,429 803 991 525 304 330 2,066 11,090

Gulf of Mexico (Texas)....... 2,725 -39 336 425 93 191 132 304 38 625 2,544

Miscellaneousb . . . . . . . . . . . . . . 138 1 12 14 18 31 57 38 8 14 239

U.S. Total .................. 211,085 1,147 32,174 16,713 14,740 15,148 27,107 796 1,188 19,466 237,726

Table 8. Dry Natural Gas Proved Reserves, Reserves Changes, and Production, 2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 31

Figure 20. Changes in Dry Natural Gas Proved Reserves by Area, 2006 to 2007

Figure 19. Dry Natural Gas Proved Reserves by Area, 2007

Source: En ergy In for ma tion Ad min is tra tion, Of fice of Oil and Gas.
Texas had the largest increase in production in 2007 (12

percent, 655 billion cubic feet), while New Mexico

declined the most (5 percent, 77 billion cubic feet).

Discussion of Reserves Changes

The following graphic portrays the beginning- and

end-of-year dry natural gas proved reserves, and the

components of natural gas proved reserves change

during 2007, at the same volumetric scale. Note that the

scale starts at 200 billion cubic feet rather than at zero.

Figure 20 maps the change in dry gas proved reserves

from 2006 to 2007 by area. The table below shows how

the top eight areas fared, compared to the total United

States:

Change in

U.S. Gas Reserves

Area (billion cubic feet)

Texas +10,255

Wyoming +6,161

Colorado +4,702

Alaska +1,672

Oklahoma +1,567

Gulf of Mexico Federal Offshore -915

New Mexico -689

Louisiana -429

Area Subtotal +22,324

U.S. Total +26,641

Figure 4 in Chapter 2 shows the components of change

in dry natural gas proved reserves for 2007 and the

preceding 10 years.

Total Discoveries

Total discoveries are those reserves attributable to field

extensions, new field discoveries, and new reservoir

discoveries in old fields; they result from drilling

exploratory wells. The following graphic shows total

discoveries by component for 2003-2007.

Total discoveries of dry natural gas reserves were

29,091 billion cubic feet in 2007, a 25 percent increase

from the level reported in 2006. Seven areas reported

total discoveries of dry natural gas exceeding 1 trillion

cubic feet in 2007:

2007 Total Discoveries

Area (Billion cubic feet)

Texas 11,330

Wyoming 4,668

Colorado 2,850

Oklahoma 2,442

Gulf of Mexico Federal Offshore 1,633

Louisiana 1,381

Arkansas 1,175

Area Subtotal 25,479

U.S. Total 29,091

Extensions

The largest component of total discoveries in 2007 was

extensions of existing gas fields. Extensions were

27,107 billion cubic feet, 24 percent more than 2006 and

82 percent more than the prior 10-year average (14,924

billion cubic feet).

Energy Information Administration

32 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Natural Gas Proved Reserves Changes, 2007
Areas with the largest extensions and their percentage

of total extensions were:

Percent of

Area 2007 Extensions

Texas 40

Wyoming 17

Colorado 10

Oklahoma 9

Louisiana 5

Arkansas 4

Area Subotal 85

New Field Discoveries

New field discoveries were 796 billion cubic feet in

2007, 95 percent more than in 2006 (409 billion cubic

feet). The areas with the largest new field discoveries

were the Gulf of Mexico Federal Offshore (608 billion

cubic feet, 76 percent of the total), and Texas (78 billion

cubic feet, 10 percent of the total).

In the prior 10 years, U.S. operators had reported an

annual average of 1,555 billion cubic feet of reserves

from new field discoveries. Reserves from new field

discoveries in 2007 were 51 percent of that average.

New Reservoir Discoveries in Old Fields

New reservoir discoveries in old fields were 1,188

billion cubic feet, 3 percent more than 2006 (1,155

billion cubic feet). The areas with the largest new

reservoir discoveries in old fields and their percentage

of the total were: Texas (535 billion cubic feet, 45

percent), Gulf of Mexico Federal Offshore (368 billion

cubic feet, 31 percent), Louisiana (134 billion cubic feet,

11 percent), and Oklahoma (56 billion cubic feet, 5

percent).

In the prior 10 years, U.S. operators had reported an

annual average of 1,878 billion cubic feet of reserves

from new reservoirs discovered in old fields. Reserves

from new reservoirs discovered in old fields in 2007

were 63 percent of that average.

Revisions and Adjustments

There were 32,174 billion cubic feet of revision

increases, 16,713 billion cubic feet of revision decreases,

and 1,147 billion cubic feet of adjustments in 2007. Net

revisions and adjustments were therefore a net increase

of 16,608 billion cubic feet in 2007. In the prior 10 years,

U.S. operators reported an average of net revisions and

adjustments of 3,639 billion cubic feet.

Sales and Acquisitions

Sales represents that volume of dry natural gas proved

reserves deducted from an operator’s total reserves

through sale or transfer of operations of an existing gas

field or property to another operator (not a volume of

production “sold” at the wellhead). Similarly,

Acquisitions is that volume of proved reserves added to

an operator’s total reserves by purchase or transfer of

operations of an existing gas field or property.

There are several reasons why sales and acquisitions

volumes are not equal. Since operators have different

engineering staffs and resources, or different

development plans or schedules, the estimate of

proved reserves for a field can change upon a change in

operatorship. Timing of the transfer of operations can

also impact these volumes.

There were 14,740 billion cubic feet of sales

transactions between operators in 2007, and 15,148

billion cubic feet of acquisitions transactions. The net

difference of 408 billion cubic feet was added to the

national total of dry natural gas proved reserves.

Production

The estimated 2007 U.S. dry natural gas production

was 19,466 billion cubic feet (Table 8), a 5-percent

increase from 2006 (18,545 billion cubic feet). Areas

with the largest production and their percentage of

total production were:

Percent of 2007 U.S.

Area Dry Gas Production

Texas 32

Gulf of Mexico Federal Offshore 14

Wyoming 9

Oklahoma 9

New Mexico 7

Colorado 7

Louisiana 6

Area Subtotal 84

Wet Natural Gas

U. S. proved reserves of wet natural gas as of December

31, 2007, were 247,789 billion cubic feet, a 12-percent

increase over the 2006 volume (Table 9). At year-end

2007, proved wet natural gas reserves for the lower 48

States had increased by 12 percent compared to 2006,

and those of Alaska had increased by 16 percent.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 33
Energy Information Administration

34 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

aIncludes Federal offshore Alabama.

b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves.” They may differ from the official Energy Information Administration production data for natural gas for 2007 contained in the

Natural Gas Annual 2007, DOE/EIA-0131(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska ..................... 10,333 2 2,168 113 11 6 28 0 0 391 12,022

Lower 48 States ............. 210,083 988 31,236 17,355 15,507 15,964 28,227 814 1,244 19,927 235,767

Alabama ................... 3,963 1 165 36 308 386 125 0 17 277 4,036

Arkansas ................... 2,271 -29 321 146 298 280 1,149 0 27 269 3,306

California ................... 2,935 35 372 288 173 243 18 0 1 264 2,879

Coastal Region Onshore . . . . . 214 2 33 27 4 6 0 0 0 12 212

Los Angeles Basin Onshore . . 161 2 16 17 0 0 0 0 0 8 154

San Joaquin Basin Onshore . . 2,470 31 311 229 167 237 14 0 1 238 2,430

State Offshore . . . . . . . . . . . . . 90 0 12 15 2 0 4 0 0 6 83

Colorado ................... 17,682 100 4,037 598 772 463 2,893 15 24 1,364 22,480

Florida . . . . . . . . . . . . . . . . . . . . . 50 -1 113 0 48 0 0 0 0 4 110

Kansas .................... 4,197 82 434 236 69 68 158 0 0 386 4,248

Kentucky ................... 2,369 5 65 160 4 6 391 0 0 84 2,588

Louisiana................... 10,710 216 1,042 1,138 2,343 1,685 1,275 0 139 1,294 10,292

North .................... 6,795 88 439 430 2,095 1,260 939 0 1 560 6,437

South Onshore............. 3,473 117 513 612 182 373 317 0 108 644 3,463

State Offshore . . . . . . . . . . . . . 442 11 90 96 66 52 19 0 30 90 392

Michigan ................... 3,117 -47 793 213 1,061 1,259 30 0 0 187 3,691

Mississippi. . . . . . . . . . . . . . . . . . 816 35 54 50 24 79 147 0 1 100 958

Montana ................... 1,069 11 94 75 41 39 82 0 1 113 1,067

New Mexico................. 19,104 167 2,699 2,588 615 406 636 22 11 1,445 18,397

East ..................... 4,295 95 536 454 318 240 468 22 11 508 4,387

West .................... 14,809 72 2,163 2,134 297 166 168 0 0 937 14,010

New York. . . . . . . . . . . . . . . . . . . 363 33 46 45 3 0 19 7 0 45 375

North Dakota . . . . . . . . . . . . . . . . 539 10 77 70 44 49 66 1 4 60 572

Ohio. . . . . . . . . . . . . . . . . . . . . . . 975 138 144 198 0 0 39 0 0 71 1,027

Oklahoma .................. 18,535 2 2,243 1,449 1,639 1,662 2,525 6 59 1,760 20,184

Pennsylvania ................ 3,064 182 327 420 4 41 360 7 3 183 3,377

Texas...................... 65,805 74 9,760 5,094 6,276 6,777 11,290 83 569 6,631 76,357

RRC District 1 ............. 1,109 -1 74 117 191 252 72 0 0 97 1,101

RRC District 2 Onshore ...... 2,166 -163 299 231 283 327 573 1 16 319 2,386

RRC District 3 Onshore ...... 3,278 40 503 554 648 616 296 45 73 547 3,102

RRC District 4 Onshore ...... 8,474 68 1,018 878 1,896 1,449 1,066 33 219 1,226 8,327

RRC District 5 ............. 12,648 95 3,235 957 23 151 3,256 0 3 1,134 17,274

RRC District 6 ............. 9,481 87 1,852 860 230 403 1,811 0 104 933 11,715

RRC District 7B ............ 1,663 -30 176 85 47 89 804 0 0 158 2,412

RRC District 7C ............ 5,727 -15 396 209 2,012 2,134 394 0 3 390 6,028

RRC District 8 ............. 6,855 26 768 620 356 357 739 0 133 599 7,303

RRC District 8A ............ 1,384 14 266 86 6 6 62 1 0 110 1,531

RRC District 9 ............. 6,765 50 572 126 48 6 1,302 0 18 554 7,985

RRC District 10 ............ 5,950 -71 587 348 536 987 892 3 0 532 6,932

State Offshore . . . . . . . . . . . . . 305 -26 14 23 0 0 23 0 0 32 261

Utah....................... 5,211 12 1,125 329 490 547 752 4 0 369 6,463

Virginia .................... 2,302 -25 108 36 0 27 262 0 0 109 2,529

West Virginia ................ 4,654 16 319 370 2 25 425 11 1 198 4,881

Wyoming ................... 24,463 20 5,024 1,890 351 673 4,852 2 0 1,897 30,896

Federal Offshorea ............ 15,750 -50 1,862 1,912 924 1,218 675 618 379 2,803 14,813

Pacific (California) . . . . . . . . . . 811 -5 48 10 1 3 0 0 0 41 805

Gulf of Mexico (Louisiana)a . . . 12,201 1 1,477 1,476 830 1,023 543 313 341 2,135 11,458

Gulf of Mexico (Texas)....... 2,738 -46 337 426 93 192 132 305 38 627 2,550

Miscellaneousb . . . . . . . . . . . . . . 139 1 12 14 18 31 58 38 8 14 241

U.S. Total .................. 220,416 990 33,404 17,468 15,518 15,970 28,255 814 1,244 20,318 247,789

Table 9. Natural Gas Proved Reserves, Reserves Changes, and Production, Wet After Lease Separation,

2007 (billion cubic feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07
The volumetric differences between the estimates

reported in Table 8 (dry) and Table 9 (wet) result from

the removal of natural gas liquids at natural gas

processing plants. See Appendix F for a discussion of

the methodology used to generate the wet and dry

natural gas reserves estimates tabulated in this report.

Nonassociated Natural Gas

Proved Reserves

Proved reserves of nonassociated (NA) natural gas,

wet after lease separation, in the United States

increased by 13 percent (24,345 billion cubic feet) in

2007 to 215,121 billion cubic feet (Table 10). The lower

48 States’ NA wet natural gas proved reserves

increased 13 percent to a level of 213,851 billion cubic

feet, while Alaska had a 12 percent decline to a level of

1,270 billion cubic feet.

Seven areas accounted for 82 percent of U.S. NA wet

natural gas proved reserves in 2007:

Percent of 2007 U.S.

Area NA Gas Reserves

Texas 32

Wyoming 14

Colorado 10

Oklahoma 9

New Mexico 8

Gulf of Mexico Federal Offshore 5

Louisiana 4

Area Subtotal 82

Total Discoveries

NA wet natural gas total discoveries of 29,096 billion

cubic feet in 2007 were 24 percent more than the 2006

total of 23,541 billion cubic feet. Areas with the most

total discoveries of NA wet natural gas in 2007 were

Texas (11,555 billion cubic feet), Wyoming (4,853

billion cubic feet), Colorado (2,752 billion cubic feet),

and Oklahoma (2,487 billion cubic feet).

Production

U.S. production of NA wet natural gas increased 5

percent from an estimated 17,092 billion cubic feet in

2006 to 18,022 billion cubic feet in 2007. The leading

producing areas were Texas (33 percent of the national

total), the Gulf of Mexico Federal Offshore (12 percent),

Wyoming (10 percent), Oklahoma (9 percent), New

Mexico (7 percent), Colorado (7 percent), and

Louisiana (7 percent).

Associated-Dissolved Natural Gas

Proved Reserves

Proved reserves of associated-dissolved (AD) natural

gas, wet after lease separation, in the United States

increased 10 percent to 32,668 billion cubic feet in 2007

(Table 11). Proved reserves of AD wet natural gas in

Alaska increased 21 percent to 10,752 billion cubic feet,

and increased in the lower 48 States by 6 percent to

21,916 billion cubic feet.

The areas of the country with the largest AD wet

natural gas reserves and their percentage of the total

were:

Percent of 2007 U.S.

Area AD Gas Reserves

Alaska 33

Texas 23

Gulf of Mexico Federal Offshore 12

California 7

New Mexico 6

Area Subtotal 81

These areas logically correspond to the areas of the

country with the largest volumes of crude oil reserves.

Alaska’s AD wet gas proved reserves surpassed those

of Texas for the second year in a row.

Production

U.S. production of AD wet natural gas increased 1

percent from an estimated 2,281 billion cubic feet in

2006 to 2,296 billion cubic feet in 2007. Production of

AD wet natural gas in the lower 48 States was

essentially unchanged (2,063 billion cubic feet in 2006

and 2,069 billion cubic feet in 2007). Alaska’s AD wet

gas production increased 4 percent from 218 billion

cubic feet in 2006 to 227 billion cubic feet in 2007.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 35
Energy Information Administration

36 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

aIncludes Federal offshore Alabama.

b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves.” They may differ from the official Energy Information Administration production data for natural gas for 2007 contained in the

Natural Gas Annual 2007, DOE/EIA-0131(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska ..................... 1,447 1 70 103 8 5 22 0 0 164 1,270

Lower 48 States ............. 189,329 713 27,934 15,561 14,395 14,615 27,135 768 1,171 17,858 213,851

Alabama ................... 3,945 2 153 35 303 385 125 0 17 273 4,016

Arkansas ................... 2,227 -22 310 139 298 280 1,149 0 27 265 3,269

California . . . . . . . . . . . . . . . . . . . 780 29 80 186 165 234 14 0 1 101 686

Coastal Region Onshore ..... 6 0 0 5 0 0 0 0 0 0 1

Los Angeles Basin Onshore . . 0 0 0 0 0 0 0 0 0 0 0

San Joaquin Basin Onshore . . 769 28 80 180 165 234 13 0 1 99 681

State Offshore ............. 5 1 0 1 0 0 1 0 0 2 4

Colorado ................... 16,141 91 3,823 584 769 448 2,713 15 24 1,260 20,642

Florida ..................... 0 0 0 0 0 0 0 0 0 0 0

Kansas .................... 4,115 74 423 221 69 68 152 0 0 377 4,165

Kentucky ................... 2,333 5 65 158 4 6 391 0 0 84 2,554

Louisiana................... 10,149 201 907 1,044 2,307 1,589 1,255 0 131 1,230 9,651

North .................... 6,705 80 432 407 2,091 1,259 937 0 1 552 6,364

South Onshore............. 3,058 112 412 553 150 278 299 0 101 597 2,960

State Offshore . . . . . . . . . . . . . 386 9 63 84 66 52 19 0 29 81 327

Michigan ................... 2,925 -48 791 210 1,041 1,235 30 0 0 170 3,512

Mississippi. . . . . . . . . . . . . . . . . . 795 33 48 49 22 70 147 0 1 95 928

Montana . . . . . . . . . . . . . . . . . . . 874 10 34 43 13 13 64 0 1 92 848

New Mexico................. 17,332 129 2,445 2,425 502 284 524 22 11 1,264 16,556

East ..................... 2,605 56 307 308 205 123 356 22 11 334 2,633

West .................... 14,727 73 2,138 2,117 297 161 168 0 0 930 13,923

New York. . . . . . . . . . . . . . . . . . . 361 24 46 45 3 0 19 7 0 44 365

North Dakota . . . . . . . . . . . . . . . . 182 5 13 33 0 1 4 0 0 17 155

Ohio. . . . . . . . . . . . . . . . . . . . . . . 801 92 122 65 0 0 39 0 0 63 926

Oklahoma .................. 17,735 17 1,965 1,363 1,514 1,554 2,422 6 59 1,656 19,225

Pennsylvania ................ 2,913 77 318 271 4 40 337 7 3 173 3,247

Texas...................... 58,736 -11 8,776 4,523 5,819 6,142 10,912 81 562 6,029 68,827

RRC District 1 ............. 1,048 -6 51 109 187 250 71 0 0 89 1,029

RRC District 2 Onshore ...... 2,048 -162 250 220 271 318 573 1 16 304 2,249

RRC District 3 Onshore ...... 2,789 16 445 444 565 483 269 44 72 481 2,628

RRC District 4 Onshore ...... 8,364 62 980 854 1,895 1,446 1,065 33 219 1,210 8,210

RRC District 5 ............. 12,591 92 3,233 951 23 151 3,256 0 3 1,128 17,224

RRC District 6 ............. 9,205 79 1,807 826 222 402 1,806 0 104 887 11,468

RRC District 7B ............ 1,589 -35 161 77 33 86 804 0 0 145 2,350

RRC District 7C ............ 4,531 -15 271 167 1,880 1,972 316 0 0 314 4,714

RRC District 8 ............. 3,891 14 501 423 198 188 559 0 130 395 4,267

RRC District 8A . . . . . . . . . . . . 82 14 5 11 1 2 9 0 0 12 88

RRC District 9 ............. 6,660 4 554 116 48 6 1,302 0 18 534 7,846

RRC District 10 ............ 5,634 -49 507 302 496 838 859 3 0 498 6,496

State Offshore . . . . . . . . . . . . . 304 -25 11 23 0 0 23 0 0 32 258

Utah....................... 4,894 12 1,085 326 490 543 713 4 0 340 6,095

Virginia .................... 2,302 -25 108 36 0 27 262 0 0 109 2,529

West Virginia ................ 4,638 16 318 370 2 25 425 11 1 197 4,865

Wyoming ................... 24,116 34 4,852 1,860 289 653 4,851 2 0 1,828 30,531

Federal Offshorea ............ 10,915 -46 1,240 1,561 763 987 539 575 325 2,178 10,033

Pacific (California) . . . . . . . . . . 55 0 0 0 0 0 0 0 0 2 53

Gulf of Mexico (Louisiana)a . . . 8,500 1 963 1,172 674 804 410 309 294 1,628 7,807

Gulf of Mexico (Texas)....... 2,360 -47 277 389 89 183 129 266 31 548 2,173

Miscellaneousb . . . . . . . . . . . . . . 120 14 12 14 18 31 48 38 8 13 226

U.S. Total .................. 190,776 714 28,004 15,664 14,403 14,620 27,157 768 1,171 18,022 215,121

Table 10. Nonassociated Natural Gas Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2007 (billion cubic feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 37

aIncludes Federal offshore Alabama.

b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves.” They may differ from the official Energy Information Administration production data for natural gas for 2007 contained in the

Natural Gas Annual 2007, DOE/EIA-0131(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska ..................... 8,886 1 2,098 10 3 1 6 0 0 227 10,752

Lower 48 States ............. 20,754 275 3,302 1,794 1,112 1,349 1,092 46 73 2,069 21,916

Alabama . . . . . . . . . . . . . . . . . . . 18 -1 12 1 5 1 0 0 0 4 20

Arkansas . . . . . . . . . . . . . . . . . . . 44 -7 11 7 0 0 0 0 0 4 37

California ................... 2,155 6 292 102 8 9 4 0 0 163 2,193

Coastal Region Onshore . . . . . 208 2 33 22 4 6 0 0 0 12 211

Los Angeles Basin Onshore . . 161 2 16 17 0 0 0 0 0 8 154

San Joaquin Basin Onshore . . 1,701 3 231 49 2 3 1 0 0 139 1,749

State Offshore . . . . . . . . . . . . . 85 -1 12 14 2 0 3 0 0 4 79

Colorado ................... 1,541 9 214 14 3 15 180 0 0 104 1,838

Florida . . . . . . . . . . . . . . . . . . . . . 50 -1 113 0 48 0 0 0 0 4 110

Kansas . . . . . . . . . . . . . . . . . . . . 82 8 11 15 0 0 6 0 0 9 83

Kentucky . . . . . . . . . . . . . . . . . . . 36 0 0 2 0 0 0 0 0 0 34

Louisiana. . . . . . . . . . . . . . . . . . . 561 15 135 94 36 96 20 0 8 64 641

North . . . . . . . . . . . . . . . . . . . . 90 8 7 23 4 1 2 0 0 8 73

South Onshore. . . . . . . . . . . . . 415 5 101 59 32 95 18 0 7 47 503

State Offshore . . . . . . . . . . . . . 56 2 27 12 0 0 0 0 1 9 65

Michigan . . . . . . . . . . . . . . . . . . . 192 1 2 3 20 24 0 0 0 17 179

Mississippi. . . . . . . . . . . . . . . . . . 21 2 6 1 2 9 0 0 0 5 30

Montana . . . . . . . . . . . . . . . . . . . 195 1 60 32 28 26 18 0 0 21 219

New Mexico................. 1,772 38 254 163 113 122 112 0 0 181 1,841

East ..................... 1,690 39 229 146 113 117 112 0 0 174 1,754

West . . . . . . . . . . . . . . . . . . . . 82 -1 25 17 0 5 0 0 0 7 87

New York. . . . . . . . . . . . . . . . . . . 2 9 0 0 0 0 0 0 0 1 10

North Dakota . . . . . . . . . . . . . . . . 357 5 64 37 44 48 62 1 4 43 417

Ohio. . . . . . . . . . . . . . . . . . . . . . . 174 46 22 133 0 0 0 0 0 8 101

Oklahoma . . . . . . . . . . . . . . . . . . 800 -15 278 86 125 108 103 0 0 104 959

Pennsylvania . . . . . . . . . . . . . . . . 151 105 9 149 0 1 23 0 0 10 130

Texas...................... 7,069 85 984 571 457 635 378 2 7 602 7,530

RRC District 1 . . . . . . . . . . . . . 61 5 23 8 4 2 1 0 0 8 72

RRC District 2 Onshore . . . . . . 118 -1 49 11 12 9 0 0 0 15 137

RRC District 3 Onshore . . . . . . 489 24 58 110 83 133 27 1 1 66 474

RRC District 4 Onshore . . . . . . 110 6 38 24 1 3 1 0 0 16 117

RRC District 5 . . . . . . . . . . . . . 57 3 2 6 0 0 0 0 0 6 50

RRC District 6 . . . . . . . . . . . . . 276 8 45 34 8 1 5 0 0 46 247

RRC District 7B . . . . . . . . . . . . 74 5 15 8 14 3 0 0 0 13 62

RRC District 7C ............ 1,196 0 125 42 132 162 78 0 3 76 1,314

RRC District 8 ............. 2,964 12 267 197 158 169 180 0 3 204 3,036

RRC District 8A ............ 1,302 0 261 75 5 4 53 1 0 98 1,443

RRC District 9 . . . . . . . . . . . . . 105 46 18 10 0 0 0 0 0 20 139

RRC District 10 . . . . . . . . . . . . 316 -22 80 46 40 149 33 0 0 34 436

State Offshore . . . . . . . . . . . . . 1 -1 3 0 0 0 0 0 0 0 3

Utah. . . . . . . . . . . . . . . . . . . . . . . 317 0 40 3 0 4 39 0 0 29 368

Virginia .................... 0 0 0 0 0 0 0 0 0 0 0

West Virginia . . . . . . . . . . . . . . . . 16 0 1 0 0 0 0 0 0 1 16

Wyoming . . . . . . . . . . . . . . . . . . . 347 -14 172 30 62 20 1 0 0 69 365

Federal Offshorea ............ 4,835 -4 622 351 161 231 136 43 54 625 4,780

Pacific (California) . . . . . . . . . . 756 -5 48 10 1 3 0 0 0 39 752

Gulf of Mexico (Louisiana)a . . . 3,701 0 514 304 156 219 133 4 47 507 3,651

Gulf of Mexico (Texas). . . . . . . 378 1 60 37 4 9 3 39 7 79 377

Miscellaneousb . . . . . . . . . . . . . . 19 -13 0 0 0 0 10 0 0 1 15

U.S. Total .................. 29,640 276 5,400 1,804 1,115 1,350 1,098 46 73 2,296 32,668

Table 11. Associated-Dissolved Natural Gas Proved Reserves, Reserves Changes, and Production

Wet After Lease Separation, 2007 (billion cubic feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07
The areas of the country with the largest AD wet

natural gas production and their percentage of the total

were:

Percent of 2007 U.S.

Area AD Gas Production

Gulf of Mexico Federal Offshore 26

Texas 26

Alaska 10

New Mexico 8

California 7

Area Subtotal 77

Again, these areas logically correspond to the areas of

the country with the largest volumes of crude oil

production.

Coalbed and Shale Natural Gas

Proved Reserves

Unconventional resources are playing an increasingly

important role in U.S. dry natural gas reserves and

production.

Proved reserves and production from coal reservoirs

increased rapidly from 1989 through 2002 before

stabilizing and even dropping slightly in 2006 (Figure

21). However, coalbed natural gas reserves increased

11.5 percent in 2007. Coalbed proved reserves now

account for about 9 percent of U.S. dry natural gas

reserves. While coalbed natural gas production

decreased in 2007, it still accounted for about 9 percent

of U.S. dry natural gas production (Figure 22).

Improved technology now allows high economic

returns for development of reserves in shale reservoirs

at the gas prices prevalent in 2006 and 2007. As a result,

proved reserves of shale gas have been rapidly

increasing. EIA has collected data on proved natural

gas reserves from shale reservoirs for two years. Shale

gas proved reserves increased 50 percent in 2007 and

are now at about 9 percent of the U.S. total (Figure 23).

Table 12 lists the proved reserves and production of

natural gas from two unconventional sources, coalbed

and shale, as reported to EIA in 2007. The historical

table of coalbed methane proved reserves and

production from 1989-2007 can be found in Appendix

D, Table D11.

Energy Information Administration

38 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure 21. Coalbed Natural Gas Proved Reserves, 1989-2007

Source: Energy Information Administration, Office of Oil and Gas.
Table 12. Reported Unconventional Natural Gas Proved Reserves and Production

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Coalbed Coalbed Shale Shale

Reported Reported Reported Reported

State and Subdivision Production Reserves Production Reserves

Alaska .............................. 0 0 0 0

Lower 48 States ..................... 1,742 21,868 1,187 21,496

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 2,126 0 0

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . WS WS 78 1,095

California ........................... 0 0 0 0

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . 521 7,870 0 0

Florida .............................. 0 0 0 0

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WS WS 0 0

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 ES ES

Louisiana. . . . . . . . . . . . . . . . . . . . . . . . . . . . WS WS 0 0

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 123 2,830

Mississippi........................... 0 0 0 0

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . . . WS WS WS WS

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . 391 4,171 0 0

East . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 390 0 0

West . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 3,781 0 0

New York 0 0 0 0

North Dakota. . . . . . . . . . . . . . . . . . . . . . . . . 0 0 1 18

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ES ES 0 0

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 1,264 3 133

Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . ES ES ES ES

Texas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 967 17,115

RRC District 1 ...................... 0 0 0 0

RRC District 2 Onshore ............... 0 0 0 0

RRC District 3 Onshore ............... 0 0 0 0

RRC District 4 Onshore ............... 0 0 0 0

RRC District 5 . . . . . . . . . . . . . . . . . . . . . . 0 0 429 8,055

RRC District 6 ...................... 0 0 0 0

RRC District 7B . . . . . . . . . . . . . . . . . . . . . 0 0 90 2,014

RRC District 7C ..................... 0 0 0 0

RRC District 8 ...................... 0 0 1 4

RRC District 8A ..................... 0 0 0 0

RRC District 9 . . . . . . . . . . . . . . . . . . . . . . 0 0 447 7,042

RRC District 10...................... 0 0 0 0

State Offshore ...................... 0 0 0 0

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 922 0 0

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 1,948 0 0

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . ES ES 0 0

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 2,734 0 0

Federal Offshore ...................... 0 0 0 0

Eastern Statesa. . . . . . . . . . . . . . . . . . . . . . . 31 392 3 166

Western Statesb . . . . . . . . . . . . . . . . . . . . . . 52 441 12 139

US Total . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,742 21,868 1,187 21,496

ES=State data withheld, included in Eastern States.

WS=State data withheld, included in Western States.

aEastern States include Illinois, Indiana, Kentucky, Ohio, Pennsylvania, Tennessee, and West Virginia.

bWestern States include Arkansas, Kansas, Louisiana, Montana, North Dakota, and South Dakota.

Source: Energy Information Administration, Office of Oil and Gas.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 39
Energy Information Administration

40 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure 22. Coalbed Natural Gas Production, 1989-2007

Source: Energy Information Administration, Office of Oil and Gas.

Figure 23. Coalbed and Shale Natural Gas Proved Reserves, 2006-2007

Source: Energy Information Administration, Office of Oil and Gas.
Areas of Note:

Large Discoveries and

Reserves Additions

The following State or area discussions summarize

notable activities during the year concerning expected

new field reserves, development plans, and possible

production rates as reported in various trade

publications. The citations do not necessarily reflect

EIA’s concurrence, but are considered important

enough to be brought to the reader’s attention.

Texas

Texas had the largest volumetric increase in dry

natural gas proved reserves in 2007 (10,255 billion

cubic feet), a 17-percent increase. Production also

increased 12 percent. This resulted primarily from

extensions in the Newark East Field of north central

Texas and natural gas fields located in the Permian

Basin of west Texas.

Barnett Shale (Newark East Field): In 2007,

natural gas production from the Barnett Shale

rose from 705 billion cubic feet in 2006 to 949

billion cubic feet. The Texas Railroad

Commission maintains a website that provides

updated Barnett Shale statistics {43}:

http://www.rrc.state.tx.us/barnettshale

Wyoming

Wyoming's dry natural gas reserves increased by 26

percent (6,161 billion cubic feet) in 2007. This resulted

primarily from extensions to existing fields and

nonassociated natural gas revision increases.

Pinedale Field: On October 30, 2007, Ultra

Petroleum announced results of its ongoing

delineation drilling program in and around the

Pinedale Field. Six of the 21 delineation wells

planned for 2007 had sufficient production

history to enable estimation of reserves. All six

had reserves better than the pre-drill estimates,

on average 167 percent more. The current plan

is to continue this delineation effort for at least

the next 5 years. (Ultra Petroleum Press Release,

October 30, 2007) {44}.

Colorado

Colorado's dry natural gas reserves increased by 27

percent (4,702 billion cubic feet) in 2007. Large coalbed

methane revision increases for the San Juan Basin Gas

Area were a major portion of this increase.

Areas of Note:

Large Declines in Reserves

The following areas had large declines in dry natural

gas proved reserves due to downward revisions or

unreplaced production.

Gulf of Mexico Federal Offshore

Proved dry natural gas reserves in the Gulf of Mexico

Federal Offshore decreased by 6 percent (915 billion

cubic feet) in 2007. Production also decreased by 2

percent from 2,738 billion cubic feet in 2006 to 2,691

billion cubic feet in 2007.

New Mexico

New Mexico’s proved dry natural gas reserves

decreased by 4 percent (689 billion cubic feet) in 2007.

Production in New Mexico decreased 5 percent (77

billion cubic feet) in 2007.

Louisiana

Louisiana's proved dry natural gas reserves decreased

by 4 percent (429 billion cubic feet) in 2007. Production

in Louisiana decreased 4 percent (52 billion cubic feet)

in 2007.

Reserves in

Nonproducing Status

Nonproducing proved natural gas reserves (wet after

lease separation) of 78,094 billion cubic feet were

reported in 2007, 17 percent more than the 66,714

billion cubic feet reported in 2006 (Appendix D, Table

D10). About 34 percent of the reserves in

nonproducing status were located in Texas. Wyoming

had 15 percent, Colorado had 12 percent, and 9 percent

were in the Gulf of Mexico Federal Offshore. Wells or

reservoirs are nonproducing due to any of several

operational reasons. These include awaiting well

workovers, the drilling of extensions or additional

development wells, installation of production or

pipeline facilities, and depletion of other zones or

reservoirs before recompletion in reservoirs not

currently open to production (called “behind pipe”

reserves).

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 41

5. Natural Gas Liquids Statistics

Natural Gas Liquids

Proved Reserves

U.S. natural gas liquids proved reserves increased 8

percent to 9,143 million barrels in 2007 (Table 13).

Reserves additions replaced 181 percent of 2007 natural

gas liquids production.

The reserves of seven areas accounted for 88 percent of

the Nation’s natural gas liquids proved reserves.

Percent of

Area U.S. NGL Reserves

Texas 40

Utah and Wyoming 12

Oklahoma 10

New Mexico 9

Gulf of Mexico Federal Offshore 7

Colorado 6

Alaska 4

Area Subtotal 88

The volumes of natural gas liquids proved reserves

and production shown in Table 13 are the sum of the

natural gas plant liquid volumes listed in Table 14 and

the lease condensate volumes listed in Table 15.

Discussion of Reserves Changes

The following graphic portrays the beginning- and

end-of-year natural gas liquids proved reserves, and

the components of natural gas liquids proved reserves

change during 2007, at the same volumetric scale. Note

that the scale starts at 7 billion barrels rather than at

zero.

Total Discoveries

Total discoveries of natural gas liquids reserves were

1,118 million barrels in 2007, an increase of 13 percent

from 2006 (993 million barrels) (see graph below).

Areas with the largest total discoveries were:

Percent of 2007 U.S.

Area NGL Total Discoveries

Texas 46

Utah and Wyoming 18

Oklahoma 11

Gulf of Mexico Federal Offshore 7

Colorado 6

Louisiana 4

New Mexico 4

Area Subtotal 96

Extensions

Extensions were 1,030 million barrels in 2007, 62

percent more than the 2006 volume of 924 million

barrels. Areas with the largest extensions were Texas

(47 percent of the National total), Utah and Wyoming

(20 percent), Oklahoma (12 percent), and Colorado (7

percent).

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 43

Natural Gas Liquids Proved Reserves Changes, 2007
Table 13. Natural Gas Liquids Proved Reserves, Reserves Changes, and Production, 2007a

(million barrels of 42 U.S. gallons)

Changes in Reserves During 2007

Published New Reservoir

Proved Revision Revision New Field Discoveries Estimated Proved

Reserves Adjustments Increases Decreases Sales Acquisitions Extensions Discoveries in Old Fields Production Reserves

State and Subdivision 12/31/06 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/07

Energy Information Administration

44 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

aThis table is natural gas plant liquids plus lease condensate.

b

Includes Federal offshore Alabama.

c

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, New York, Ohio, Oregon, Pennsylvania, South Dakota,

Tennessee, and Virginia.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves,” and Form EIA-64A, “Annual Report of the Origin of Natural Gas Liquids Production.” They may differ from the official Energy

Information Administration production data for natural gas and natural gas liquids for 2007 contained in the publications Petroleum Supply

Annual 2007, DOE/EIA-0340(07) and Natural Gas Annual 2007 DOE/EIA-0131(07).

Source: Energy Information Administration, Office of Oil and Gas.

Alaska . . . . . . . . . . . . . . . . . . . . . 338 0 0 0 0 0 0 0 0 13 325

Lower 48 States ............. 8,134 -139 1,187 765 670 771 1,030 30 58 818 8,818

Alabama . . . . . . . . . . . . . . . . . . . 56 -13 2 2 4 16 2 0 0 4 53

Arkansas . . . . . . . . . . . . . . . . . . . 4 -2 0 0 0 0 1 0 0 0 3

California . . . . . . . . . . . . . . . . . . . 132 0 16 15 7 10 1 0 0 11 126

Coastal Region Onshore . . . . . 22 -7 2 2 0 0 0 0 0 1 14

Los Angeles Basin Onshore . . 10 1 1 3 0 0 0 0 0 0 9

San Joaquin Basin Onshore . . 100 6 13 10 7 10 1 0 0 10 103

State Offshore ............. 0 0 0 0 0 0 0 0 0 0 0

Colorado . . . . . . . . . . . . . . . . . . . 478 -23 105 23 22 10 67 0 0 33 559

Florida . . . . . . . . . . . . . . . . . . . . . 3 -2 2 0 1 0 0 0 0 0 2

Kansas . . . . . . . . . . . . . . . . . . . . 209 -9 22 12 3 3 7 0 0 19 198

Kentucky . . . . . . . . . . . . . . . . . . . 105 -23 2 5 0 0 13 0 0 3 89

Louisiana. . . . . . . . . . . . . . . . . . . 280 33 49 48 42 35 36 0 10 50 303

North . . . . . . . . . . . . . . . . . . . . 89 14 11 8 27 15 16 0 0 10 100

South Onshore. . . . . . . . . . . . . 159 11 30 32 10 16 19 0 7 32 168

State Offshore . . . . . . . . . . . . . 32 8 8 8 5 4 1 0 3 8 35

Michigan . . . . . . . . . . . . . . . . . . . 42 7 11 4 15 17 0 0 0 3 55

Mississippi.................. 8 0 1 1 0 1 1 0 0 1 9

Montana . . . . . . . . . . . . . . . . . . . 10 1 1 1 0 0 1 0 0 1 11

New Mexico. . . . . . . . . . . . . . . . . 861 17 126 117 33 25 39 1 1 76 844

East . . . . . . . . . . . . . . . . . . . . . 295 11 39 35 21 19 33 1 1 37 306

West . . . . . . . . . . . . . . . . . . . . 566 6 87 82 12 6 6 0 0 39 538

North Dakota . . . . . . . . . . . . . . . . 55 1 8 7 4 5 6 0 0 6 58

Oklahoma . . . . . . . . . . . . . . . . . . 892 -4 110 73 93 80 119 0 2 84 949

Texas...................... 3,335 -113 428 291 389 495 484 5 29 325 3,658

RRC District 1 . . . . . . . . . . . . . 42 12 3 6 12 12 3 0 0 5 49

RRC District 2 Onshore . . . . . . 90 4 14 12 12 15 27 0 1 16 111

RRC District 3 Onshore . . . . . . 234 -3 35 42 43 99 23 3 6 41 271

RRC District 4 Onshore . . . . . . 333 -2 47 42 71 56 46 2 8 50 327

RRC District 5 . . . . . . . . . . . . . 53 -8 10 5 0 0 10 0 0 4 56

RRC District 6 . . . . . . . . . . . . . 357 -24 79 35 8 14 73 0 3 33 426

RRC District 7B . . . . . . . . . . . . 133 4 16 7 4 7 68 0 0 14 203

RRC District 7C . . . . . . . . . . . . 439 35 34 21 170 173 33 0 0 32 491

RRC District 8 . . . . . . . . . . . . . 566 -52 61 53 26 39 58 0 10 45 558

RRC District 8A . . . . . . . . . . . . 233 8 45 17 1 2 11 0 0 19 262

RRC District 9 . . . . . . . . . . . . . 385 -78 34 6 2 0 59 0 1 26 367

RRC District 10 . . . . . . . . . . . . 466 -9 50 44 40 78 73 0 0 40 534

State Offshore ............. 4 0 0 1 0 0 0 0 0 0 3

Utah and Wyoming . . . . . . . . . . . 887 -5 173 64 16 28 205 0 0 68 1,140

West Virginia . . . . . . . . . . . . . . . . 110 0 8 9 0 1 10 0 0 5 115

Federal Offshoreb . . . . . . . . . . . . 653 -7 116 91 41 45 36 24 16 127 624

Pacific (California) .......... 4 0 0 0 0 0 0 0 0 0 4

Gulf of Mexico (Louisiana)b . . . 575 -3 90 84 40 44 25 13 16 108 528

Gulf of Mexico (Texas). . . . . . . 74 -4 26 7 1 1 11 11 0 19 92

Miscellaneousc . . . . . . . . . . . . . . 14 3 7 2 0 0 2 0 0 2 22

U.S. Total .................. 8,472 -139 1,187 765 670 771 1,030 30 58 831 9,143
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 45

Table 14. Natural Gas Plant Liquids Proved Reserves and Production, 2007

(million barrels of 42 U.S. gallons)

2007 2007 2007 2007

State and Subdivision Reserves Production State and Subdivision Reserves Production

Alaska. . . . . . . . . . . . . . . . . . . . . . 325 13

Lower 48 States.............. 7,323 637

Alabama . . . . . . . . . . . . . . . . . . . . 32 2

Arkansas.................... 2 0

California. . . . . . . . . . . . . . . . . . . . 126 11

Coastal Region Onshore . . . . 14 1

Los Angeles Basin Onshore . . 9 0

San Joaquin Basin Onshore. . 103 10

State Offshore............. 0 0

Colorado . . . . . . . . . . . . . . . . . . . . 452 27

Florida...................... 2 0

Kansas . . . . . . . . . . . . . . . . . . . . . 194 18

Kentucky. . . . . . . . . . . . . . . . . . . . 88 3

Louisiana . . . . . . . . . . . . . . . . . . . 191 30

North. . . . . . . . . . . . . . . . . . . . 69 6

South Onshore . . . . . . . . . . . . 97 18

State Offshore. . . . . . . . . . . . . 25 6

Michigan . . . . . . . . . . . . . . . . . . . . 50 3

Mississippi .................. 3 0

Montana . . . . . . . . . . . . . . . . . . . . 11 1

New Mexico . . . . . . . . . . . . . . . . . 788 66

East . . . . . . . . . . . . . . . . . . . . 274 32

West . . . . . . . . . . . . . . . . . . . . 514 34

North Dakota. . . . . . . . . . . . . . . . . 54 6

Oklahoma . . . . . . . . . . . . . . . . . . . 797 69

Texas ...................... 3,158 272

RRC District 1. . . . . . . . . . . . . 43 4

RRC District 2 Onshore . . . . . 94 13

RRC District 3 Onshore . . . . . 143 25

RRC District 4 Onshore . . . . . 250 37

RRC District 5. . . . . . . . . . . . . 50 3

RRC District 6. . . . . . . . . . . . . 324 26

RRC District 7B . . . . . . . . . . . 200 13

RRC District 7C . . . . . . . . . . . 464 30

RRC District 8. . . . . . . . . . . . . 525 43

RRC District 8A . . . . . . . . . . . 260 19

RRC District 9. . . . . . . . . . . . . 347 24

RRC District 10. . . . . . . . . . . . 458 35

State Offshore............. 0 0

Utah and Wyoming . . . . . . . . . . . . 878 54

West Virginia. . . . . . . . . . . . . . . . . 114 5

Federal Offshorea. . . . . . . . . . . . . 369 69

Pacific (California) ......... 0 0

Gulf of Mexico (Louisiana)a . . 365 68

Gulf of Mexico (Texas) ...... 4 1

Miscellaneousb . . . . . . . . . . . . . . . 14 1

U.S. Total ................... 7,648 650

a

Includes Federal Offshore Alabama.

b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, New York, Ohio, Oregon, Pennsylvania, South Dakota,

Tennessee, and Virginia.

Note: The production estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas

Reserves,” and Form EIA-64A, “Annual Report of the Origin of Natural Gas Liquids Production.” They may differ from the official Energy

Information Administration production data for natural gas plant liquids for 2007 contained in the publications Petroleum Supply Annual 2007,

DOE/EIA-0340(2007) and Natural Gas Annual 2007, DOE/EIA-0131(2007).

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

46 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table 15. Lease Condensate Proved Reserves and Production, 2007

(million barrels of 42 U.S. gallons)

2007 2007 2007 2007

State and Subdivision Reserves Production State and Subdivision Reserves Production

Alaska ..................... 0 0

Lower 48 States ............. 1,495 181

Alabama . . . . . . . . . . . . . . . . . . . 21 2

Arkansas ................... 1 0

California ................... 0 0

Coastal Region Onshore .... 0 0

Los Angeles Basin Onshore . . 0 0

San Joaquin Basin Onshore. . 0 0

State Offshore ............ 0 0

Colorado . . . . . . . . . . . . . . . . . . . 107 6

Florida ..................... 0 0

Kansas .................... 4 1

Kentucky ................... 1 0

Louisiana . . . . . . . . . . . . . . . . . . 112 20

North . . . . . . . . . . . . . . . . . . . 31 4

South Onshore . . . . . . . . . . . 71 14

State Offshore . . . . . . . . . . . . 10 2

Michigan ................... 5 0

Mississippi ................. 6 1

Montana ................... 0 0

New Mexico . . . . . . . . . . . . . . . . 56 10

East . . . . . . . . . . . . . . . . . . . 32 5

West . . . . . . . . . . . . . . . . . . . 24 5

North Dakota ................ 4 0

Oklahoma . . . . . . . . . . . . . . . . . . 152 15

Texas . . . . . . . . . . . . . . . . . . . . . 500 53

RRC District 1 ............ 6 1

RRC District 2 Onshore . . . . 17 3

RRC District 3 Onshore . . . . 128 16

RRC District 4 Onshore . . . . 77 13

RRC District 5 ............ 6 1

RRC District 6 . . . . . . . . . . . . 102 7

RRC District 7B .......... 3 1

RRC District 7C . . . . . . . . . . 27 2

RRC District 8 . . . . . . . . . . . . 33 2

RRC District 8A ........... 2 0

RRC District 9 . . . . . . . . . . . . 20 2

RRC District 10 . . . . . . . . . . . 76 5

State Offshore ............ 3 0

Utah and Wyoming . . . . . . . . . . . 262 14

West Virginia ................ 1 0

Federal Offshore a . . . . . . . . . . . . 255 58

Pacific (California) ........ 4 0

Gulf of Mexico (Louisiana)a . . 163 40

Gulf of Mexico (Texas) . . . . . 88 18

Miscellaneous b .............. 8 1

U.S. Total .................. 1,495 181

a

Includes Federal Offshore Alabama.

b

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, New York, Ohio, Oregon, Pennsylvania, South Dakota,

Tennessee, and Virginia.

Note: The estimates in this table are based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves” 2007.

Source: Energy Information Administration, Office of Oil and Gas.
New Field Discoveries

New field discoveries in 2007 (30 million barrels) were

88 percent higher than in 2006 (16 million barrels).

Areas with the largest new field discoveries were the

Gulf of Mexico Federal Offshore (80 percent) and

Texas (17 percent).

New Reservoir Discoveries in Old Fields

New reservoir discoveries in old fields in 2007 (58

million barrels) were 9 percent higher than they were

in 2006 (53 million barrels). Areas with the largest new

reservoir discoveries in old fields were Texas (50

percent of the National total), the Gulf of Mexico

Federal Offshore (28 percent), and Louisiana (17

percent).

Revisions and Adjustments

In 2007, there were 1,187 million barrels of revision

increases, 765 million barrels of revision decreases,

and -139 million barrels of adjustments. The net of

revisions and adjustments was 283 million barrels.

Sales and Acquisitions

There were 771 million barrels of acquisitions and 670

million barrels of sales in 2007. The net of these

transactions added 101 million barrels of natural gas

liquids proved reserves.

Production

Natural gas liquids production was an estimated 831

million barrels in 2007, an increase of 2 percent from

2006’s production (811 million barrels).

Six areas accounted for about 87 percent of the

Nation’s natural gas liquids production.

Percent of 2007

Area U.S. NGL Production

Texas 39

Gulf of Mexico Federal Offshore 15

Oklahoma 10

New Mexico 9

Utah and Wyoming 8

Louisiana 6

Area Subtotal 87

Natural Gas Plant Liquids

Proved Reserves

Natural gas plant liquids proved reserves increased in

2007 to 7,648 million barrels, a 7-percent increase from

the 2006 level (7,133 million barrels) (Table 14).

Six areas accounted for about 83 percent of the

Nation’s natural gas plant liquids proved reserves:

Percent of 2007

Area U.S. Gas Plant Liqids

Texas 41

Utah and Wyoming 11

Oklahoma 10

New Mexico 10

Colorado 6

Gulf of Mexico Federal Offshore 5

Area Subtotal 83

Production

Natural gas plant liquids production increased 3

percent in 2007—from 629 million barrels in 2006 to

650 million barrels of production (Table 14).

The top six areas for proved reserves of natural gas

plant liquids accounted for about 87 percent of the

Nation’s natural gas plant liquids production:

Percent of 2007 U.S.

Area Gas Plant Liquids Producion

Texas 42

Oklahoma 11

Gulf of Mexico Federal Offshore 11

New Mexico 10

Utah and Wyoming 8

Louisiana 5

Area Subtotal 87

Natural gas processing plants are usually located in

the same general area where the natural gas is

produced. Table E4 in Appendix E lists the volumes of

natural gas produced and processed in the same State

and the volumes of liquids extracted.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report 47
Lease Condensate

Proved Reserves

Proved reserves of lease condensate in the United

States were 1,495 million barrels in 2007 (Table 15).

This was 12 percent higher than the volume reported in

2006 (1,339 million barrels).

The reserves of five areas accounted for about 85

percent of the Nation’s lease condensate proved

reserves.

Percent of 2007 U.S.

Area Condensate Reserves

Texas 33

Utah and Wyoming 18

Gulf of Mexico Federal Offshore 17

Oklahoma 10

Louisiana 7

Area Subtotal 85

Production

Production of lease condensate was 181 million barrels

in 2007, a slight decrease from 2006’s production (182

million barrels). The production of 5 areas accounted

for about 88 percent of the Nation’s lease condensate

production.

Percent of 2007 U.S.

Area Condensate Production

Gulf of Mexico Federal Offshore 32

Texas 29

Louisiana 11

Oklahoma 8

Utah and Wyoming 8

Area Subtotal 88

Reserves in

Nonproducing Status

Like crude oil and natural gas, not all lease condensate

proved reserves were producing during 2007. Proved

reserves of 559 million barrels of lease condensate, an

increase of 11 percent from 2006’s level (504 million

barrels), were reported in nonproducing status in 2007

(Appendix D, Table D10). About 25 percent of the

nonproducing lease condensate reserves were located

in Texas, 24 percent in Utah and Wyoming, and 21

percent were in the Gulf of Mexico Federal Offshore.

Energy Information Administration

48 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
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Energy Information Administration

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Energy Information Administration

50 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Appendix A

Operator Level Data

This appendix provides a series of tables of the proved

reserves and production by production size class for

the years 2002 through 2007 for crude oil and natural

gas well operators. These tables show the volumetric

change and percent change by production size class

from the previous year and from 2002. In addition they

show the 2007 average per operator in each class. All

companies that reported to EIA on Form EIA-23 were

ranked by production size for each of the 6 years. We

computed company production size classes as the sum

of the barrel oil equivalent of the crude oil production,

lease condensate production, and wet gas production

for each operator. The companies were then placed in

the following production size classes: 1-10, 11-20,

21-100, 101-500, and all "other" oil and gas operators.

The "other" category of operator contains 13,274 small

operators. We estimated production and reserves for

small operators for 2007 from a sample of

approximately 4 percent. Class 1-10 contains the 10

highest producing companies during each year on a

barrel oil equivalent (BOE) basis. These companies

may not necessarily be the same 10 companies each

year. The total natural gas production and proved

reserves are reported in Table 9 of this report. The total

crude oil production and proved reserves are reported

in Table 6 of this report.

Natural Gas Proved Reserves

The wet natural gas proved reserves reported for 2002

through 2007 have changed from 195,561 billion cubic

feet to 247,789 billion cubic feet or 27 percent (Table

A1). These proved reserves continue to be concentrated

in the larger companies. In 2007, the top 20 operators

(Class 1-10 and Class 11-20) producing companies had

58 percent of the proved reserves of natural gas in the

United States. The next two size classes contain 80 and

400 companies and accounted for 27 and 10 percent of

the U.S. natural gas proved reserves, respectively. The

top 20 operators had an increase of 27 percent in their

natural gas proved reserves from 2002 to 2007. The rest

of the operators in (Class 21-100, Class 101-500, and

Class Other) had an increase of 28 percent in their

reserves in the same time period. In 2007, the top 20

operators' natural gas reserves had an increase of 7

percent from 2006.

Natural Gas Production

Wet natural gas production has increased from 19,373

billion cubic feet in 2006 to 20,318 billion cubic feet in

2007 or 5 percent (Table A2). In 2007, the top 20

producing companies had 56 percent of the production

of wet natural gas in the United States. The next two

size classes have 25 percent and 13 percent of the wet

natural gas production, respectively. The top 20

operators had a decrease of 4 percent in wet natural gas

production from 2002 to 2007. The rest of the operators

had an increase of 7 percent from 2002 to 2007.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report A-1

0

50

100

150

200

250

300

2002 2003 2004 2005 2006 2007

Trillion Cubic Feet

1-10 11-20 21-100 101-500 Others

21-100

25%

101-500

13%

Others

6%

1-10

39%

11-20

17%

Wet Natural Gas Reserves by Operator Size Class, 2002-2007

Natural Gas Production by Operator Size Class, 2007
Crude Oil Proved Reserves

The crude oil proved reserves reported by Operator

Production Size Class 1-10 for 2002 through 2007 have

changed from 13,346 million barrels to 11,437 million

barrels or a decrease of 14 percent (Table A3). The 10

largest producing companies in 2007 had 54 percent of

U.S. proved reserves of crude oil. The 20 largest oil and

gas producing companies in 2007 had 63 percent of

proved reserves of crude oil. Proved reserves of crude

oil in the United States increased 1 percent in 2007 from

2006.

Crude Oil Production

Crude oil production reported for 2006 to 2007 has

increased from 1,652 million barrels to 1,691 million

barrels or 2 percent (Table A4). The 20 largest oil and

gas producing companies had 59 percent of U.S.

production of crude oil in the United States in 2007. In

2002 they accounted for 68 percent of production.

Crude Oil and Natural Gas Fields

The number of fields in the United States in which

Category I and Category II operators were active

increased during the 2002-2007 period (Table A5).

From 2002-2007, the number of fields in which the top

20 operators were active increased by 1,230 fields (21

percent) while in 2007 the number increased by 38

fields from 2006. We also include statistics for operator

Category sizes at the bottom portion of tables in this

appendix. These are the categories used by EIA in

processing and assessing reserves surveys and are

presented here as additional perspective. For further

explanation of categories sizes see definitions and

descriptions in Appendix E.

Ranked Crude Oil and

Natural Gas Production

Table A6 lists the top U.S. oil and gas operators ranked

by reported 2007 operated production data. About 75

percent of the production of crude oil or natural gas is

reported by the top 50 operators.

Energy Information Administration

A-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

0

5

10

15

20

25

30

2002 2003 2004 2005 2006 2007

Billion Barrels

1-10 11-20 21-100 101-500 Others

1-10

50%

11-20

9%

21-100

19%

101-500

11%

Others

11%

`

Crude Oil Reserves by Operator Size Class, 2002-2007

Crude Oil Production by Operator Size Class, 2007
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report A-3

Class 1-10 88,100 82,222 81,325 80,785 97,372 110,559 13,187 22,460 11,055.924

Percent of Total 45.0% 41.7% 40.4% 37.9% 44.2% 44.6% 13.5% 25.5%

Class 11-20 25,938 29,890 38,643 47,078 38,134 34,331 -3,803 8,393 3,433.131

Percent of Total 13.3% 15.2% 19.2% 22.1% 17.3% 13.9% -10.0% 32.4%

Class 21-100 50,633 53,098 50,149 52,061 52,064 65,795 13,731 15,162 822.435

Percent of Total 25.9% 26.9% 24.9% 24.4% 23.6% 26.6% 26.4% 29.9%

Class 101-500 19,723 20,030 20,912 21,737 21,877 24,591 2,714 4,868 61.478

Percent of Total 10.1% 10.2% 10.4% 10.2% 9.9% 9.9% 12.4% 24.7%

Class Other (13,274) 11,167 11,905 10,170 11,647 10,968 12,512 1,544 1,345 0.943

Percent of Total 5.7% 6.0% 5.1% 5.5% 5.0% 5.0% 14.1% 12.0%

Category I (158) 173,325 173,225 178,269 189,644 182,133 206,699 24,566 33,374 1,324.994

Percent of Total 88.6% 87.9% 88.6% 88.9% 82.6% 83.4% 13.5% 19.3%

Category II (510) 11,051 11,983 12,494 11,838 27,294 28,365 1,071 17,314 57.073

Percent of Total 5.7% 6.1% 6.2% 5.5% 12.4% 11.4% 3.9% 156.7%

Category III (13,121) 11,184 11,937 10,437 11,826 10,989 12,725 1,736 1,540 0.970

Percent of Total 5.7% 6.1% 5.2% 5.5% 5.0% 5.1% 15.8% 13.8%

Total Published 195,561 197,145 201,200 213,308 220,416 247,789 27,373 52,228 17.990

Table A1. Natural Gas Proved Reserves, Wet After Lease Separation, by Operator Production Size Class,

2002–2007

(billion cubic feet at 14.73 pia and 60° Fahrenheit)

2006–2007 2002–2007 2007

Volume and Volume and Average

Percent Percent Reserves

Size Class 2002 2003 2004 2005 2006 2007 Change Change per Operator

Note: There were 13,121 active Category III operators in the 2007 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 727 Category III operators (Table E2). The "other" size class represents 13,274 operators in the

2007 frame (13,774 active operators minus the 500 largest operators).

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

A-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Class 1-10 8,996 8,220 7,617 7,068 7,956 7,997 41 -999 799.714

Percent of Total 44.4% 40.6% 38.1% 36.7% 41.1% 39.4% 0.5% -11.1%

Class 11-20 2,854 3,136 3,647 3,534 3,078 3,362 284 508 336.218

Percent of Total 14.1% 15.5% 18.2% 18.4% 15.9% 16.5% 9.2% 17.8%

Class 21-100 4,763 5,275 4,982 4,832 4,492 5,020 528 257 62.749

Percent of Total 23.5% 26.1% 24.9% 25.1% 23.2% 24.7% 11.7% 5.4%

Class 101-500 2,475 2,386 2,559 2,506 2,605 2,692 87 217 6.730

Percent of Total 12.2% 11.8% 12.8% 13.0% 13.4% 13.2% 3.3% 8.8%

Class Other (13,274) 1,161 1,215 1,213 1,318 1,241 1,247 6 86 0.094

Percent of Total 5.7% 6.0% 6.1% 6.8% 6.4% 6.1% 0.5% 7.4%

Category I (158) 17,335 17,347 17,036 16,311 15,092 15,923 831 -1,412 102.071

Percent of Total 85.6% 85.7% 85.1% 84.7% 77.9% 78.4% 5.5% -8.1%

Category II (510) 1,738 1,648 1,718 1,605 3,026 3,129 103 1,391 6.295

Percent of Total 8.6% 8.1% 8.6% 8.3% 15.6% 15.4% 3.4% 80.0%

Category III (13,121) 1,176 1,236 1,263 1,342 1,255 1,266 11 91 0.096

Percent of Total 5.8% 6.1% 6.3% 7.0% 6.5% 6.2% 0.9% 7.7%

Total Published 20,248 20,231 20,017 19,259 19,373 20,318 945 70 1.475

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 4.9% 0.3%

Table A2. Natural Gas Production, Wet After Lease Separation, by Operator Production Size Class,

2002–2007

(billion cubic feet at 14.73 pia and 60° Fahrenheit)

2006–2007 2002–2007 2007

Volume and Volume and Average

Percent Percent Production

Size Class 2002 2003 2004 2005 2006 2007 Change Change per Operator

Note: There were 13,121 active Category III operators in the 2007 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 727 Category III operators (Table E2). The "other" size class represents 13,274 operators in the

2007 frame (13,774 active operators minus the 500 largest operators).

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report A-5

Class 1-10 13,346 13,355 12,454 11,775 11,352 11,437 85 -1,908 1,143.711

Percent of Total 58.9% 61.0% 58.3% 54.1% 54.1% 53.7% 0.8% -14.3%

Class 11-20 2,817 1,907 2,053 2,659 2,048 1,933 -115 -884 193.274

Percent of Total 12.4% 8.7% 9.6% 12.2% 9.8% 9.1% -5.6% -31.4%

Class 21-100 3,230 3,483 3,711 3,915 4,066 4,412 346 1,182 55.155

Percent of Total 14.2% 15.9% 17.4% 18.0% 19.4% 20.7% 8.5% 36.6%

Class 101-500 1,817 1,705 1,761 1,969 2,111 2,136 25 320 5.340

Percent of Total 8.0% 7.8% 8.2% 9.1% 10.1% 10.0% 1.2% 17.6%

Class Other (13,274) 1,468 1,440 1,393 1,439 1,395 1,399 3 -69 0.105

Percent of Total 6.5% 6.6% 6.5% 6.6% 6.7% 6.6% 0.2% -4.7%

Category I (158) 20,213 19,499 19,055 19,348 17,927 18,244 317 -1,969 116.948

Percent of Total 89.1% 89.1% 89.2% 88.9% 85.5% 85.6% 1.8% -9.7%

Category II (510) 992 937 906 954 1,642 1,658 16 666 3.337

Percent of Total 4.4% 4.3% 4.2% 4.4% 7.8% 7.8% 1.0% 67.1%

Category III (13,121) 1,472 1,456 1,410 1,456 1,403 1,415 12 -57 0.108

Percent of Total 6.5% 6.6% 6.6% 6.7% 6.7% 6.6% 0.9% -3.9%

Total Published 22,677 21,891 21,371 21,757 20,972 21,317 345 -1,360 1.548

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 1.6% -6.0%

Table A3. Crude Oil Proved Reserves by Operator Production Size Class, 2002–2007

(million barrels of 42 U.S. gallons)

2006–2007 2002–2007 2007

Volume and Volume and Average

Percent Percent Reserves

Size Class 2002 2003 2004 2005 2006 2007 Change Change per Operator

Note: There were 13,121 active Category III operators in the 2007 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 727 Category III operators (Table E2). The "other" size class represents 13,274 operators in the

2007 frame (13,774 active operators minus the 500 largest operators).

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

A-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Class 1-10 1,037 1,047 986 912 820 846 25 -191 84.589

Percent of Total 55.3% 55.8% 54.2% 52.6% 49.7% 50.0% 3.1% -18.4%

Class 11-20 233 205 180 178 170 157 -13 -76 15.691

Percent of Total 12.4% 10.9% 9.9% 10.3% 10.3% 9.3% -7.8% -32.7%

Class 21-100 240 272 303 293 309 318 9 78 3.979

Percent of Total 12.8% 14.5% 16.6% 16.9% 18.7% 18.8% 2.9% 32.6%

Class 101-500 181 178 172 178 173 187 14 6 0.467

Percent of Total 9.7% 9.5% 9.5% 10.3% 10.5% 11.1% 8.0% 3.2%

Class Other (13,274) 184 175 178 173 179 183 4 -1 0.014

Percent of Total 9.8% 9.3% 9.8% 10.0% 10.8% 10.8% 2.2% -0.4%

Category I (158) 1,573 1,574 1,534 1,451 1,314 1,346 33 -227 8.631

Percent of Total 83.9% 83.9% 84.3% 83.7% 79.5% 79.6% 2.5% -14.4%

Category II (510) 115 124 105 105 157 159 2 44 0.320

Percent of Total 6.1% 6.6% 5.8% 6.1% 9.5% 9.4% 1.2% 37.9%

Category III (13,121) 187 179 180 176 181 186 4 -1 0.014

Percent of Total 10.0% 9.5% 9.9% 10.2% 11.0% 11.0% 2.4% -0.6%

Total Published 1,875 1,877 1,819 1,733 1,652 1,691 39 -184 0.123

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 2.4% -9.8%

Table A4. Crude Oil Production by Operator Production Size Class, 2002–2007

(million barrels of 42 U.S. gallons)

2006–2007 2002–2007 2007

Volume and Volume and Average

Percent Percent Production

Size Class 2002 2003 2004 2005 2006 2007 Change Change per Operator

Note: There were 13,121 active Category III operators in the 2007 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 727 Category III operators (Table E2). The "other" size class represents 13,274 operators in the

2007 frame (13,774 active operators minus the 500 largest operators).

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report A-7

Class 1-10 3,596 3,689 3,409 3,738 4,667 4,535 -132 939 453.500

Percent of Total 12.9% 13.2% 12.4% 13.2% 16.4% 15.5% -2.8% 26.1%

Class 11-20 2,392 2,492 3,352 2,488 2,513 2,683 170 291 268.300

Percent of Total 8.6% 8.9% 12.2% 8.8% 8.8% 9.2% 6.8% 12.2%

Class 21-100 7,947 8,168 8,071 9,196 8,433 8,890 457 943 111.125

Percent of Total 28.4% 29.3% 29.4% 32.6% 29.6% 30.4% 5.4% 11.9%

Class 101-500 12,661 11,859 10,698 10,845 11,219 11,495 276 -1,166 28.738

Percent of Total 45.3% 42.5% 39.0% 38.4% 39.4% 39.3% 2.5% -9.2%

Rest 1,349 1,709 1,929 1,952 1,662 1,610 -52 261 10.523

Percent of Total 4.8% 6.1% 7.0% 6.9% 5.8% 5.5% -3.1% 19.3%

Category I 17,049 16,760 17,368 17,858 16,953 16,921 -32 -128 108.468

Percent of Total 61.0% 60.0% 63.3% 63.3% 59.5% 57.9% -0.2% -0.8%

Category II 10,473 10,688 9,486 9,738 11,161 12,123 962 1,650 24.392

Percent of Total 37.5% 38.3% 34.5% 34.5% 39.2% 41.5% 8.6% 15.8%

Total 27,945 27,917 27,459 28,219 28,494 29,213 719 1,268 44.737

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 2.5% 4.5%

Note: Includes only data from Category I and Category II operators. In 2007 there were 156 Category I operators and 497 Category II

operators. The "rest" size class had 153 operators in 2007.

Source: Energy Information Administration, Office of Oil and Gas.

Table A5. Operator Field Count by Operator Production Size Class, 2002–2007

2006–2007 2002–2007 2007 Average

Number and Number and Number of

Percent Percent Fields per

Size Class 2002 2003 2004 2005 2006 2007 Change Change Operator
Ta ble A6. Top 50 U.S. Op er a tors Ranked by Re ported 2007 Op er ated Pro duc tion Data

To tal Nat u ral Gas

Crude Oil Pro duc tion Pro duc tion

 Rank Com pany Name (thou sand bar rels/day) Rank Com pany Name (milion cu bic feet/day)

1 BP PLC ................................. 654 1 CONOCOPHILLIPS CO.................. 3,549

2 CHEV RON CORP ......................... 427 2 BP PLC............................... 3,028

3 CONOCOPHILLIPS CO .................... 373 3 ANADARKO PE TRO LEUM CORP ......... 2,463

4 SHELL OIL CO ........................... 339 4 CHES A PEAKE EN ERGY CORP ........... 2,433

5 OC CI DEN TAL PE TRO LEUM CORP........... 283 5 DEVON EN ERGY CORP................. 2,351

6 AERA EN ERGY LLC ....................... 178 6 CHEV RON CORP ...................... 1,998

7 ANADARKO PE TRO LEUM CORP ............ 158 7 XTO EN ERGY INC...................... 1,890

8 EXXONMOBIL CORP ...................... 115 8 ENCANA OIL & GAS INC................. 1,793

9 APACHE CORP........................... 107 9 EXXONMOBIL CORP ................... 1,746

10 PLAINS EXPLORATION & PRODUCTION CO ... 62 10 SHELL OIL CO ......................... 1,663

Top 10 Volume Subtotal 2,696 Top 10 Volume Subtotal 22,914

Top 10 Percentage of U.S. Total 53% Top 10 Percentage of U.S. Total 41%

11 KINDER MORGAN ENERGY PARTNERS....... 55 11 E O G RESOURCES INC ................ 1,348

12 AMERADA HESS CORP..................... 54 12 WIL LIAMS EN ERGY INC................. 1,192

13 NO BLE EN ERGY INC ....................... 52 13 APACHE CORP ........................ 1,151

14 DEVON EN ERGY CORP .................... 52 14 EL PASO EN ERGY ....................... 981

15 MAR A THON OIL CORP ..................... 44 15 SAM SON RE SOURCES CO................ 851

16 MERIT EN ERGY CO........................ 43 16 OC CI DEN TAL PE TRO LEUM CORP.......... 789

17 XTO EN ERGY INC ......................... 42 17 DO MIN ION RE SOURCES INC.............. 726

18 DENBURY RE SOURCES INC ................ 39 18 NEW FIELD EX PLO RA TION CO............. 680

19 EN CORE OP ER AT ING LP ................... 38 19 QUESTAR CORP ........................ 659

20 CHESAPEAKE ENERGY CORP .............. 36 20 MARATHON OIL CORP ................... 625

Top 20 Volume Subtotal 3,151 Top 20 Volume Subtotal 31,916

Top 20 Percentage of U.S. Total 61% Top 20 Percentage of U.S. Total 57%

21 E O G RESOURCES INC .................... 34 21 PIONEER NATURAL RESOURCES USA INC . . 574

22 ENI PE TRO LEUM CO INC ................... 32 22 NO BLE EN ERGY INC..................... 487

23 CON TI NEN TAL RE SOURCES INC ............ 31 23 FOR EST OIL CORP ...................... 411

24 PI O NEER NAT U RAL RE SOURCES USA INC .... 31 24 MERIT EN ERGY CO...................... 404

25 CITY OF LONG BEACH ..................... 29 25 CIMAREX EN ERGY CO ................... 403

26 DO MIN ION RE SOURCES INC................ 29 26 UL TRA PE TRO LEUM INC ................. 386

27 CI TATION OIL & GAS CORP ................. 27 27 SANDRIDGE EN ERGY.................... 362

28 ST MARY LAND & EX PLO RATION CO ......... 25 28 EQ UI TA BLE RE SOURCES INC ............. 324

29 ALLIANT EN ERGY CORP ................... 25 29 ENERGEN RESOURCES CORP ............ 305

30 MURPHY OIL CORP........................ 24 30 KCS EN ERGY INC ....................... 269

31 HILCORP EN ERGY CO ..................... 24 31 SEECO INC............................. 269

32 ENERGEN RESOURCES CORP .............. 24 32 CABOT OIL & GAS CORP ................. 246

33 CIMAREX EN ERGY CO ..................... 24 33 YATES PE TRO LEUM CORP ............... 241

34 EL PASO EN ERGY ......................... 23 34 BILL BARRETT CORP .................... 237

35 NEW FIELD EX PLO RA TION CO............... 23 35 PLAINS EX PLO RA TION & PRO DUC TION CO . 236

36 BERRY PE TRO LEUM CO ................... 22 36 W & T OFF SHORE INC ................... 229

37 W & T OFF SHORE INC ..................... 20 37 HUNT OIL CO ........................... 223

38 STONE EN ERGY CORP..................... 19 38 HILCORP EN ERGY CO ................... 223

39 SWIFT EN ERGY CO........................ 19 39 EXCO RE SOURCES INC .................. 216

40 SAM SON RE SOURCES CO.................. 17 40 MCMORAN OIL & GAS LLC ................ 214

41 SANDRIDGE EN ERGY...................... 17 41 MAR I NER EN ERGY INC................... 207

42 A T P OIL & GAS CORP ..................... 17 42 J - W OPERATING CO .................... 203

43 EN ERGY XXI GOM LLC ..................... 15 43 RANGE RE SOURCES CORP .............. 199

44 ENCANA OIL & GAS INC .................... 14 44 ST MARY LAND & EX PLO RATION CO ....... 195

45 NEXEN PE TRO LEUM USA INC ............... 14 45 HUNT PE TRO LEUM CORP ................ 188

46 ENERPLUS RE SOURCES (USA) CORP........ 14 46 AMERADA HESS CORP................... 187

47 FOR EST OIL CORP ........................ 14 47 ENI PE TRO LEUM CO INC ................. 187

48 MAR I NER EN ERGY INC..................... 13 48 C N X GAS CO LLC ...................... 183

49 HENRY PE TRO LEUM LP .................... 13 49 UNIT CORP............................. 177

50 WALTER OIL & GAS CORP .................. 12 50 FIDELITY EXPLORATION & PROD CO....... 171

Top 50 Volume Subtotal 3,796 Top 50 Volume Subtotal 40,072

Top 50 Percentage of U.S. Total 74% Top 50 Percentage of U.S. Total 72%

Note: Crude oil pro duc tion in cludes pro duc tion of lease con den sate. To tal nat u ral gas pro duc tion is wet af ter lease sep a ra tion.

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

A-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Appendix B

Top 100 Oil and Gas Fields

This appendix presents estimates of the proved

reserves and production of the largest or top 100

liquids or gas fields as ranked by reserves or by

production. The total liquids production and reserve

data include both crude oil and lease condensate, and

are labeled as liquids. The total gas production and

reserve data is wet after lease separation. Although

there is considerable grouping of field-level statistics

within the tables, rough orders of magnitude may be

estimated for the proved reserves and production of

these fields. The tables rank the top 100 fields by

production (Table B3 and Table B4) rather than by their

reserves (Table B1 and Table B2).

Some of the fields in the top 100 are operated by only

one or two operators, therefore, the totals for proved

reserves are combined in four groups top 10, top 20, top

50, and top 100 to avoid revealing company

proprietary data. Many of these same fields are in each

of the tables B1, B2, B3, and B4. The top liquids fields

with the more recent discovery dates are typically

located in the deep waters of the Gulf of Mexico

Offshore or Alaska. The gas fields with the more recent

discovery dates are normally located in the deep Gulf

of Mexico Offshore, New Mexico, Colorado, and

Wyoming.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report B-1

Summary for the Top 100 Fields for 2007 Liquids and Gas

12/31/2007 12/31/2007 Estimated

Proved Nonproducing 2007 Rank Group Reserves Percent Reserves Percent Production Percent

Table B1. Top 100 U.S. Fields as Ranked by Liquids Proved Reserves (million barrels)

Top 10 6,896.1 30.2% 1,872.6 31.1% 359.2 19.2%

Top 20 9,389.8 41.2% 2,560.3 42.6% 526.5 28.1%

Top 50 12,724.3 55.8% 3,370.1 56.0% 757.5 40.5%

Top 100 14,935.7 65.5% 4,097.8 68.1% 927.0 49.5%

Others 7,876.3 34.5% 1,916.2 31.9% 945.0 50.5%

Total 22,812.0 100.0% 6,014.0 100.0% 1,872.0 100.0%

Table B2. Top 100 U.S. Fields as Ranked by Gas Proved Reserves (billion cubic feet)

Top 10 74,307.4 30.0% 22,553.0 28.9% 4,554.7 22.4%

Top 20 95,713.3 38.6% 26,694.4 34.2% 5,654.8 27.8%

Top 50 126,605.5 51.1% 40,051.1 51.3% 7,748.2 38.1%

Top 100 148,486.7 59.9% 48,297.9 61.8% 9,296.5 45.8%

Others 99,302.3 40.1% 29,796.1 38.2% 11,021.5 54.2%

Total 247,789.0 100.0% 78,094.0 100.0% 20,318.0 100.0%

Table B3. Top 100 U.S. Fields as Ranked by Liquids Production (million barrels)

Top 10 n/a n/a n/a n/a 433.4 23.2%

Top 20 n/a n/a n/a n/a 596.8 31.9%

Top 50 n/a n/a n/a n/a 832.3 44.5%

Top 100 n/a n/a n/a n/a 1,003.2 53.6%

Others n/a n/a n/a n/a 868.8 46.4%

Total n/a n/a n/a n/a 1,872.0 100.0%

Table B4. Top 100 U.S. Fields as Ranked by Gas Production (billion cubic feet)

Top 10 n/a n/a n/a n/a 4,650.4 22.9%

Top 20 n/a n/a n/a n/a 5,956.8 29.3%

Top 50 n/a n/a n/a n/a 8,179.9 40.3%

Top 100 n/a n/a n/a n/a 9,895.5 48.7%

Others n/a n/a n/a n/a 10,422.5 51.3%

Total n/a n/a n/a n/a 20,318.0 100.0%
Table B1. Top 100 Liquids Fields

Ranked by Reserves

The top 100 liquids fields by reserves had 14,936

million barrels of proved reserves accounting for 66

percent of the total United States as of December 31,

2007, (Table 6 and Table 15) and 68 percent of the

reported nonproducing reserves. In the top 20 liquids

fields for 2007 there are eight fields, which are in the

deep water of the Gulf of Mexico Federal Offshore or

Alaska. The top 100 liquids fields by reserves had 927

million barrels of production, or 50 percent of the 2007

U.S. total (Table 6 and Table 15).

Table B2. Top 100 Gas Fields

Ranked by Reserves

The top 100 gas fields by reserves had 148,487 billion

cubic feet of wet natural gas proved reserves or 60

percent of the total, as of December 31, 2007 (Table 9)

and 62 percent of the reported nonproducing reserves.

The top 100 gas fields by reserves had 9,297 billion

cubic feet of production, or 46 percent of the 2007 U.S.

total (Table 9).

Table B3. Top 100 Liquids Fields

Ranked by Production

The top 100 liquids fields by production had 1,003

million barrels of production, or accounted for 54

percent of the 2007 U.S. total (Table 6 and Table 15).

Table B4. Top 100 Gas Fields

Ranked by Production

The top 100 gas fields had 9,896 billion cubic feet of

production, or 48 accounted for percent of the 2007 U.S.

total (Table 9).

Energy Information Administration

B-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

LIQUIDS PROVED RESERVES

1-10

30%

11-20

11%

21-50

15%

51-100

10%

All Others

34%

`

WET GAS PRODUCTION

1-10

23%

11-20

6%

21-50

11%

51-100

8%

All Others

52%

LIQUIDS PRODUCTION

1-10

23%

11-20

9%

21-50

13%

51-100

9%

All Others

46% `

WET GAS PROVED RESERVES

1-10

30%

11-20

9%

21-50

12%

51-100

9%

All Others

40%
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report B-3

Table B1. Top 100 U.S. Fields Ranked by Liquids Proved Reserves from Estimated 2007 Field Level Dataa

(million barrels of 42 U.S. gallons)

2007 Estimated Rank Group

Production Proved Nonproducing Discovery

Num Field Name Location Volume Reserves Reserves Year

1 PRUDHOE BAY AK 96.3 1967

2 WASSON TX 23.6 1937

3 SPRABERRY TREND AREA TX 28.1 1949

4 BELRIDGE SOUTH CA 37.0 1911

5 MISSISSIPPI CANYON BLK 807 (MARS-URSA ) FG 75.2 (1-10) 1989

6 KUPARUK RIVER AK 43.0 1969

7 MISSISSIPPI CANYON BLK 778 (THUNDER HORSE ) FG 0.0 1999

8 MIDWAY-SUNSET CA 38.0 1901

9 ELK HILLS CA 16.4 1919

10 GREEN CANYON BLK 743 (ATLANTIS ) FG 1.6 1998

Top 10 Volume Subtotal 359.2 6,896.1 1,872.6

Top 10 Percentage of U.S. Total 19.2% 30.2% 31.1%

11 CEDAR HILLS MT & ND & SD 26.6 1951

12 KERN RIVER CA 30.1 1899

13 SLAUGHTER TX 11.3 1937

14 WILMINGTON CA 14.9 1932

15 WATTENBERG CO 11.0 (11-20) 1970

16 ALPINE AK 33.7 1994

17 MILNE POINT AK 12.2 1982

18 SALT CREEK WY 3.0 1889

19 GREEN CANYON BLK 826 (MAD DOG ) FG 16.5 1998

20 LEVELLAND TX 8.0 1945

Top 20 Volume Subtotal 526.5 9,389.8 2,560.3

Top 20 Percentage of U.S. Total 28.1% 41.2% 42.6%

21 CYMRIC CA 18.4 1916

22 LOST HILLS CA 12.2 1910

23 SEMINOLE TX 7.5 1936

24 GREEN CANYON BLK 640 (TAHITI ) FG 0.0 2002

25 ELM COULEE MT 18.4 2000

26 GREATER ANETH UT 3.7 1956

27 GOLDSMITH TX 5.8 1935

28 HONDO FP 5.6 1969

29 ORION AK 3.7 2002

30 PESCADO FP 4.4 1970

31 YATES TX 9.9 1926

32 MISSISSIPPI CANYON BLK 383 (KEPLER ) FG 25.3 1987

33 SHO-VEL-TUM OK 7.8 1905

34 COWDEN NORTH TX 5.0 1930

35 HOBBS NM & TX 4.5 (21-50) 1945

36 VENTURA CA 4.2 1916

37 NORTHSTAR AK 13.9 1984

38 ENDICOTT AK 4.6 1978

39 GIDDINGS TX 6.5 1960

40 INGLEWOOD CA 3.1 1924

41 MONUMENT BUTTE UT 4.3 1964

42 SAN ARDO CA 3.4 1947

43 WEST SAK AK 6.4 969

44 GREEN CANYON BLK 644 (HOLSTEIN ) FG 12.3 1999

45 SACATE FP 3.9 1970

46 POINT MCINTYRE AK 8.8 1988

47 GREEN CANYON BLK 562 (K 2 ) FG 10.9 1999

48 KELLY-SNYDER TX 10.1 1948

49 BOREALIS AK 4.6 2001

50 WARD-ESTES NORTH TX 1.8 1927

Top 50 Volume Subtotal 757.5 12,724.3 3,370.1

Top 50 Percentage of U.S. Total 40.5% 55.8% 56.0%
Energy Information Administration

B-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

51 MISSISSIPPI CANYON BLK 127 (HORN MT. ) FG 8.4 2000

52 FUHRMAN-MASCHO TX 3.3 1930

53 VACUUM NM 5.5 1929

54 ROBERTSON NORTH TX 4.1 1956

55 FULLERTON TX 4.1 1942

56 MCELROY TX 4.7 1926

57 SALT CREEK TX 4.5 1942

58 COALINGA CA 5.6 1887

59 MISSISSIPPI CANYON BLK 696 (BLIND FAITH ) FG 0.0 2005

60 ARROYO GRANDE CA 0.5 1906

61 RANGELY CO 5.2 1902

62 PINEDALE WY 2.4 1955

63 ATWATER VALLEY BLK 575 (NEPTUNE (AT) ) FG 0.0 1995

64 LAKE WASHINGTON LA 8.3 1931

65 ANTON-IRISH TX 3.4 1944

66 WESTBROOK TX 2.0 1920

67 GREEN CANYON BLK 654 (SHENZI ) FG 0.1 2003

68 GARDEN BANKS BLK 171 (SALSA ) FG 4.5 1988

69 EAST TEXAS TX 4.2 1930

70 BREA-OLINDA CA 1.2 1897

71 POSTLE OK 1.9 1958

72 CEDAR LAKE TX 2.0 1939

73 AURORA AK 3.5 1969

74 HAWKINS TX 2.4 1940

75 LISBURNE AK 3.7 (51-100) 1967

76 NATURAL BUTTES UT 1.9 1940

77 POLARIS AK 0.9 2000

78 VIOSCA KNOLL BLK 786 (PETRONIUS ) FG 11.2 1995

79 BURBANK OK 0.8 1920

80 EUNICE MONUMENT NM 1.9 1929

81 KERN FRONT CA 1.7 1925

82 MEANS TX 3.1 1934

83 TARN AK 5.8 1991

84 PARSHALL ND 1.9 2006

85 POSO CREEK CA 1.3 1929

86 GRAND ISLE BLK 43 FG 3.0 1956

87 MISSISSIPPI CANYON BLK 773 (DEVILS TOWER ) FG 11.6 1999

88 MISSISSIPPI CANYON BLK 84 (KING) FG 16.8 1993

89 FULLER TX 0.5 1951

90 NIKAITCHUQ AK 0.0 2005

91 GOLDEN TREND OK 2.0 1945

92 HUGOTON GAS AREA KS & OK & TX 1.5 1922

93 JONAH WY 3.7 1977

94 WELCH TX 1.5 1942

95 HOWARD-GLASSCOCK TX 2.6 1925

96 GREEN CANYON BLK 339 (FRONT RUNNER ) FG 3.6 2001

97 MISSISSIPPI CANYON BLK 20 FG 1.3 1982

98 ALTAMONT-BLUEBELL UT 2.0 1949

99 FITTS OK 1.7 1933

100 IATAN EAST HOWARD TX 1.3 1926

Top 100 Volume Subtotal 927.0 14,935.7 4,097.8

Top 100 Percentage of U.S. Total 49.5% 65.5% 68.1%

Table B1. Top 100 U.S. Fields Ranked by Liquids Proved Reserves from Estimated 2007 Field Level Dataa

(Continued)

(million barrels of 42 U.S. gallons)

2007 Estimated Rank Group

Production Proved Nonproducing Discovery

Num Field Name Location Volume Reserves Reserves Year

a

Includes lease condensate.

Notes: The U.S. total production estimate of 1,872 million barrels and the U.S. total reserves estimate of 22,812 million barrels, used to

calculate the percentages in this table, are from the combined totals of Table 6 (crude oil) and Table 15 (lease condensate) in this publication.

Column totals may not add due to independent rounding.

FP = Federal Offshore Pacific.

FG = Federal Offshore Gulf of Mexico.

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report B-5

Table B2. Top 100 U.S. Fields Ranked by Gas Proved Reserves from Estimated 2007 Field Level Dataa

(billion cubic feet)

2007 Estimated Rank Group

Production Proved Nonproducing Discovery

Num Field Name Location Volume Reserves Reserves Year

1 SAN JUAN BASIN GAS AREA CO & NM 1320.7 1927

2 NEWARK EAST TX 1110.3 1981

3 PRUDHOE BAY AK 168.7 1967

4 PINEDALE WY 313.4 1955

5 HUGOTON GAS AREA KS & OK & TX 357.8 (1-10) 1922

6 NATURAL BUTTES UT 170.4 1940

7 JONAH WY 366.3 1977

8 WATTENBERG CO 169.0 1970

9 ANTRIM MI 136.1 1965

10 PRB COALBED MT & WY 442.0 1992

Top 10 Volume Subtotal 4,554.7 74,307.4 22,553.0

Top 10 Percentage of U.S. Total 22.4% 30.0% 28.9%

11 FOGARTY CREEK WY 161.7 1975

12 CARTHAGE TX 231.7 1936

13 NORTHSTAR AK 0.0 1984

14 RATON BASIN GAS AREA CO & NM 123.7 1998

15 LOWER MOBILE BAY AREA AL & FG 163.0 (11-20) 1979

16 GRAND VALLEY CO 132.6 1985

17 SPRABERRY TREND AREA TX 87.9 1949

18 LAKE RIDGE WY 71.1 1981

19 SAWYER TX 82.3 1960

20 BIG SANDY KY 45.9 1926

Top 20 Volume Subtotal 5,654.8 95,713.3 26,694.4

Top 20 Percentage of U.S. Total 27.8% 38.6% 34.2%

21 FREESTONE TX 97.3 1949

22 MADDEN WY 132.6 1968

23 ELM GROVE LA 119.9 1916

24 PARACHUTE CO 99.4 1985

25 OAKWOOD VA 63.6 1990

26 B-43 (FAYETTEVILLE) AR 91.8 2004

27 MAMM CREEK CO 93.1 1959

28 PINON TX 65.6 1982

29 RULISON CO 82.3 1958

30 OAK HILL TX 99.0 1958

31 BALD PRAIRIE TX 59.8 1976

32 STILES RANCH OK & TX 72.6 1978

33 ELK HILLS CA 130.2 1919

34 STRONG CITY DISTRICT OK 84.2 1966

35 FARRAR TX 64.2 (21-50) 1963

36 WILD ROSE WY 31.5 1975

37 MISSISSIPPI CANYON BLK 807 (MARS-URSA ) FG 98.1 1989

38 WAMSUTTER WY 35.6 1958

39 ECHO SPRINGS WY 29.3 1976

40 CARTHAGE NORTH TX 26.0 1966

41 MINDEN TX 39.0 1954

42 STANDARD DRAW WY 24.4 1979

43 TEAGUE TX 74.6 1945

44 BUFFALO WALLOW TX 62.2 1969

45 HALEY TX 107.2 1983

46 PICEANCE CREEK CO 17.9 1930

47 VERNON LA 78.4 1967

48 NORA VA 31.7 1949

49 RED OAK-NORRIS OK 55.8 1910

50 MESA UNIT WY 25.9 1981

Top 50 Volume Subtotal 7,748.2 126,605.5 40,051.1

Top 50 Percentage of U.S. Total 38.1% 51.1% 51.3%
Energy Information Administration

B-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table B2. Top 100 U.S. Fields Ranked by Gas Proved Reserves from Estimated 2007 Field Level Dataa

(Continued)

(billion cubic feet)

2007 Estimated Rank Group

Production Proved Nonproducing Discovery

Num Field Name Location Volume Reserves Reserves Year

51 PINE HOLLOW SOUTH OK 33.4 1959

52 MOCANE-LAVERNE GAS AREA KS & OK & TX 53.0 1946

53 DRUNKARDS WASH UT 53.7 1989

54 GOLDEN TREND OK 33.8 1945

55 BEAR GRASS TX 35.1 1977

56 JOHN AMORUSO TX 59.2 2005

57 GIDDINGS TX 86.5 1960

58 MAYFIELD NE OK 80.2 1951

59 OVERTON TX 47.8 1973

60 BELUGA RIVER AK 48.0 1962

61 CEDARDALE NE OK 34.5 1957

62 CASPIANA LA 34.7 1925

63 HONDO FP 17.8 1969

64 WATONGA-CHICKASHA TREND OK 39.3 1948

65 WASSON TX 40.5 1937

66 SHO-VEL-TUM OK 31.9 1905

67 GURNEE COAL DEGAS AL 3.8 1990

68 TIP TOP WY 17.1 1928

69 RILEY RIDGE WY 0.1 1980

70 VERDEN OK 26.2 1948

71 SLIGO LA 41.5 1922

72 ELK CITY OK 44.8 1947

73 BRUFF WY 29.9 1969

74 ENDICOTT AK 10.1 1978

75 GOMEZ TX 35.3 (51-100) 1963

76 KINTA OK 56.3 1914

77 DOWDY RANCH TX 32.1 1999

78 MISSISSIPPI CANYON BLK 778 (THUNDER HORSE ) FG 0.0 1999

79 SULPHUR CREEK CO 6.6 1955

80 DEW TX 30.1 1982

81 CEMENT OK 44.1 1916

82 BETHANY-LONGSTREET LA & TX 34.2 1921

83 TRAIL RIDGE CO 5.8 1990

84 COALGATE NE OK 12.5 1978

85 WAYNOKA NE OK 21.5 1956

86 TIERNEY WY 5.5 1973

87 NACONICHE CREEK TX 18.6 1978

88 LOGANSPORT-JOAQUIN LA & TX 32.6 1931

89 FRENCHIE DRAW WY 14.0 1961

90 BLOCKER TX 23.4 1954

91 HEMPHILL TX 26.4 1961

92 BOONSVILLE TX 28.1 1945

93 WILBURTON OK 28.4 1941

94 EAST BREAKS BLK 602 (NANSEN ) FG 32.2 1999

95 CLEBURNE WEST TX 20.9 1992

96 KUPARUK RIVER AK 19.9 1969

97 OZONA NE TX 21.7 1966

98 CHEROKEE BASIN COAL GAS AR KS 35.7 1891

99 MISSISSIPPI CANYON BLK 383 (KEPLER ) FG 44.1 1987

100 BECKVILLE TX 15.2 1974

Top 100 Volume Subtotal 9,296.5 148,486.7 48,297.9

Top 100 Percentage of U.S. Total 45.8% 59.9% 61.8%

a

Total wet gas after lease separation.

Note: The U.S. total production estimate of 20,318 billion cubic feet and the U.S. total reserves estimate of 247,789 billion cubic feet, used

to calculate the percentages in this table, are from Table 9 in this publication. Column totals may not add due to independent rounding.

FP = Federal Offshore Pacific.

FG = Federal Offshore Gulf of Mexico.

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report B-7

Table B3. Top 100 U.S. Fields Ranked by Liquids Production from Estimated 2007 Field Level Dataa

(million barrels of 42 U.S. gallons)

2007 Estimated Discovery

Num Field Name Location Production Volume Year

1 PRUDHOE BAY AK 96.3 1967

2 MISSISSIPPI CANYON BLK 807 (MARS-URSA ) FG 75.2 1989

3 KUPARUK RIVER AK 43.0 1969

4 MIDWAY-SUNSET CA 38.0 1901

5 BELRIDGE SOUTH CA 37.0 1911

6 ALPINE AK 33.7 1994

7 KERN RIVER CA 30.1 1899

8 SPRABERRY TREND AREA TX 28.1 1949

9 CEDAR HILLS MT & ND & SD 26.6 1951

10 MISSISSIPPI CANYON BLK 383 (KEPLER ) FG 25.3 1987

Top 10 Volume Subtotal 433.4

Top 10 Percentage of U.S. Total 23.2%

11 WASSON TX 23.6 1937

12 CYMRIC CA 18.4 1916

13 ELM COULEE MT 18.4 2000

14 MISSISSIPPI CANYON BLK 84 (KING) FG 16.8 1993

15 GREEN CANYON BLK 826 (MAD DOG ) FG 16.5 1998

16 ELK HILLS CA 16.4 1919

17 WILMINGTON CA 14.9 1932

18 NORTHSTAR AK 13.9 1984

19 GREEN CANYON BLK 644 (HOLSTEIN ) FG 12.3 1999

20 MILNE POINT AK 12.2 1982

Top 20 Volume Subtotal 596.8

Top 20 Percentage of U.S. Total 31.9%

21 LOST HILLS CA 12.2 1910

22 MISSISSIPPI CANYON BLK 773 (DEVILS TOWER ) FG 11.6 1999

23 SLAUGHTER TX 11.3 1937

24 VIOSCA KNOLL BLK 786 (PETRONIUS ) FG 11.2 1995

25 WATTENBERG CO 11.0 1970

26 GREEN CANYON BLK 158 (BRUTUS ) FG 11.0 1989

27 GREEN CANYON BLK 562 (K 2 ) FG 10.9 1999

28 KELLY-SNYDER TX 10.1 1948

29 YATES TX 9.9 1926

30 POINT MCINTYRE AK 8.8 1988

31 MISSISSIPPI CANYON BLK 127 (HORN MT. ) FG 8.4 2000

32 LAKE WASHINGTON LA 8.3 1931

33 LEVELLAND TX 8.0 1945

34 SHO-VEL-TUM OK 7.8 1905

35 SEMINOLE TX 7.5 1936

36 GREEN CANYON BLK 680 (CONSTITUTION ) FG 6.6 2001

37 GIDDINGS TX 6.5 1960

38 WEST SAK AK 6.4 1969

39 NANUQ AK 6.2 2000

40 MISSISSIPPI CANYON BLK 429 (ARIEL ) FG 6.2 1995

41 GOLDSMITH TX 5.8 1935

42 TARN AK 5.8 1991

43 MISSISSIPPI CANYON BLK 582 (MEDUSA ) FG 5.7 1998

44 HONDO FP 5.6 1969

45 COALINGA CA 5.6 1887

46 FIORD AK 5.6 1992

47 VACUUM NM 5.5 1929

48 EWING BANK BLK 873 (LOON) FG 5.3 1985

49 EAST BREAKS BLK 602 (NANSEN ) FG 5.3 1999

50 RANGELY CO 5.2 1902

Top 50 Volume Subtotal 832.3

Top 50 Percentage of U.S. Total 44.5%
Energy Information Administration

B-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table B3. Top 100 U.S. Fields Ranked by Liquids Production from Estimated 2007 Field Level Dataa

(Continued)

(million barrels of 42 U.S. gallons)

2007 Estimated Discovery

Num Field Name Location Production Volume Year

51 COWDEN NORTH TX 5.0 1930

52 MCELROY TX 4.7 1926

53 BOREALIS AK 4.6 2001

54 ENDICOTT AK 4.6 1978

55 HOBBS NM & TX 4.5 1945

56 GARDEN BANKS BLK 171 (SALSA ) FG 4.5 1988

57 SALT CREEK TX 4.5 1942

58 PESCADO FP 4.4 1970

59 SAN JUAN BASIN GAS AREA CO & NM 4.4 1927

60 MONUMENT BUTTE UT 4.3 1964

61 VENTURA CA 4.2 1916

62 EAST TEXAS TX 4.2 1930

63 ROBERTSON NORTH TX 4.1 1956

64 FULLERTON TX 4.1 1942

65 MISSISSIPPI CANYON BLK 755 (GOMEZ ) FG 4.0 1986

66 SACATE FP 3.9 1970

67 BURR FERRY NORTH LA & TX 3.8 1946

68 LISBURNE AK 3.7 1967

69 ORION AK 3.7 2002

70 JONAH WY 3.7 1977

71 GREATER ANETH UT 3.7 1956

72 GREEN CANYON BLK 339 (FRONT RUNNER ) FG 3.6 2001

73 GARDEN BANKS BLK 260 (BALDPATE ) FG 3.6 1991

74 EUGENE ISLAND SA BLK 330 FG 3.5 1971

75 AURORA AK 3.5 1969

76 SAN ARDO CA 3.4 1947

77 ANTON-IRISH TX 3.4 1944

78 FUHRMAN-MASCHO TX 3.3 1930

79 INGLEWOOD CA 3.1 1924

80 MEANS TX 3.1 1934

81 GRAND ISLE BLK 43 FG 3.0 1956

82 MISSISSIPPI CANYON BLK 109 (AMBERJACK ) FG 3.0 1983

83 SALT CREEK WY 3.0 1889

84 LOST SOLDIER WY 2.9 1916

85 NEWARK EAST TX 2.8 1981

86 POINT PEDERNALES FP 2.8 1983

87 MAIN PASS SA BLK 299 FG 2.8 1967

88 GREEN CANYON BLK 768 (TICONDEROGA ) FG 2.7 2004

89 JAY AL & FL 2.6 1951

90 HOWARD-GLASSCOCK TX 2.6 1925

91 DOLLARHIDE NM & TX 2.6 1945

92 OREGON BASIN WY 2.5 1912

93 COGDELL TX 2.4 1949

94 HAWKINS TX 2.4 1940

95 PINEDALE WY 2.4 1955

96 ELK BASIN MT & WY 2.4 1915

97 GRAYBURG JACKSON NM 2.3 1929

98 PANHANDLE TX 2.3 1910

99 JO-MILL TX 2.3 1953

100 MCARTHUR RIVER AK 2.2 1965

Top 100 Volume Subtotal 1,003.2

Top 100 Percentage of U.S. Total 53.6%

a

Includes lease condensate.

Notes: The U.S. total production estimate of 1,834 million barrels, used to calculate the percentages in this table, are from the combined

totals of Table 6 and Table 15 in this publication. Column totals may not add due to independent rounding.

FP = Federal Offshore Pacific.

FG = Federal Offshore Gulf of Mexico.

Source: Energy Information Administration, Office of Oil and Gas.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report B-9

1 SAN JUAN BASIN GAS AREA CO & NM 1320.7 1927

2 NEWARK EAST TX 1110.3 1981

3 PRB COALBED MT & WY 442.0 1992

4 JONAH WY 366.3 1977

5 HUGOTON GAS AREA KS & OK & TX 357.8 1922

6 PINEDALE WY 313.4 1955

7 CARTHAGE TX 231.7 1936

8 NATURAL BUTTES UT 170.4 1940

9 WATTENBERG CO 169.0 1970

10 PRUDHOE BAY AK 168.7 1967

Top 10 Volume Subtotal 4,650.4

Top 10 Percentage of U.S. Total 22.9%

11 LOWER MOBILE BAY AREA AL & FG 163.0 1979

12 FOGARTY CREEK WY 161.7 1975

13 ANTRIM MI 136.1 1965

14 GRAND VALLEY CO 132.6 1985

15 MADDEN WY 132.6 1968

16 ELK HILLS CA 130.2 1919

17 RATON BASIN GAS AREA CO & NM 123.7 1998

18 ELM GROVE LA 119.9 1916

19 HALEY TX 107.2 1983

20 PARACHUTE CO 99.4 1985

Top 20 Volume Subtotal 5,956.8

Top 20 Percentage of U.S. Total 29.3%

21 OAK HILL TX 99.0 1958

22 MISSISSIPPI CANYON BLK 807 (MARS-URSA ) FG 98.1 1989

23 FREESTONE TX 97.3 1949

24 MAMM CREEK CO 93.1 1959

25 B-43 (FAYETTEVILLE) AR 91.8 2004

26 SPRABERRY TREND AREA TX 87.9 1949

27 GIDDINGS TX 86.5 1960

28 MCALLEN RANCH TX 84.4 1960

29 STRONG CITY DISTRICT OK 84.2 1966

30 RULISON CO 82.3 1958

31 SAWYER TX 82.3 1960

32 MAYFIELD NE OK 80.2 1951

33 VERNON LA 78.4 1967

34 SAVELL TX 77.0 1997

35 YATES TX 74.9 1926

36 TEAGUE TX 74.6 1945

37 STILES RANCH OK & TX 72.6 1978

38 LAKE RIDGE WY 71.1 1981

39 PINON TX 65.6 1982

40 FARRAR TX 64.2 1963

41 OAKWOOD VA 63.6 1990

42 MISSISSIPPI CANYON BLK 731 (MENSA ) FG 63.4 1986

43 BUFFALO WALLOW TX 62.2 1969

44 BALD PRAIRIE TX 59.8 1976

45 JOHN AMORUSO TX 59.2 2005

46 KINTA OK 56.3 1914

47 RED OAK-NORRIS OK 55.8 1910

48 DRUNKARDS WASH UT 53.7 1989

49 MOCANE-LAVERNE GAS AREA KS & OK & TX 53.0 1946

50 CEDAR HILLS MT & ND & SD 50.4 1951

Top 50 Volume Subtotal 8,179.9

Top 50 Percentage of U.S. Total 40.3%

Table B4. Top 100 U.S. Fields Ranked by Gas Production from Estimated 2007 Field Level Dataa

(billion cubic feet)

2007 Estimated Discovery

Num Field Name Location Production Volume Year
Energy Information Administration

B-10 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table B4. Top 100 U.S. Fields Ranked by Gas Production from Estimated 2007 Field Level Dataa

(Continued)

(billion cubic feet)

2007 Estimated Discovery

Num Field Name Location Production Volume Year

51 BELUGA RIVER AK 48.0 1962

52 OVERTON TX 47.8 1973

53 BIG SANDY KY 45.9 1926

54 ELK CITY OK 44.8 1947

55 CEMENT OK 44.1 1916

56 MISSISSIPPI CANYON BLK 383 (KEPLER ) FG 44.1 1987

57 HAYNES TX 43.0 1954

58 SLIGO LA 41.5 1922

59 BURR FERRY NORTH LA & TX 41.3 1946

60 WASSON TX 40.5 1937

61 EXSUN TX 39.7 1974

62 WATONGA-CHICKASHA TREND OK 39.3 1948

63 MINDEN TX 39.0 1954

64 B M T TX 36.6 1994

65 LA PERLA TX 35.9 1958

66 CHEROKEE BASIN COAL GAS AR KS 35.7 1891

67 WAMSUTTER WY 35.6 1958

68 GOMEZ TX 35.3 1963

69 BEAR GRASS TX 35.1 1977

70 CASPIANA LA 34.7 1925

71 CEDARDALE NE OK 34.5 1957

72 BETHANY-LONGSTREET LA & TX 34.2 1921

73 GOLDEN TREND OK 33.8 1945

74 PINE HOLLOW SOUTH OK 33.4 1959

75 VAQUILLAS RANCH TX 33.0 1978

76 LOGANSPORT-JOAQUIN LA & TX 32.6 1931

77 PANOLA OK 32.5 1964

78 EAST BREAKS BLK 602 (NANSEN ) FG 32.2 1999

79 DOWDY RANCH TX 32.1 1999

80 SHO-VEL-TUM OK 31.9 1905

81 NORA VA 31.7 1949

82 WILD ROSE WY 31.5 1975

83 CHEYENNE WEST OK 31.2 1971

84 MENDOTA NW TX 30.9 1962

85 DEW TX 30.1 1982

86 BRUFF WY 29.9 1969

87 BLOCK 31 TX 29.6 1945

88 ROLETA TX 29.5 1955

89 ECHO SPRINGS WY 29.3 1976

90 COOK INLET NORTH AK 28.8 1962

91 JAVELINA TX 28.4 1947

92 MILLS RANCH OK & TX 28.4 1945

93 WILBURTON OK 28.4 1941

94 BOONSVILLE TX 28.1 1945

95 DOUGLASS WEST TX 28.0 1967

96 TRAWICK TX 27.2 1949

97 BROWN-BASSETT TX 26.9 1953

98 GREENWOOD-WASKOM LA & TX 26.7 1924

99 HEMPHILL TX 26.4 1961

100 VERDEN OK 26.2 1948

Top 100 Volume Subtotal 9,895.5

Top 100 Percentage of U.S. Total 48.7%

a

Total wet gas after lease separation.

Note: The U.S. total production estimate of 19,259 billion cubic feet, used to calculate the percentages in this table, are from Table 9 in this

publication. Column totals may not add due to independent rounding.

FP = Federal Offshore Pacific.

FG = Federal Offshore Gulf of Mexico.

Source: Energy Information Administration, Office of Oil and Gas.
Appendix C

Conversion to the Metric System

Public Law 100–418, the Omnibus Trade and

Competitiveness Act of 1988, states: “It is the

declared policy of the United States—

(1) to designate the metric system of measurement as 

the preferred system of weights and measures for

United States trade and commerce. . . .

(2) to require that each Federal agency, by the end of

Fiscal Year 1992, use the metric system of

measurement in its procurements, grants, and other

business–related activities."{45}

Table C1 is in keeping with the spirit of this law.

The petroleum industry in the United States is slowly 

moving in the direction prescribed by this law and

the data collected by EIA are collected in the units

that are still common to the U.S. petroleum industry,

namely barrels and cubic feet. Standard metric

conversion factors were used to convert the National

level volumes in Table 1 to the metric equivalents in

Table C1. Barrels were multiplied by 0.1589873 to

convert to cubic meters and cubic feet were

multiplied by 0.02831685 to convert to cubic meters.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2006 Annual Report C-1
Energy Information Administration

C-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2006 Annual Report

Table C1. U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids,

in Metric Units, 1997 – 2007

Revisions

a

Net of Sales New Reservoir ProvedcChange

Net and and New Field Discoveries TotalbEstimated Reserves from

Adjustments Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

Crude Oil (million cubic meters)

1997 82.6 145.4 228.0 NA 75.8 101.3 18.9 196.0 339.9 3,584.5 84.1

1998 -101.5 82.3 -19.2 NA 52.0 24.2 19.1 95.3 316.5 3,344.1 -240.4

1999 22.1 289.2 311.3 NA 41.2 51.0 23.1 115.3 310.3 3,460.4 116.3

2000 22.7 118.6 141.3 -3.2 121.8 43.9 39.6 205.3 298.9 3,504.9 44.5

2001 -0.6 -25.1 -25.8 -13.8 137.7 223.7 46.4 407.8 304.5 3,568.6 63.7

2002 66.1 114.5 180.6 3.8 78.2 47.7 24.5 150.4 298.1 3,605.4 36.8

2003 25.9 14.9 40.9 -63.3 67.7 112.1 16.1 195.9 298.4 3,480.4 -125.0

2004 11.8 66.8 78.5 3.7 98.1 5.2 21.0 124.3 289.2 3,397.7 -82.7

2005 35.1 90.5 125.6 44.2 128.0 32.6 6.5 167.1 275.5 3,459.1 61.4

2006 14.9 0.3 15.3 30.8 80.1 4.8 6.8 91.7 262.6 3,334.3 -124.8

2007 10.3 190.8 201.1 -3.0 103.5 10.5 11.6 125.6 268.8 3,389.1 54.9

Dry Natural Gas (billion cubic meters)

1997 -16.70 138.81 122.11 NA 299.73 75.92 67.45 443.10 544.00 4,735.23 21.21

1998 -46.30 162.54 116.24 NA 232.11 30.41 61.22 323.74 530.09 4,645.12 -90.11

1999 27.81 297.44 325.25 NA 199.44 44.40 62.18 306.02 535.98 4,740.41 95.29

2000 -25.23 197.14 171.91 114.15 418.72 56.15 67.05 541.93 544.22 5,024.17 283.76

2001 77.64 -65.64 12.01 74.47 463.83 101.32 79.29 644.44 560.08 5,195.01 170.84

2002 105.54 26.53 132.07 10.76 418.21 37.72 47.97 503.90 548.02 5,293.72 98.71

2003 80.45 -46.38 34.07 29.28 465.93 34.60 45.59 546.12 550.05 5,353.10 59.38

2004 -3.23 21.07 17.84 52.22 515.31 21.49 34.15 570.95 542.78 5,451.36 98.23

2005 53.43 76.43 129.86 72.04 596.07 26.67 34.21 656.95 522.67 5,787.54 336.18

2006 21.04 -51.99 -30.95 84.84 616.68 11.58 32.71 660.97 525.14 5,977.26 189.72

2007 32.48 437.81 470.29 767.58 22.54 22.54 33.64 823.77 551.22 6,731.65 754.39

Natural Gas Liquids (million cubic meters)

1997 -2.2 45.9 43.7 NA 85.1 18.1 14.3 117.5 137.4 1,267.6 23.8

1998 -57.4 33.1 -24.3 NA 60.9 10.5 14.0 85.4 132.4 1,196.2 -71.4

1999 15.8 115.6 131.4 NA 49.8 8.1 14.0 71.9 142.5 1,257.0 60.8

2000 -13.2 73.0 59.8 23.1 102.5 14.6 16.2 133.4 146.4 1,326.7 69.7

2001 -68.2 -21.0 -89.2 16.2 114.0 21.9 22.6 158.5 141.5 1,270.8 -55.9

2002 9.9 4.9 14.8 8.6 97.3 7.6 12.4 117.3 140.5 1,270.9 0.1

2003 -53.7 -25.6 -79.3 4.8 100.0 5.6 11.4 117.0 127.5 1,185.9 -85.0

2004 43.4 15.4 58.8 17.8 116.7 4.1 8.6 129.4 131.5 1,260.5 74.6

2005 -14.1 3.3 -10.8 24.8 137.2 5.1 6.7 149.0 125.3 1,298.1 37.7

2006 27.5 -26.2 1.3 18.6 146.9 2.5 8.4 157.9 128.9 1,346.9 48.8

2007 -22.1 67.1 45.0 16.1 163.8 4.8 9.2 177.7 132.1 1,453.6 106.7

aRevisions and adjustments = Col. 1 + Col. 2.

b

Total discoveries = Col. 5 + Col. 6 + Col. 7.

cProved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA–23, “Annual Survey of Domestic Oil and Gas Reserves” and Form EIA–64A, “Annual Report of the

Origin of Natural Gas Liquids Production.” The following conversion factors were used to convert data: barrels = 0.1589873 per cubic meter 

and cubic feet = 0.02831685 per cubic meter. Number of decimal digits varies in order to accurately reproduce corresponding equivalents

shown on Table 1 in Chapter 2.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1997–2007 annual reports, DOE/EIA–0216.{20–30}
Appendix D

Historical Reserves Statistics

EIA maintains a data archive of all published proved

reserves volumes at the State and National level.

Appendix D provides a series of tables of the proved

reserves and production of crude oil, natural gas,

and natural gas liquids for the U.S. and the lower 48

States for the years 1977 through 2007.

All historical statistics included have previously been

published in the annual reports of 1977 through 2006

of the EIA publication U.S. Crude Oil, Natural Gas,

and Natural Gas Liquids Reserves Annual Report,

DOE EIA-0216.{1-30}

Liquid volumes are in million barrels of 42 U.S.

gallons. Gas volumes are in billion cubic feet (Bcf), at

14.73 psia and 60° Fahrenheit. NA appears in this

appendix wherever data are not available or are

withheld to avoid disclosure of data which may be

proprietary. An asterisk (*) marks those estimates

associated with sampling errors (95 percent

confidence interval) greater than 20 percent of the

value estimated.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-1

Data Archive Link

http://www.eia.doe.gov/oil_gas/natural_gas/data_publications/crude_oil_natural_gas_reserves/cr.html

The Data Archive is listed in the "Special Files" section of the destination site.
Energy Information Administration

D-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table D1. U.S. Proved Reserves of Crude Oil, 1976–2007

(million barrels of 42 U.S. gallons)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1976 – – – – – – – – – e33,502 –

1977 f-40 386 346 NA 496 168 130 794 2,862 31,780 -1,722

1978 366 1,390 1,756 NA 444 267 116 827 3,008 31,355 -425

1979 337 437 774 NA 424 108 104 636 2,955 29,810 -1,545

1980 219 1,889 2,108 NA 572 143 147 862 2,975 29,805 -5

1981 138 1,271 1,409 NA 750 254 157 1,161 2,949 29,426 -379

1982 -83 434 351 NA 634 204 193 1,031 2,950 27,858 -1,568

1983 462 1,511 1,973 NA 629 105 190 924 3,020 27,735 -123

1984 159 2,445 2,604 NA 744 242 158 1,144 3,037 28,446 711

1985 429 1,598 2,027 NA 742 84 169 995 3,052 28,416 -30

1986 57 855 912 NA 405 48 81 534 2,973 26,889 -1,527

1987 233 2,316 2,549 NA 484 96 111 691 2,873 27,256 367

1988 364 1,463 1,827 NA 355 71 127 553 2,811 26,825 -431

1989 213 1,333 1,546 NA 514 112 90 716 2,586 26,501 -324

1990 86 1,483 1,569 NA 456 98 135 689 2,505 26,254 -247

1991 163 223 386 NA 365 97 92 554 2,512 24,682 -1,572

1992 290 735 1,025 NA 391 8 85 484 2,446 23,745 -937

1993 271 495 766 NA 356 319 110 785 2,339 22,957 -788

1994 189 1,007 1,196 NA 397 64 111 572 2,268 22,457 -500

1995 122 1,028 1,150 NA 500 114 343 957 2,213 22,351 -106

1996 175 737 912 NA 543 243 141 927 2,173 22,017 -334

1997 520 914 1,434 NA 477 637 119 1,233 2,138 22,546 529

1998 -638 518 -120 NA 327 152 120 599 1,991 21,034 -1,512

1999 139 1,819 1,958 NA 259 321 145 725 1,952 21,765 731

2000 143 746 889 -20 766 276 249 1,291 1,880 22,045 280

2001 -4 -158 -162 -87 866 1,407 292 2,565 1,915 22,446 401

2002 416 720 1,136 24 492 300 154 946 1,875 22,677 231

2003 163 94 257 -398 426 705 101 1,232 1,877 21,891 -786

2004 74 420 494 23 617 33 132 782 1,819 21,371 -520

2005 221 569 790 278 805 205 41 1,051 1,733 21,757 386

2006 94 2 96 194 504 30 43 577 1,652 20,972 -785

2007 65 1,200 1,265 -19 651 66 73 790 1,691 21,317 345

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves”. They may differ from the official Energy

Information Administration production data for crude oil contained in the Petroleum Supply Annual, DOE/EIA-0340.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1977 through 2007 annual reports, DOE/EIA-0216.{1-30}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-3

Table D2. U.S. Lower 48 Proved Reserves of Crude Oil, 1976–2007

(million barrels of 42 U.S. gallons)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1976 – – – – – – – – – e24,928 –

1977 f–40 383 343 NA 496 168 130 794 2,698 23,367 -1,561

1978 -48 509 461 NA 444 142 116 702 2,559 21,971 -1,396

1979 342 429 771 NA 424 108 104 636 2,443 20,935 -1,036

1980 210 1,524 1,734 NA 479 143 147 769 2,384 21,054 119

1981 276 1,009 1,285 NA 750 254 157 1,161 2,357 21,143 89

1982 -82 684 602 NA 633 204 193 1,030 2,323 20,452 -691

1983 462 949 1,411 NA 625 105 190 920 2,355 20,428 -24

1984 160 1,587 1,747 NA 742 207 158 1,107 2,399 20,883 455

1985 361 1,667 2,028 NA 581 84 169 834 2,385 21,360 477

1986 70 359 429 NA 399 48 81 528 2,303 20,014 -1,346

1987 233 1,353 1,586 NA 294 38 101 433 2,155 19,878 -136

1988 359 1,181 1,540 NA 340 43 127 510 2,062 19,866 -12

1989 214 1,113 1,327 NA 342 108 87 537 1,903 19,827 -39

1990 151 1,001 1,152 NA 371 98 135 604 1,853 19,730 -97

1991 164 50 214 NA 327 97 87 511 1,856 18,599 -1,131

1992 297 277 574 NA 279 8 84 371 1,821 17,723 -876

1993 250 198 448 NA 343 319 109 771 1,760 17,182 -541

1994 187 527 714 NA 316 64 111 491 1,697 16,690 -492

1995 117 756 873 NA 434 114 333 881 1,673 16,771 81

1996 172 728 900 NA 479 115 141 735 1,663 16,743 -28

1997 514 695 1,209 NA 459 520 119 1,098 1,665 17,385 642

1998 -639 315 -324 NA 299 56 120 475 1,554 15,982 -1,403

1999 138 1,669 1,807 NA 253 242 145 640 1,564 16,865 883

2000 144 622 766 132 540 276 157 973 1,552 17,184 319

2001 -5 -71 -76 -87 716 1,126 292 2,134 1,560 17,595 411

2002 414 567 981 24 467 300 146 913 1,514 17,999 404

2003 162 5 167 -398 391 705 101 1,197 1,520 17,445 -554

2004 75 373 448 23 506 33 74 613 1,485 17,044 -401

2005 223 467 690 278 749 205 41 995 1,421 17,586 542

2006 93 153 246 194 404 30 43 477 1,410 17,093 -493

2007 65 747 812 -26 611 21 73 705 1,430 17,154 61

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves”. They may differ from the official Energy

Information Administration production data for crude oil contained in the Petroleum Supply Annual, DOE/EIA-0340.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1977 through 2007 annual reports, DOE/EIA-0216.{1-30}
Energy Information Administration

D-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table D3. U.S. Proved Reserves of Dry Natural Gas, 1976–2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1976 – – – – – – – – – e213,278 –

1977 f–20 -1,605 -1,625 NA 8,129 3,173 3,301 14,603 18,843 207,413 -5,865

1978 2,429 -1,025 1,404 NA 9,582 3,860 4,579 18,021 18,805 208,033 620

1979 -2,264 -219 -2,483 NA 8,950 3,188 2,566 14,704 19,257 200,997 -7,036

1980 1,201 1,049 2,250 NA 9,357 2,539 2,577 14,473 18,699 199,021 -1,976

1981 1,627 2,599 4,226 NA 10,491 3,731 2,998 17,220 18,737 201,730 2,709

1982 2,378 455 2,833 NA 8,349 2,687 3,419 14,455 17,506 201,512 -218

1983 3,090 -15 3,075 NA 6,909 1,574 2,965 11,448 15,788 200,247 -1,265

1984 -2,241 3,129 888 NA 8,299 2,536 2,686 13,521 17,193 197,463 -2,784

1985 -1,708 2,471 763 NA 7,169 999 2,960 11,128 15,985 193,369 -4,094

1986 1,320 3,572 4,892 NA 6,065 1,099 1,771 8,935 15,610 191,586 -1,783

1987 1,268 3,296 4,564 NA 4,587 1,089 1,499 7,175 16,114 187,211 -4,375

1988 2,193 -15,060 -12,867 NA 6,803 1,638 1,909 10,350 16,670 168,024 -19,187

1989 3,013 3,030 6,043 NA 6,339 1,450 2,243 10,032 16,983 167,116 -908

1990 1,557 5,538 7,095 NA 7,952 2,004 2,412 12,368 17,233 169,346 2,230

1991 2,960 4,416 7,376 NA 5,090 848 1,604 7,542 17,202 167,062 -2,284

1992 2,235 6,093 8,328 NA 4,675 649 1,724 7,048 17,423 165,015 -2,047

1993 972 5,349 6,321 NA 6,103 899 1,866 8,868 17,789 162,415 -2,600

1994 1,945 5,484 7,429 NA 6,941 1,894 3,480 12,315 18,322 163,837 1,422

1995 580 7,734 8,314 NA 6,843 1,666 2,452 10,961 17,966 165,146 1,309

1996 3,785 4,086 7,871 NA 7,757 1,451 3,110 12,318 18,861 166,474 1,328

1997 -590 4,902 4,312 NA 10,585 2,681 2,382 15,648 19,211 167,223 749

1998 -1,635 5,740 4,105 NA 8,197 1,074 2,162 11,433 18,720 164,041 -3,182

1999 982 10,504 11,486 NA 7,043 1,568 2,196 10,807 18,928 167,406 3,365

2000 -891 6,962 6,071 4,031 14,787 1,983 2,368 19,138 19,219 177,427 10,021

2001 2,742 -2,318 424 2,630 16,380 3,578 2,800 22,758 19,779 183,460 6,033

2002 3,727 937 4,664 380 14,769 1,332 1,694 17,795 19,353 186,946 3,486

2003 2,841 -1,638 1,203 -10,092 16,454 1,222 1,610 19,286 19,425 189,044 2,098

2004 -114 744 630 1,844 18,198 759 1,206 20,163 19,168 192,513 3,469

2005 1,887 2,699 4,856 2,544 21,050 942 1,208 23,200 18,458 204,385 11,872

2006 743 -1,836 -1,093 2,996 21,778 409 1,155 23,342 18,545 211,085 6,700

2007 1147 15,461 16,608 408 27,107 796 1,188 23,342 19,466 237,726 26,641

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

g

An unusually large revision decrease to North Slope dry natural gas reserves was made in 1988. It recognizes some 24.6 trillion cubic

feet of downward revisions reported during the last few years by operators because of economic and market conditions. EIA in previous years

carried these reserves in the proved category.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” and Form EIA-64A, “Annual Report of the Origin

of Natural Gas Liquids Production”. They may differ from the official Energy Information Administration production data for natural gas

contained in the Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1977 through 2007 annual reports, DOE/EIA-0216.{1-30}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-5

Table D4. U.S. Lower 48 Proved Reserves of Dry Natural Gas, 1976–2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1976 – – – – – – – – – e180,838 –

1977 f–21 -1,540 -1,561 NA 8,056 3,173 3,301 14,530 18,637 175,170 -5,668

1978 2,446 -758 1,688 NA 9,582 3,860 4,277 17,719 18,589 175,988 818

1979 -2,202 -707 -2,909 NA 8,949 3,173 2,566 14,688 19,029 168,738 -7,250

1980 1,163 62 1,225 NA 9,046 2,539 2,577 14,162 18,486 165,639 -3,099

1981 1,840 2,506 4,346 NA 10,485 3,731 2,994 17,210 18,502 168,693 3,054

1982 2,367 -1,748 619 NA 8,349 2,687 3,419 14,455 17,245 166,522 -2,171

1983 3,089 421 3,510 NA 6,908 1,574 2,965 11,447 15,515 165,964 -558

1984 -2,245 2,617 372 NA 8,298 2,536 2,686 13,520 16,869 162,987 -2,977

1985 -1,349 2,500 1,151 NA 7,098 999 2,960 11,057 15,673 159,522 -3,465

1986 1,618 4,144 5,762 NA 6,064 1,099 1,761 8,924 15,286 158,922 -600

1987 1,066 2,645 3,711 NA 4,542 1,077 1,499 7,118 15,765 153,986 -4,936

1988 2,017 8,895 10,912 NA 6,771 1,638 1,909 10,318 16,270 158,946 4,960

1989 2,997 2,939 5,936 NA 6,184 1,450 2,243 9,877 16,582 158,177 -769

1990 1,877 4,572 6,449 NA 7,898 2,004 2,412 12,314 16,894 160,046 1,869

1991 2,967 3,860 6,827 NA 5,074 848 1,563 7,485 16,849 157,509 -2,537

1992 1,946 5,937 7,883 NA 4,621 649 1,724 6,994 17,009 155,377 -2,132

1993 915 4,779 5,694 NA 6,076 899 1,858 8,833 17,396 152,508 -2,869

1994 1,896 5,289 7,185 NA 6,936 1,894 3,480 12,310 17,899 154,104 1,596

1995 973 7,223 8,196 NA 6,801 1,666 2,452 10,919 17,570 155,649 1,545

1996 3,640 4,055 7,695 NA 7,751 1,390 3,110 12,251 18,415 157,180 1,531

1997 -609 3,192 2,583 NA 10,571 2,681 2,382 15,634 18,736 156,661 -519

1998 -1,463 5,696 4,233 NA 8,195 1,070 2,162 11,427 18,207 154,114 -2,547

1999 849 10,452 11,301 NA 7,041 1,512 2,173 10,726 18,469 157,672 3,558

2000 -914 8,755 7,841 4,214 12,838 1,983 2,355 17,176 18,713 168,190 10,518

2001 2,753 -2,216 537 2,630 16,321 3,504 2,796 21,621 19,318 174,660 6,470

2002 3,692 914 4,606 380 14,707 1,332 1,686 17,725 18,893 178,478 3,818

2003 2,840 -1,830 1,010 1,034 16,373 1,202 1,609 19,184 18,947 180,759 2,281

2004 -113 319 206 1,844 18,057 759 1,171 19,987 18,690 184,106 3,347

2005 1,889 2,560 4,449 2,542 20,988 920 1,198 23,106 17,989 196,214 12,108

2006 789 -4,313 -3,524 2,996 21,729 409 1,153 23,291 18,137 200,840 4,626

2007 1146 13,426 14,572 412 27,079 796 1,188 29,063 19,078 225,809 24,969

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” and Form EIA-64A, “Annual Report of the Origin

of Natural Gas Liquids Production”. They may differ from the official Energy Information Administration production data for natural gas

contained in the Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1977 through 2006 annual reports, DOE/EIA-0216.{1-30}
Energy Information Administration

D-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table D5. U.S. Proved Reserves of Wet Natural Gas, After Lease Separation, 1978–2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1978 – – – – – – – – – e208,033 –

1979 5,356 -223 5,133 NA 9,332 3,279 2,637 15,248 20,079 208,335 302

1980 1,253 1,137 2,390 NA 9,757 2,629 2,648 15,034 19,500 206,259 -2,076

1981 2,057 2,743 4,800 NA 10,979 3,870 3,080 17,929 19,554 209,434 3,175

1982 2,598 455 3,053 NA 8,754 2,785 3,520 15,059 18,292 209,254 -180

1983 4,363 57 4,420 NA 7,263 1,628 3,071 11,962 16,590 209,046 -208

1984 -2,413 3,333 920 NA 8,688 2,584 2,778 14,050 18,032 205,984 -3,062

1985 -1,299 2,687 1,388 NA 7,535 1,040 3,053 11,628 16,798 202,202 -3,782

1986 2,137 3,835 5,972 NA 6,359 1,122 1,855 9,336 16,401 201,109 -1,093

1987 1,199 3,522 4,721 NA 4,818 1,128 1,556 7,502 16,904 196,428 -4,681

1988 2,180 -14,931 f-12,751 NA 7,132 1,677 1,979 10,788 17,466 f176,999 –19,429

1989 2,537 3,220 5,757 NA 6,623 1,488 2,313 10,424 17,752 175,428 -1,571

1990 1,494 5,837 7,331 NA 8,287 2,041 2,492 12,820 18,003 177,576 2,148

1991 3,368 4,569 7,937 NA 5,298 871 1,655 7,824 18,012 175,325 -2,251

1992 2,543 6,374 8,917 NA 4,895 668 1,773 7,336 18,269 173,309 -2,016

1993 1,048 5,541 6,589 NA 6,376 927 1,930 9,233 18,641 170,490 -2,819

1994 1,977 5,836 7,813 NA 7,299 1,941 3,606 12,846 19,210 171,939 1,449

1995 889 8,091 8,980 NA 7,204 1,709 2,518 11,431 18,874 173,476 1,537

1996 4,288 4,277 8,565 NA 8,189 1,491 3,209 12,889 19,783 175,147 1,671

1997 -730 5,057 4,327 NA 11,179 2,747 2,455 16,381 20,134 175,721 574

1998 -1,624 5,982 4,358 NA 8,630 1,116 2,240 11,986 19,622 172,433 -3,288

1999 1,102 11,182 12,284 NA 7,401 1,622 2,265 11,288 19,856 176,159 3,726

2000 -1,295 7,456 6,161 4,286 15,550 2,055 2,463 20,068 20,164 186,510 10,351

2001 1,849 -2,438 -589 2,715 17,183 3,668 2,898 23,749 20,642 191,743 5,233

2002 4,004 1,038 5,042 428 15,468 1,374 1,752 18,594 20,248 195,561 3,816

2003 2,323 -1,715 608 1,107 17,195 1,252 1,653 20,100 20,231 197,145 1,584

2004 170 825 995 1,975 19,068 790 1,244 21,102 20,017 201,200 4,055

2005 1,693 2,715 4,408 2,674 22,069 973 1,243 24,285 19,259 213,308 12,108

2006 946 -2,099 -1,153 3,178 22,834 425 1,197 24,456 19,373 220,416 7,108

2007 990 15,936 16,926 452 28,255 814 12,744 41,813 20,318 247,789 27,373

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

An unusually large revision decrease to North Slope wet natural gas reserves was made in 1988. It recognizes some 25 trillion cubic feet

of downward revisions reported during the last few years by operators because of economic and market conditions. EIA in previous years

carried these reserves in the proved category.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves”. They may differ from the official Energy

Information Administration production data for natural gas contained in the Natural Gas Annual, DOE/EIA-013.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2007 annual reports, DOE/EIA-0216.{3-30}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-7

Table D6. U.S. Lower 48 Proved Reserves of Wet Natural Gas, After Lease Separation, 1978–2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1978 – – – – – – – – – e175,988 –

1979 5,402 -711 4,691 NA 9,331 3,264 2,637 15,232 19,851 176,060 72

1980 1,218 150 1,368 NA 9,446 2,629 2,648 14,723 19,287 172,864 -3,196

1981 2,270 2,650 4,920 NA 10,973 3,870 3,076 17,919 19,318 176,385 3,521

1982 2,586 -1,748 838 NA 8,754 2,785 3,520 15,059 18,030 174,252 -2,133

1983 4,366 493 4,859 NA 7,262 1,628 3,071 11,961 16,317 174,755 503

1984 -2,409 2,821 412 NA 8,687 2,584 2,778 14,049 17,708 171,508 -3,247

1985 -1,313 2,713 1,400 NA 7,463 1,040 3,053 11,556 16,485 167,979 -3,529

1986 2,114 4,410 6,524 NA 6,357 1,122 1,845 9,324 16,073 167,754 -225

1987 1,200 2,868 4,068 NA 4,772 1,116 1,556 7,444 16,553 162,713 -5,041

1988 2,025 9,390 11,415 NA 7,099 1,677 1,979 10,755 17,063 167,820 5,107

1989 2,545 3,128 5,673 NA 6,467 1,485 2,313 10,265 17,349 166,409 -1,411

1990 1,811 4,859 6,670 NA 8,232 2,041 2,492 12,765 17,661 168,183 1,774

1991 3,367 4,013 7,380 NA 5,281 871 1,614 7,766 17,657 165,672 -2,511

1992 2,265 6,217 8,482 NA 4,840 668 1,773 7,281 17,851 163,584 -2,088

1993 996 4,971 5,967 NA 6,349 927 1,922 9,198 18,245 160,504 -3,080

1994 1,924 5,613 7,537 NA 7,294 1,941 3,606 12,841 18,756 162,126 1,622

1995 1,304 7,525 8,829 NA 7,162 1,709 2,518 11,389 18,443 163,901 1,775

1996 4,219 4,246 8,465 NA 8,183 1,430 3,209 12,822 19,337 165,851 1,950

1997 -835 3,322 2,487 NA 11,165 2,747 2,455 16,367 19,657 165,048 -803

1998 -1,461 5,937 4,476 NA 8,628 1,112 2,240 11,980 19,104 162,400 -2,648

1999 958 11,130 12,088 NA 7,399 1,566 2,242 11,207 19,391 166,304 3,904

2000 -1,294 9,273 7,979 4,471 13,574 2,055 2,450 18,079 19,654 177,179 10,875

2001 1,849 -2,336 -487 2,715 17,123 3,593 2,894 23,610 20,175 182,842 5,663

2002 4,004 1,038 5,042 428 15,468 1,374 1,752 18,594 20,248 19,5561 3,816

2003 2,324 -1,909 415 1,107 17,114 1,232 1,652 19,998 19,751 188,797 1,769

2004 170 395 565 1,975 18,927 790 1,209 20,926 19,536 192,727 3,930

2005 1,694 2,575 4,269 2,672 22,007 951 1,233 24,191 18,788 205,071 12,344

2006 996 -4,603 -3,607 3,178 22,784 425 1,195 24,404 18,963 210,083 5,012

2007 988 13,881 14,869 457 28,227 814 1,244 30,285 19,927 235,767 25,684

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

– = Not applicable.

Notes: Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are

based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves”. They may differ from the official Energy

Information Administration production data for natural gas contained in the Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2007 annual reports, DOE/EIA-0216.{3-30}
Energy Information Administration

D-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table D7. U.S. Proved Reserves of Natural Gas Liquids, 1978–2007

(million barrels of 42 U.S. gallons)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1978 – – – – – – – – – e6,772 –

1979 f64 -49 15 NA 364 94 97 555 727 6,615 -157

1980 153 104 257 NA 418 90 79 587 731 6,728 113

1981 231 86 317 NA 542 131 91 764 741 7,068 340

1982 299 -21 278 NA 375 112 109 596 721 7,221 153

1983 849 66 915 NA 321 70 99 490 725 7,901 680

1984 -123 142 19 NA 348 55 96 499 776 7,643 -258

1985 426 162 588 NA 337 44 85 466 753 7,944 301

1986 367 223 590 NA 263 34 72 369 738 8,165 221

1987 231 191 422 NA 213 39 55 307 747 8,147 -18

1988 11 453 464 NA 268 41 72 381 754 8,238 91

1989 -277 123 -154 NA 259 83 74 416 731 7,769 -469

1990 -83 221 138 NA 299 39 73 411 732 7,586 -183

1991 233 130 363 NA 189 25 55 269 754 7,464 -122

1992 225 261 486 NA 190 20 64 274 773 7,451 -13

1993 102 124 226 NA 245 24 64 333 788 7,222 -229

1994 43 197 240 NA 314 54 131 499 791 7,170 -52

1995 192 277 469 NA 432 52 67 551 791 7,399 229

1996 474 175 649 NA 451 65 109 625 850 7,823 424

1997 -14 289 275 NA 535 114 90 739 864 7,973 150

1998 -361 208 -153 NA 383 66 88 537 833 7,524 -449

1999 99 727 826 NA 313 51 88 452 896 7,906 382

2000 -83 459 376 145 645 92 102 839 921 8,345 439

2001 -429 -132 -561 102 717 138 142 997 890 7,993 -352

2002 62 31 93 54 612 48 78 738 884 7,994 1

2003 -338 -161 -499 30 629 35 72 736 802 7,459 -535

2004 273 97 370 112 734 26 54 814 827 7,928 469

2005 -89 21 -68 156 863 32 42 937 788 8,165 237

2006 173 -165 8 117 924 16 53 993 811 8,472 307

2007 -139 422 283 101 1,030 30 58 1,118 831 9,143 671

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

– = Not applicable.

Notes: Natural Gas Liquids volumes in this table are a sum of lease condensate and natural gas plant liquids for the year referenced.

Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are based on data

reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” and Form EIA-64A, “Annual Report of the Origin of Natural

Gas Liquids Production”. They may differ from the official Energy Information Administration production data for natural gas liquids contained

in the publications Petroleum Supply Annual, DOE/EIA-0340 and Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2007 annual reports, DOE/EIA-0216.{3-30}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-9

Table D8. U.S. Lower 48 Proved Reserves of Natural Gas Liquids, 1978–2007

(million barrels of 42 U.S. gallons)

Revisionsb Net of Sales New Reservoir Provedd Change

Net and and New Field Discoveries Totalc Estimated Reserves from

Adjustmentsa Revisions Adjustments Acquisitions Extensions Discoveries in Old Fields Discoveries Production 12/31 Prior Year

Year (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

1978 – – – – – – – – – e6,749 –

1979 f63 -49 14 NA 364 94 97 555 726 6,592 -157

1980 165 104 269 NA 418 90 79 587 731 6,717 125

1981 233 85 318 NA 542 131 91 764 741 7,058 341

1982 300 -21 279 NA 375 112 109 596 721 7,212 154

1983 850 66 916 NA 321 70 99 490 725 7,893 681

1984 -115 123 8 NA 348 55 96 499 776 7,624 -269

1985 70 152 222 NA 334 44 85 463 748 7,561 -63

1986 363 226 589 NA 263 34 72 369 735 7,784 223

1987 179 191 370 NA 212 39 55 306 731 7,729 -55

1988 10 452 462 NA 267 41 72 380 734 7,837 108

1989 -273 123 -150 NA 259 83 74 416 714 7,389 -448

1990 -60 221 161 NA 298 39 73 410 714 7,246 -143

1991 183 138 321 NA 187 25 55 267 730 7,104 -142

1992 225 254 479 NA 183 20 64 267 746 7,104 0

1993 101 124 225 NA 245 24 64 333 761 6,901 -203

1994 38 196 234 NA 314 54 131 499 765 6,869 -32

1995 204 230 434 NA 432 52 67 551 761 7,093 224

1996 417 178 595 NA 450 56 109 615 817 7,486 393

1997 -107 55 -52 NA 533 114 90 737 829 7,342 -144

1998 -74 208 134 NA 383 66 88 537 809 7,204 -138

1999 102 617 719 NA 304 50 86 440 848 7,515 311

2000 9 459 468 145 645 92 102 839 899 8,068 553

2001 -429 -280 -709 -102 717 138 142 997 870 7,588 -480

2002 42 31 73 54 612 48 78 738 864 7,589 1

2003 -338 -161 -499 30 629 35 72 736 784 7,072 -517

2004 273 97 370 112 734 26 54 814 809 7,559 487

2005 -89 21 -68 156 863 32 42 937 771 7,813 254

2006 173 -165 8 117 924 16 53 993 797 8,134 321

2007 -139 422 283 101 1,030 30 58 1,118 818 8,818 684

aIncludes operator reported corrections for the years 1978 through 1981. After 1981 operators included corrections with revisions.

b

Revisions and adjustments = Col. 1 + Col. 2. c

Total discoveries = Col. 5 + Col. 6 + Col. 7.

d

Proved reserves = Col. 10 from prior year + Col. 3 + Col. 4 + Col. 8 - Col. 9. e

Based on following year data only.

f

Consists only of operator reported corrections and no other adjustments.

– = Not applicable.

Notes: Natural Gas Liquids volumes in this table are a sum of lease condensate and natural gas plant liquids for the year referenced.

Old means discovered in a prior year. New means discovered during the report year. The production estimates in this table are based on data

reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” and Form EIA-64A, “Annual Report of the Origin of Natural

Gas Liquids Production”. They may differ from the official Energy Information Administration production data for natural gas liquids contained

in the publications Petroleum Supply Annual, DOE/EIA-0340 and Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2007 annual reports, DOE/EIA-0216.{3-30}
Energy Information Administration

D-10 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Ta ble D9. Deep water Pro duc tion and Proved Re serves of the Gulf of Mex ico Fed eral Off shore, 1992-2007

Gulf of Mexico Depth

Greater than Less than Deep water

Year To tal Lou i si anaaTexas 200 me ters 200 me ters Per cent age

Crude Oil (mil lion bar rels of 42 U.S. gal lons)

Pro duc tion

1992 267 253 14 46 221 17.2

1993 266 252 14 46 220 17.3

1994 265 245 20 53 212 20.1

1995 292 262 30 77 215 26.4

1996 303 265 38 90 213 29.7

1997 342 298 44 123 219 36.0

1998 372 336 36 171 201 46.0

1999 421 376 45 228 193 54.2

2000 419 381 38 234 185 55.8

2001 459 417 42 286 173 62.2

2002 451 395 57 288 163 63.9

2003 485 426 59 336 149 69.3

2004 467 404 63 310 157 66.4

2005 409 342 67 305 104 75.0

2006 406 348 58 318 87 78.5

2007 414 372 42 313 101 75.6

Re serves

1992 1,835 1,643 192 557 1,278 30.4

1993 2,072 1,880 192 824 1,248 39.8

1994 2,127 1,922 205 877 1,250 41.2

1995 2,518 2,269 249 1,241 1,277 49.3

1996 2,567 2,357 210 1,311 1,256 51.1

1997 2,949 2,587 362 1,682 1,267 57.0

1998 2,793 2,483 310 1,611 1,182 57.8

1999 2,744 2,442 302 1,626 1,118 59.3

2000 3,174 2,751 423 2,021 1,153 63.7

2001 4,288 3,877 411 3,208 1,080 74.8

2002 4,444 4,088 356 3,372 1,072 75.9

2003 4,554 4,251 303 3,627 927 79.6

2004 4,144 3,919 225 3,280 864 79.2

2005 4,042 3,851 191 3,272 770 81.0

2006 3,655 3,500 155 2,983 672 81.6

2007 3,464 3,320 144 2,836 628 81.9
Ta ble D9. Deep water Pro duc tion and Proved Re serves of the Gulf of Mex ico Fed eral Off shore, 1992-2007

(con tin ued)

Gulf of Mexico Depth

Greater than Less than Deep water

Year To tal Lou i si anaaTexas 200 me ters 200 me ters Per cent age

Nat u ral Gas, Wet Af ter Lease Sep a ra tion

(bil lion cu bic feet at 14.73 psia and 60° Fahr en heit)

Pro duc tion

1992 4,576 3,292 1,284 166 4,410 3.6

1993 4,651 3,383 1,268 229 4,422 4.9

1994 4,797 3,505 1,292 294 4,503 6.1

1995 4,679 3,421 1,258 354 4,315 7.8

1996 5,045 3,752 1,293 549 4,496 10.9

1997 5,230 3,984 1,246 577 4,653 11.0

1998 4,967 3,817 1,150 724 4,243 14.6

1999 5,000 3,829 1,171 1,124 3,876 22.5

2000 4,901 3,747 1,154 1,196 3,705 24.4

2001 5,027 3,843 1,184 1,367 3,660 27.2

2002 4,544 3,541 1,003 1,365 3,180 30.0

2003 4,397 3,330 1,067 1,545 2,852 35.1

2004 3,967 2,890 1,077 1,251 2,716 31.5

2005 2,968 2,056 912 1,070 1,898 36.1

2006 2,805 2,036 769 1,112 1,692 39.6

2007 2,762 2,135 627 1,050 1,712 38.0

Re serves

1992 27,050 20,006 7,044 3,273 23,777 12.1

1993 26,463 19,751 6,712 3,495 22,968 13.2

1994 27,626 21,208 6,418 4,772 22,854 17.3

1995 28,229 21,664 6,565 5,811 22,418 20.6

1996 28,153 22,119 6,034 6,389 21,764 22.7

1997 28,455 22,428 6,027 7,491 20,964 26.3

1998 26,937 21,261 5,676 7,575 19,362 28.1

1999 26,062 20,172 5,890 7,726 18,336 29.6

2000 26,891 20,466 6,425 8,731 18,160 32.5

2001 27,100 20,290 6,810 11,229 15,871 41.4

2002 25,347 19,113 6,234 10,540 14,807 41.6

2003 22,522 17,168 5,354 10,041 12,481 44.6

2004 19,288 15,144 4,144 8,591 10,698 44.5

2005 17,427 14,073 3,354 8,042 9,385 46.1

2006 14,938 12,201 2,737 6,690 8,248 44.8

2007 14,008 11,458 2,550 6,550 7,458 46.8

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-11
Energy Information Administration

D-12 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Ta ble D9. Deep water Pro duc tion and Proved Re serves of the Gulf of Mex ico Fed eral Off shore, 1992-2007

(con tin ued)

Gulf of Mexico Depth

Greater than Less than Deep water

Year To tal Lou i si anaaTexas 200 me ters 200 me ters Per cent age

Nat u ral Gas Liq uids (mil lion bar rels of 42 U.S. gal lons)

Pro duc tion

1992 91 76 15 4 87 4.4

1993 97 80 17 6 91 6.2

1994 98 83 15 6 92 6.1

1995 85 71 14 12 73 14.1

1996 101 84 17 13 88 12.9

1997 140 123 17 17 123 12.1

1998 139 120 19 26 113 18.7

1999 167 136 31 51 116 30.5

2000 199 164 35 84 115 42.2

2001 192 147 45 96 96 50.0

2002 184 149 35 66 118 36.0

2003 148 120 28 55 93 37.2

2004 155 127 28 51 104 32.9

2005 123 98 25 44 79 35.8

2006 125 102 23 50 75 39.6

2007 127 108 19 48 79 37.8

Re serves

1992 590 472 118 91 499 15.4

1993 605 490 115 97 508 16.0

1994 603 500 103 110 493 18.2

1995 630 496 134 294 336 46.7

1996 753 621 132 300 456 39.8

1997 906 785 121 349 557 38.5

1998 919 776 143 387 532 42.1

1999 994 833 161 411 583 41.3

2000 1,074 921 153 468 606 43.6

2001 967 785 182 443 524 45.8

2002 965 783 182 407 558 42.2

2003 717 598 119 262 455 36.5

2004 713 615 98 292 421 32.9

2005 688 603 85 248 440 36.0

2006 649 575 74 291 358 44.8

2007 620 528 92 290 330 46.8
Ta ble D9. Deep water Pro duc tion and Proved Re serves of the Gulf of Mex ico Fed eral Off shore, 1992-2007

(con tin ued)

Gulf of Mexico Depth

Greater than Less than Deep water

Year To tal Lou i si anaaTexas 200 me ters 200 me ters Per cent age

Dry Nat u ral Gas (bil lion cu bic feet at 14.73 psia and 60° Fahr en heit)

Pro duc tion

1992 4,508 3,233 1,275 162 4,346 3.6

1993 4,577 3,319 1,258 224 4,353 4.9

1994 4,725 3,440 1,285 288 4,437 6.1

1995 4,627 3,376 1,251 361 4,266 7.8

1996 4,991 3,706 1,285 544 4,447 10.9

1997 5,133 3,895 1,238 565 4,568 11.0

1998 4,872 3,728 1,144 711 4,161 14.6

1999 4,885 3,721 1,164 1,099 3,786 22.5

2000 4,773 3,626 1,147 1,165 3,608 24.4

2001 4,913 3,735 1,178 1,334 3,578 27.4

2002 4,423 3,427 996 1,328 3,095 30.0

2003 4,306 3,244 1,062 1,513 2,793 35.1

2004 3,874 2,802 1,072 1,222 2,652 31.5

2005 2,906 1,997 909 1,069 1,837 36.8

2006 2,738 1,973 765 1,086 1,652 39.6

2007 2,691 2,066 625 1,024 1,667 38.1

Re serves

1992 26,649 19,653 6,996 3,225 23,424 12.1

1993 26,044 19,383 6,661 3,438 22,606 13.2

1994 27,218 20,835 6,383 4,709 22,509 17.3

1995 27,917 21,392 6,525 5,751 22,166 20.6

1996 27,852 21,856 5,996 6,322 21,530 22.7

1997 27,922 21,934 5,988 7,343 20,579 26.3

1998 26,422 20,774 5,648 7,425 18,997 28.1

1999 25,451 19,598 5,853 7,533 17,918 29.6

2000 26,172 19,788 6,384 8,506 17,666 32.5

2001 26,456 19,721 6,735 10,943 15,513 41.4

2002 24,689 18,500 6,189 10,266 14,423 41.6

2003 22,059 16,728 5,331 9,835 12,224 44.6

2004 18,812 14,685 4,127 8,379 10,433 44.5

2005 17,007 13,665 3,342 8,043 8,964 47.3

2006 14,549 11,824 2,725 6,516 8,033 44.8

2007 13,634 11,090 2,544 6,382 7,252 46.8

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report D-13
Energy Information Administration

D-14 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Ta ble D9. Deep water Pro duc tion and Proved Re serves of the Gulf of Mex ico Fed eral Off shore, 1992-2007

(con tin ued)

Gulf of Mexico Depth

Greater than Less than Deep water

Year To tal Lou i si anaaTexas 200 me ters 200 me ters Per cent age

Lease Con den sate (mil lion bar rels of 42 U.S. gal lons)

Pro duc tion

1992 44 35 9 2 42 4.4

1993 46 35 11 3 43 6.2

1994 47 37 10 3 44 6.1

1995 49 40 9 7 42 14.1

1996 60 49 11 8 52 12.9

1997 70 59 11 8 62 12.1

1998 72 57 15 13 59 18.7

1999 87 61 26 27 60 30.5

2000 106 76 30 45 61 42.2

2001 101 60 41 51 50 50.2

2002 90 60 30 38 52 42.2

2003 78 53 25 30 48 38.5

2004 74 49 25 27 47 36.2

2005 62 39 23 26 36 41.9

2006 58 37 21 23 35 40.1

2007 58 40 18 22 36 37.9

Re serves

1992 310 226 84 48 262 15.4

1993 316 235 81 51 265 16.0

1994 311 233 78 57 254 18.2

1995 412 305 107 192 220 46.7

1996 527 422 105 210 317 39.8

1997 527 433 94 203 324 38.5

1998 557 435 122 234 323 42.1

1999 567 430 137 234 333 41.3

2000 560 433 127 244 316 43.6

2001 482 325 157 221 261 45.8

2002 454 300 154 195 259 43.0

2003 353 251 102 135 218 38.2

2004 290 205 85 103 187 35.6

2005 272 196 76 104 168 38.2

2006 249 185 64 90 159 36.2

2007 251 163 88 111 140 44.2

a

Includes Fed eral Off shore Al a bama.

Source: Based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Re serves.”
Ta ble D10. 2007 Re ported Proved Nonproducing Re serves of Crude Oil, Lease Con den sate, and

Wet Nat u ral Gas, After Lease Separationa

Lease Nonassociated As so ci ated To tal

Crude Oil Con den sate Gas Dis solved Gas Gas

State and Sub di vi sion (mil lion bbls) (mil lion bbls) (bcf) (bcf) (bcf)

Alaska .................................. 400 0 21 317 338 

Lower 48 States ........................... 5,055 559 6,869 70,887 77,756 

Al a bama................................. 0 1 0 225 225 

Ar kan sas ................................ 0 0 2 1,045 1,047 

Cal i for nia ................................ 335 0 466 175 641 

Coastal Re gion On shore.................. 42 0 14 0 14 

Los An geles Ba sin On shore ............... 98 0 16 0 16 

San Joaquin Ba sin On shore ............... 168 0 426 173 599 

State Off shore.......................... 27 0 10 2 12 

Col o rado ................................ 122 53 969 8,177 9,146 

Florida .................................. 12 0 98 0 98 

Kan sas.................................. 9 0 2 148 150 

Ken tucky ................................ 0 0 0 232 232 

Lou i si ana ................................ 193 41 363 3,976 4,339 

North ................................. 11 10 22 2,549 2,571 

South On shore ......................... 164 29 311 1,324 1,635 

State Off shore.......................... 18 2 30 103 133 

Mich i gan ................................ 2 1 12 674 686 

Mis sis sippi ............................... 35 1 6 200 206 

Montana................................. 90 0 23 128 151 

New Mex ico .............................. 147 11 294 3,682 3,976 

East.................................. 147 10 287 612 899 

West ................................. 0 1 7 3,070 3,077 

New York ................................ 0 0 0 49 49 

North Da kota ............................. 107 1 60 12 72 

Ohio .................................... 8 0 3 125 128 

Oklahoma ............................... 118 54 154 5,926 6,080 

Penn syl va nia ............................. 0 0 5 709 714 

Texas ................................... 1,186 140 1,998 24,549 26,547 

RRC Dis trict 1 .......................... 27 2 19 361 380 

RRC Dis trict 2 On shore .................. 16 4 57 770 827 

RRC Dis trict 3 On shore .................. 22 14 92 717 809 

RRC Dis trict 4 On shore .................. 2 30 38 2,751 2,789 

RRC Dis trict 5 .......................... 1 0 17 8,024 8,041 

RRC Dis trict 6 .......................... 18 44 6 4,139 4,145 

RRC Dis trict 7B......................... 1 1 0 807 807 

RRC Dis trict 7C ........................ 137 7 515 1,250 1,765 

RRC Dis trict 8 .......................... 454 4 674 1,514 2,188 

RRC Dis trict 8A......................... 484 0 441 4 445 

RRC Dis trict 9 .......................... 12 9 13 2,289 2,302 

RRC Dis trict 10 ......................... 12 23 126 1,850 1,976 

State Off shore.......................... 0 2 0 73 73 

Utah .................................... 174 28 167 2,272 2,439 

Vir ginia.................................. 0 0 0 894 894 

West Vir ginia ............................. 0 0 0 1,010 1,010 

Wy o ming ................................ 208 105 67 11,533 11,600 

Fed eral Off shoreb......................... 2,304 123 2,180 5,081 7,261 

Pa cific (Cal i for nia)....................... 20 4 43 48 91 

Gulf of Mex ico (Lou i si ana)b............... 2,231 85 1,970 4,139 6,109 

Gulf of Mex ico (Texas) ................... 53 34 167 894 1,061 

Mis cel la neousc........................... 5 0 0 65 65 

U.S. To tal ................................ 5,455 559 6,890 71,204 78,094 

aIn cludes only those op er a tors who pro duced dur ing the re port year 400,000 bar rels of crude oil or 2 billion cu bic feet of wet nat u ral gas,

or more (Cat e gory I and Cat e gory II op er a tors).

bIn cludes Fed eral off shore Al a bama.

c

In cludes Ar i zona, Mary land, Mis souri, Ne vada, Or e gon, South Da kota and Ten nes see.

Source: Form EIA-23, "An nual Sur vey of Do mes tic Oil and Gas Re serves," 2007.

Energy Information Administration D-15

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Energy Information Administration

D-16 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table D11. Coalbed Natural Gas Proved Reserves and Production for 1989–2007

(billion cubic feet at 14.73 psia and 60° Fahrenheit)

New Eastern Western United

Year Alabama Colorado Mexico Utah Wyoming Virginia Statesa Statesb Othersc States

Reserves

1989 537 1,117 2,022 NA NA NA NA NA 0 3,676

1990 1,224 1,320 2,510 NA NA NA NA NA 33 5,087

1991 1,714 2,076 4,206 NA NA NA NA NA 167 8,163

1992 1,968 2,716 4,724 NA NA NA NA NA 626 10,034

1993 1,237 3,107 4,775 NA NA NA NA NA 1,065 10,184

1994 976 2,913 4,137 NA NA NA NA NA 1,686 9,712

1995 972 3,461 4,299 NA NA NA NA NA 1,767 10,499

1996 823 3,711 4,180 NA NA NA NA NA 1,852 10,566

1997 1,077 3,890 4,351 NA NA NA NA NA 2,144 11,462

1998 1,029 4,211 4,232 NA NA NA NA NA 2,707 12,179

1999 1,060 4,826 4,080 NA NA NA NA NA 3,263 13,229

2000 1,241 5,617 4,278 1,592 1,540 NA 1,399 41 -- 15,708

2001 1,162 6,252 4,324 1,685 2,297 NA 1,453 358 -- 17,531

2002 1,283 6,691 4,380 1,725 2,371 NA 1,488 553 -- 18,491

2003 1,665 6,473 4,396 1,224 2,759 NA 1,528 698 -- 18,743

2004 1,900 5,787 5,166 934 2,085 NA 1,620 898 -- 18,390

2005 1,773 6,772 5,249 902 2,446 NA 1,822 928 -- 19,892

2006 2,068 6,344 4,894 750 2,448 1,813 273 1,030 -- 19,620

2007 2,126 7,870 4,171 922 2,734 1,948 392 1,705 -- 21,868

Production

1989 23 12 56 NA NA NA NA NA 0 91

1990 36 26 133 NA NA NA NA NA 1 196

1991 68 48 229 NA NA NA NA NA 3 348

1992 89 82 358 NA NA NA NA NA 10 539

1993 103 125 486 NA NA NA NA NA 18 752

1994 108 179 530 NA NA NA NA NA 34 851

1995 109 226 574 NA NA NA NA NA 47 956

1996 98 274 575 NA NA NA NA NA 56 1,003

1997 111 312 597 NA NA NA NA NA 70 1,090

1998 123 401 571 NA NA NA NA NA 99 1,194

1999 108 432 582 NA NA NA NA NA 130 1,252

2000 109 451 550 74 133 NA 58 NA -- 1,379

2001 111 490 517 83 278 NA 69 NA -- 1,562

2002 117 520 471 103 302 NA 68 NA -- 1,614

2003 98 488 451 97 344 NA 71 NA -- 1,600

2004 121 520 528 82 320 NA 72 NA -- 1,720

2005 113 515 514 75 336 NA 90 NA -- 1,732

2006 114 477 510 66 378 81 24 108 -- 1,758

2007 114 521 391 75 399 84 31 127 -- 1,742

aIncludes Illinois, Indiana, Ohio, Pennsylvania, Virginia, and West Virginia. In 2006 and 2007, Virginia is individually listed.

bIncludes Arkansas, Kansas, Louisiana, Montana, and Oklahoma.

c

Includes Oklahoma, Pennsylvania, Utah, Virginia, West Virginia, and Wyoming. These states are individually listed or grouped in Eastern

States and Western States for 2000-2007.

NA -- Not applicable.

Source: Energy Information Administration, Office of Oil and Gas.
Appendix E

Summary of Data Collection Operations

Form EIA-23 Survey Design

The data collected on Form EIA-23, “Annual Survey of

Domestic Oil and Gas Reserves,” were used to produce

this report. This section provides information

concerning the survey design, response statistics,

reporting requirements, and frame maintenance.

Form EIA-23 is mailed annually to all known large and

intermediate size operators, and a scientifically

selected sample of small operators. Operator size

categories were based upon their annual production as

indicated in various Federal, State, and commercial

records. The term State/subdivision refers to an

individual subdivision within a State or an individual

State that is not subdivided. Operators were divided

into the three size categories shown below.

Category I - Large Operators: Operators who

produced 1.5 million barrels or more of crude oil,

or 15 billion cubic feet or more of natural gas, or

both.

Category II - Intermediate Operators: Operators

who produced at least 400,000 barrels of crude

oil or 2 billion cubic feet of natural gas, or both,

but less than Category I operators.

Category III - Small Operators: Operators who

produced less than the Category II operators.

Category III operators were further subdivided into

operators sampled with Certainty (Certainty) and

operators that were randomly sampled

(Noncertainty).

Data were filed for calendar year 2007 by crude oil or

natural gas well operators who were active as of

December 31, 2007. EIA defines an operator as an

organization or person responsible for the

management and day-to-day operation of crude oil or

natural gas wells. The purpose of this definition is to

eliminate responses from royalty owners, working

interest owners (unless they are also operators), and

others not directly responsible for operations. An

operator need not be a separately incorporated entity.

To minimize reporting burden, corporations are

permitted to report on the basis of operating units of

the company convenient for them. A large corporation

may be represented by a single form or by several

forms.

Table E1 shows a comparison of the EIA-23 sample and

sampling frame between 2000 and 2007, and depicts

the number of active operators, with 2002 showing the

largest in the series. The 2007 sampling frame consisted

of 158 Category I, 510 Category II, 292 Category III

Certainty, and 12,814 Category III Noncertainty

operators, for a total of 13,774 active operators. The

survey sample consisted of 960 operators selected with

certainty that included all of the Category I and II

Certainty operators, the 292 smaller operators that

were selected with certainty because of their size in

relation to the area or areas in which they operated, and

478 Noncertainty operators selected as a systematic

random sample of the remaining operators.

Form EIA-23

Response Statistics

Each company and its parent company or subsidiaries

were required to file Form EIA-23 if they met the

survey specifications. Response to the 2007 survey is

summarized in Table E2. EIA makes a considerable

effort to gain responses from all operators. About 4

percent of those selected turned out to be nonoperators

(those that reported being nonoperators during the

report year and operators that could not be located). Of

the 75 nonoperators, 17 had successor operators that

had taken over the production of the nonoperator.

These successor operators were subsequently sampled.

The overall response rate for the 2007 survey was 96

percent. For the 59 operators that did not respond,

production data were obtained from State or other

sources.

Form EIA-23 Reporting

Requirements

The collection format for Form EIA-23 actually consists

of two forms. The form the respondent is required to

file is dependent upon the annual production levels of

crude oil, natural gas, and lease condensate. Category I

and Category II operators file a more detailed field

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report E-1
level data form. Category III operators file a summary

report which is aggregated at a State/subdivision level.

The cover page required of all respondents identifies

each operator by name and address (Figure I1,

Appendix I). The oil and gas producing industry

includes a large number of small enterprises. To

minimize reporting burden, only a sample of small

operators were required to file a summary report of

Form EIA-23 (Figures I2 and I3, Appendix I). Report

year production data were required by

State/subdivision areas for crude oil, natural gas, and

lease condensate. Proved reserves data for operators

were required only for those properties where

estimates existed in the respondent’s records.

All Category I and Category II operators were required

to file field level data on Schedule A, “Operated Proved

Reserves, Production, and Related Data by Field,” for

each oil and/or gas field in which the respondent

operated properties (Figure I4, Appendix I). All

Category I and those Category II operators who had

reserve estimates were required to file on a total

operated basis for crude oil, nonassociated natural gas,

associated-dissolved natural gas, and lease condensate.

The following data items were required to be filed:

proved reserves at the beginning and the end of the

report year, revision increases and revision decreases,

sales and acquisitions, extensions, new field

discoveries, new reservoirs in old fields, production,

prospect name, reservoir type, nonproducing reserves,

Energy Information Administration

E-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table E1. Comparison of the EIA-23 Sample and Sampling Frame, 2000-2007

Number of Operators

Operator Category 2000 2001 2002 2003 2004 2005 2006 2007

Certainty

Category I. . . . . . . . . . . . . 175 179 176 164 164 172 173 158

Category II . . . . . . . . . . . . 436 485 480 512 532 522 467 510

Category III. . . . . . . . . . . . 854 559 388 399 275 195 232 292

Sampled ............. 1,465 1,223 1,044 1,075 971 889 872 960

Percent Sampled . . . . . . . 100 100 100 100 100 100 100 100

Noncertainty

Sampled .............. 1,311 644 533 479 370 505 483 478

Percent Sampled ....... 7 3 3 3 2 4 4 4

Total

Active Operators........ 22,102 22,519 22,823 20,923 20,670 15,158 13,820 13,774

Not Sampled .......... 19,326 20,652 21,246 19,369 19,329 13,764 12,465 12,336

Sampled .............. 2,776 1,867 1,577 1,554 1,341 1,394 1,355 1,438

Percent Sampled . . . . . . . 13 8 7 7 7 9 10 10

Source: Energy Information Administration, Office of Oil and Gas.

Table E2. Form EIA-23 Survey Response Statistics, 2007

Original Netb Responding Nonrespondinge

Sample Successora Category Non-c Adjustedd Operators Operators

Operator Category Selected Operators Changes operators Sample Number Percent Number Percent

Certainty

Category I . . . . . . . 158 1 0 -3 156 156 100.0 0 0.0

Category II . . . . . . . 510 14 -11 -16 497 497 100.0 0 0.0

Category III . . . . . . . 292 2 15 -21 288 268 93.1 20 6.9

Subtotal. . . . . . . . . 960 17 4 -40 941 921 97.9 20 2.1

Noncertainty . . . . . . . . 478 0 -4 -35 439 427 97.3 39 8.9

Total ............ 1,438 17 0 -75 1,380 1,348 97.7 59 4.3

a

Successor operators are those, not initially sampled, that have taken over the production of a sampled operator.

b

Net of recategorized operators in the sample (excluding nonoperators).

c

Includes former operators reporting that they were not operators during the report year and operators that could not be located who are treated as nonoperators. d

Adjusted sample equals original sample plus successor operators plus net category changes minus nonoperators.

e

For the 59 operators (20 Category III operators and 39 Noncertainty operators) that did not respond, production data were obtained from State or other sources.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves” 2007.
field discovery year, water depth, and field location

information.

Category II operators who did not have reserves

estimates were required to file the field location

information and report year production for the four

hydrocarbon types from properties where reserves

were not estimated. These respondents used Schedule

B, “Footnotes,” to provide clarification of reported data

items when required in the instructions, or electively to

provide narrative or detail to explain any data item

filed (Figure I5, Appendix I).

Crude oil and lease condensate volumes were reported

rounded to thousands of barrels of 42 U.S. gallons at

60Fahrenheit, and natural gas volumes were reported

rounded to millions of cubic feet. All natural gas

volumes were requested to be reported at 60

Fahrenheit and a pressure base of 14.73 pounds per

square inch absolute. Other minor report preparation

standards were specified to assure that the filed data

could be readily processed.

Oil and Gas Field Coding

A major effort to create standardized codes for all

identified oil or gas fields throughout the United States

was implemented during the 1982 survey year.

Information from previous lists was reviewed and

reconciled with State lists and a consolidated list was

created. The publication of the Oil and Gas Field Code

Master List 2007, in January 2008, was the 26th annual

report and reflected data collected through December

2007. This list was made available to operators to assist

in identifying the field code data necessary for the

preparation of Form EIA-23.

Form EIA-23 Comparison with

Other Data Series

Estimated crude oil, lease condensate, and natural gas

production volumes from Form EIA-23 were compared

with official EIA production data supplied by Federal

and State oil and natural gas regulatory agencies and

published in EIA’s monthly and annual reports.

Reports published by the Federal and State oil and

natural gas regulatory agencies were used to compare

specific operator production responses to these

agencies with Form EIA-23 responses. When

significant differences were found, responses were

researched to detect and reconcile possible reporting

errors.

For 2007, Form EIA-23 National estimates of

production were 1,872 million barrels for crude oil and

lease condensate or 24 million barrels (1.3 percent)

higher than that reported in the Petroleum Supply

Annual 2007 for crude oil and lease condensate (1,848

million barrels). Form EIA-23 National estimates of

production for dry natural gas were 19,465 billion cubic

feet, 187 billion cubic feet (almost 1 percent) higher

than the Natural Gas Monthly, October 2008 for 2007 dry

natural gas production (19,278 billion cubic feet).

Form EIA-23

Frame Maintenance

Operator frame maintenance is a major data quality

control effort. Extensive effort is expended to keep the

frame as current as possible. The Form EIA-23 frame

contains a listing of all crude oil and natural gas well

operators in the United States and must be maintained

and updated regularly in order to ensure an accurate

frame from which to draw the sample for the annual

crude oil and natural gas reserves survey. The original

frame, created in 1977, is revised annually. In addition,

outside sources, such as State publications and

electronic data, and commercial information data bases

such as HPDI, LLC., are used to obtain information on

operator status and to update addresses for the frame

each year.

A maintenance procedure is utilized in conjunction

with State production records and commercial

information data bases to update possible crude oil and

natural gas well operators presently listed on EIA’s

master frame and add new operators to the master

frame. This procedure identifies active operators and

nonoperators which improves the frame for future

sample selections for the annual survey. Table E3

provides a summary of changes made to the Form

EIA-23 frame of crude oil and natural gas well

operators for the 2007 survey mailing. These changes

resulted from all frame maintenance activities.

The Form EIA-23 operator frame contained a total of

68,616 entries as of December 31, 2007. Of these, 14,043

were confirmed operators. These are operators who

have filed in the past or for whom the EIA has recent

production data from an outside source. The remaining

operators (including both definite and probable

nonoperators) exist as a pool of names and addresses

that may be added to the active list if review indicates

activity.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report E-3
Form EIA-64A Survey Design

The data for this report are also collected on Form

EIA-64A, “Annual Report of the Origin of Natural Gas

Liquids Production.” This section provides

information concerning the survey design, response

statistics, reporting requirements, and frame

maintenance for Form EIA-64A.

Form EIA-23 for report years 1977 and 1978 required

natural gas well operators to report their natural gas

data on a fully dry basis. It was discovered in the course

of those surveys that many operators had little or no

knowledge of the extraction of liquids from their

produced natural gas streams once custody transfer

had taken place. Therefore, these operators reverted to

reporting the only natural gas volume data they had in

their possession. These volume data were for dryer

natural gas than that which had passed through the

wellhead, but wetter than fully dry natural gas. With

reference to Figure E1, they reported their volumes

either at the wellhead or after removal of lease

condensate in their lease or field separation facilities.

Some of the larger operators, however, also owned or

operated natural gas processing plants. They reported

their volumes after removal of both lease condensate

and plant liquids, as required by Form EIA-23. The

aggregate volumes resulting from the 1977 and 1978

surveys, therefore, were neither fully dry (as was

intended) nor fully wet. They do appear to have been

more dry than wet simply because the operators who

reported fully dry volumes also operated properties

that contained the bulk of proved natural gas reserves.

The EIA recognized that its estimates of proved

reserves of natural gas liquids (NGL) had to reflect not

only those volumes extractable in the future under

current economic and operating conditions at the lease

or field (lease condensate), but also volumes (plant

liquids) extractable downstream at existing natural gas

processing plants. Form EIA-64, which already

canvassed these processing plants, did not request that

the plants’ production volumes be attributed to source

areas. Beginning with the 1979 survey, a new form to

collect plant liquids production according to the area or

areas where their input natural gas stream had been

produced was mailed to all of the operating plants. The

instructions for filing the Form EIA-23 were altered to

collect data from natural gas well operators that

reflected those volumes of natural gas dried only

through the lease or field separation facilities. The

reporting basis of these volumes are referred to as “wet

after lease separation.” The methodology used to

estimate NGL reserves by State and State subdivision is

provided in Appendix F.

Form EIA-64A

Response Statistics

EIA mailed EIA-64A forms to all known natural gas

processing plant operators as of February 1, 2007. In

addition, plant operators whose plants were shut down

or dismantled during 2007 were required to complete

forms for the portion of 2007 when the plants were in

operation.

Natural gas processing plant operators were requested

to file a Form EIA-64A for each of their plants. A total of

214 operators of 496 plants were sent forms. This

number included 5 new plants, 3 reactivated plants,

and 2 successor plants, all identified after the initial

2007 survey mailing. A total of 11 plants were reported

as nonoperating according to the Form EIA-64A

definition. For the 20th consecutive year the response

rate was 100 percent.

Form EIA-64A respondents were requested to report

natural gas liquids production data by area of origin.

Table E4 summarizes the responses by plant operators

Energy Information Administration

E-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table E3. Summary of the 2007 Operator Frame

Activity, Form EIA-23

Total 2006 Operator Frame ............. 68,616

Operators ....................... 13,774

Nonoperators .................... 54,842

Changes to 2007 Operator Status . . . . . . 365

From Nonoperator to Operatora

. . . . . . 294

From Operator to Nonoperator . . . . . . 71

Recycles Old Operator ID's ......... -336

New Operators. . . . . . . . . . . . . . . . . . . 336

No Changes to 2007 Operator Status . . . 68,251

Operators ....................... 13,749

Nonoperators .................... 54,502

Total 2007 Operator Frame ............ 68,616

Operators ....................... 13,997

Nonoperators .................... 54,619

Note: Includes operator frame activity through December 31, 2007.

a

No additions were made since EIA ID numbers are now being

recycled when no useable data are available with a specific EIA ID

number. This procedure will increase the number of Nonoperator to

Operator changes more than usual.

Source: Energy Information Administration, Office of Oil and Gas.
of the volume and origin of natural gas delivered to the

processing plants and the volume of the natural gas

liquids extracted by the plants by State. The majority of

the plant operators reported only one area of origin for

the natural gas that was processed by a plant. The State

or area of origin reported is generally also the plant’s

location.

Form EIA-64A

Reporting Requirements

Form EIA-64A consisted of the reporting schedule

shown in Figure I6, Appendix I. The form identifies the

plant, its geographic location, the plant operator’s

name and address, and the parent company name. The

certification was signed by a responsible official of the

operating entity. The form pertains to the volume of

natural gas received and of natural gas liquids

produced at the plant, allocated to each area of origin.

Operators also filed the data pertaining to the amount

of natural gas shrinkage that resulted from extraction

of natural gas liquids at the plant, and the amount of

fuel used in processing.

Natural gas liquids volumes were reported rounded to

thousands of barrels of 42 U.S. gallons at 60

Fahrenheit, and natural gas volumes were reported

rounded to millions of cubic feet. All natural gas

volumes were requested to be reported at 60

Fahrenheit and a pressure base of 14.73 pounds per

square inch absolute. Other minor report preparation

standards were specified to assure that the filed data

could be readily processed.

Form EIA-64A Comparison

with Other Data Series

Form EIA-64A plant liquids production data were

compared with data collected on Form EIA-816,

“Monthly Natural Gas Liquids Report.” Aggregated

production from Form EIA-816 represents the net

volume of natural gas processing plant liquid output

less input for the report year. These data are published

in EIA’s Petroleum Supply Annual reports. The Form

EIA-64A annual responses reflect all corrections and

revisions to EIA’s monthly estimates. Differences,

when found, were reconciled in both sources. For 2007,

the Form EIA-64A National estimates (Table E4) were

1.2 percent (7,497 thousand barrels) higher than the

Petroleum Supply Annual 2007 volume of 650,794

thousand barrels for natural gas plant liquids

production.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report E-5

Figure E1. Natural Gas Liquids Extraction Flows

Source: Energy Information Administration, Office of Oil and Gas.
Form EIA-64A

Frame Maintenance

The Form EIA-64A plant frame contains data on all

known active and inactive natural gas processing

plants in the United States. The 2007 plant frame was

compared to listings of natural gas processing plants

from Form EIA-816, “Monthly Natural Gas Liquids

Report”; the LPG Almanac; and the Oil and Gas Journal.

A list of possible additions to the plant frame was

compiled. Table E5 summarizes the Form EIA-64A

plant frame changes made as a result of the

comparisons as of March 1, 2008.

Energy Information Administration

E-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table E5. Form EIA-64A 2007 Plant Frame Activity

Frame as of 2006 survey mailing . . . . . . . 491

Additions. . . . . . . . . . . . . . . . . . . . 99

Deletions . . . . . . . . . . . . . . . . . . . –94

Frame as of 2007 survey mailing . . . . . . . 496

Note: Includes operator frame activity through March 1, 2008.

Source: Energy Information Administration, Office of Oil and Gas.

Table E4. Natural Gas Processed and Liquids Extracted at Natural Gas Processing Plants, 2007

Volume of Natural Gas Delivered to Processing Plants

State Federal Out of State Natural Gas Total Liquids

Plant Location Production Production Production Processed Extracted

(million cubic feet) (thousand barrels)

Alaska .................. 2,965,956 0 0 2,965,956 22,419

Alabama ................ 36,238 221,205 0 257,443 13,381

Arkansas ................ 11,532 0 0 11,532 126

California ................ 206,125 114 0 206,239 11,388

Colorado ................ 888,081 0 624 888,705 27,447

Florida .................. 1,269 0 1,153 2,422 103

Kansas ................. 318,567 0 72,455 391,022 19,600

Kentucky ................ 38,158 0 0 38,158 1,455

Louisiana ................ 1,045,012 1,812,431 0 2,857,443 77,905

Michigan ................ 29,436 0 0 29,436 2,547

Mississippi ............... 5,096 219,500 0 224,596 9,133

Montana................. 13,646 0 0 13,646 1,168

North Dakota ............. 69,653 0 0 69,653 5,647

New Mexico. . . . . . . . . . . . . . 811,312 0 0 811,312 66,007

Oklahoma ............... 953,871 0 10,838 964,709 66,458

Texas ................... 4,146,194 0 41,164 4,187,358 273,082

Utah. . . . . . . . . . . . . . . . . . . . 193,027 0 2,674 195,701 2,241

West Virginia ............. 102,625 0 30,797 133,422 6,009

Wyoming ................ 1,381,987 0 17,583 1,399,570 51,488

Miscellanousa ............ 15,058 0 0 15,058 687

Total . . . . . . . . . . . . . . . . . . . 13,232,843 2,253,250 177,288 15,663,381 658,291

aIncludes Illinois, Ohio, and Pennsylvania.

Source: Form EIA-64A, “Annual Report of the Origin of Natural Gas Liquids Production,” 2007
Appendix F

Statistical Considerations

Sampling Plan

The goal was a sample that would provide estimates of

reserves and production of crude oil, natural gas, and

lease condensate for the United States. A stratified

sample using a single stage and systematic selection

with probability proportional to size was designed.

The measure of size was the volume of production for

crude oil, natural gas, and lease condensate by State by

company in 2006. There were two strata: companies

selected with certainty and companies selected under

the systematic probability proportional to size design.

Operators of crude oil and natural gas wells were

selected as the appropriate respondent population

because they have access to the most current and

detailed information, and therefore, presumably have

better reserve estimates than do other possible classes

of respondents, such as working interest or royalty

owners. EIA conducts extensive frame maintenance

activities each year to identify all current operators of

crude oil and natural gas wells in the country. While

large operators are quite well known, they comprise

only a small portion of all operators. The small

operators are not well known and are difficult to

identify because they go into and out of business, alter

their corporate identities, and change addresses

frequently.

Sample Design

To meet survey objectives, while minimizing

respondent burden, a sampling strategy has been used

since 1977. EIA publishes data on reserves and

production for crude oil, natural gas, and lease

condensate by State for most States, and by subdivision

for the States of California, Louisiana, New Mexico,

and Texas.The total volume of production varies

among the State/subdivisions. To meet the survey

objectives while controlling total respondent burden,

EIA selected the following target sampling error for the

2007 survey for each product class.

Each operator is asked to report production and

reserves for crude oil, natural gas, and lease condensate

for each State/subdivision in which he operates. The

term State/subdivision refers to an individual

subdivision within a State or an individual State that is

not subdivided.

EIA selected the following target sampling error for the

2006 survey for each product class.

1.0 percent for National estimates and for each

of the States having subdivisions: Alaska,

California, Louisiana, New Mexico, and Texas.

2.5 percent for each State having 1 percent or

more of estimated lower 48 States reserves or

production in 2006 for any product class.

4 percent for each State/subdivision having less

than 1 percent of estimated U.S. reserves or

production in 2006 (lower 48 States) for all 3

product class.

8 percent for States not published separately.

Certainty Stratum

There are three components to the certainty stratum

Category I, Category II, and certain Category III Small

Operators.

Category I - Large Operators: Operators who

produced a total of 1.5 million barrels or more of

crude, or 15 billion cubic feet or more of natural

gas, or both in 2006.

Category II - Intermediate Operators: Operators

who produced a total of at least 400,000 barrels

of crude oil or 2 billion cubic feet of natural gas,

or both, but less than Category I operators in

2006, and additionally, all coalbed methane and

Federal Offshore operators.

Category III - Small Operators: Operators who

produced less than the Category II operators in

2006.

Small operators were further subdivided into certainty

and noncertainty strata. Small operators who satisfied

any of the following criteria based upon their

production shown in the operator frame are certainty

operators:

All other operators with production or reserves

in a State/subdivision that exceed selected

cutoff levels.

The largest operator in each State/subdivision

regardless of level of production or reserves.

Operators with production or reserves of oil or

gas for six or more State/subdivisions.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-1
Ta ble F1. 2007 EIA–23 Ini tial Num ber of Oper a tors in Sur vey Sam ple 

Num ber of Num ber of Num ber of

Cer tainty Multi–State Noncertainty Tar get Er ror

State and Sub di vi sion Op er a tors Op er a tors Op er a tors Oil Gas

Al a bama On shore 36 1 10 0.040 0.025

Alaska 8 0 0

Ar kan sas 62 9 15 0.040 0.025

Cal i for nia - Coastal Re gion On shore 15 1 2 0.080 0.080

Cal i for nia - Los An geles Ba sin On shore 17 5 2 0.010 0.010

Cal i for nia - San Joaquin Ba sin On shore 41 3 5 0.025 0.040

Col o rado 116 3 24 0.025 0.010

Florida 4 0 0 0.025 0.025

Il li nois 33 29 24 0.040 0.040

In di ana 35 18 22 0.040 0.080

Kan sas 163 86 70 0.040 0.080

Ken tucky 40 21 13 0.025 0.010

Lou i si ana-North 114 18 31 0.040 0.040

Lou i si ana-South On shore 200 25 30 0.010 0.010

Mich i gan 34 5 6 0.010 0.010

Mis sis sippi 77 2 15 0.040 0.040

Montana 65 1 9 0.040 0.040

Ne braska 16 1 12 0.040 0.040

New Mex ico - East 150 5 36 0.040 0.080

New Mex ico - West 53 8 6 0.025 0.025

New York 16 4 4 0.025 0.010

North Da kota 64 0 6 0.080 0.040

Ohio 27 37 8 0.040 0.040

Oklahoma 258 66 105 0.040 0.040

Penn syl va nia 42 10 7 0.025 0.025

Texas - RRC Dis trict 1 128 5 37 0.040 0.040

Texas - RRC Dis trict 2 On shore 192 3 39 0.025 0.025

Texas - RRC Dis trict 3 On shore 248 4 49 0.040 0.025

Texas - RRC Dis trict 4 On shore 202 7 33 0.025 0.025

Texas - RRC Dis trict 5 105 4 22 0.040 0.010

Texas - RRC Dis trict 6 173 7 43 0.040 0.010

Texas - RRC Dis trict 7B 148 30 91 0.025 0.010

Texas - RRC Dis trict 7C 161 5 54 0.025 0.025

Texas - RRC Dis trict 8 190 1 47 0.040 0.025

Texas - RRC Dis trict 8A 170 0 53 0.010 0.010

Texas - RRC Dis trict 9 149 25 84 0.010 0.040

Texas - RRC Dis trict 10 142 32 45 0.025 0.025

Utah 54 0 6 0.040 0.010

Vir ginia 20 0 0 0.040 0.025

West Vir ginia 32 15 5 0.080 0.040

Wy o ming 148 10 16 0.040 0.025

Off shore Ar eas 334 0 2 0.025 0.025

Other Statesa50 5 1 0.080 0.080

To tal

b

964 511

b

404 0.010 0.010

a

In cludes Ar i zona, Idaho, Iowa, Mary land, Mis souri, Ne vada, Or e gon, South Da kota, Ten nes see, and Wash ing ton.

bNon du pli ca tive count of op era tors by States.

Note: Sam pling rate was 10 per cent ex cept in Alaska, Flor ida On shore, Vir ginia, and Off shore ar eas where sam pling rate was 100

per cent.

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

F-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Noncertainty Stratum

Small operators not in the certainty stratum were

classified in the noncertainty stratum. They were

systematically sampled with probability proportional

to size. Only the operators in the following 6 states

were included in the noncertainty sample: Illinois,

Indiana, Kentucky, Pennsylvania, Tennessee, and West

Virginia. All other States were treated as certainty

stratum.

-In each State/subdivision the balance between the

number of operators and the sample size was

determined in an iterative procedure designed to

minimize the number of total respondents. The

iteration for each State/subdivision began with only

the Category I and Category II operators in the

certainty stratum. The size of the sample of small

operators required to meet the target variance was

calculated based on the variance of the volumes of

those operators. For a number of State/subdivisions

with high correlations between frame values across

pairs of consecutive years, an adjusted target variance

was calculated, that utilized the information about the

correlations. This allowed the selection of a smaller

sample that still met the target sampling error criteria.

Independent samples of single location operators

(operators who, according to the sampling frame,

operate in only one State/subdivision) were selected

from each State/subdivision using systematic random

sampling.

State/subdivision volume estimates are calculated as

the sum of the certainty strata and all of the estimates

for the sampling strata in that region. The sampling

variance of the estimated total is the sum of the

sampling variances for the sampling strata. There is no

sampling error associated with the certainty stratum.

The square root of the sampling variance is the

standard error. It can be used to provide confidence

intervals for the State/subdivision totals.

For the States in which subdivision volume estimates

are published, the State total is the sum of the

individual volume estimates for the subdivisions. The

U.S. total is the sum of the State estimates. A sampling

variance is calculated for each State/subdivision and

for the U.S. Total. Table F1 shows sampling rates.

Total U.S. Reserve Estimates

Conceptually, the estimates of U.S. reserves and

production can be thought of as the sum of the

estimates for the individual States. Correspondingly,

the estimates for the four States for which estimates are

published separately by subdivision (California,

Louisiana, New Mexico, and Texas) can be thought of

as the sum of the estimates by subdivision. The

remaining States are not subdivided and may be

considered as a single subdivision.

The estimates of year-end proved reserves and annual

production for any State/subdivision is the sum of the

volumes in the State/subdivision reported by the

certainty stratum operators and an estimate of the total

volume in the State/subdivision by the noncertainty

stratum operators. The total volume of certainty

operators in the State/subdivision is simply the sum of

individual operator's volumes. The estimated total

volume of noncertainty operators in the

State/subdivision is the weighted sum of the reports of

the noncertainty sample operators.

In many State/subdivisions, the accuracy of the oil and

gas estimates was improved by using the probability

proportional to size procedure. This procedure took

advantage of the correlation between year-to-year

production reports. The weights used for estimating

the oil production were different from the weights used

for estimating the gas production.

The weight used for the estimation is the reciprocal of

the probability of selection for the stratum from which

the sample operator was selected. In making estimates

for a State/ subdivision, separate weights are applied

as appropriate for noncertainty operators shown in the

frame as having had production in only the

State/subdivision, for those shown as having had

production in that State/subdivision and up to four

other State/ subdivisions, and for operators with no

previous record of production in the

State/subdivision. National totals were then obtained

by summation of the component totals.

Imputation and Estimation for

Reserves Data

There were 439 operators sampled proportional to size

(Table E2) that responded as Category III noncertainty

operators. Only 50 of these, located in 6 states, had their

data weighted and used to estimate the production and

reserves of the operators that were not sampled in

those states. The remaining 389 noncertainty sampled

operators were treated as certainty sampled operators

with a weight of 1 and were used in states where the

bulk of the operator production data was obtained

from auxiliary State data (Table F2-F5).

The data reported by operator category on Form

EIA-23 and data imputed and estimated for report year

2007 are summarized in Tables F2, F3, F4, and F5. The

reported data in Table F2 shows that those responding

operators accounted for 93.7 percent of the published

production for wet natural gas and 95.7 percent of the

reserves shown in Table 9. Data shown in Table F3

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-3
indicate that those responding operators accounted for

94.5 percent of the nonassociated natural gas

production and 95.6 percent of the reserves published

in Table 10. The reported data shown in Table F4

indicate that those responding operators accounted for

79.5 percent of published crude oil production and 93.8

percent of the reserves shown in Table 6. Additionally,

Table F5 indicates that those responding operators

accounted for 92.3 percent of the published production

and 84.8 percent of the published proved reserves for

lease condensate shown in Table 15.

In order to estimate reserve balances for National and

State/subdivision levels, a series of imputation and

estimation steps at the operator level must be carried

out.

Year-end reserves for operators who provided

production data only were imputed on the basis

of their production volumes.

Imputation was also applied to the small and

intermediate operators as necessary to provide

data on each of the reserve balance categories

(i.e., revisions, extensions, or new discoveries).

Imputation was required for the natural gas

data of the small operators to estimate their

volumes of associated-dissolved and

nonassociated natural gas.

Adjustments to maintain reserves balance.

Methods used are discussed in the following sections.

Imputation of Year-End Proved Reserves

Category I operators were required to submit year-end

estimates of proved reserves. Category II and Category

III operators were required to provide year-end

estimates of proved reserves only if such estimates

existed in their records. Some of these respondents

provided estimates for all of their operated properties,

others provided estimates for only a portion of their

properties, and still others provided no estimates for

any of their properties. All respondents did, however,

provide annual production data.

A year-end proved reserves estimate was imputed

from reported production data in each case where an

estimate was not provided by the respondent. A R/P

function was derived and used to calculate a

reserves-to-production (R/P) ratio, based on operator

size and the geographic region where the operator's

properties were located. The R/P function has the

following functional form for each geographic region:

Calculated P/[P+R] = Beta * EXP(Alpha * ln (1 + MOS))

Alpha, Beta = Regional Coefficients (calculated)

MOS = Measure of size for a respondent, which

is equal to the barrel oil equivalent volume of

a respondent’s 2006 production.

Table F6 lists the coefficients used for each region and

the number of observations on which it was based. The

regional areas used are similar to the National

Petroleum Council Regions (Figure F1). These regions

generally follow the boundaries of geologic provinces

wherein the stage of resource development tends to be

somewhat similar.

Once the R/P ratio was obtained for an operator, it

could be multiplied by the reported or estimated

production to give a proved reserves estimate.

Operators that had production plus end of year

reserves equal to zero were excluded from the

respondents selected to calculate the R/P coefficients.

Rather than rely on a weighted sample, the R/P

function was used to estimate the proved reserves of all

noncertainty operators in these States. This technique

improved the correlation of EIA data with State and

commercial production data, and reduced the burden

of reporting and analysis on both EIA and the

noncertainty operators in these States.

Imputation of Changes to Proved

Reserves by Component of Change

Category II and Category III operators that do not keep

reserves data were not asked to provide estimates of

beginning-of-year reserves or annual changes to

proved reserves by component of change, i.e.,

revisions, extensions, and discoveries. When they did

not provide estimates, these volumes were estimated

by either:

applying an algebraic allocation scheme which

preserved the relative relationships between

these items within each State/subdivision, as

reported by Category I and Category II

operators, or

applying a modified version of the R/P

function to each separate component of change,

calculated with its own set of geographically

dependent coefficients. This method was used

in all four states where the R/P Function was

applied to calculate end of year reserves.

Energy Information Administration

F-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-5

Table F2. Summary of Form EIA-23 Reported, Imputed, and Estimated Natural Gas Data for 2007,

Wet after Lease Separation (million cubic feet at 14.73 psia and 60o Fahrenheit)

Operator Category

Certainty Noncertainty Auxillary

Level of Reporting I II III III State Data Total

Reported

Number of Operators . . . . . . . . . . . . . . . 156 497 288 439 9,324 10,704

Proved Reserves as of 12/31/06 ...... 192,939,286 17,390,372 275,120 0 0 210,604,778

(+) Revision Increases ............ 27,892,861 4,242,700 22,252 0 0 32,157,813

(-) Revision Decreases ............ 13,574,786 2,927,766 19,440 0 0 16,521,992

(-) Sales ....................... 13,084,210 2,226,057 201,468 0 0 15,511,735

(+) Acquisitions .................. 9,867,217 6,059,406 16,780 0 0 15,943,403

(+) Extensions................... 22,660,941 4,352,000 60,283 0 0 27,073,224

(+) New Field Discoveries.......... 589,968 211,047 0 0 0 801,015

(+) New Reservoirs in Old Fields .... 941,482 252,811 0 0 0 1,194,293

(-) Production With

Proved Reserves Reported ..... 16,671,585 2,047,865 4,062 0 0 18,723,512

(-) Production Without

Proved Reserves Reported ..... 0 249,676 3,797 0 0 253,473

Proved Reserves as of 12/31/07 ...... 211,561,394 25,320,441 149,465 0 0 237,031,300

Imputed and Estimated

Number of Operators ............... - - - 3,070 - 3,070

Proved Reserves as of 12/31/06 ...... - - - - - -

(+) Revision Increases ............ 0 0 0 0 1,247,943 1,247,943

(-) Revision Decreases ............ 0 0 0 0 945,370 945,370

(-) Sales ....................... 0 0 0 0 0 0

(+) Acquisitions .................. 0 0 0 0 28,542 28,542

(+) Extensions................... 0 0 0 0 1,182,840 1,182,840

(+) New Field Discoveries.......... 0 0 0 0 15,450 15,450

(+) New Reservoirs in Old Fields .... 0 0 0 0 51,906 51,906

(-) Production With

Proved Reserves Reported ..... 0 0 0 0 88,184 88,184

(-) Production Without

Proved Reserves Reported ..... 0 157,392 123,941 281,333 690,920 1,253,586

Proved Reserves as of 12/31/07 ...... 0 1,642,214 1,079,609 2,721,823 5,319,393 10,763,039

Total

Number of Operators . . . . . . . . . . . . . . . 156 497 288 3,509 9,324 13,774

Proved Reserves as of 12/31/06 ...... 192,939,286 17,390,372 275,120 0 0 210,604,778

(+) Revision Increases ............ 27,892,861 4,242,700 22,252 0 1,247,943 33,405,756

(-) Revision Decreases ............ 13,574,786 2,927,766 19,440 0 945,370 17,467,362

(-) Sales ....................... 13,084,210 2,226,057 201,468 0 0 15,511,735

(+) Acquisitions .................. 9,867,217 6,059,406 16,780 0 28,542 15,971,945

(+) Extensions................... 22,660,941 4,352,000 60,283 0 1,182,840 28,256,064

(+) New Field Discoveries.......... 589,968 211,047 0 0 15,450 816,465

(+) New Reservoirs in Old Fields .... 941,482 252,811 0 0 51,906 1,246,199

(-) Production With

Proved Reserves Reported ..... 16,671,585 2,047,865 4,062 0 88,184 18,811,696

(-) Production Without

Proved Reserves Reported ..... 0 407,068 127,738 281,333 690,920 1,507,059

Proved Reserves as of 12/31/07 ...... 211,561,394 26,962,655 1,229,074 2,721,823 5,319,393 247,794,339

Summary

Total Number of Operators . . . . . . . . . 156 497 288 3,509 9,324 13,774

Percent of Total................ 1.1% 3.6% 2.1% 25.5% 67.7% 100.0%

Total Production in 2007 ........... 16,671,585 2,454,933 131,800 281,333 779,104 20,318,755

Percent of Total................ 82.1% 12.1% 0.6% 1.4% 3.8% 100.0%

Total Proved Reserves 12/31/07 ..... 211,561,394 26,962,655 1,229,074 2,721,823 5,319,393 247,794,339

Percent of Total................ 85.4% 10.9% 0.5% 1.1% 2.1% 100.0%

a

There were 439 noncertainty responses, 50 were used with their sample weights and 389 were treated as Certainty III operators.

– = Not applicable.

Notes: Table 9 totals include imputed and estimated wet natural gas proved reserves rounded at the State/subdivision level. Field level data

are reported volumes and may not balance due to submission of incomplete reserve component records.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.
Energy Information Administration

F-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table F3. Summary of Form EIA-23 Reported, Imputed, and Estimated Nonassociated Natural Gas Data

for 2007, Wet after Lease Separation (million cubic feet at 14.73 psia and 60o Fahrenheit)

Operator Category

Certainty Noncertainty Auxillary

Level of Reporting I II III III State Data Total

Reported

Number of Operators . . . . . . . . . . . . . . . 156 497 288 439 9,324 10,704

Proved Reserves as of 12/31/06 ...... 166,185,699 15,722,876 228,829 0 0 182,137,404

(+) Revision Increases ............ 23,291,549 3,669,234 15,646 0 0 26,976,429

(-) Revision Decreases ............ 12,258,754 2,710,398 12,994 0 0 14,982,146

(-) Sales ....................... 12,064,119 2,132,407 201,468 0 0 14,397,994

(+) Acquisitions .................. 9,037,696 5,541,141 12,706 0 0 14,591,543

(+) Extensions................... 21,809,567 4,184,924 59,418 0 0 26,053,909

(+) New Field Discoveries.......... 548,812 205,006 0 0 0 753,818

(+) New Reservoirs in Old Fields .... 875,444 246,155 0 0 0 1,121,599

(-) Production With

Proved Reserves Reported ..... 14,800,167 1,837,184 3,293 0 0 16,640,644

(-) Production Without

Proved Reserves Reported . . . . . 17 385,015 7,643 0 0 392,675

Proved Reserves as of 12/31/07 ...... 182,625,749 22,902,263 98,844 0 0 205,626,856

Imputed and Estimated

Number of Operators ............... - - - 3,070 - 3,070

Proved Reserves as of 12/31/06 ...... - - - - - -

(+) Revision Increases ............ 0 0 0 0 1,028,107 1,028,107

(-) Revision Decreases ............ 0 0 0 0 683,341 683,341

(-) Sales ....................... 0 0 0 0 0 0

(+) Acquisitions .................. 0 0 0 0 28,542 28,542

(+) Extensions................... 0 0 0 0 1,105,078 1,105,078

(+) New Field Discoveries.......... 0 0 0 0 15,075 15,075

(+) New Reservoirs in Old Fields .... 0 0 0 0 50,585 50,585

(-) Production With

Proved Reserves Reported ..... 0 0 0 0 81,611 81,611

(-) Production Without

Proved Reserves Reported ..... 0 151,681 114,007 265,688 375,469 906,845

Proved Reserves as of 12/31/07 ...... 0 1,586,236 990,703 2,576,939 4,342,044 9,495,922

Total

Number of Operators . . . . . . . . . . . . . . . 156 497 288 3,509 9,324 13,774

Proved Reserves as of 12/31/06 ...... 166,185,699 15,722,876 228,829 0 0 182,137,404

(+) Revision Increases ............ 23,291,549 3,669,234 15,646 0 1,028,107 28,004,536

(-) Revision Decreases ............ 12,258,754 2,710,398 12,994 0 683,341 15,665,487

(-) Sales ....................... 12,064,119 2,132,407 201,468 0 0 14,397,994

(+) Acquisitions .................. 9,037,696 5,541,141 12,706 0 28,542 14,620,085

(+) Extensions................... 21,809,567 4,184,924 59,418 0 1,105,078 27,158,987

(+) New Field Discoveries.......... 548,812 205,006 0 0 15,075 768,893

(+) New Reservoirs in Old Fields .... 875,444 246,155 0 0 50,585 1,172,184

(-) Production With

Proved Reserves Reported ..... 14,800,167 1,837,184 3,293 0 81,611 16,722,255

(-) Production Without

Proved Reserves Reported . . . . . 17 536,696 121,650 265,688 375,469 1,299,520

Proved Reserves as of 12/31/07 ...... 182,625,749 24,488,499 1,089,547 2,576,939 4,342,044 215,122,778

Summary

Total Number of Operators . . . . . . . . . 156 497 288 3,509 9,324 13,774

Percent of Total................ 1.1% 3.6% 2.1% 25.5% 67.7% 100.0%

Total Production in 2007 ........... 14,800,184 2,373,880 124,943 265,688 457,080 18,021,775

Percent of Total................ 82.1% 13.2% 0.7% 1.5% 2.5% 100.0%

Total Proved Reserves 12/31/07 ..... 182,625,749 24,488,499 1,089,547 2,576,939 4,342,044 215,122,778

Percent of Total................ 84.9% 11.4% 0.5% 1.2% 2.0% 100.0%

a

There were 439 noncertainty responses, 50 were used with their sample weights and 389 were treated as Certainty III operators.

– = Not applicable.

Notes: Table 10 totals include imputed and estimated nonassociated wet natural gas proved reserves rounded at the State/subdivision level.

Field level data are reported volumes and may not balance due to submission of incomplete reserve component records.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-7

Table F4. Summary of Form EIA-23 Reported, Imputed, and Estimated Crude Oil Data for 2007,

(thousand barrels of 42 U.S. gallons)

Operator Category

Certainty Noncertainty Auxillary

Level of Reporting I II III III State Data Total

Reported

Number of Operators . . . . . . . . . . . . . . . 156 497 288 439 9,324 10,704

Proved Reserves as of 12/31/06 ...... 18,191,093 1,436,722 9,468 0 0 19,637,283

(+) Revision Increases ............ 1,902,879 218,892 2,831 0 0 2,124,602

(-) Revision Decreases ............ 876,019 127,187 2,947 0 0 1,006,153

(-) Sales ....................... 725,908 83,677 0 0 0 809,585

(+) Acquisitions .................. 469,951 318,256 6,370 0 0 794,577

(+) Extensions................... 558,787 52,974 366 0 0 612,127

(+) New Field Discoveries.......... 65,440 1,594 0 0 0 67,034

(+) New Reservoirs in Old Fields .... 61,864 10,465 0 0 0 72,329

(-) Production With

Proved Reserves Reported ..... 1,360,438 126,833 753 0 0 1,488,024

(-) Production Without

Proved Reserves Reported ..... 7 14,592 444 0 0 15,043

Proved Reserves as of 12/31/07 ...... 18,287,661 1,701,490 15,335 0 0 20,004,486

Imputed and Estimated

Number of Operators ............... - - - 3,070 - 3,070

Proved Reserves as of 12/31/06 ...... - - - - - -

(+) Revision Increases ............ 0 0 0 0 152,032 152,032

(-) Revision Decreases ............ 0 0 0 0 72,065 72,065

(-) Sales ....................... 0 0 0 0 0 0

(+) Acquisitions .................. 0 0 0 0 0 0

(+) Extensions................... 0 0 0 0 43,635 43,635

(+) New Field Discoveries. . . . . . . . . . 0 0 0 0 718 718

(+) New Reservoirs in Old Fields .... 0 0 0 0 3,305 3,305

(-) Production With

Proved Reserves Reported ..... 0 0 0 0 20,428 20,428

(-) Production Without

Proved Reserves Reported ..... 0 17,618 18,996 36,614 95,948 169,176

Proved Reserves as of 12/31/07 ...... 0 138,291 191,696 329,987 647,767 1,307,741

Total

Number of Operators . . . . . . . . . . . . . . . 156 497 288 3,509 9,324 13,774

Proved Reserves as of 12/31/06 ...... 18,191,093 1,436,722 9,468 0 0 19,637,283

(+) Revision Increases ............ 1,902,879 218,892 2,831 0 152,032 2,276,634

(-) Revision Decreases ............ 876,019 127,187 2,947 0 72,065 1,078,218

(-) Sales ....................... 725,908 83,677 0 0 0 809,585

(+) Acquisitions .................. 469,951 318,256 6,370 0 0 794,577

(+) Extensions................... 558,787 52,974 366 0 43,635 655,762

(+) New Field Discoveries.......... 65,440 1,594 0 0 718 67,752

(+) New Reservoirs in Old Fields .... 61,864 10,465 0 0 3,305 75,634

(-) Production With

Proved Reserves Reported ..... 1,360,438 126,833 753 0 20,428 1,508,452

(-) Production Without

Proved Reserves Reported ..... 7 32,210 19,440 36,614 95,948 184,219

Proved Reserves as of 12/31/07 ...... 18,287,661 1,839,781 207,031 329,987 647,767 21,312,227

Summary

Total Number of Operators . . . . . . . . . 156 497 288 3,509 9,324 13,774

Percent of Total................ 1.1% 3.6% 2.1% 25.5% 67.7% 100.0%

Total Production in 2007 ........... 1,360,445 159,043 20,193 36,614 116,376 1,692,671

Percent of Total................ 80.4% 9.4% 1.2% 2.2% 6.9% 100.0%

Total Proved Reserves 12/31/07 ..... 18,287,661 1,839,781 207,031 329,987 647,767 21,312,227

Percent of Total................ 85.8% 8.6% 1.0% 1.5% 3.0% 100.0%

a

There were 439 noncertainty responses, 50 were used with their sample weights and 389 were treated as Certainty III operators.

– = Not applicable.

Notes: Table 6 totals include imputed and estimated crude oil proved reserves rounded at the State/subdivision level. Field level data are

reported volumes and may not balance due to submission of incomplete reserve component records.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.
Energy Information Administration

F-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table F5. Summary of Form EIA-23 Reported, Imputed, and Estimated Lease Condensate Data for 2007,

(thousand barrels of 42 U.S. gallons)

Operator Category

Certainty Noncertainty Auxillary

Level of Reporting I II III III State Data Total

Reported

Number of Operators . . . . . . . . . . . . . . . 156 497 288 439 9,324 10,704

Proved Reserves as of 12/31/06 ...... 965,527 231,313 193 0 0 1,197,033

(+) Revision Increases ............ 183,570 63,391 47 0 0 247,008

(-) Revision Decreases ............ 149,518 55,065 31 0 0 204,614

(-) Sales ....................... 152,665 17,784 0 0 0 170,449

(+) Acquisitions .................. 132,420 33,364 0 0 0 165,784

(+) Extensions................... 128,187 43,584 0 0 0 171,771

(+) New Field Discoveries.......... 3,496 3,815 0 0 0 7,311

(+) New Reservoirs in Old Fields .... 10,875 8,570 0 0 0 19,445

(-) Production With

Proved Reserves Reported ..... 134,695 31,231 88 0 0 166,014

(-) Production Without

Proved Reserves Reported . . . . . 30 673 0 0 0 703

Proved Reserves as of 12/31/07 ...... 987,311 280,052 190 0 0 1,267,553

Imputed and Estimated

Number of Operators ............... - - - 3,070 - 3,070

Proved Reserves as of 12/31/06 ...... - - - - - -

(+) Revision Increases ............ 0 0 0 0 36,233 36,233

(-) Revision Decreases . . . . . . . . . . . . 0 0 0 0 811 811

(-) Sales ....................... 0 0 0 0 0 0

(+) Acquisitions .................. 0 0 0 0 15,894 15,894

(+) Extensions................... 0 0 0 0 42,527 42,527

(+) New Field Discoveries.......... 0 0 0 0 8,136 8,136

(+) New Reservoirs in Old Fields .... 0 0 0 0 -4,537 -4,537

(-) Production With

Proved Reserves Reported ..... 0 0 0 0 4,434 4,434

(-) Production Without

Proved Reserves Reported . . . . . 0 374 1,552 1,926 7,377 11,229

Proved Reserves as of 12/31/07 ...... 0 2,231 8,729 10,960 207,507 229,427

Total

Number of Operators . . . . . . . . . . . . . . . 156 497 288 3,509 9,324 13,774

Proved Reserves as of 12/31/06 ...... 965,527 231,313 193 0 0 1,239,957

(+) Revision Increases ............ 183,570 63,391 47 0 36,233 283,241

(-) Revision Decreases ............ 149,518 55,065 31 0 811 205,425

(-) Sales ....................... 152,665 17,784 0 0 0 170,449

(+) Acquisitions .................. 132,420 33,364 0 0 15,894 181,678

(+) Extensions................... 128,187 43,584 0 0 42,527 214,298

(+) New Field Discoveries.......... 3,496 3,815 0 0 8,136 15,447

(+) New Reservoirs in Old Fields .... 10,875 8,570 0 0 -4,537 14,908

(-) Production With

Proved Reserves Reported ..... 134,695 31,231 88 0 4,434 170,448

(-) Production Without

Proved Reserves Reported . . . . . 30 1,047 1,552 1,926 7,377 11,932

Proved Reserves as of 12/31/07 ...... 987,311 282,283 8,919 10,960 207,507 1,496,980

Summary

Total Number of Operators . . . . . . . . . 156 497 288 3,509 9,324 13,774

Percent of Total................ 1.1% 3.6% 2.1% 25.5% 67.7% 100.0%

Total Production in 2007 ........... 134,725 32,278 1,640 1,926 11,811 182,380

Percent of Total................ 73.9% 17.7% 0.9% 1.1% 6.5% 100.0%

Total Proved Reserves 12/31/07 ..... 987,311 282,283 8,919 10,960 207,507 1,496,980

Percent of Total................ 66.0% 18.9% 0.6% 0.7% 13.9% 100.0%

a

There were 439 noncertainty responses, 50 were used with their sample weights and 389 were treated as Certainty III operators.

– = Not applicable.

Notes: Table 15 totals include imputed and estimated lease condensate proved reserves rounded at the State/subdivision level. Field level

data are reported volumes and may not balance due to submission of incomplete reserve component records.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-9

Table F6. Statistical Parameters of Reserves Estimation Equation by Region for 2007

Number of Nonzero Equation Coefficients

Region R/P Pairs Oil Gas LC

Number Region Oil Gas LC Alpha Beta Alpha Beta Alpha Beta

1 Alaska. . . . . . . . . . . . . . . . . . 7 10 0 -0.1206 0.2625 -0.1328 0.6229 0.0000 0.0000

2 Pacific Coast States . . . . . . . . . . . 46 55 4 -0.1206 0.2488 -0.1328 0.3327 -0.1267 0.4425

2A Federal Offshore Pacific ......... 7 7 - -0.1206 0.1907 -0.1328 0.1994 0.0000 0.0000

3 Western Rocky Mountains . . . . . . . . 87 142 58 -0.1206 0.1741 -0.1328 0.2729 -0.1267 0.3035

4 Northern Rocky Mountains . . . . . . . . 168 173 47 -0.1206 0.2445 -0.1328 0.3063 -0.1267 0.2291

5 West Texas and East New Mexico . . . . 465 489 174 -0.1206 0.2092 -0.1328 0.3122 -0.1267 0.4342

6 Western Gulf Basin . . . . . . . . . . . 500 827 542 -0.1206 0.2887 -0.1328 0.3724 -0.1267 0.5177

6A Gulf of Mexico . . . . . . . . . . . . . . 70 136 110 -0.1206 0.4535 -0.1328 0.7084 -0.1267 0.7487

7 Mid-Continent . . . . . . . . . . . . . . 283 369 138 -0.1206 0.4728 -0.1328 0.3223 -0.1267 0.3325

8 + 9 Michigan Basin and Eastern Interior . . . . 80 56 11 -0.1206 0.1807 -0.1328 0.1379 -0.1267 0.2064

10 + 11 Appalachians . . . . . . . . . . . . . . 26 74 10 -0.1206 0.2177 -0.1328 0.1497 -0.1267 0.3731

United States .............. 1,739 2,338 1,094 -0.1206 0.2857 -0.1328 0.3406 -0.1267 0.4596

Source: Based on data filed on Form EIA-23,"Annual Survey of Domestic Oil and Gas Reserves, 2007".

Figure F1. Form EIA-23 Regional Boundaries
Both methods preserved an exact annual reserves

balance of the following form:

The algebraic allocation method used for all but six

states in the 2007 survey worked as follows: A ratio was

calculated as the sum of the annual production and

year-end proved reserves of those respondents who

did not provide the reserves balance components,

divided by the sum of year-end proved reserves and

annual production of those respondents of similar size

who did provide these quantities. This ratio was then

multiplied by each of the reserves balance components

reported by Category I and some Category II operators,

to obtain imputed volumes for the reserves balances of

the other Category II operators and certainty and

noncertainty operators. These were then added to the

State/subdivision totals.

Imputation of Natural Gas Volumes

Small operators in the certainty and noncertainty strata

were not asked to segregate their natural gas volumes

by type of natural gas, i.e., nonassociated natural gas

(NA) and associated-dissolved natural gas (AD). The

total estimated year-end proved reserves of natural gas

and the total annual production of natural gas reported

by, or imputed to, operators in the State/subdivision

certainty and noncertainty strata were, therefore,

subdivided into the NA and AD categories, by

State/subdivision, in the same proportion as was

reported by large and intermediate operators in the

same area.

Adjustments

The instructions for Schedule A of Form EIA-23 specify

that, when reporting reserves balance data, the

following arithmetic equation must hold:

Any remaining difference in the State/subdivision

annual reserves balance between the published

previous year-end proved reserves and current

year-end proved reserves not accounted for by the

imputed reserves changes was included in the

adjustments for the area. One of the primary reasons

that adjustments are necessary is the instability of the

noncertainty operators sampled each year. There is no

guarantee that in the smaller producing

States/subdivision the same number of small

operators will be selected each year, or that the

operators selected will be of comparable sizes when

paired with operators selected in a prior year. Thus,

some instability of this stratum from year to year is

unavoidable, resulting in minor adjustments.

Some of the adjustments are, however, more

substantial, and could be required for any one or more

of the following reasons:

The frame coverage may or may not have

improved between survey years, such that more

or fewer certainty operators were included in

2007 than in 2006.

One or more operators may have reported data

incorrectly on Schedule A in 2007 or 2006, but

not both, and the error was not detected by edit

processing.

Operation of properties was transferred during

2007 from operators not in the frame or

noncertainty operators not selected for the

sample to certainty operators or noncertainty

operators selected for the sample.

Respondent changed classification of natural

gas from NA to AD or vice versa.

The trend in reserve changes imputed for the

small operators, which was based on the trend

reported by the large operators, did not reflect

the actual trend for the small operators.

Energy Information Administration

F-10 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Proved Reserves at End of Previous Year

+ Revision Increases

– Revision Decreases

– Sales

+ Acquisitions

+ Extensions

+ New Field Discoveries

+ New Reservoir Discoveries in Old Fields

– Report Year Production

= Proved Reserves at End of Report Year

Published Proved Reserves at End of Previous Report Year

+ Adjustments

+ Revision Increases

– Revision Decreases

– Sales

+ Acquisitions

+ Extensions

+ New Field Discoveries

+ New Reservoir Discoveries in Old Fields

– Report Year Production

= Published Proved Reserves at End of Report Year
noncertainty operators, who have grown

substantially in size since they were added to

the frame, occasionally cause a larger standard

error than expected.

The noncertainty sample for either year in a

state may have been an unusual one.

The causes of adjustments are known for some but not

all areas. The only problems whose effects cannot be

expected to balance over a period of several years are

those associated with an inadequate frame or those

associated with any actual trend in reserves changes

for small operators not being the same as those for large

operators. EIA continues to attempt to improve sources

of operator data to resolve problems in frame

completeness.

Sampling Reliability of the Estimates

The sample of noncertainty operators selected is only

one of the large number of possible samples that could

have been selected and each would have resulted in

different estimates. The standard error or sampling

error of the estimates provides a measure of this

variability. When probability sampling methods are

used, as in the EIA-23 survey, the sampling error of

estimates can also be estimated from the survey data.

The estimated sampling error can be used to compute a

confidence interval around the survey estimate, with a

prescribed degree of confidence that the interval covers

the value that would have been obtained if all

operators in the frame had been surveyed. If the

estimated volume is denoted by Vs and its sampling

error by S.E.(Vs), the confidence interval can be

expressed as:

Vs k S.E.(Vs)

where k is a multiple selected to provide the desired

level of confidence. For this survey, k was taken equal

to 2. Then there is approximately 95 percent confidence

that the interval:

Vs 2 S.E.(Vs)

includes the universe value, for both the estimates of

reserves and production volumes. Correspondingly,

for approximately 95 percent of the estimates in this

report, the difference between the published estimate

and the value that would be found from a complete

survey of all operators is expected to be less than twice

the sampling error of the estimate. Tables F7 and F8

provide estimates for 2S.E.(Vs) by product. These

estimates are directly applicable for constructing

approximate 95 percent confidence intervals. For

example, the 95 percent confidence interval for dry

natural gas proved reserves is 237,726 ±359 billion

cubic feet. The sampling error of Vs is equal to the

sampling error of the noncertainty estimate Vsr because

the certainty total is not subject to sampling error. The

estimated sampling error of a noncertainty estimate is

the square root of its estimated sampling variance.

Sources of Errors

The EIA maintains an evaluation program to assess the

accuracy and quality of proved reserve estimates

gathered on Form EIA-23. Field teams consisting of

petroleum engineers from EIA's Reserves and

Production Division conduct technical reviews of

reserve estimates and independently estimate the

proved reserves of a selected sample of operator

properties. The results of these reviews are used to

evaluate the accuracy of reported reserve estimates.

Operators are apprised of the team's findings to assist

them in completing future filings. The magnitude of

errors due to differences between reserve volumes

submitted by operators on the Form EIA-23 and those

estimated by EIA petroleum engineers on their field

trips were generally within accepted professional

engineering standards. Several sources of possible

error, apart from sampling error, are associated with

the Form EIA-23 survey:

Operator nonresponse

Respondent estimation errors

Reporting errors and data processing errors

Inadequate frame coverage

Errors associated with statistical estimates.

Imputation for Operator Nonresponse

The nonresponse rate for certainty operators for the

2007 survey (Appendix E, Table E2) was 2.1 percent

and for the noncertainty operators 8.9 percent. An

imputation was made for the production and reserves

for the 39 nonresponding operators.

Respondent Estimation Errors

The principal data elements of the Form EIA-23 survey

consist of respondent estimates of proved reserves of

crude oil, natural gas, and lease condensate.

Unavoidably, the respondents are bound to make some

estimation errors, i.e., until a particular reservoir has

been fully produced to its economic limit and

abandoned, its reserves are not subject to direct

measurement but must be inferred from limited,

imperfect, or indirect evidence. A more complete

discussion of the several techniques of estimating

proved reserves, and the many problems inherent in

the task, appears in Appendix G.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-11
Energy Information Administration

F-12 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

United States............... 7 1

Alabamab

.................. 0 0

Alaskaa ................... 0 0

Arkansasb ................. 0 0

Californiab ................. 0 0

Coloradob ................. 0 0

Floridaa ................... 0 0

Illinois .................... 0 0

Indiana ................... 0 0

Kansasb

................... 0 0

Kentucky .................. 0 0

Louisianab ................. 0 0

Michiganb ................. 0 0

Mississippib ................ 0 0

Montanab

.................. 0 0

Nebraska.................. 0 0

New Mexicob .............. 0 0

North Dakotab .............. 0 0

Ohiob ..................... 0 0

Oklahomab ................ 0 0

Pennsylvania............... 0 0

Texasb .................... 0 0

Utahb ..................... 0 0

Virginiaa

................... 0 0

West Virginia ............... 0 0

Wyomingb ................. 0 0

Federal Offshorea ........... 0 0

Miscellaneousc ............. 2 0

Table F7. Factors for Confidence Intervals (2S.E.) for Crude Oil Proved Reserves and Production, 2007

(million barrels of 42 U.S. gallons)

2007 2007 2007 2007

State and Subdivision Reserves Production State and Subdivision Reserves Production

Table F8. Factors for Confidence Intervals (2S.E.) for Natural Gas Proved Reserves and Production,

Wet After Lease Separation, 2007 (billion cubic feet at 14.73 psia and 60o Fahrenheit)

2007 2007 2007 2007

State and Subdivision Reserves Production State and Subdivision Reserves Production

United States. . . . . . . . . . . . . . . 359 28

Alabamab

.................. 0 0

Alaskaa ................... 0 0

Arkansasb ................. 0 0

Californiab ................. 0 0

Coloradob ................. 0 0

Floridaa ................... 0 0

Kansasb

................... 0 0

Kentucky .................. 0 0

Louisianab ................. 0 0

Michiganb ................. 0 0

Mississippib ................ 0 0

Montanab

.................. 0 0

New Mexicob ............... 0 0

New Yorkb ................. 0 0

North Dakotab .............. 0 0

Ohiob ..................... 0 0

Oklahomab ................ 0 0

Pennsylvania. . . . . . . . . . . . . . . 52 4

Texasb .................... 0 0

Utahb ..................... 0 0

Virginiaa

................... 0 0

West Virginia ............... 6 0

Wyomingb ................. 0 0

Federal Offshorea c .......... 0 0

Miscellaneousd ............. 4 0

a

Sampling rate was 100 percent in Alaska, Florida Onshore, Virginia, and Offshore areas.

b

Sampling was not used. Estimates for each operator were made using an imputation function.

c

Includes Arizona, Missouri, Nevada, South Dakota, Tennessee, and Virginia.

Notes: Confidence intervals are associated with Table 6 reserves and production data.

Factors for confidence intervals for each State and the United States are independently estimated and do not add.

Source: Factor estimates based on data filed on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007.

a

Sampling rate was 100 percent in Alaska, Florida Onshore, Virginia, and Offshore areas.

b

Sampling was not used. Estimates for each operator were made using an imputation function.

c

Includes Federal offshore Alabama.

d

Includes Arizona, Illinois, Indiana, Maryland, Missouri, Nebraska, Nevada, Oregon, South Dakota, and Tennessee.

Notes: Confidence intervals are associated with Table 8 reserves and production data.

Factors for confidence intervals for each State and the United States are independently estimated and do not add.

Source: Factor estimates based on data filed on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2007
Reporting and Data Processing Errors

Reporting errors on the part of respondents are of

definite concern in a survey of the magnitude and

complexity of the Form EIA-23 program. Several steps

were taken by EIA to minimize and detect such

problems. The survey instrument itself was carefully

developed, and included a detailed set of instructions

for filing data, subject to a common set of definitions

similar to those already used by the industry. Editing

software is continually developed to detect different

kinds of probable reporting errors and flag them for

resolution by analysts, either through confirmation of

the data by the respondent or through submission of

amendments to the filed data. Data processing errors,

consisting primarily of random keypunch errors, are

detected by the same software.

Frame Coverage Errors

Of all the sources of controllable error connected with

the Form EIA-23 survey, errors in the operator frame

were expected to be the most important. If the frame

does not list all operators in a given State, the sample

selected from the frame for the State will not represent

the entire operator population, a condition called

under coverage. Under coverage is a problem with

certain States, but it does not appear to be a problem

with respect to the National proved reserve estimates

for either crude oil or natural gas. While it is relatively

straightforward to use existing sources to identify large

operators and find addresses for them, such is not the

case for small operators. A frame such as that used in

the 2007 survey is particularly likely to be deficient in

States where a large portion of total reserves and

production is accounted for by small operators. EIA is

continuing to work to remedy the under coverage

problem in those States where it occurred.

Imputation Errors

Some error, generally expected to be small, is an

inevitable result of the various estimations outlined.

These imputation errors have not yet been completely

addressed by EIA and it is possible that estimation

methods may be altered in future surveys. Nationally,

6.1 percent of the crude oil proved reserve estimates,

4.9 percent of the wet natural gas proved reserve

estimates, and 15.3 percent of the lease condensate

proved reserve estimates resulted from the imputation

and estimation of reserves for those certainty and

noncertainty operators who did not provide estimates

for all of their properties, in combination with the

expansion of the sample of noncertainty operators to

the full population. Errors for the latter were

quantitatively calculated, as discussed in the previous

section. Standard errors, for the former, would tend to

cancel each other from operator to operator, and are,

therefore, expected to be negligible, especially at the

National level of aggregation. In States where a large

share of total reserves is accounted for by Category III

and smaller Category II operators, the errors are

expected to be somewhat larger than in States where a

large share of total reserves is accounted for by

Category I and larger Category II operators.

Calculation of Reserves of

Natural Gas Liquids and

Dry Natural Gas

Natural Gas Liquids Reserve Balance

The published reserves, production, and reserves

change statistics for crude oil, lease condensate, and

natural gas, wet after lease separation, were derived

from the data reported on Form EIA-23 and the

application of the imputation methods discussed

previously. The information collected on Form

EIA-64A was then utilized in converting the estimates

of the wet natural gas reserves into two components:

plant liquids reserve data and dry natural gas reserve

data. The total natural gas liquids reserve estimates

presented in Table 14 were computed as the sum of

plant liquids estimates (Table 15) and lease condensate

(Table 16) estimates.

To generate estimates for each element in the reserves

balance for plant liquids in a given producing area, the

first step was to group all natural gas processing plants

that reported this area as an area-of-origin on their

Form EIA-64A, and then sum the liquids production

attributed to this area over all respondents. Next, the

ratio of the liquids production to the total wet natural

gas production for the area was determined. This ratio

represented the percentage of the wet natural gas that

was recovered as natural gas liquids. Finally, it was

assumed that this ratio was applicable to the reserves

and each component of reserve changes (except

adjustments), as well as production. Therefore, each

element in the wet natural gas reserves balance was

multiplied by this recovery factor to yield the

corresponding estimate for plant liquids. Adjustments

of natural gas liquids were set equal to the difference

between the end of previous year reserve estimates,

based upon the current report year Form EIA-23 and

Form EIA-64A surveys, and the end of current year

reserve estimates published in the preceding year's

annual reserves report.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report F-13
Natural Gas Reserve Balance

This procedure involved downward adjustments of the

natural gas data, wet after lease separation, in

estimating the volumes of natural gas on a fully dry

basis. These reductions were based on estimates of the

gaseous equivalents of the liquids removed (in the case

of production), or expected to be removed (in the case

of reserves), from the natural gas stream at natural gas

processing plants. Form EIA-64A collected the

volumetric reduction, or shrinkage, of the input natural

gas stream that resulted from the removal of the NGL

at each natural gas processing plant.

The shrinkage volume was then allocated to the plant's

reported area or areas of origin. Because shrinkage is,

by definition, roughly in proportion to the NGL

recovered, i.e. the NGL produced, the allocation was in

proportion to the reported NGL volumes for each area

of origin. However, these derived shrinkage volumes

were rejected if the ratio between the shrinkage and the

NGL production (gas equivalents ratio) fell outside

certain limits of physical accuracy. The ratio was

expected to range between 1.558 MMCF per thousand

barrels (where NGL consists primarily of ethane) and

0.940 MMCF per thousand barrels (where NGL

consists primarily of natural gasolines). When the

computed gas equivalents ratio fell outside these

limits, an imputed ratio was utilized to estimate the

plant's natural gas shrinkage allocation to each

reported area of origin.

This imputed ratio was that calculated for the

aggregate of all other plants reporting production and

shrinkage, and having a gas equivalent ratio within the

aforesaid limits, from the area in question. The

imputed area ratio was applied only if there were at

least five plants on which to base its computation. If

there were less than five plants, the imputed ratio was

calculated based on all plants in the survey whose

individual gas equivalents ratio was within the

acceptable limits. Less than one percent of the liquids

production was associated with shrinkage volumes

imputed in this manner. Based on the 2007 Form

EIA-64A survey, the national weighted average gas

equivalents ratio was computed to be 1,413 cubic feet of

natural gas shrinkage per barrel of NGL recovered. The

total shrinkage volume (reported plus imputed) for all

plants reporting a given area of origin was then

subtracted from the estimated value of natural gas

production, wet after lease separation, yielding dry

natural gas production for the area. The amount of the

reduction in the wet natural gas production was then

expressed as a percentage of the wet natural gas

production. Dry natural gas reserves and reserve

changes were determined by reducing the wet natural

gas reserves and reserve changes by the same

percentage reduction factor.

A further refinement of the estimation process was

used to generate an estimate of the natural gas liquids

reserves in those States with coalbed methane fields.

The States where this procedure was applied were

Alabama, Colorado, Kansas, New Mexico, Oklahoma,

Pennsylvania, Utah, Virginia, West Virginia, and

Wyoming. The first step in the process was to identify

all Form EIA-23 reported coalbed methane fields.

Coalbed methane fields contain no extractable natural

gas liquids. Therefore, when the normal shrinkage

procedure was applied to the wet gas volume reserve

components, the estimate of State coalbed methane

volumes were excluded and were not reduced for

liquid extraction. Following the computation for

shrinkage, each coalbed field gas volume reserve

components was added back to each of the dry gas

volume reserve components in a State. The effect of this

is that the large increases in reserves in some States

from coalbed methane fields did not cause

corresponding increases in the State natural gas liquids

proved reserves.

Energy Information Administration

F-14 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Appendix G

Estimation of Reserves and Resources

Oil and Gas Resource Base

Universally accepted definitions have not been

developed for the many terms used by geologists,

engineers, accountants and others to denote various

components of overall oil and gas resources. In part,

this is because most of these terms describe estimated

and therefore uncertain, rather than measured,

quantities. The lack of standardized terminology

sometimes leads to inaccurate understanding of the

meaning and/or import of estimates. Particularly

common is an apparently widespread lack of

understanding of the substantial difference between

the terms “reserves” and “resources”, as indicated by

the frequent misuse of either term in place of the other.

The total resource base of oil and gas is the entire

volume formed and trapped in–place within the Earth

before any production. The largest portion of this total

resource base is nonrecoverable by current or

foreseeable technology. Most of the nonrecoverable

volume occurs at very low concentrations throughout

the earth's crust and cannot be extracted short of

mining the rock or the application of some other

approach that would consume more energy than it

produced. An additional portion of the total resource

base cannot be recovered because currently available

production techniques cannot extract all of the in–place

oil and gas even when present in commercially viable

concentrations. The inability to recover all of the

in–place oil and gas from a producible deposit occurs

because of unfavorable economics, intractable physical

forces, or a combination of both. Recoverable

resources, the subset of the total resource base that is of

societal and economic interest, are defined so as to

exclude these nonrecoverable portions of the total

resource base.

The tree diagram presented in Figure G1 outlines a

simplified version of the total resource base and its

components in two dimensions. The total resource base

first consists of the recoverable and nonrecoverable

portions discussed above. The next level down divides

recoverable resources into discovered and

undiscovered segments. Discovered resources are

further separated by whether or not they are

economically recoverable. Economically

unrecoverable resources are sometimes called

contingent resources. Economically recoverable

resources are then subdivided by proved reserves and

unproved reserves categories. Proved reserves are

additionally subdivided into subtypes, e.g. proved

non-producing reserves.

A three-dimensional diagram of the Total In-Place

Resource base is presented in Figure G2. This diagram

represents the total in-place resource base as mapped

over three axes: Probability, Activity, and Economics.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report G-1

Total Oil & Gas Resource Base

Undiscovered

Resources

Cumulative

Production

Possible

Reserves

Probable

Reserves

Proved Ultimate

Recovery

Proved

Developed

Producing

Economically

Unrecoverable

Resources

Economically Recoverable Resources

(Ultimate Recovery)

Discovered Resources

(Oil and Gas In-place)

Proved

Undeveloped

Proved

Non-Producing

Proved

Developed

Non-Producing

Proved

Reserves

Form

EIA-23

Includes

Other Reserves

(Not Proved)

Figure G1. Components of the Oil and Gas

Resource Base

Source: Energy Information Administration, Office of Oil and Gas, Reserves and Production Division.
Figure G2. Resource Base

Energy Information Administration

G-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

OBSERVE THAT:

• Proved Reserves are a small subset of the Initially-In-Place Resource Base.

• A substantial portion of the Initially-In-Place Resource Base remains to be discovered.

• It is quite possible that future discoveries may exceed current cumulative production.

• The median undiscovered volume, IIP50 , which is larger than the expected or mean volume, has a 50 percent probability of being

exceeded.

Notes: Variable R represents a volume of Reserves, C represents Contingent Resources, and IIP represents Initially-In-Place Resources.

Numeric subscripts (e.g. R50, IIP90) indicate the probability that the associated volume exists.

Drawing is not scaled to any volumetric estimates. Probability distributions in this diagram are nonlinear.

Source: Energy Information Administration, Office of Oil and Gas, Reserves and Production Division.
Illustrated in Figure G2 are proved, probable, and

possible reserves, developed or undeveloped reserves,

contingent resources (economic and uneconomic),

nonlinear probability distributions for reserves,

contingent resources, and undiscovered

initially-in-place resources.

The terms in Figure G2 are consistent with the resource

definitions adopted by the Society of Petroleum

Engineers (SPE) as set forth in their 2007 document,

Petroleum Resources Management System, prepared by its

Oil and Gas Reserves Committee; reviewed and jointly

sponsored by the World Petroleum Council (WPC), the

American Association of Petroleum Geologists

(AAPG), and the Society of Petroleum Evaluation

Engineers (SPEE). {46}

Recoverable Resources

Discovered recoverable resources are those

economically recoverable quantities of oil and gas for

which specific locations are known. While the specific

locations of estimated undiscovered recoverable

resources are not yet known, they are believed to exist

in geologically favorable settings.

Current estimates of undiscovered recoverable

resources merit discussion in order to provide a useful

sense of scale relative to proved reserves. The sources

of official estimates of domestic undiscovered

recoverable resources are two agencies of the

Department of the Interior (DOI), the United States

Geological Survey (USGS) for onshore areas and those

offshore waters subject to State jurisdiction, and the

Minerals Management Service (MMS) for those

offshore waters under Federal jurisdiction.

The USGS defines undiscovered recoverable

conventional resources as those expected to be resident

in accumulations of sufficient size and quality that they

could be produced using conventional recovery

technologies, without regard to present economic

viability. Therefore, only part of the USGS

undiscovered recoverable conventional resource is

economically recoverable now. The USGS also defines

a class of resources that occur in “continuous–type”

accumulations. Unlike conventional oil and gas

accumulations, continuous–type accumulations do not

occur in discrete reservoirs of limited areal extent. They

include accumulations in low–permeability (tight)

sandstones, shales, and chalks, and those in coal beds.

Again, only part of the continuous–type technically

recoverable resource is economically recoverable now.

In fact, only a small portion of the in–place

continuous–type resource accumulations are estimated

to be technically recoverable now. Table G1 presents a

compilation of USGS and MMS estimates.

Technically recoverable resources of dry natural gas

(discovered, unproved, and undiscovered) are

estimated at 1,533 trillion cubic feet (Table G1).

Adding the 2007 U.S. proved reserves of 248 trillion

cubic feet yields a technically recoverable resource

target of 1,781 trillion cubic feet. This is about 91 times

the 2007 dry gas production level.

Other organizations have also estimated unproven

technically recoverable gas resources. For example, the

Potential Gas Committee (PGC), an industry

sponsored group, provides detailed geology–based gas

resource estimates every 2 years. In 2006 the PGC mean

estimate of potential gas resources was 1,321 trillion

cubic feet, about 211 trillion cubic feet less than the

estimates in Table G1. The differences among these

estimates are usually due to the availability of newer

data, differences in coverage or resource category

definitions, and legitimate but differing data

interpretations.

While the estimation of undiscovered resources is

certainly a more imprecise endeavor than is the

estimation of proved reserves, it is clear that substantial

volumes of technically recoverable oil and gas

resources remain to be found and produced

domestically. Current estimates indicate that as much

domestic gas remains to be found and then produced

as has been to date. Of course, much effort, investment

and time will be required to bring this gas to market.

There is a perception that the oil resource base has been

more intensively developed than the gas resource base.

And in fact, more oil has been produced in the United

States than is estimated as remaining recoverable.

Nevertheless, the ratio of unproven technically

recoverable oil resources to 2007 oil production (Table

G1) was about 105 to 1, higher than the comparable gas

ratio.

Discovered Resources

In addition to cumulative production, which is the sum

of current year production and the production in all

prior years, estimates of discovered recoverable

resources include estimates of reserves. Broadly,

reserves are those volumes that are believed to be

economically recoverable in the future from known

deposits through the eventual application of present or

anticipated technology.

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U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report G-3
Energy Information Administration

G-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table G1. Mean Estimates of Technically Recoverable Oil and Gas Resources by

Deposit Type and Location

Natural Gas

Crude Oil Natural Gas (Dry) Liquids

Area (billion barrels) (trillion cubic feet) (billion barrels)

Undiscovered Conventionally Reservoired Fields

Alaska Onshore + State Offshore 26.04 126.75 2.23

Alaska Federal Offshore 26.61a 132.06 0.00a

Lower 48 States Onshore + State Offshore 18.24 178.21 5.56

Lower 48 States Federal Offshore 59.27a 287.82 0.00a

Alaska Subtotal 52.65 258.81 2.23

Lower 48 States Subtotal 77.51 466.03 5.56

Technically Recoverable Resources in U.S.

Undiscovered Conventionally Reservoired Fields 130.16 724.84 7.79

Ultimate Recovery Appreciation

Alaska Onshore + State Offshore 6.96 12.30 0.41

Lower 48 States Onshore + State Offshore 31.70 442.50 17.85

U.S. Federal Offshore 6.88a 30.91 0.00a

Technically Recoverable Resources in U.S.

from Ultimate Recovery Appreciation in Discovered

Conventionally Reservoired Fields 45.54 485.71 18.26

Continuous Type Deposits

Alaska Non-coal bed 0.00 0.00 0.00

Lower 48 States Non-coal bed 2.13 236.89 3.80

Alaska Coal bed 0.00 18.06 0.00

Lower 48 States Coal bed 0.00 67.32 0.00

Non-coal bed Subtotal 2.13 236.89 3.80

Coal bed Subtotal 0.00 85.38 0.00

Technically Recoverable Resources in U.S.

from Continuous Type Deposits 2.13 322.27 3.80

U.S. Totals All Sources

U.S. Onshore + State Offshore 85.07 1,082.03 29.85

Federal Offshore 92.76a 450.79 0.00a

U.S. Technically Recoverable Resources 177.83 1,532.82 29.85

a The MMS jointly reports natural gas liquids with crude oil for the Federal Offshore.

Additional Notes: Proved Reserves are excluded from these estimates as are undiscovered oil resources in tar deposits and oil shales, and

undiscovered gas resources in geopressured brines and gas hydrates.

Zero (0) indicates either that none exists in this area or that no estimate of this resource has been made for this area, or in the instance of

Federal offshore natural gas liquids resources that they are jointly reported with crude oil.

Federal Onshore excludes Indian and Native lands even when Federally managed in trust.

Federal Offshore indicates MMS estimates for Federal Offshore jurisdictions (Outer Continental Shelf and deeper water areas seaward of State

Offshore).

Data Sources: National Oil and Gas Resource Assessment Team, 2007 Assessment Updates, United States Geological Survey, Washington DC,

December 2007 at <http://energy.cr.usgs.gov/oilgas/noga/ass_updates.html>

Resource Evaluation Division, Assessment of Undiscovered Technically Recoverable Oil and Gas Resources of the Nation's Outer Continental

Shelf, 2006, MMS Fact Sheet RED-2006-01b, Minerals Management Service, Washington, DC, February 2006 at

<http://www.mms.gov/revaldiv/PDFs/2006NationalAssessmentBrochure.pdf>.

The ultimate recovery appreciation estimates for Alaska and the Lower 48 States Onshore Plus State Waters were developed by the Reserves

and Production Division, Office of Oil and Gas, Energy Information Administration, based on data available as of year-end 2006.
Reserves

Reserves include both proved reserves and other

reserves. Several different reserve classification

systems are in use by different organizations, as

preferred for operational reasons. These systems utilize

and incorporate various definitions of terms such as

measured reserves, indicated reserves, inferred reserves,

probable reserves, and possible reserves. As used by the

different organizations, the definitions that attach to

these terms sometimes overlap, or the terms may

require a slightly different interpretation from one

organization to the next. Nevertheless, all kinds of

“other reserves” are generally less well known and

therefore less precisely quantifiable than proved

reserves, and their eventual recovery is less assured.

Measured reserves are defined by the USGS as that part

of the identified (i.e., discovered) economically

recoverable resource that is estimated from geologic

evidence and supported directly by engineering

data.{47} They are similarly defined by the MMS,

although its system also subdivides them by degree of

development and producing status.{48} Measured

reserves are demonstrated with reasonable certainty to

be recoverable in future years from known reservoirs

under existing economic and operating conditions, and

are essentially equivalent to proved reserves as defined

by the EIA. Effectively, estimates of proved reserves

may be thought of as reasonable estimates (as opposed

to exact measures) of “on–the–shelf inventory”.

Inferred reserves and indicated reserves, due to their

more uncertain economic or technical recoverability,

are included in the “other reserves” category. The

USGS defines inferred reserves as that part of the

identified economically recoverable resource, over and

above both measured and indicated (see below)

reserves, that will be added to proved reserves in the

future through extensions, revisions, and the discovery

of new pay zones in already discovered fields.{47}

Inferred reserves are considered equivalent to

“probable reserves” by many analysts, for example,

those of the PGC.

Proved Reserves

The EIA defines proved reserves as those volumes of

oil and gas that geological and engineering data

demonstrate with reasonable certainty to be

recoverable in future years from known reservoirs

under existing economic and operating conditions.

When deterministic proved reserves estimation

methods are used, the term reasonable certainty is

intended to express a high degree of confidence that the

estimated quantities will be recovered. When

probabilistic methods are used there should be at least

a 90 percent probability that the actual quantities

recovered will exceed the estimate.

Proved reserves are either proved producing or proved

nonproducing (i.e., resident in reservoirs that did not

produce during the report year). The latter may

represent a substantial fraction of total proved

reserves.

Reserve Estimation

Methodologies

The adoption of a standard definition of proved

reserves for each type of hydrocarbon surveyed by the

Form EIA–23 program provided a far more consistent

response from operators than if each operator had used

their own definition. Such standards, however, do not

guarantee that the resulting estimates themselves are

determinate. Regardless of the definition selected,

proved reserves cannot be measured directly. They are

estimated quantities that are inferred on the basis of the

best geological, engineering, and economic data

available to the estimator, who generally uses

considerable judgment in the analysis and

interpretation of the data. Consequently, the accuracy

of a given estimate varies with and depends on the

quality and quantity of raw data available, the

estimation method used, and the training and

experience of the estimator. The element of judgment

commonly accounts for the differences among

independent estimates for the same reservoir or field.

Data Used in Making

Reserve Estimates

The raw data used in estimating proved reserves

include the engineering and geological data for

reservoir rock and its fluid content. These data are

obtained from direct and indirect measurements. The

data available for a given reservoir vary in kind,

quality, and quantity. When a reservoir is first

discovered only data from a single well are available,

and prior to flow testing or actual production, proved

reserves can only be inferred. As development of the

reservoir proceeds, and flow tests are made or actual

production commences, more and more data become

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report G-5
available, enabling proved reserves estimates to

become more accurate.

Many different kinds of data are useful in making

reserves estimates. They may include: data on porosity,

permeability, and fluid saturations of the reservoir

rocks (obtained directly from core analysis or from

various types of electrical measurements taken in a

well or several wells); data on the production of fluids

from a well or several wells; geologic maps of the areal

extent, thickness, and continuity of the reservoir rocks

(inferred from well logs, geophysical, and geological

data); and reservoir pressure and temperature data.

Also involved are economic data including the current

price of crude oil and natural gas, and various

developmental and operating costs.

Reserve Estimation Techniques

Depending on the kinds and amounts of data available,

and a judgment on the reliability of those data, the

estimator will select one of several methods of making

a proved reserves estimate. Methods based on

production performance data are generally more

accurate than those based strictly on inference from

geological and engineering data. Such methods include

the Production Decline method (for crude oil or natural

gas reservoirs), the Material Balance method (for crude

oil reservoirs), the Pressure Decline method (which is

actually a material balance, for natural gas reservoirs),

and the Reservoir Simulation method (for crude oil or

natural gas reservoirs). The reservoir type and

production mechanisms and the types and amounts of

reliable data available determine which of these

methods is more appropriate for a given reservoir.

These methods are of comparable accuracy.

Methods not based upon production data include the

Volumetric method (for crude oil or natural gas

reservoirs) and the Nominal method. Of these, the

Volumetric method is the more accurate. Both methods,

however, are less accurate than those based on

production data. Table G2 summarizes the various

methods.

Judgmental Factors

in Reserve Estimation

The determination of rock and hydrocarbon fluid

properties involves judgment and is subject to some

uncertainty; however, the construction of the geologic

maps and cross sections and the determination of the

size of the reservoir are the major judgmental steps in

the Volumetric method, and are subject to the greatest

uncertainty. Estimates made using the Material Balance

method, the Reservoir Simulation method, or the

Pressure Decline method are based on the estimator's

judgment that the type of reservoir drive mechanism

has been identified and on the specification of

abandonment conditions. Estimates based on the

Production Decline method are subject to judgment in

constructing the trend line, and are based on the

estimator's assumption of reservoir performance

through abandonment.

Contributing to the degree of uncertainty inherent in

the above methods for estimating reserves are other

factors associated with economic considerations and

the perceived reservoir limits, which together influence

the final reserves estimate. A brief discussion of these

other factors follows.

Economic considerations: There has been continuing

debate about the effects of prices on proved reserves.

Although no all–inclusive statement can be made on

the impact of price, the points at issue can be discussed

and some general remarks can be made about some

circumstances where price may be a factor.

Energy Information Administration

G-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Table G2. Reserve Estimation Techniques

Method Comments

Volumetric Applies to crude oil and natural gas reservoirs. Based on raw engineering and geologic data.

Material Balance Applies to crude oil and natural gas reservoirs. Is used in estimating reserves. Usually of more value in predicting reserves,

and reservoir performance.

Pressure Decline Applies to nonassociated and associated

gas reservoirs. The method is a special

case of material balance equation in the

absence of water influx.

Production Decline Applies to crude oil and natural gas reservoirs during production decline (usually in

the later stages of reservoir life).

Reservoir SimulationApplies to crude oil and natural gas reservoirs. Is used in estimating reserves. Usually of more value in predicting reservoir

performance. Accuracy increases when

matched with past pressure and production data.

Nominal Applied to crude oil and natural gas reservoirs. Based on rule of thumb or analogy

with another reservoir or reservoirs believed to be similar; least accurate of

methods used.
Developed gas fields – In a gas reservoir, price

affects the economic limit (i.e., the production

rate required to meet operating costs) and,

therefore, the abandonment pressure. Thus, price

change has some effect on the conversion of

noneconomic hydrocarbon resources to the

category of proved reserves. In both nearly

depleted reservoirs and newly developed

reservoirs, the actual increase in the quantity of

proved reserves resulting from price rises is

generally limited in terms of national volumes

(even though the percentage increase for a given

reservoir may be great).

Developed oil fields – In developed crude oil

reservoirs many of the same comments apply;

however, there is an additional consideration. If

the price is raised to a level sufficient to justify

initiation of an improved recovery project, and if

the improved recovery technique is effective,

then the addition to ultimate recovery from the

reservoir can be significant. Because of the

speculative nature of predicting prices and costs

many years into the future, proved reserves are

estimated on the basis of current prices, costs,

and operating practices in effect as of the date

the estimation was made.

Successful exploration efforts – Price can have a

major impact on whether a new discovery is

produced or abandoned. For example, the

decision to set casing in a new onshore

discovery, or to install a platform as the result of

an offshore discovery, are both price–sensitive. If

the decision is made to set pipe or to install a

platform, the discoveries in both cases will add

to the proved reserves total. If such projects are

abandoned, they will make no contribution to

the proved reserves total.

Effect of operating conditions: Operating conditions

are subject to change caused by changes in economic

conditions, unforeseen production problems, new

production practices or methods, and the operator's

financial position. As with economic conditions,

operating conditions to be expected at the time of

abandonment are speculative. Thus, current operating

conditions are used in estimating proved reserves. In

considering the effect of operating conditions, a

distinction must be made between processes and

techniques that would normally be applied by a

prudent operator in producing his oil and gas, and

initiation of changes in operating conditions that

would require substantial new investment.

Compression – Compression facilities are

normally installed when the productive capacity

or deliverability of a natural gas reservoir or its

individual wells declines. In other cases

compression is used in producing shallow,

low–pressure reservoirs or reservoirs in which

the pressure has declined to a level too low for

the gas to flow into a higher pressure pipeline.

The application of compression increases the

pressure and, when economical, is used to make

production into the higher pressure pipeline

possible. Compression facilities normally require

a significant investment and result in a change in

operating conditions. It increases the proved

reserves of a reservoir, and reasonably accurate

estimates of the increase can be made.

Well stimulation – Procedures that increase

productive capacity (workovers, such as

acidizing or fracturing, and other types of

production practices) are routine field

operations. The procedures accelerate the rate of

production from the reservoir, or extend its life,

and they have only small effect on proved

reserves. Reasonable estimates of their

effectiveness can be made.

Improved recovery techniques – These techniques

involve the injection of a fluid or fluids into a

reservoir to augment natural reservoir energy.

Because the response of a given reservoir to the

application of an improved recovery technique

cannot be accurately predicted, crude oil

production that may ultimately result from the

application of these techniques is classified as

“indicated additional reserves of crude oil”

rather than as proved reserves until response of

the reservoir to the technique has been

demonstrated. In addition, improved recovery

methods are not applicable to all crude oil

reservoirs. Initiation of improved recovery

techniques may require significant investment.

Infill drilling – Infill drilling (drilling of additional

wells within a field/reservoir) may result in a

higher recovery factor, and, therefore, be

economically justified. Predictions of whether

infill drilling will be justified under current

economic conditions are generally based on the

expected production behavior of the infill wells.

Reservoir limits: The initial proved reserves estimate

made from the discovery well is subject to significant

uncertainty because one well provides little

information on the size of the reservoir. The area

proved by a discovery well is frequently estimated on

the basis of experience in a given producing region.

Where there is continuity of the producing formation

over wide geographic areas, a relatively large proved

area may be assigned. In some cases where reliable

geophysical and geological data are available, a

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report G-7
reasonable estimate of the extent of the reservoir can be

made by drilling a relatively small number of

delineation wells. Conversely, a relatively small

proved area may be assigned when the producing

formation is of limited continuity, owing to either

structural or lithological factors.

Additional wells provide more information and reduce

the uncertainty of the reserves estimate. As additional

wells are drilled, the geometry of the reservoir and,

consequently, its bulk volume, become more clearly

defined. This process accounts for the large extensions

to proved reserves typical of the early stages of most

reservoir development.

Unconventional Production and

Proved Reserves

Last year for the 2006 survey, a new Form EIA-23L data

element called Type Code replaced the underutilized

MMS Code. The Type Code is used to categorize proved

reserves and production from a field as either

Conventional (C) or one of four types of Unconventional

reservoirs: Coal Bed (CB); Chalk (CH); Shale(SH); or other

Low Permeability (LP) reservoirs (permeability of 0.1

millidarcy or less).

Type Code was added because the importance of

unconventional resources of natural gas and crude oil

to domestic energy supply continues to increase.

For the 2007 survey, the data received were considered

incomplete for certain categories of unconventional

proved reserves and production. Only the reported

volumes of coalbed natural gas and shale natural gas

are published in this 2007 report. (see Table 12, Chapter

4).

In future reports, as operators familiarize themselves

with the Type Code, we expect increased coverage and

reliability from the reported volumes.

Energy Information Administration

G-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Appendix H

Fig ure H1. Sub di vi sions of Alaska

Source: Af ter U.S. Geo logi cal Sur vey.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report H-1

Maps of Se lected State Sub di vi sions
Fig ure H2. Sub di vi sions of Cali for nia

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

H-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Fig ure H3. Sub di vi sions of Lou isi ana

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report H-3
Fig ure H4. Sub di vi sions of New Mex ico

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

H-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Fig ure H5. Sub di vi sions of Texas

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report H-5
Fig ure H6. Western Plan ning Area, Gulf of Mex ico Outer Con ti nen tal Shelf Re gion

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

H-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Fig ure H7. Cen tral Plan ning Area, Gulf of Mex ico Outer Con ti nen tal Shelf Re gion

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report H-7
Fig ure H8. East ern Plan ning Area, Gulf of Mex ico Outer Con ti nen tal Shelf Re gion

Source: En ergy In for ma tion Ad min istra tion, Of fice of Oil and Gas.

Energy Information Administration

H-8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report I-1

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE

Figure I1. Form EIA-23, Cover Page

Appendix I

Annual Survey Forms for Domestic Oil and Natural Gas Reserves
Energy Information Administration

I-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure I2. Form EIA-23, Summary Report – Page 1

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report I-3

Figure I3. Form EIA-23, Summary Report – Page 2

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE
Energy Information Administration

I-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure I4. Form EIA-23, Detail Report – Schedule A

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report I-5

Figure I5. Form EIA-23, Detail Report – Schedule B

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE
Energy Information Administration

I-6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report

Figure I6. Form EIA-64A

Source: Energy Information Administration, Offfice of Oil and Gas.

SAMPLE
Glossary

This glossary contains definitions of the technical terms used in this report and employed by respondents in

completing Form EIA--23, “Annual Survey of Domestic Oil and Gas Reserves,” or Form EIA--64A, “Annual

Report of the Origin of Natural Gas Liquids Production,” for the report year 2001.

Acquisitions: The volume of proved reserves gained

by the purchase of an existing fields or properties,

from the date of purchase or transfer.

Adjustments: The quantity which preserves an exact

annual reserves balance within each State or State

subdivision of the following form:

These adjustments are the yearly changes in the

published reserve estimates that cannot be attributed

to the estimates for other reserve change categories

because of the survey and statistical estimation

methods employed. For example, variations as a

result of changes in the operator frame, different

random samples or imputations for missing or

unreported reserve changes, could contribute to

adjustments.

Affiliated (Associated) Company: An “affiliate” of,

or a person “affiliated” with, a specific person is a

person that directly, or indirectly through one or

more intermediaries: controls; or is controlled by; or

is under common control with, the person specified.

(See Person and Control)

Control: The term “control” (including the terms

“controlling,” “controlled by,” and “under common

control with”) means the possession, direct or

indirect, of the power to direct or cause the direction

of the management and policies of a person, whether

through the ownership of voting shares, by contract,

or otherwise. (See Person)

Corrections: (See Revisions)

Crude Oil: A mixture of hydrocarbons that exists in

the liquid phase in natural underground reservoirs

and remains liquid at atmospheric pressure after

passing through surface separating facilities. Crude

oil may also include:

1. Small amounts of hydrocarbons that exist in the

gaseous phase in natural underground

reservoirs but are liquid at atmospheric

pressure after being recovered from oil well

(casinghead) gas in lease separators, and that

subsequently are comingled with the crude

stream without being separately measured

2. Small amounts of nonhydrocarbons produced

with the oil.

When a State regulatory agency specifies a definition

of crude oil which differs from that set forth above,

the State definition is to be followed and its use

footnoted on Schedule B of Form EIA--23.

Extensions: The reserves credited to a reservoir

because of enlargement of its proved area. Normally

the ultimate size of newly discovered fields, or newly

discovered reservoirs in old fields, is determined by

wells drilled in years subsequent to discovery. When

such wells add to the proved area of a previously

discovered reservoir, the increase in proved reserves

is classified as an extension.

Field: An area consisting of a single reservoir or

multiple reservoirs all grouped on, or related to, the

same individual geological structural feature and/or

stratigraphic condition. There may be two or more

reservoirs in a field that are separated vertically by

intervening impervious strata, or laterally by local

geologic barriers, or by both.

Field Area: A geographic area encompassing two or

more pools that have a common gathering and

metering system, the reserves of which are reported

as a single unit. This concept applies primarily to the

Appalachian region. (See Pool)

Field Discovery Year: The calendar year in which a

field was first recognized as containing economically

recoverable accumulations of oil and/or gas.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report Glossary-1

Published Proved Reserves at End of Previous Report Year

+ Adjustments

+ Revision Increases

- Revision Decreases

- Sales

+ Acquisitions

+ Extensions

+ New Field Discoveries

+ New Reservoir Discoveries in Old Fields

- Report Year Production

= Published Proved Reserves at End of Report Year
Field Separation Facility: A surface installation

designed to recover lease condensate from a

produced natural gas stream frequently originating

from more than one lease, and managed by the

operator of one or more of these leases. (See Lease

Condensate)

Gross Working Interest Ownership Basis: Gross

working interest ownership is the respondent's

working interest in a given property plus the

proportionate share of any royalty interest, including

overriding royalty interest, associated with the

working interest. (See Working Interest and Royalty

(including Overriding Royalty) Interest)

Lease Condensate: A mixture consisting primarily of

pentanes and heavier hydrocarbons which is

recovered as a liquid from natural gas in lease or

field separation facilities, exclusive of products

recovered at natural gas processing plants or

facilities.

Lease Separator: A lease separator is a facility

installed at the surface for the purpose of (a)

separating gases from produced crude oil and water

at the temperature and pressure conditions of the

separator, and/or (b) separating gases from that

portion of the produced natural gas stream which

liquefies at the temperature and pressure conditions

of the separator.

Natural Gas: A mixture of hydrocarbon compounds

and small quantities of various nonhydrocarbons

existing in the gaseous phase or in solution with

crude oil in natural underground reservoirs at

reservoir conditions. The principal hydrocarbons

normally contained in the mixture are methane,

ethane, propane, butane, and pentanes. Typical

nonhydrocarbon gases which may be present in

reservoir natural gas are water vapor, carbon

dioxide, helium, hydrogen sulfide, and nitrogen.

Under reservoir conditions, natural gas and the

liquefiable portions occur either in a single gaseous

phase in the reservoir or in solution with crude oil,

and are not distinguishable at the time as separate

substances. (See Natural Gas, Associated--Dissolved

and Natural Gas, Nonassociated)

Natural Gas, Associated--Dissolved: The combined

volume of natural gas which occurs in crude oil

reservoirs either as free gas (associated) or as gas in

solution with crude oil (dissolved).

Natural Gas, “Dry”: The actual or calculated

volumes of natural gas which remain after:

1. The liquefiable hydrocarbon portion has been

removed from the gas stream (i.e., gas after

lease, field, and/or plant separation)

2. Any volumes of nonhydrocarbon gases have

been removed where they occur in sufficient

quantity to render the gas unmarketable.

Natural Gas, Nonassociated: Natural gas not in

contact with significant quantities of crude oil in a

reservoir.

Natural Gas Liquids: Those hydrocarbons in natural

gas which are separated from the gas through the

processes of absorption, condensation, adsorption, or

other methods in gas processing or cycling plants.

Generally such liquids consist of propane and

heavier hydrocarbons and are commonly referred to

as condensate, natural gasoline, or liquefied

petroleum gases. Where hydrocarbon components

lighter than propane are recovered as liquids, these

components are included with natural gas liquids.

Natural Gas Processing Plant: A facility designed to

recover natural gas liquids from a stream of natural

gas which may or may not have passed through

lease separators and/or field separation facilities.

Another function of the facility is to control the

quality of the processed natural gas stream. Cycling

plants are considered natural gas processing plants.

Natural Gas, Wet After Lease Separation: The

volume of natural gas remaining after removal of

lease condensate in lease and/or field separation

facilities, if any, and after exclusion of

nonhydrocarbon gases where they occur in sufficient

quantity to render the gas unmarketable. Natural gas

liquids may be recovered from volumes of natural

gas, wet after lease separation, at natural gas

processing plants. (See Lease Condensate, Lease

Separator, and Field Separation Facility)

Net Revisions: (See Revisions)

New Field: A field discovered during the report

year.

New Field Discoveries: The volumes of proved

reserves of crude oil, natural gas and/or natural gas

liquids discovered in new fields during the report

year.

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Glossary-2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
New Reservoir: A reservoir discovered during the

report year.

New Reservoir Discoveries in Old Fields: The

volumes of proved reserves of crude oil, natural gas,

and/or natural gas liquids discovered during the

report year in new reservoir(s) located in old fields.

Nonproducing Reserves: Quantities of proved

liquid or gaseous hydrocarbon reserves that have

been identified, but which did not produce during

the last calendar year regardless of the availability

and/or operation of production, gathering or

transportation facilities. This includes both proved

undeveloped and proved developed non-producing

reserves.

Old Field: A field discovered prior to the report

year.

Old Reservoir: A reservoir discovered prior to the

report year.

Operator, Gas Plant: The person responsible for the

management and day--to--day operation of one or

more natural gas processing plants as of December

31 of the report year. The operator is generally a

working interest owner or a company under contract

to the working interest owner(s). Plants shut down

during the report year are also to be considered

“operated” as of December 31. (See Person)

Operator, Oil and/or Gas Well: The person

responsible for the management and day--to--day

operation of one or more crude oil and/or natural

gas wells as of December 31 of the report year. The

operator is generally a working interest owner or a

company under contract to the working interest

owner(s). Wells included are those which have

proved reserves of crude oil, natural gas, and/or

lease condensate in the reservoirs associated with

them, whether or not they are producing. Wells

abandoned during the report year are also to be

considered “operated” as of December 31. (See

Person, Proved Reserves of Crude Oil, Proved

Reserves of Natural Gas, Proved Reserves of Lease

Condensate, Report Year, and Reservoir)

Ownership: (See Gross Working Interest

Ownership Basis)

Parent Company: The parent company of a business

entity is an affiliated company which exercises

ultimate control over that entity, either directly or

indirectly through one or more intermediaries. (See

Affiliated (Associated) Company and Control)

Person: An individual, a corporation, a partnership,

an association, a joint--stock company, a business

trust, or an unincorporated organization.

Pool: In general, a reservoir. In certain situations a

pool may consist of more than one reservoir. (See

Field Area)

Plant Liquids: Those volumes of natural gas liquids

recovered in natural gas processing plants.

Production, Crude Oil: The volumes of crude oil

which are extracted from oil reservoirs during the

report year. These volumes are determined through

measurement of the volumes delivered from lease

storage tanks, (i.e., at the point of custody transfer)

with adjustment for (1) net differences between

opening and closing lease inventories, and for (2)

basic sediment and water. Oil used on the lease is

considered production.

Production, Lease Condensate: The volume of lease

condensate produced during the report year. Lease

condensate volumes include only those volumes

recovered from lease or field separation facilities.

(See Lease Condensate)

Production, Natural Gas, Dry: The volume of

natural gas withdrawn from reservoirs during the

report year less (1) the volume returned to such

reservoirs in cycling, repressuring of oil reservoirs

and conservation operations; less (2) shrinkage

resulting from the removal of lease condensate and

plant liquids; and less (3) nonhydrocarbon gases

where they occur in sufficient quantity to render the

gas unmarketable. Volumes of gas withdrawn from

gas storage reservoirs and native gas, which has been

transferred to the storage category, are not

considered production. This is not the same as

marketed production, since the latter also excludes

vented and flared gas, but contains plant liquids.

Production, Natural Gas, Wet after Lease

Separation: The volume of natural gas withdrawn

from reservoirs during the report year less (1) the

volume returned to such reservoirs in cycling,

repressuring of oil reservoirs and conservation

operations; less (2) shrinkage resulting from the

removal of lease condensate; and less (3)

nonhydrocarbon gases where they occur in sufficient

quantity to render the gas unmarketable. Volumes of

gas withdrawn from gas storage reservoirs and

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report Glossary-3
native gas, which has been transferred to the storage

category, are not considered production. This is not

the same as marketed production, since the latter

excludes vented and flared gas.

Production, Natural Gas Liquids: The volume of

natural gas liquids removed from natural gas in lease

separators, field facilities, gas processing plants or

cycling plants during the report year.

Production, Plant Liquids: The volume of liquids

removed from natural gas in natural gas processing

plants or cycling plants during the report year.

Proved Reserves of Crude Oil: Proved reserves of

crude oil as of December 31 of the report year are the

estimated quantities of all liquids defined as crude

oil, which geological and engineering data

demonstrate with reasonable certainty to be

recoverable in future years from known reservoirs

under existing economic and operating conditions.

Reservoirs are considered proved if economic

producibility is supported by actual production or

conclusive formation test (drill stem or wire line), or

if economic producibility is supported by core

analyses and/or electric or other log interpretations.

The area of an oil reservoir considered proved

includes (1) that portion delineated by drilling and

defined by gas--oil and/or oil--water contacts, if any;

and (2) the immediately adjoining portions not yet

drilled, but which can be reasonably judged as

economically productive on the basis of available

geological and engineering data. In the absence of

information on fluid contacts, the lowest known

structural occurrence of hydrocarbons is considered

to be the lower proved limit of the reservoir.

Volumes of crude oil placed in underground storage

are not to be considered proved reserves.

Reserves of crude oil which can be produced

economically through application of improved

recovery techniques (such as fluid injection) are

included in the “proved” classification when

successful testing by a pilot project, or the operation

of an installed program in the reservoir, provides

support for the engineering analysis on which the

project or program was based.

Estimates of proved crude oil reserves do not include

the following: (1) oil that may become available from

known reservoirs but is reported separately as

“indicated additional reserves”; (2) natural gas

liquids (including lease condensate); (3) oil, the

recovery of which is subject to reasonable doubt

because of uncertainty as to geology, reservoir

characteristics, or economic factors; (4) oil that may

occur in undrilled prospects; and (5) oil that may be

recovered from oil shales, coal, gilsonite, and other

such sources. It is not necessary that production,

gathering or transportation facilities be installed or

operative for a reservoir to be considered proved.

Proved Reserves of Lease Condensate: Proved

reserves of lease condensate as of December 31 of the

report year are the volumes of lease condensate

expected to be recovered in future years in

conjunction with the production of proved reserves

of natural gas as of December 31 of the report year,

based on the recovery efficiency of lease and/or field

separation facilities installed as of December 31 of

the report year. (See Lease Condensate and Proved

Reserves of Natural Gas)

Proved Reserves of Natural Gas: Proved reserves of

natural gas as of December 31 of the report year are

the estimated quantities which analysis of geological

and engineering data demonstrate with reasonable

certainty to be recoverable in future years from

known reservoirs under existing economic and

operating conditions.

Reservoirs are considered proved if economic

producibility is supported by actual production or

conclusive formation test (drill stem or wire line), or

if economic producibility is supported by core

analyses and/or electric or other log interpretations.

The area of a gas reservoir considered proved

includes: (1) that portion delineated by drilling and

defined by gas--oil and/or gas--water contacts, if

any; and (2) the immediately adjoining portions not

yet drilled, but which can be reasonably judged as

economically productive on the basis of available

geological and engineering data. In the absence of

information on fluid contacts, the lowest known

structural occurrence of hydrocarbons is considered

to be the lower proved limit of the reservoir.

Volumes of natural gas placed in underground

storage are not to be considered proved reserves.

For natural gas, wet after lease separation, an

appropriate reduction in the reservoir gas volume

has been made to cover the removal of the

liquefiable portions of the gas in lease and/or field

separation facilities and the exclusion of

nonhydrocarbon gases where they occur in sufficient

quantity to render the gas unmarketable.

For dry natural gas, an appropriate reduction in the

gas volume has been made to cover the removal of

the liquefiable portions of the gas in lease and/or

Energy Information Administration

Glossary-4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report
field separation facilities, and in natural gas

processing plants, and the exclusion of

nonhydrocarbon gases where they occur in sufficient

quantity to render the gas unmarketable.

It is not necessary that production, gathering, or

transportation facilities be installed or operative for a

reservoir to be considered proved. It is to be

assumed that compression will be initiated if and

when economically justified.

Proved Reserves of Natural Gas Liquids: Proved

reserves of natural gas liquids as of December 31 of

the report year are those volumes of natural gas

liquids (including lease condensate) demonstrated

with reasonable certainty to be separable in the

future from proved natural gas reserves, under

existing economic and operating conditions.

Proved Ultimate Recovery: The sum of proved

reserves and cumulative production at a specified

point in time. It measures the maximum recoverable

volume known at that time and is a dynamic quantity

that is expected to change over time for any field,

group of fields, State, or Country. In most instances,

therefore, an estimate of Proved Ultimate Recovery

does not represent the all-time maximum recoverable

volume of resources for a given field or area.

Also, the proved ultimate recovery of a field, a group

of fields, a State, or a Country grows (appreciates)

over time in most instances.

Report Year: The calendar year to which data

reported in this publication pertain.

Reserves: (See Proved Reserves)

Reserve Additions: Consist of adjustments, net

revisions, extensions to old reservoirs, new reservoir

discoveries in old fields, and new field discoveries.

Reserves Changes: Positive and negative revisions,

extensions, new reservoir discoveries in old fields,

and new field discoveries, which occurred during the

report year.

Reservoir: A porous and permeable underground

formation containing an individual and separate

natural accumulation of producible hydrocarbons (oil

and/or gas) which is confined by impermeable rock

or water barriers and is characterized by a single

natural pressure system.

Revisions: Changes to prior year--end proved

reserves estimates, either positive or negative,

resulting from new information other than an

increase in proved acreage (extension). Revisions

include increases of proved reserves associated with

the installation of improved recovery techniques or

equipment. They also include correction of prior

report year arithmetical or clerical errors and

adjustments to prior year--end production volumes

to the extent that these alter reported prior year

reserves estimates.

Royalty (Including Overriding Royalty) Interests:

These interests entitle their owner(s) to a share of the

mineral production from a property or to a share of

the proceeds therefrom. They do not contain the

rights and obligations of operating the property, and

normally do not bear any of the costs of exploration,

development, and operation of the property.

Sales: The volume of proved reserves deducted from

an operator’s total reserves when selling an existing

field or property, during the calendar year.

Subdivision: A prescribed portion of a given State

or other geographical region defined in this

publication for statistical reporting purposes.

Subsidiary Company: A company which is

controlled through the ownership of voting stock, or

a corporate joint venture in which a corporation is

owned by a small group of businesses as a separate

and specific business or project for the mutual

benefit of the members of the group. (See Control)

Total Discoveries: The sum of extensions, new

reservoir discoveries in old fields, and new field

discoveries, which occurred during the report year.

Total Liquid Hydrocarbon Reserves: The sum of

crude oil and natural gas liquids reserves volumes.

Total Operated Basis: The total reserves or

production associated with the wells operated by an

individual operator. This is also commonly known as

the “gross operated” or “8/8ths” basis.

Working Interest: A working interest permits the

owner(s) to explore, develop and operate a property.

The working interest owner(s) bear(s) the costs of

exploration, development and operation of the

property, and in return is (are) entitled to a share of

the mineral production from the property or to a

share of the proceeds therefrom.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2007 Annual Report Glossary-5