DOE/EIA–0216(2001)

Distribution Category

UC–950

U.S. Crude Oil, Natural Gas,

and Natural Gas Liquids Reserves

2001 Annual Report

November 2002

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 2001 Annual Report is the 25th

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, 2001, as well as production volumes

for the United States and selected States and State

subdivisions for the year 2001. 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 indicated additional crude

oil reserves and crude oil, natural gas, and lease

condensate reserves in nonproducing reservoirs. A

discussion of notable oil and gas exploration and

development activities during 2001 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 gas proved reserves group for 2001; 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

Kenneth A. Vagts, 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, Dewayne

Cravens, Paul Chapman, and Gwen Cox. 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

Rafi M. Zeinalpour

Phone: 214.720.6191

E–mail: rzeinalp@eia.doe.gov

Fax 214.720.6155

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report iii
Energy Information Administration

iv U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

COVER PHOTO:

We would like to thank Ocean Energy, Incorporated of Houston, Texas for

permission to print an illustration of Ocean’s Nansen Truss Spar, the first of its

kind installed in the world. Construction of the Nansen Truss Spar platform

was completed in 4th quarter of 2001 in the deep water of the East Breaks

region of the Gulf of Mexico. A second Truss Spar platform was installed at

Ocean’s Boomvang Field, also in the East Breaks region. Combined, these

platforms have a production capacity of up to 80,000 barrels of oil and 400

million cubic feet of gas.
Contents

Page

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

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

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

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

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

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 ................................................. 9

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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

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

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

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

New Reservoir Discoveries in Old Fields. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

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

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

Areas of Note: Large Discoveries and Reserve Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Gulf of Mexico Federal Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

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

Areas of Note: Large Reserve Declines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Other Decline Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Reserves in Nonproducing Reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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

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

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

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

Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Sales and Acquisitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Wet Natural Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Nonassociated Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report v
Associated-Dissolved Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Coalbed Methane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Areas of Note: Large Discoveries and Reserves Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Areas of Note: Large Reserves Declines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Reserves in Nonproducing Reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5. Natural Gas Liquids Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Natural Gas Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Discoveries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Revisions and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Sales and Acquisitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Natural Gas Plant Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Lease Condensate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Proved Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Reserves in Nonproducing Reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Appendices

A. Operator Data by Size Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

B. Top 100 Oil and Gas Fields for 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

C. Conversion to the Metric System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

D. Historical Reserves Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

E. Summary of Data Collection Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

F. Statistical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

G. Estimation of Reserves and Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

H. Maps of Selected State Subdivisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

I. Annual Survey Forms for Domestic Oil and Gas Reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Tables

1. U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids, 1991-2001 ............ 4

2. Reserves Changes, 1977-2001 ........................................... 9

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, 1977-2001 . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4. U.S. Exploratory and Development Well Completions, 1970-2001 . . . . . . . . . . . . . . . . . . . . . . . . . 12

Page

5. International Oil and Natural Gas Reserves as of December 31, 2001 . . . . . . . . . . . . . . . . . . . . . . . 18

6. Crude Oil Proved Reserves, Reserves Changes, and Production, 2001 . . . . . . . . . . . . . . . . . . . . . . 22

7. Reported Reserves in Nonproducing Reservoirs for Crude Oil, 2001. . . . . . . . . . . . . . . . . . . . . . . . 27

8. Dry Natural Gas Proved Reserves, Reserves Changes, and Production, 2001 . . . . . . . . . . . . . . . . . . 30

Energy Information Administration

vi U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
9. Natural Gas Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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

Wet After Lease Separation, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

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

Wet After Lease Separation, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

12. U.S. Coalbed Methane Proved Reserves and Production, 1989-2001 . . . . . . . . . . . . . . . . . . . . . . . 37

13. Natural Gas Liquids Proved Reserves, Reserves Changes, and Production, 2001 . . . . . . . . . . . . . . . . 42

14. Natural Gas Plant Liquids Proved Reserves and Production, 2001. . . . . . . . . . . . . . . . . . . . . . . . . 43

15. Lease Condensate Proved Reserves and Production, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Figures

1. U.S. Crude Oil Proved Reserves, 1991-2001 .................................... 5

2. Components of Reserves Changes for Crude Oil, 1991-2001 ........................... 5

3. U.S. Dry Natural Gas Proved Reserves, 1991-2001 ................................ 6

4. Components of Reserves Changes for Dry Natural Gas, 1991-2001 ........................ 6

5. U.S. Natural Gas Liquids Proved Reserves, 1991-2001 .............................. 8

6. Components of Reserves Changes for Natural Gas Liquids, 1991-2001 ...................... 8

7. U.S. Exploratory Gas Well Completions, 1977-2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8. U.S. Exploratory Oil Well Completions, 1977-2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

9. U.S. Total Discoveries of Dry Natural Gas per Exploratory Gas Well Completion, 1977-2001 . . . . . . . . . . . 14

10. U.S. Total Discoveries of Crude Oil per Exploratory Oil Well Completion, 1977-2001 . . . . . . . . . . . . . . . 14

11. Reserves-to-Production Ratios for Crude Oil, 1945-2001. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

12. Reserves-to-Production Ratios for Wet Natural Gas, 1945-2001 . . . . . . . . . . . . . . . . . . . . . . . . . . 16

13. Components of Ultimate Recovery for Crude Oil and Lease Condensate, 1977-2001 . . . . . . . . . . . . . . . 17

14. Components of Ultimate Recovery for Wet Natural Gas, 1977-2001 . . . . . . . . . . . . . . . . . . . . . . . . 17

15 Reserve Additions Replace 121 Percent of 2001 U.S. Crude Oil Production . . . . . . . . . . . . . . . . . . . . 21

16. 2001 Crude Oil Proved Reserves by Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

17. Changes in Crude Oil Proved Reserves by Area, 2000 to 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . 23

18. Reserve Additions Replace 131 Percent of 2001 U.S. Dry Gas Production . . . . . . . . . . . . . . . . . . . . 29

19. 2001 Dry Natural Gas Proved Reserves by Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

20. Changes in Dry Natural Gas Proved Reserves by Area, 2000 to 2001 . . . . . . . . . . . . . . . . . . . . . . . 31

21. Coalbed Methane Proved Reserves, 1989-2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report vii
Executive Summary:

U.S. Crude Oil, Natural Gas, and

Natural Gas Liquids Reserves 2001 Annual Report

U.S. crude oil and natural gas proved reserves

increased in 2001, replacing production by

substantial margins. One new deepwater field

accounted for a significant portion of all new oil

reserves. Thunder Horse Field is located in

Mississippi Canyon Blocks 776, 777, and 778, 125

miles south-east of New Orleans at a water depth of

6,000 feet. After full development, Thunder Horse is

expected to be the largest field in the Gulf of Mexico.

Developing this field in water over a mile deep will

be another technical achievement in the Federal

Offshore.

U.S. crude oil proved reserves increased by almost 2

percent. Reserves additions in 2001 were 121 percent

of domestic oil production. From 1977 through 1996,

proved reserves of crude oil declined 17 out of 19

years. In striking contrast, they increased 4 out of the

last 5 years. New field discoveries of oil in 2001 were

at the highest level since Alaska’s Prudhoe Bay Field

was booked in the 1970s. The majority of crude oil

proved reserves additions came from the deepwater

Gulf of Mexico Federal Offshore and Alaska, both of

which are frontier areas.

The majority of natural gas proved reserves

additions were in Wyoming, Colorado, and Texas.

Significant reserves were added in the Powder River

Basin coalbed methane fields and the Pinedale Field

in Wyoming, the Lobo Trend and Barnett Shale gas

fields in Texas, and the Wattenberg Field and the

coalbed methane fields in Colorado.

Natural gas liquids reserves decreased in 2001.

Usually, when gas reserves increase, the natural gas

liquids associated with that gas also increase.

However, coalbed methane was a large portion of

the new gas reserves in 2001, and coalbed methane

has effectively no natural gas liquids content. As a

result, reserves of natural gas liquids declined in

2001 when production outpaced reserves additions in

conventional gas reservoirs.

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. Petroleum engineering and

geological judgment are required in estimating

proved reserves, therefore the results are not precise

measurements. This report of 2001 U.S. proved

reserves of crude oil, natural gas, and natural gas

liquids is the 25th in an annual series prepared by

the Energy Information Administration.

Crude Oil

Total discoveries of crude oil in 2001 resulted mainly

from exploration in the deepwater Gulf of Mexico

Federal Offshore and on the Alaskan North Slope.

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 2,565 million barrels in 2001, almost

twice the year 2000 discoveries and greater than

three times the prior 10-year average.

The majority of crude oil total discoveries in 2001

were new field discoveries, particularly in the Gulf of

Mexico Federal Offshore and Alaska. Operators

discovered 1,407 million barrels in new fields in 2001

-- four times as much as in 2000 and over six times as

much as the prior 10-year average.

Extensions to existing fields accounted for 866

million barrels of crude oil reserves additions. This

was a 13 percent increase over 2000 extensions, and

almost twice as much as the prior 10-year average.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report ix

As of December 31, 2001 proved reserves were:

Crude Oil (million barrels)

2000 22,045

2001 22,446

Increase 1.8%

Dry Natural Gas (billion cubic feet)

2000 177,427

2001 183,460

Increase 3.4%

Natural Gas Liquids (million barrels)

2000 8,345

2001 7,993

Decrease -4.2%
New reservoir discoveries in old fields were 292

million barrels, 17 percent more than in 2000 and 93

percent more than the prior 10-year average.

Reserves additions are the sum of total discoveries,

revisions and adjustments, and sales and

acquisitions. The net of revisions and adjustments

was a very small component of crude oil reserves

additions in 2001 (-162 million barrels). In past years,

net revisions and adjustments have been as much as

54 percent of annual crude oil reserves additions.

The sales component of the crude oil reserves

changes (529 million barrels) was less than the

revision decreases component in 2001 and

acquisitions (442 million barrels) were less than

revision increases. The net of sales and acquisitions

of crude oil proved reserves was -87 million barrels.

Other 2001 crude oil events of note:

• The annual average domestic first purchase

price for crude oil decreased 18 percent from

the 2000 level to $21.84 per barrel.

• Exploratory and developmental oil completions

were up 8 percent from 2000.

• In May 2000, BP Amoco contracted Mustang

Engineering to provide preliminary front-end

engineering/design services for topside

facilities to produce Thunder Horse Field. It

will be developed in a phased approach. Initial

production is expected by 2005 from a floating

production facility that will be capable of

producing 250,000 barrels of oil per day.

Natural Gas

Operators added 3.4 percent to proved reserves of

dry natural gas in 2001. Reserves additions were 131

percent of domestic dry natural gas production. U.S.

natural gas proved reserves have increased in seven

of the last eight years. Most of the reserve increases

were in Texas, Wyoming, and Colorado. The Gulf of

Mexico and New Mexico had a slight increase, and

Oklahoma had a slight decrease.

U.S. total discoveries of dry gas reserves were 22,758

billion cubic feet in 2001. This was 96 percent more

than the prior 10-year average and 19 percent more

than in 2000.

New field discoveries were 3,578 billion cubic feet, 80

percent more than the volume discovered in 2000

and 140 percent more than the prior 10-year average.

Field extensions were 16,380 billion cubic feet, 11

percent more than extensions in 2000 and also more

than twice the prior 10-year average of 7,802 billion

cubic feet.

New reservoir discoveries in old fields were 2,800

billion cubic feet, up 18 percent from 2000 and 20

percent more than the prior 10-year average.

Natural gas net revisions and adjustments were 424

billion cubic feet. The net of sales and acquisitions of

dry natural gas proved reserves was 2,630 billion

cubic feet.

Coalbed methane proved reserves and production

continued to grow in 2001. Coalbed methane

accounted for 9.6 percent of proved dry gas reserves

and 7.9 percent of dry gas production.

Other 2001 natural gas events of note:

• Natural gas prices were up 12 percent in 2001

to an average of $4.12 per thousand cubic feet

(MCF) at the wellhead, as compared to $3.69

per MCF in 2000. However, the prices started

high in January 2001 ($8.06 per MCF) and

declined to an annual low of $2.38 per MCF in

December.

• Exploratory gas well completions increased 54

percent in 2001 and development well drilling

was up 39 percent. Operators drilled 25 percent

more wells for gas in 2001 than in 2000.

• U.S. gas production increased by 2 percent in

2001 to the highest level since 1977, the year

EIA initiated its proved reserves report series.

Natural Gas Liquids

U.S. natural gas liquids proved reserves decreased

4.2 percent to 7,993 million barrels in 2001. Natural

gas liquids reserves are the sum of natural gas plant

liquids and lease condensate reserves.

Total proved reserves of liquid hydrocarbons (crude

oil plus natural gas liquids) were 30,439 million

barrels in 2001, a slight increase from the 2000 level.

Natural gas liquids represented 26 percent of total

liquid hydrocarbon proved reserves in 2001.

Data

These estimates are based upon analysis of data from

Form EIA-23, Annual Survey of Domestic Oil and

Gas Reserves, filed by 1,439 operators of oil and gas

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

Origin of Natural Gas Liquids Production, filed by

operators of 525 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.

Energy Information Administration

x U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
1. Introduction

Background

The principal focus of this report is to provide 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 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 with how

reserves fit in the description of overall oil and gas

resources should see Appendix G.

This report provides proved reserves estimates for

calendar year 2001. 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

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 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-23 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 were 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 were estimated using statistical

calculations that preserved 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. Details on the selection of these

operators and the determination of the reserves

volumes is found in Appendix F.

The published reserve estimates include an additional

term, adjustments, calculated by the EIA, that

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 1
preserves an exact annual reserves balance of the form:

Adjustments are the annual changes in the published

reserve estimates that cannot be attributed to the

estimates for 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-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 22,519 probable active operators and the

Form EIA-64A plant frame contained 525 probable

active natural gas processing plants in the United

States when the 2001 surveys were initiated. As usual,

additional operators were added to the survey as it

progressed, and many operators initially in the sample

frame were found to be inactive in 2001.

For the report year 2001, EIA mailed 672 EIA-23 forms

to known large and intermediate size oil and gas well

operators that were believed to be active during 2001.

Eight (8) of the 672 companies were additions or new

companies. Thirty-nine (39) of the 672 ceased operating

oil and/or gas properties (became non-operator) during

the survey year. In addition, 40 of the 672 operators

were reduced in size from Category I or II to Category

III. An additional 18 companies (over and above the

672) increased in size from Category III to Category II.

EIA mailed 525 EIA-64A forms to natural gas

processing plant operators. More than one form is

received for a plant that has more than one operator

during the year. Forms were received from 100 percent

of the operators of the 525 unique active natural gas

processing plants in the Form EIA-64A survey.

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 2001,

the Form EIA-23 National production estimates were

less than 1 percent higher than the comparable

Petroleum Supply Annual (PSA) 2001 volumes for crude

oil and lease condensate combined, and were less than

2 percent higher than the comparable Natural Gas

Monthly, October 2002 volume for 2001 dry natural gas.

For report year 2001, the Form EIA-64A National

estimates were less than 2 percent lower than the PSA

2001 volume for natural gas plant liquids production.

Accuracy in reserves reporting is EIA’s first and

foremost goal for this report. Estimates of production

within this report may differ from those made

specifically to estimate oil or gas production like those

in the PSA.

Energy Information Administration

2 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 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, 2001:

 Crude Oil — 22,446 million barrels

 Dry Natural Gas — 183,460 billion cubic feet

 Natural Gas Liquids — 7,993 million barrels.

This Overview summarizes the 2001 proved reserves

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

liquids on a National level and provides historical

comparisons between 2001 and prior years. Table 1 lists

the estimated annual reserve balances since 1991 for

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

Crude Oil

Proved reserves of crude oil increased by 401 million

barrels in 2001. Figure 1 shows the crude oil proved

reserves levels by major region and Figure 2 shows the

components of reserves changes from 1991 through

2001.

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

increased in 2001 due to reserves additions in the

Lower 48 States offshore.

The components of reserves changes for crude oil are

shown in Figure 2. EIA tracks the 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

2,565 million barrels in 2001, over three times the prior

10-year average (813 million barrels) and almost twice

those in 2000 (1,291 million barrels).

Most crude oil total discoveries in 2001 were from new

field discoveries, rather than extensions to existing fields.

New fields accounted for 1,407 million barrels of crude

oil reserves additions. This was over five times the

volume of 2000 new field discoveries(276 million barrels).

Extensions of 866 million barrels were 13 percent higher

than those of 2000 (766 million barrels) and almost

twice the prior 10-year average (438 million barrels).

New reservoir discoveries in old fields were 292 million

barrels, 17 percent more than in 2000 (249 million

barrels) and 93 percent more than the prior 10-year

average (152 million barrels).

Reserves additions are the sum of total discoveries,

revisions and adjustments, and sales and acquisitions.

In 2001, there were -4 million barrels of adjustments,

1,601 million barrels of revision increases and 1,759

million barrels of revision decreases. The 2001 net of

revisions and adjustments was -162 million barrels.

The sales component of the crude oil reserves changes

(529 million barrels) was smaller than the revision

decreases component in 2001, and acquisitions (442

million barrels) were smaller than revision increases. The

net of sales and acquisitions of crude oil proved

reserves was -87 million barrels.

Production of crude oil was an estimated 1,915 million

barrels in 2001 (lease condensate not included, see

Natural Gas Liquids section below for condensate

volumes). This was up 2 percent from 2000’s level (1,880

million barrels) and down 13 percent from the prior

10-year average (2,191 million barrels). Operators

replaced 121% of crude oil production with reserves

additions in 2001.

Natural Gas

Dry natural gas proved reserves increased by 6,033

billion cubic feet in 2001. Figure 3 shows the dry

natural gas proved reserves levels by major region.

Figure 4 shows the components of reserves changes

from 1991 through 2001.

U.S. total discoveries of dry gas reserves were 22,758

billion cubic feet in 2001. This was almost twice the

prior 10-year average (11,608 billion cubic feet) and 19

percent more than in 2000 (19,138 billion cubic feet).

Field extensions were 16,380 billion cubic feet, 11

percent more than the extensions in 2000 and also more

than twice the prior 10-year average of 7,802 billion

cubic feet.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 3
Energy Information Administration

4 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table 1. Total U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids, 1990-2000

Revisionsa Net of Sales New Reservoir Provedc Change Net and and New Field Discoveries Totalb 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)

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 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

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

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

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

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 -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

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

bTotal discoveries = Col. 5 + Col. 6 + Col. 7. cProved 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

2001 contained in the Petroleum Supply Annual 2001, DOE/EIA-0340(01) and the Natural Gas Annual 2001, DOE/EIA-0131(01).
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 5

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1991-2001 annual reports, DOE/EIA-0216.{14-24}

-3

-2

-1

0

1

2

3

4

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Crude Oil, Billion Barrels

-3

-2

-1

0

1

2

3

4

Extensions New Fields New Reservoirs

Production Net Revisions & Adjustments Net Acquisitions & Sales

Net Reserves Changes

Figure 2. Components of Reserves Changes for Crude Oil, 1991-2001

0

5

10

15

20

25

30

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Crude Oil, Billions of Barrels

0

5

10

15

20

25

30

U.S. Total

Lower 48 Onshore

Lower 48 Offshore

Alaska

Figure 1. U.S. Crude Oil Proved Reserves, 1991-2001
Energy Information Administration

6 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Figure 4. Components of Reserves Changes for Dry Natural Gas, 1991-2001

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1990-2000 annual reports, DOE/EIA-0216.{14-24}

Figure 3. U.S. Dry Natural Gas Proved Reserves, 1991-2001

-30

-15

0

15

30

45

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Dry Natural Gas, Trillion Cubic Feet

-30

-15

0

15

30

45

Extensions New Fields New Reservoirs

Production Net Revisions & Adjustments Net Acquisitions & Sales

Net Reserves Changes

0

20

40

60

80

100

120

140

160

180

200

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Dry Natural Gas, Trillion Cubic Feet

0

20

40

60

80

100

120

140

160

180

200

U.S. Total

Lower 48 Onshore

Lower 48 Offshore

Alaska
New field discoveries were 3,578 billion cubic feet, 80

percent more than the volume discovered in 2000 (1,983

billion cubic feet) and more than twice the prior 10-year

average (1,471 billion cubic feet).

New reservoir discoveries in old fields were 2,800 billion

cubic feet, up 18 percent from 2000 (2,368 billion cubic

feet) and 20 percent more than the prior 10-year

average (2,334 billion cubic feet).

Natural gas net revisions and adjustments were 424

billion cubic feet. The net of sales and acquisitions of dry

natural gas proved reserves was 2,630 billion cubic feet.

Production removed an estimated 19,779 billion cubic

feet of proved reserves from the National total. Dry gas

production increased by 3 percent compared to 2000.

Operators replaced 131 percent of dry natural gas

production with reserves additions.

Coalbed methane production and reserves are

included in the 2001 totals. However, EIA tracks these

reserves in order to record the development and

performance of this gas source. Coalbed methane

proved reserves increased in 2001 to a volume of 17,531

billion cubic feet. Coalbed methane accounted for 9.5

percent of 2001 U.S. dry natural gas reserves and 8

percent of 2001 U.S. dry gas production.

Natural Gas Liquids

Proved reserves of natural gas liquids decreased 352

million barrels to 7,993 million barrels during 2001— a

4 percent decrease from 2000 levels. Figure 5 shows the

natural gas liquids proved reserves levels by major

region and Figure 6 shows the components of reserves

changes from 1991 through 2001.

Operators replaced 60 percent of their 2001 natural gas

liquids production with reserve additions. Total

discoveries added 997 million barrels (primarily from

extensions), net revisions and adjustments subtracted 561

million barrels, and net sales and acquisitions added 102

million barrels.

Total proved reserves of liquid hydrocarbons (crude oil

plus natural gas liquids) were 30,439 million barrels in

2001—a slight increase from the 2000 level. Natural gas

liquids represented 26 percent of total liquid

hydrocarbon proved reserves in 2001.

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 2001. Table 2 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 2001 proved reserves estimates as a

means of gauging the past year against history.

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

 discovered an average of 890 million barrels per

year of new reserves

 had proved reserves additions of an average

2,133 million barrels per year from total

discoveries, net revisions and adjustments, and net

sales and acquisitions.

 ended each year with an average net reduction

in U.S. proved reserves of 442 million barrels

(the difference between post-1976 average

annual production and post-1976 average

annual reserve additions) because production

has outpaced reserve additions.

Since 1977, crude oil reserves have been primarily

sustained by proved ultimate recovery appreciation in

existing fields rather than the discovery of new oil

fields. Only 11 percent of reserves additions since 1976

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 22,249 million barrels of total discoveries

accounted for 42 percent of reserves additions.

Compared to the averages of reserves changes since

1977, 2001 was a major up year for crude oil discoveries.

Total discoveries of crude oil (2,565 million barrels) in

2001 were almost three times greater than the post-1976

U.S. average (890 million barrels per year).

Looking at the components of total discoveries in 2001:

 2001’s new field discoveries greatly exceeded the

post-1976 average. New field discoveries in 2001

accounted for 55 percent of reserves additions,

and were 6 times larger than the historical

average, and

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 7
Energy Information Administration

8 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Figure 5. U.S. Natural Gas Liquids Proved Reserves, 1991-2001

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1990-2000 annual reports, DOE/EIA-0216.{14-24}

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Natural Gas Liquids, Billion Barrels

Extensions New Fields New Reservoirs

Production Net Revisions & Adjustments Net Sales & Acquisitions

Net Reserves Changes

Figure 6. Components of Reserves Changes for Natural Gas Liquids, 1991-2001

0

1

2

3

4

5

6

7

8

9

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Natural Gas Liquids, Billion Barrels

0

1

2

3

4

5

6

7

8

9

U.S. Total

Lower 48 Onshore

Lower 48 Offshore

Alaska
 extensions and new reservoir discoveries in old fields

exceeded the post-1976 averages for crude oil.

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

 discovered an average of 12,691 billion cubic

feet per year of new reserves,

 had proved reserves additions of an average

16,681 billion cubic feet per year from total

discoveries, net revisions and adjustments, and net

sales and acquisitions, and

 had an average net reduction in U.S. reserves of

1,193 billion cubic feet per year.

Like crude oil reserves, natural gas reserves have been

sustained primarily by proved ultimate recovery

appreciation since 1977. Usually extensions rather than

net revisions and adjustments are the largest component.

Extensions account for 49 percent while net revisions and

adjustments account for only 24 percent of all reserves

additions since 1977. In 2001, net revisions, adjustments,

sales, and acquisitions were 12 percent of all reserves

additions. In 2001, extensions were 63 percent of all

reserves additions.

Compared to the averages of reserves changes since

1977, 2001 was an up year for natural gas reserves

additions from total discoveries. Operators reported

22,758 billion cubic feet of total discoveries of dry natural

gas proved reserves, 79 percent more than the

post-1976 average (12,691 billion cubic feet). Also, the

net of revisions, adjustments, sales, and acquisitions was

23 percent lower in 2001 (3,054 billion cubic feet)

compared to the post-1976 U.S. average (3,990 billion

cubic feet per year).

Economics and Drilling

Economics: This section describes the price behavior in

2001 and the following section addresses drilling.

Table 3 lists the average annual domestic wellhead

prices of crude oil and natural gas, as well as the

average number of active rotary drilling rigs, from 1977

to 2001.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 9

Table 2. Reserves Changes, 1977-2001

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 ........... 4,687 187 10.8 5,638 226 10.6

New Reservoir Discoveries in Old Fields . . 3,593 144 8.3 3,715 149 7.0

Extensions ................ 11,365 455 26.3 12,896 516 24.2

Total Discoveries ............. 19,645 786 45.4 22,249 890 41.7

Revisions, Adjustments, Sales & Acquisitions 23,642 946 54.6 31,078 1,243 58.3

Total Reserves Additions ......... 43,287 1,731 100.0 53,327 2,133 100.0

Production ................ 50,556 2,022 116.8 64,383 2,575 120.7

Net Reserves Change ........... -7,269 -291 -16.8 -11,056 -442 -20.7

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 ........... 49,636 1,985 11.5 49,858 1,994 12.0

New Reservoir Discoveries in Old Fields . . 63,624 2,545 14.7 64,029 2,561 15.4

Extensions ................ 200,455 8,018 46.4 203,382 8,135 48.8

Total Discoveries ............. 313,715 12,549 72.7 317,269 12,691 76.1

Revisions, Adjustments, Sales & Acquisitions 118,030 4,721 27.3 99,756 3,990 23.9

Total Reserves Additions ......... 431,745 17,270 100.0 417,025 16,681 100.0

Production ................ 437,923 17,517 101.4 446,843 17,874 107.2

Net Reserves Change ........... -6,178 -247 -1.4 -29,818 -1,193 -7.2

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 1977-2001 annual reports, DOE/EIA-0216.{1-24}
Energy Information Administration

10 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 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, 1977-2001

Crude Oil Natural Gas

Year Current 2001 Constant Current 2001 Constant

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

1977 8.57 20.83 0.79 1.92 2,001

1978 9.00 20.42 0.91 2.06 2,259

1979 12.64 26.48 1.18 2.47 2,177

1980 21.59 41.41 1.59 3.05 2,909

1981 31.77 55.74 1.98 3.47 3,970

1982 28.52 47.10 2.46 4.06 3,105

1983 26.19 41.61 2.59 4.11 2,232

1984 25.88 39.64 2.66 4.07 2,428

1985 24.09 35.77 2.51 3.73 1,980

1986 12.51 18.17 1.94 2.82 964

1987 15.40 21.72 1.67 2.36 936

1988 12.58 17.16 1.69 2.31 936

1989 15.86 20.84 1.69 2.22 869

1990 20.03 25.33 1.71 2.16 1,010

1991 16.54 20.18 1.64 2.00 860

1992 15.99 19.05 1.74 2.07 721

1993 14.25 16.58 2.04 2.37 754

1994 13.19 15.03 1.85 2.11 775

1995 14.62 16.31 1.55 1.73 723

1996 18.46 20.20 2.17 2.37 779

1997 17.23 18.49 2.32 2.49 943

1998 10.87 11.52 1.96 2.08 827

1999 15.56 16.26 2.19 2.29 625

2000 January 23.53 24.33 2.60 2.69 775

February 25.48 26.28 2.73 2.82 763

March 26.19 26.96 2.66 2.74 773

April 23.20 23.83 2.86 2.94 805

May 25.58 26.23 3.04 3.12 844

June 27.62 28.28 3.77 3.86 878

July 26.81 27.43 3.84 3.93 942

August 27.91 28.51 3.73 3.81 987

September 29.72 30.31 4.26 4.34 1,011

October 29.65 30.20 4.58 4.66 1,055

November 30.36 30.86 4.40 4.47 1,067

December 24.46 24.80 5.77 5.85 1,097

2000 26.72 27.35 3.69 3.78 918

2001 January 24.58 24.82 8.06 8.14 1,118

February 25.27 25.44 5.84 5.88 1,136

March 23.02 23.12 5.15 5.17 1,166

April 23.41 23.48 5.21 5.22 1,206

May 24.06 24.08 4.56 4.56 1,234

June 23.43 23.41 3.88 3.88 1,270

July 22.94 22.85 3.39 3.38 1,278

August 23.08 22.97 3.23 3.21 1,252

September 22.37 22.26 2.55 2.54 1,193

October 18.73 18.67 2.40 2.39 1,111

November 16.49 16.44 2.74 2.73 1,000

December 15.54 15.48 3.93 3.92 901

2001 21.84 21.84 4.12 4.12 1,155

=Revised data.

Sources: Current dollars and number of rigs: Monthly Energy Review October 2002, DOE/EIA-0035(2001/10). 2001 constant dollars:

U.S. Department of Commerce, Bureau of Economic Analysis, Gross Domestic Product Implicit Price Deflators, October 2002.
The U.S. crude oil first purchase price started at an

average of $24.46 per barrel in December 2000, rose to

$25.27 in February 2001, then declined to $15.54 per

barrel in December 2001. The average U.S. crude oil

first purchase price decreased from $26.72 in 2000 to

$21.84 per barrel in 2001.

Oil prices vary by region. In Texas the average 2001

crude oil first purchase price was $23.41 per barrel,

$20.11 per barrel in California, $24.82 per barrel in

Colorado, $22.55 per barrel in Ohio, and $18.38 per

barrel in the California Federal Offshore. The lowest

average crude oil first purchase price in 2001 was

$18.18 per barrel for the Alaska North Slope oil.{25}

The average annual wellhead natural gas price

increased from $3.69 in 2000 to $4.12 per thousand

cubic feet in 2001. Natural gas prices started at $8.06 per

thousand cubic feet in January 2001 and declined to

$3.93 per thousand cubic feet by December 2001. The

lowest average price of the year was $2.40 per thousand

cubic feet in October 2001. {26}

Drilling: From 2000 to 2001, the annual average active

rig count increased from 918 to 1,155 (Table 3), a 26

percent increase in active rigs.

Looking first at exploratory wells, there were 2,715

exploratory wells drilled in 2001 (Table 4). Of these, 11

percent were completed as oil wells, 35 percent were

completed as gas wells, and 54 percent were dry holes.

The total (which includes dry holes) was 26 percent

more than the revised 2000 total. Exploratory oil and

gas completions in 2001 were 36 percent higher

(Figures 7 and 8) than in 2000.

Figures 9 and 10 show the average volume of

discoveries per exploratory well for dry natural gas and

oil, respectively, since 1977. The average volume of oil

discoveries per exploratory well increased significantly

in 2001. The 2001 average volume of gas discoveries

per exploratory well decreased, as would be expected

given the large increase in the number of wells drilled

in search of gas.

The numbers of successful development wells

increased 10 percent for oil and 34 percent for gas from

their 2000 levels. Altogether there were an estimated

34,139 exploratory and development wells drilled in

2001. This is 23 percent more than in 2000 and 43

percent more than the average number of wells drilled

annually in the prior 10 years (23,914).

For the ninth 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 were announced in 2001,

and are expected to have a major impact on the energy

industry in the future:

On August 1, 2001, Kerr-McGee Corporation

announced completion of its acquisition of HS

Resources, Incorporated. Through this transaction

Kerr-McGee will acquire proved reserves of 1.3 trillion

cubic feet of natural gas equivalent, and gas gathering

systems, undeveloped acreage and other assets valued

at approximately $300 million. The acquired reserves

are predominately natural gas located in northeastern

Colorado in the Denver-Julesburg Basin. {27}

On September 10, 2001, Dominion and Louis Dreyfus

Natural Gas Corporation jointly announced that

Dominion agreed to acquire Louis Dreyfus Natural

Gas for $2.3 billion in cash, stock and assumed debt.

On November 1, 2001, the transaction was completed.

{28}

On October 9, 2001, Chevron Corporation and Texaco

Incorporated announced that their merger had been

completed following stockholder approvals. The new

company changed its name to ChevronTexaco

Corporation. {29}

On November 18, 2001, Conoco Incorporated and

Phillips Petroleum Company announced their

intention to merge and filed a joint proxy

statement/prospectus with the Securities and Exchange

Commission. {30}

In December 2001, Unocal announced a 50-50 venture

with Forest Oil Corporation for exploration and

production operations in the Gulf of Mexico. {31}

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 2001 Annual Report 11
Energy Information Administration

12 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table 4. U.S. Exploratory and Development Well Completions,a 1970-2001

Exploratory Total Exploratory and Development

Year Oil Gas Dry Total Oil Gas Dry Total

1970 763 478 6,193 7,434 13,043 4,031 11,099 28,173

1971 664 472 5,995 7,131 11,903 3,983 10,382 26,268

1972 690 659 6,202 7,551 11,437 5,484 11,013 27,934

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 1,764 2,081 9,039 12,884 32,639 17,333 20,638 70,610

1981 2,636 2,514 12,349 17,499 43,598 20,166 27,789 91,553

1982 2,431 2,125 11,247 15,803 39,199 18,979 26,219 84,397

1983 2,023 1,593 10,148 13,764 37,120 14,564 24,153 75,837

1984 2,198 1,521 11,278 14,997 42,605 17,127 25,681 85,413

1985 1,679 1,190 8,924 11,793 35,118 14,168 21,056 70,342

1986 1,084 793 5,549 7,426 19,097 8,516 12,678 40,291

1987 925 754 5,049 6,728 16,164 8,055 11,112 35,331

1988 855 732 4,693 6,280 13,636 8,555 10,041 32,232

1989 607 705 3,924 5,236 10,204 9,539 8,188 27,931

1990 654 689 3,715 5,058 12,198 11,044 8,313 31,555

1991 592 534 3,314 4,440 11,770 9,526 7,596 28,892

1992 493 423 2,513 3,429 8,757 8,209 6,118 23,084

1993 502 548 2,469 3,519 8,407 10,017 6,328 24,752

1994 570 726 2,405 3,701 6,721 9,538 5,307 21,566

1995 542 570 2,198 3,310 7,627 8,354 5,075 21,056

1996 483 570 2,136 3,189 8,314 9,302 5,282 22,898

1997 428 536 2,110 3,074 10,436 11,327 5,702 27,465

1998 R 291 R 504 R 1,647 R 2,442 7,064 R 11,308 R 4,840 R 23,212

1999 R 154 R 530 R 1,195 R 1,879 4,136 R 10,877 R 3,364 R 18,377

2000 R 261 R 609 R 1,288 R 2,158 R 7,358 R 16,455 R 4,025 R 27,838

2001 310 961 1,444 2,715 8,060 22,083 3,996 34,139

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

Sources: Years 1970-1972: Energy Information Administration, Office of Oil and Gas. Years 1973-2000: EIA Monthly Energy Review

October 2002, DOE/EIA-0035(2002/10).
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 13

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

0

500

1,000

1,500

2,000

2,500

3,000

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Exploratory Gas Wells

0

500

1,000

1,500

2,000

2,500

3,000

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Exploratory Oil Wells

Figure 7. U.S. Exploratory Gas Well Completions, 1977-2001

Figure 8. U.S. Exploratory Oil Well Completions, 1977-2001
Energy Information Administration

14 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

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

0

5

10

15

20

25

30

35

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Billion Cubic Feet Discovered per Exploratory Well

0

1

2

3

4

5

6

7

8

9

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Million Barrels Discovered per Exploratory Oil Well

Figure 9. U.S. Total Discoveries of Dry Natural Gas per Exploratory Gas Well Completion, 1977-2001

Figure 10. U.S. Total Discoveries of Crude Oil per Exploratory Oil Well Completion, 1977-2001
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 an 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, the U.S. R/P ratio for crude oil increased

because significant production from these reserves did

not begin until 7 years after booking due to the need to

first build the Trans Alaska pipeline. 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 oil

production reached high levels.

In 2001, U.S. crude oil proved reserves and oil

production increased, resulting in no significant

change to the National average R/P ratio of 11.7.

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 2001 National

average R/P ratio for crude oil was 11.7-to-1. Areas with

relatively high R/P ratios are the Permian Basin of Texas

and New Mexico, and California, where enhanced oil

recovery techniques such as carbon dioxide (CO2)

injection or steamflooding have improved

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 have helped

add 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 well

developed. The market for natural gas grew rapidly

after World War II, lowering the R/P ratio. From 2000 to

2001 the U.S. average R/P ratio for natural gas remained

unchanged from 9.2 since both proved reserves and

production increased in 2001.

Different marketing, transportation, and production

characteristics for gas are seen when looking at

regional average R/P ratios, compared to the 2001 U.S.

average R/P ratio of about 9.2-to-1. Areas with a higher

range of R/P ratios than the National average were the

Pacific offshore and the Rockies, and also include areas

such as Alabama and Colorado where considerable

booking of coalbed methane reserves has recently

occurred. 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

EIA has in past reports defined Ultimate Recovery as

the sum of proved reserves and cumulative

production. However, despite EIA’s definition, the

volume presented by EIA has often been

misinterpreted as the maximum recoverable volume of

resources for an area. This neglects the addition of

proved reserves over time through ultimate recovery

appreciation (a.k.a. reserves growth or field growth)

and has led some to make overly-pessimistic resource

assessments for the United States. EIA therefore

introduced the term, Proved Ultimate Recovery:

Proved Ultimate Recovery is the sum of

proved reserves and cumulative production. It is

expected to change over time for any field, group

of fields, State, or Country. Proved Ultimate

Recovery does not represent the maximum

recoverable volume of resources for an area. It is

instead a gauge of how much has already been

produced plus proved reserves. Proved reserves

of crude oil or natural gas are the estimated

quantities of petroleum which 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.

Figures 13 and 14 show successive estimates of proved

ultimate recovery and its components (proved reserves

and cumulative production) for both crude oil plus lease

condensate and wet natural gas, over the period 1977

through 2001. They illustrate the continued

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 15
Energy Information Administration

16 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Sources: Annual reserves and production - American Petroleum Institute and American Gas Association (1945–1976) {32} and Energy

Information Administration, Office of Oil and Gas (1977–2000){1-24}. Cumulative production: U.S. Oil and Gas Reserves by Year of Field

Discovery (1977-1988).{33}

0

5

10

15

20

25

30

35

45 50 55 60 65 70 75 80 85 90 95 00

R/P Ratio

United States

Lower 48 States

0

5

10

15

20

25

30

35

45 50 55 60 65 70 75 80 85 90 95 00

R/P Ratio

United States

Lower 48 States

Figure 11. Reserves-to-Production Ratios for Crude Oil, 1945-2001

Figure 12. Reserves-to-Production Ratios for Wet Natural Gas, 1945-2001
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 17

Sources: Annual reserves and production - American Petroleum Institute and American Gas Association (1945–1976) {32} and Energy

Information Administration, Office of Oil and Gas (1977–2000){1-24}. Cumulative production: U.S. Oil and Gas Reserves by Year of Field

Discovery (1977-1988).{33}

0

50

100

150

200

250

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Billions of Barrels

Cumulative Production

Proved Reserves

Ultimate Recovery

0

200

400

600

800

1,000

1,200

1,400

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

Trillions of Cubic Feet

Cumulative Production

Proved Reserves

Ultimate Recovery

Figure 13. Components of Proved Ultimate Recovery for Crude Oil and Lease Condensate, 1977-2001

Figure 14. Components of Proved Ultimate Recovery for Wet Natural Gas, 1977-2001
Table 5. International Oil and Natural Gas Reserves as of December 31, 2001

Oil

(million barrels)

Natural Gas

(billion cubic feet)

Oil & Gas World Oil & Gas World

Ranka Country Journal Oil Rankb Country Journal Oil

1 Saudi Arabiac ........ d261,750 d261,650 1 Former U.S.S.R........ 1,959,231 1,935,243

2 Iraqc ............... 112,500 115,000 2 Iranc ................ 812,300 939,371

3 Kuwaitc ............. d96,500 d98,850 3 Qatarc .............. 508,540 757,700

4 Iranc ............... 89,700 99,083 4 Saudi Arabiac......... d219,500 d228,200

5 United Arab Emiratesc . 97,800 62,815 5 United Arab Emiratesc . . 212,100 204,050

6 Venezuelac .......... 76,862 47,620 6 United States ........ e177,427 172,635

7 Former U.S.S.R. ...... 57,086 65,364 7 Algeriac ............. 159,700 175,000

8 Libyac .............. 29,500 30,000 8 Venezuelac........... 147,585 149,207

9 Nigeriac............. 24,000 30,000 9 Nigeriac ............. 124,000 159,000

10 China .............. 24,000 29,500 10 Iraqc ................ 109,800 112,600

Top 10 Total . . . . . . . . . . . . . . 870,521 842,482 Top 10 Total............... 4,430,183 4,833,006

11 Mexico ............. 26,941 23,114 11 Indonesiac ........... 92,500 87,500

12 United States........ e22,045 21,500 12 Australia ............. 90,000 80,000

13 Qatar. . . . . . . . . . . . . . . 15,207 13,817 13 Malaysia............. 75,000 82,519

14 Algeriac............. 9,200 17,000 14 Norway.............. 44,037 77,194

15 Norway ............. 9,447 10,271 15 Netherlands .......... 62,542 57,045

16 Brazil............... 8,465 8,550 16 Canada.............. 59,733 59,700

17 Indonesiac .......... 5,000 9,165 17 Kuwaitc.............. d52,700 d56,600

18 Oman .............. 5,506 5,900 18 Libyac............... 46,400 46,900

19 Angola ............. 5,412 5,970 19 China ............... 48,300 42,796

20 Canada ............. 4,858 5,365 20 Egypt ............... 35,180 54,126

21 United Kingdom ...... 4,930 4,551 21 Mexico .............. 29,505 38,950

22 India ............... 4,840 3,819 22 Oman ............... 29,280 30,500

23 Malaysia ............ 3,000 4,457 23 Argentina ............ 27,460 26,780

24 Australia ............ 3,500 3,828 24 Bolivia............... 24,000 27,361

25 Egypt .............. 2,948 3,668 25 United Kingdom ....... 25,956 24,534

Top 25 Total . . . . . . . . . . . . . . 1,001,820 983,457 Top 25 Total............... 5,172,776 5,625,511

OPEC Total .............. 818,842 787,600 OPEC Total ............... 2,485,125 2,916,128

World Total............... 1,031,553 1,017,763 World Total ............... 5,451,065 5,919,369

aRank is based on an average of oil reserves reported by Oil & Gas Journal and World Oil. bRank is based on an average of natural gas reserves reported by Oil & Gas Journal and World Oil. cMember of the Organization of Petroleum Exporting Countries (OPEC).

dIncludes one-half of the reserves in the Neutral Zone.

eEnergy Information Administration proved reserves as of December 31, 2000 were published by the Oil & Gas Journal as its estimates as

of December 31, 2001.

Note: The Energy Information Administration does not certify these international reserves data, but reproduces the information as a matter

of convenience for the reader.

Sources: PennWell Publishing Company, Oil and Gas Journal, December 24, 2001, pp. 126-127. Gulf Publishing Company, World Oil,

August, 2002, pp. 31-35.

Energy Information Administration

18 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
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 2001 was 65,582 million barrels. This

substantially exceeds the 1977 proved reserves, but at

the end of 2001 there were still 23,846 million barrels of

crude oil plus lease condensate proved reserves.

Therefore, the Nation’s estimated proved ultimate

recovery of crude oil was fundamentally increased

during this period owing to the proved ultimate recovery

appreciation process (continued development of old

fields). In fact, only 10.6 percent of proved reserves

additions of crude oil were booked as new field

discoveries from 1976 through 2001. The rest 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 more than twice this

amount of gas was produced from 1977 through 2001

and there were still 191,743 billion cubic feet of wet

natural gas proved reserves in 2001. Only 12 percent of

proved reserve additions of natural gas were booked as

new field discoveries from 1976 through 2001.

International Perspective

International Reserves

The EIA estimates domestic oil and gas reserves but

does not systematically 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 trillion barrels of oil and 5.7 quadrillion

cubic feet of gas.

The United States ranked 12th in the world for proved

reserves of crude oil and 6th for natural gas in 2001. 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 2001. There are sometimes substantial differences

between the estimates from these sources. The Oil &

Gas Journal reported oil reserves for the United Arab

Emirates at about 98 billion barrels. This is about 56

percent higher than the World Oil estimate of 63 billion.

One reason (among many) for these differences is that

condensate is often included in foreign oil reserve

estimates.

The Oil & Gas Journal{34} estimate for world oil reserves

increased 0.3 percent in 2001, while the World Oil{35}

estimate increased 1.4 percent. For world gas reserves,

the Oil & Gas Journal reported a 3.3 percent increase,

while World Oil reported a 8.7 percent increase.

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 almost

5 times U.S. reserves. Closer to home, Venezuela has

triple and Mexico has around 15 percent more than the

United States' oil reserves. (Based on averages of the

World Oil and Oil & Gas Journal estimates).

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.{36} In 2001:

 The U.S. consumed 96,950,000,000,000,000 Btu of

energy (96.9 quadrillion Btu). This was a

decrease of 1.5 quadrillion Btu from the 2000

level of consumption.

 63 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 (24 percent).

 U.S. petroleum consumption was about 19.6

million barrels of oil and natural gas liquids

and 62.0 billion cubic feet of dry gas per day.

Dependence on Imports

The United States remains heavily dependent on

imported oil and gas to satisfy its ever-increasing

appetite for energy. In 2001, crude oil imports made up

61 percent of the U.S. crude oil supply.

Net gas imports increased slightly from the revised

2000 total of 3.54 trillion cubic feet to 3.65 trillion cubic

feet in 2001. Imports were used for approximately 17

percent of consumption. Almost all of this gas was

pipelined from Canada. Some came from Mexico,

though Mexico remains a net importer of natural gas

from the U.S., and liquefied natural gas was imported

from Algeria and Australia.

Canada, Saudi Arabia, Venezuela, and Mexico were the

primary foreign suppliers of petroleum to the United

States.{37}

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 19
List Of Appendices

Appendix A: Reserves by Operator Production Size

Class - How much of the National total of proved

reserves are owned and 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.

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 inventory of more than 45,000 oil and gas fields are

listed in Appendix B. These fields hold two-thirds of

U.S. crude oil proved reserves. Table B3 in Appendix B

lists the top U.S. operators by reported 2001 production

and indicates pending mergers announced in 2001 with

linked arrows.

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 State and National level. Readers

interested in a historical look at one specific State or

region can review these tables. We have again included

Table D9, Deepwater Production and Proved Reserves

of the Gulf of Mexico Federal Offshore 1992-2001, due

to expressed interest from the industry regarding this

area. Table D9 contains the production and proved

reserves for 1992-2001 for the Gulf of Mexico Federal

Offshore region by water depths greater than 200

meters, and less than 200 meters.

Appendix E: Summary of Data Collection

Operations - This report is based on two EIA surveys.

Proved reserves data is collected annually 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 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. Since complete coverage 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 measured directly. Reserves 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 EIA personnel when in the field

performing quality assurance checks. 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 of Domestic Oil

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

EIA-64A are presented in Appendix I.

Glossary - Contains definitions of many of the

technical terms used in this report.

Energy Information Administration

20 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
3. Crude Oil Statistics

The United States had 22,446 million barrels of crude

oil proved reserves as of December 31, 2001. This is 1.8

percent (401 million barrels) more than in 2000, and

marks the third year in a row that crude oil proved

reserves have increased.

Total discoveries of crude oil in 2001 resulted mainly

from exploration in the deepwater Gulf of Mexico

Federal Offshore and the Alaskan North Slope.

Operators replaced 121 percent of 2001 oil production

with proved reserves additions (Figure 15).

Proved Reserves

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

of December 31, 2001, by selected States and State

subdivisions.

Figure 16 maps 2001 crude oil proved reserves by area.

The following four areas account for 79 percent of U.S.

crude oil proved reserves:

Percent of

Area U.S. Oil Reserves

Texas 22

Alaska 22

Gulf of Mexico Federal Offshore 19

California 16

Area Total 79

Of these four areas, only the Gulf of Mexico had an

increase in crude oil proved reserves in 2001.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 21

Figure 15. Reserve Additions Replace 121% of 2001 U.S. Crude Oil Production.

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

.

62%

66%

78%

125%

24%

137%

115%

121%

95%

85%

0%

20%

40%

60%

80%

100%

120%

140%

160%

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Percentage of U.S. Crude Oil Production Replaced
Energy Information Administration

22 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

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

bIncludes 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 2001 contained in the

Petroleum Supply Annual 2001, DOE/EIA-0340(01).

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

Alaska ..................... 4,861 1 128 215 0 0 150 281 0 355 4,851

Lower 48 States............. 17,184 -5 1,473 1,544 529 442 716 1,126 292 1,560 17,595

Alabama. . . . . . . . . . . . . . . . . . . . 34 -4 13 1 1 1 1 0 3 4 42

Arkansas . . . . . . . . . . . . . . . . . . . 48 9 2 7 3 1 0 0 0 a7 a43

California ................... 3,813 5 232 253 3 5 99 0 0 271 3,627

Coastal Region Onshore . . . . . 455 -2 6 56 0 0 0 0 0 18 385

Los Angeles Basin Onshore. . . 292 -2 25 28 1 1 26 0 0 16 297

San Joaquin Basin Onshore . . 2,870 10 188 151 2 4 67 0 0 220 2,766

State Offshore . . . . . . . . . . . . . 196 -1 13 18 0 0 6 0 0 17 179

Colorado . . . . . . . . . . . . . . . . . . . 217 0 7 18 16 14 8 0 0 16 196

Florida . . . . . . . . . . . . . . . . . . . . . 76 1 3 1 0 0 0 0 0 4 75

Illinois. . . . . . . . . . . . . . . . . . . . . . 111 -1 3 11 2 0 2 0 0 10 92

Indiana . . . . . . . . . . . . . . . . . . . . . 15 1 1 2 1 0 0 0 0 a2 a12

Kansas. . . . . . . . . . . . . . . . . . . . . 237 -9 17 22 7 17 4 1 8 30 216

Kentucky . . . . . . . . . . . . . . . . . . . 24 1 1 2 5 0 0 0 0 2 a17

Louisiana . . . . . . . . . . . . . . . . . . . 529 48 52 60 50 67 40 0 13 75 564

North . . . . . . . . . . . . . . . . . . . . 97 2 10 14 10 15 1 0 0 14 87

South Onshore. . . . . . . . . . . . . 310 43 37 37 32 39 19 0 7 45 341

State Offshore . . . . . . . . . . . . . 122 3 5 9 8 13 20 0 6 16 136

Michigan . . . . . . . . . . . . . . . . . . . 56 -1 4 6 1 0 0 0 0 6 46

Mississippi . . . . . . . . . . . . . . . . . . 182 5 5 22 5 17 3 0 0 18 167

Montana. . . . . . . . . . . . . . . . . . . . 235 16 8 19 6 6 35 0 1 16 260

Nebraska . . . . . . . . . . . . . . . . . . . 18 -1 2 1 1 0 0 0 0 2 a15

New Mexico . . . . . . . . . . . . . . . . . 719 1 143 119 19 13 37 0 2 62 715

East . . . . . . . . . . . . . . . . . . . . . 705 1 142 117 19 13 37 0 2 61 703

West. . . . . . . . . . . . . . . . . . . . . 14 0 1 2 0 0 0 0 0 1 12

North Dakota . . . . . . . . . . . . . . . . 270 4 17 22 5 5 8 0 81 30 328

Ohio . . . . . . . . . . . . . . . . . . . . . . . 59 6 6 18 2 0 0 0 1 6 46

Oklahoma . . . . . . . . . . . . . . . . . . 610 12 50 64 28 15 13 0 1 53 556

Pennsylvania . . . . . . . . . . . . . . 15 -3 1 2 0 0 0 0 0 1 10

Texas .................... 5,273 -90 376 466 203 143 288 2 10 389 4,944

RRC District 1 . . . . . . . . . . . . . 87 -26 3 8 7 5 0 0 0 8 46

RRC District 2 Onshore . . . . . . 54 0 2 5 5 5 5 0 0 8 48

RRC District 3 Onshore . . . . . . 213 8 15 21 41 45 6 0 1 31 195

RRC District 4 Onshore . . . . . . 34 1 5 5 2 2 0 0 2 5 32

RRC District 5 . . . . . . . . . . . . . 44 1 2 17 1 4 1 0 0 5 29

RRC District 6 . . . . . . . . . . . . . 213 4 10 16 21 17 14 0 0 21 200

RRC District 7B . . . . . . . . . . . . 124 -10 6 15 4 2 1 0 0 13 91

RRC District 7C . . . . . . . . . . . . 206 -22 20 19 8 9 18 0 1 17 188

RRC District 8 ............. 2,073 -19 116 178 69 33 43 1 3 123 1,880

RRC District 8A ............ 2,022 -15 176 157 36 17 195 1 2 135 2,070

RRC District 9 . . . . . . . . . . . . . 131 -7 13 16 6 2 2 0 1 16 104

RRC District 10 . . . . . . . . . . . . 67 -5 7 9 3 2 3 0 0 7 55

State Offshore ............. 5 0 1 0 0 0 0 0 0 0 6

Utah . . . . . . . . . . . . . . . . . . . . . . . 283 -2 17 15 8 9 0 0 0 13 271

West Virginia . . . . . . . . . . . . . . . . 12 -3 1 1 0 0 0 0 0 1 8

Wyoming . . . . . . . . . . . . . . . . . . . 561 -1 23 71 20 23 19 0 3 48 489

Federal Offshore ............. 3,770 -3 487 340 143 106 158 1,123 169 492 4,835

Pacific (California) . . . . . . . . . . 596 -1 33 51 0 0 3 0 0 33 547

Gulf of Mexico (Louisiana) .... 2,751 -2 400 236 94 105 153 1,051 166 417 3,877

Gulf of Mexico (Texas). . . . . . . 423 0 54 53 49 1 2 72 3 42 411

Miscellaneousb . . . . . . . . . . . . . . 17 4 2 1 0 0 1 0 0 2 21

U.S. Total .................. 22,045 -4 1,601 1,759 529 442 866 1,407 292 1,915 22,446

Table 6. Crude Oil Proved Reserves, Reserves Changes, and Production, 2001

(Million Barrels of 42 U.S. Gallons)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 23

Figure 17. Changes in Crude Oil Proved Reserves by Area, 2000 to 2001

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

Figure 16. 2001 Crude Oil Proved Reserves by Area

4,851

547

3,627

260 328

489

271 196

715

15

556

4,944

216

564

43

167

42

4,288 75

10

17

46

46

92 12

8

Crude Oil Proved Reserves

2001, Millions of Barrels

1000 to 4944 (4)

100 to 1000 (11)

1 to 100 (17)

0 to 0 (19)

Four Areas Contain

79 Percent of U.S.

Crude Oil Proved Reserves

U.S. TOTAL:

22.446 Billion Barrels

Changes in Crude Oil Proved Reserves by Area

2000 to 2001, Millions of Barrels

1 to 1,114 (5)

0 to 0 (25)

-100 to 0 (20)

-121 to -100 (2)

Crude Oil Proved Reserves Increase Significantly

In the Gulf of Mexico.

Total U.S. Increase: +401 Million Barrels.

-329

1,114

35

-4

-10

-186

-49

-12

-3

-21

-3

-21 -4

-19

-72

-54

25 58

-10

-13 -5

-15 8

-1

-7
Discussion of Reserves Changes

Figure 17 maps the change in crude oil proved reserves

from 2000 to 2001 by area. Here’s how the top four areas

fared compared to the total United States:

Change in

U.S. Oil Reserves

Area (million barrels)

Texas -329

Alaska -10

Gulf of Mexico Federal Offshore +1,114

California -186

Area Total +589

U.S. Total +401

Figure 2 in Chapter 2 shows the components of the

changes in crude oil proved reserves for 2001 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. They result from the

drilling of exploratory wells.

Total discoveries of crude oil were 2,565 million barrels in

2001, 99 percent more than those of 2000. Only six areas

had total discoveries exceeding 50 million barrels:

 The Gulf of Mexico Federal Offshore had 1,447

million barrels of total discoveries, 56 percent of

the National total.

 Alaska had 431 million barrels of total discoveries,

17 percent of the National total.

 Texas had 300 million barrels of total discoveries,

12 percent of the National total.

 California had 99 million barrels of total

discoveries, 4 percent of the National total.

 North Dakota had 89 million barrels of total

discoveries, 3 percent of the National total.

 Louisiana had 53 million barrels of total

discoveries, 2 percent of the National total.

The United States discovered an average of 813 million

barrels of new crude oil proved reserves per year in the

prior 10 years (1991 through 2000). Total discoveries in

2001 were three times larger than that average.

Extensions

Operators reported 866 million barrels of extensions in

2001. The highest volume of extensions was reported in

Texas (288 million barrels). Operators in the Gulf of

Mexico Federal Offshore reported 155 million barrels

of extensions. Alaska was third with 150 million barrels

of extensions in 2001.

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

average of 438 million barrels ofextensions per year. The

2001 extensions were almost twice that average.

New Field Discoveries

There were 1,407 million barrels of new field discoveries

reported in 2001. Only four areas in the United States

reported any new field discoveries, and only two

contributed large volumes:

 Gulf of Mexico Federal Offshore (80 percent;

1,123 million barrels)

 Alaska (20 percent; 281 million barrels).

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

average of 223 million barrels of reserves from new field

discoveries per year. Reserves from new field discoveriesin

2001 were more than 6 times that average volume.

New Reservoir Discoveries in Old Fields

Operators in the United States reported 292 million

barrels of crude oil reserves from new reservoir

discoveries in old fields in 2001. As with new field

discoveries, the most significant portion of the new

reservoir discoveries in old fields came from the Gulf of

Mexico Federal Offshore—169 million barrels or 58

percent of the total. North Dakota had 81 million

barrels (28 percent). Louisiana had 13 million barrels (4

percent) and Texas had 10 million barrels (3 percent). In

the prior 10 years, U.S. operators reported an average of

152 million barrels of reserves from new reservoir

discoveries in old fields per year. Reserves from new

reservoir discoveries in old fieldsin 2001 were almost twice

that average.

Revisions and Adjustments

Thousands of positive and negative revisions to proved

reserves occur each year as infill 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

Energy Information Administration

24 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
reserve change categories because of the survey and

statistical estimation methods employed.

There were 1,601 million barrels of revision increases,

1,759 million barrels of revision decreases, and -4

million barrels of adjustments in 2001. Combined,

there were -162 million barrels of net revisions and

adjustments for crude oil in 2001.

Sales and Acquisitions

Sales represents that volume of crude oil proved

reserves deducted from an operator’s total by selling or

transferring operations of existing oil fields or

properties to another operator (not a volume of

production “sold” at the wellhead). Similarly,

acquisitions are that volume of proved reserves added to

an operator’s total through purchase or operations

transfer of an existing oil field or properties.

Fundamentally, tracking sales and acquisitions seems

like an exercise in accounting, but it is not that simple.

Since operators have different engineering staffs and

resources, or different development plans or schedules,

the estimate of proved reserves for a field can change

with a change in ownership. Timing of the transfer of

operations can also impact these values.

In 2001, there were 529 million barrels of sales

transactions between operators, and 442 million barrels

of acquisitions -- yielding a net difference of -87 million

barrels in 2001.

Production

U.S. production of crude oil in 2001 was an estimated

1,915 million barrels. This volume does not include

lease condensate. This was 2 percent higher than 2000’s

production of 1,880 million barrels. This increase ends a

9 year trend of production declines. The Gulf of Mexico

Federal Offshore remains the largest producing area in

the United States in 2001 with 459 million barrels of

production (24 percent of the National total). Texas and

Alaska are second and third with 20 percent and 19

percent of the total, respectively. California is fourth

with 14 percent.

In 2001, the Form EIA-23 National production

estimates were less than 1 percent greater than the

comparable Petroleum Supply Annual (PSA) 2001

volumes for crude oil and lease condensate production

combined (2,118 million barrels).

Areas of Note: Large Discoveries

and Reserves Additions

The following State and area discussions summarize

notable activities during 2001 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 2001.

Gulf of Mexico Federal Offshore

The Gulf of Mexico Federal Offshore led the Nation in

total discoveries of crude oil proved reserves in 2001, 702

million barrels of total discoveries which is 55 percent of

the National total.

 Thunder Horse Field: One new deepwater field

accounted for a significant portion of all new oil

reserves. Thunder Horse Field is located in

Mississippi Canyon Blocks 776, 777, and 778, 125

miles south-east of New Orleans at a water

depth of 6,000 feet. After full development,

Thunder Horse is expected to be the largest field

in the Gulf of Mexico. BP Amoco is the operator

of Thunder Horse Field, the development of

which in water over a mile deep will be yet

another extraordinary technical achievement in

the Federal Offshore. The Thunder Horse

platform will be the largest production

semisubmersible platform ever built. The

topsides, which will be principally built at

McDermott’s construction yard in Morgan City,

Louisiana, consist of a two-level deck measuring

about 140 meters long and 110 meters wide

composed of three of the largest modules

fabricated to date for the Gulf of Mexico. These

modules will house the crew and handle up to

250,000 barrels of oil per day, 5.6 million cubic

meters of gas per day, and 140,000 barrels per

day of produced water. {38} Total topside

weight is over 50,000 metric tons. The topsides

are to be mounted on a four-column floating

hull designed by GVA of Sweden which is likely

be built in the Far East and transported to the

Gulf of Mexico aboard a specialized carrier

vessel. The platform will be held on station by

16 mooring lines made of chain and steel wire

rope almost 6 inches in diameter with a

breaking strength of over 1,000 metric tons. Each

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 25
line will be anchored to the seabed by suction

piles, giving the platform the ability to survive

the Gulf of Mexico’s hurricanes.

 Manatee Field: On September 19, 2001, Shell

Exploration & Production Company (SEPCo)

announced plans to develop Manatee Field, a

two-well subsea production system set in 1,940

feet of water approximately 160 miles southwest

of New Orleans in Green Canyon Block 155. The

production system will be tied back five miles to

Shell’s Angus Field subsea manifold in Green

Canyon Block 113, which carries production 17

miles to Shell’s Bullwinkle Field platform in

Green Canyon 65 for processing. Manatee Field

is the fourth subsea production system utilizing

Bullwinkle as its processing hub. Previous

tiebacks to Bullwinkle include Rocky Field in

1996, Troika Field in 1997 and Angus Field in

1999. Production of Manatee Field is expected to

begin during the third quarter of 2002 and it is

expected to recover in excess of 12 million

barrels of oil equivalent, with peak production

rates potentially reaching up to 25,000 barrels of

oil per day. With the addition of Manatee Field,

Shell now holds an interest in 28 deepwater

fields in the Gulf of Mexico, the largest number

of any company. Fact Sheets, maps and a

schematic can be found at:

http://www.shellus.com/sepco. {39}

Other Gain Areas

Alaska: Alaska reported a net decline of 10 million

barrels of proved oil reserves in 2001, but had the

second largest volume of new field discoveries in 2001

(281 million barrels). Operators discovered new

satellite fields on the North Slope of Alaska.

North Dakota and Montana (Cedar Creek Anticline):

Proved oil reserves in North Dakota increased by 18

percent (58 million barrels) in 2001 compared to 2000.

Montana’s proved oil reserves increased by 10 percent

(25 million barrels). Burlington Resources Incorporated

continued development of the world’s largest

horizontally drilled waterflood in the East Lookout

Butte Field. Burlington also received permission in

2001 to unitize the southern portion of the Cedar Hills

Field and have initiated a waterflood to increase

production there. These programs have tripled

recoverable oil reserves in the two fields. {40}

Louisiana: Louisiana’s proved oil reserves increased by

6 percent (35 million barrels).

Areas of Note:

Large Reserves Declines

The following areas had large declines in crude oil

proved reserves due to downward revisions or

unreplaced production.

Texas

Texas’crude oil proved reserves declined 6 percent (329

million barrels) in 2001. Texas was first in the Nation

with extensions(288 million barrels) in 2001, but this did

not offset Texas’ oil production—an estimated 389

million barrels in 2001. Texas production declined 5

percent (20 million barrels) from its 2000 level.

California

California’s crude oil proved reserves declined 5

percent (186 million barrels) in 2001. Operators also

reported a production increase of 1 percent (3 million

barrels) over the 2000 level.

Wyoming

There was a net decline of 13 percent (72 million

barrels) in Wyoming’s crude oil proved reserves in

2001. Wyoming’s crude oil production correspondingly

declined 12 percent (6 million barrels) from its 2000

level.

Other Decline Areas

Discovery and development of new or existing oil

fields was also outpaced by crude oil production in the

following areas of the United States.

Oklahoma: Proved oil reserves decreased

by 9 percent (54 million barrels).

Pacific Federal Offshore: Proved oil

reserves decreased by 8 percent (49 million

barrels).

Energy Information Administration

26 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Reserves in

Nonproducing Reservoirs

Not all proved reserves of crude oil were contained in

reservoirs that were producing. Operators reported

5,195 million barrels of proved reserves in

nonproducing reservoirs, 29 percent more than

reported in 2000 (4,019 million barrels). Nonproducing

crude oil reserves (not including lease condensate) are

listed in Table 7.

Nonproducing reserves are those waiting for well

workovers, drilling additional development or

replacement wells, installing production or pipeline

facilities, and awaiting 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 2001 Annual Report 27

Table 7. Reported Reserves in Nonproducing Reservoirs for Crude Oil, 2001 a

(Million Barrels of 42 U.S. Gallons)

Nonproducing Nonproducing Crude Oil Crude Oil

State and Subdivision Reserves State and Subdivision Reserves

aIncludes 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). bIncludes Arizona, Missouri, Nevada, South Dakota, and Tennessee.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves,” 2001.

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389

Lower 48 States............................. 4,806

Alabama .................................. 4

Arkansas .................................. 4

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508

Coastal Region Onshore . . . . . . . . . . . . . . . . . . . 148

Los Angeles Basin Onshore . . . . . . . . . . . . . . . . . 97

San Joaquin Basin Onshore. . . . . . . . . . . . . . . . . 233

State Offshore. . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Florida .................................... 7

Illinois. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Indiana.................................... 0

Kansas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

North. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

South Onshore . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

State Offshore. . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Michigan .................................. 6

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Montana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Nebraska .................................. 0

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

East. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

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

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

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Ohio ...................................... 6

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Pennsylvania ............................... 1

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719

RRC District 1............................ 9

RRC District 2 Onshore . . . . . . . . . . . . . . . . . . . . 12

RRC District 3 Onshore . . . . . . . . . . . . . . . . . . . . 29

RRC District 4 Onshore .................... 8

RRC District 5............................ 4

RRC District 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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

RRC District 7C . . . . . . . . . . . . . . . . . . . . . . . . . . 45

RRC District 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

RRC District 8A. . . . . . . . . . . . . . . . . . . . . . . . . . . 333

RRC District 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

RRC District 10........................... 8

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

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

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

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

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Federal Offshore ............................ 2,595

Pacific (California). . . . . . . . . . . . . . . . . . . . . . . . . 62

Gulf of Mexico (Louisiana) .................. 2,352

Gulf of Mexico (Texas) . . . . . . . . . . . . . . . . . . . . . 180

Miscellaneousb ............................. 1

U.S. Total ................................. 5,195
4. Natural Gas Statistics

Dry Natural Gas

Proved Reserves

The United States had 183,460 billion cubic feet of dry

natural gas reserves as of December 31, 2001, a 3

percent increase over the 2000 level (Table 8). All

natural gas proved reserves data shown in this report

exclude natural gas held in underground storage.

Most of the reserve increases were in Wyoming,

Colorado, and Texas, owing to drilling and/or

improved stimulation technology used in the Madden,

Wattenberg, and Pinedale Fields of Wyoming, coalbed

methane fields in Wyoming and Colorado, and the

Barnett Shale and Lobo Trend gas areas in Texas. Utah

and New Mexico, which had significant gas reserves

increases in 2000, had smaller gains in 2001.

California’s and Oklahoma’s reserves declined in 2001,

despite last year’s reserves increases.

Additions to dry gas reserves in 2001 were 25,812

billion cubic feet, 11 percent less than in 2000.

Operators replaced 131 percent of dry gas production

(Figure 18). U.S. total discoveries of dry natural gas

reserves were 22,758 billion cubic feet in 2001, up 19

percent from 2000 (19,138 billion cubic feet).

Proved reserves by State are shown on the map in

Figure 19. Six areas account for 71 percent of the

Nation’s dry natural gas proved reserves:

Percent of

Area U.S. Gas Reserves

Texas 24

Gulf of Mexico Federal Offshore 14

Wyoming 10

New Mexico 9

Oklahoma 7

Colorado 7

Area Total 71

For the first time, proved reserves of dry natural gas in

Wyoming exceeded those in New Mexico. However,

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 29

Figure 18. Reserve Additions Replace 131% of 2001 U.S. Dry Natural Gas Production.

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

88% 85%

108% 107% 104%

83%

152%

131%

118%

107%

0%

20%

40%

60%

80%

100%

120%

140%

160%

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Percentage of U.S. Gas Production Replaced
Energy Information Administration

30 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

aIncludes Federal offshore Alabama.

bIncludes 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 2000 contained in the Natural Gas Annual 2001, DOE/EIA-0131(01).

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

Alaska ..................... 9,237 -11 233 335 0 0 59 74 4 461 8,800

Lower 48 States............. 168,190 2,753 18,125 20,341 11,380 14,010 16,321 3,504 2,796 19,318 174,660

Alabama.................... 4,149 36 78 218 1 3 169 42 2 345 3,915

Arkansas ................... 1,581 28 128 88 8 5 119 0 11 160 1,616

California ................... 2,849 36 162 255 7 20 210 0 2 336 2,681

Coastal Region Onshore . . . . . 234 2 14 61 0 0 0 0 0 12 177

Los Angeles Basin Onshore. . . 193 6 17 27 1 0 8 0 0 9 187

San Joaquin Basin Onshore . . 2,331 28 125 161 6 20 200 0 2 307 2,232

State Offshore . . . . . . . . . . . . . 91 0 6 6 0 0 2 0 0 8 85

Colorado ................... 10,428 155 1,882 1,513 2,468 2,794 2,120 4 7 882 12,527

Florida . . . . . . . . . . . . . . . . . . . . . 82 0 7 0 0 0 0 0 0 5 84

Kansas..................... 5,299 60 279 220 259 331 46 2 1 438 5,101

Kentucky ................... 1,760 158 348 397 50 49 42 0 23 73 1,860

Louisiana ................... 9,239 322 1,013 1,696 496 888 1,427 27 566 1,479 9,811

North .................... 3,298 49 298 522 58 189 993 1 23 390 3,881

South Onshore............. 5,245 267 648 1,091 370 524 366 17 510 931 5,185

State Offshore . . . . . . . . . . . . . 696 6 67 83 68 175 68 9 33 158 745

Michigan ................... 2,729 653 263 524 24 2 63 50 3 239 2,976

Mississippi . . . . . . . . . . . . . . . . . . 618 53 70 43 34 29 43 0 19 94 661

Montana. . . . . . . . . . . . . . . . . . . . 885 51 82 90 57 59 36 1 4 73 898

New Mexico ................. 17,322 9 1,599 1,244 312 307 1,216 21 32 1,536 17,414

East ..................... 3,537 136 470 548 201 126 479 20 17 518 3,518

West..................... 13,785 -127 1,129 696 111 181 737 1 15 1,018 13,896

New York . . . . . . . . . . . . . . . . . . . 322 -18 29 51 1 0 47 1 17 28 318

North Dakota . . . . . . . . . . . . . . . . 433 17 48 32 8 5 3 0 18 41 443

Ohio ....................... 1,185 31 129 287 87 62 9 0 12 84 970

Oklahoma .................. 13,699 196 1,458 1,895 480 671 1,325 13 52 1,481 13,558

Pennsylvania ................ 1,741 3 201 219 11 32 108 33 1 114 1,775

Texas ...................... 42,082 658 3,594 5,191 2,902 4,297 4,944 603 580 5,138 43,527

RRC District 1 ............. 1,032 17 87 120 30 44 84 7 1 104 1,018

RRC District 2 Onshore ...... 1,980 -231 146 246 93 270 175 14 108 322 1,801

RRC District 3 Onshore ...... 3,873 54 422 498 563 639 413 86 85 741 3,770

RRC District 4 Onshore ...... 9,645 228 809 1,211 674 712 1,284 300 258 1,395 9,956

RRC District 5 ............. 3,168 15 398 650 22 822 779 51 5 335 4,231

RRC District 6 ............. 5,976 159 408 419 886 1,110 404 5 15 644 6,128

RRC District 7B . . . . . . . . . . . . 312 -7 21 42 15 10 24 0 0 51 252

RRC District 7C ............ 3,504 175 285 790 425 449 413 0 24 315 3,320

RRC District 8 ............. 5,388 58 431 569 111 117 340 67 67 533 5,255

RRC District 8A ............ 1101 5 81 90 13 13 62 0 1 75 1,085

RRC District 9 ............. 1626 77 109 127 18 16 790 0 1 185 2,289

RRC District 10 ............ 4,079 82 381 404 46 75 152 1 8 373 3,955

State Offshore . . . . . . . . . . . . . 398 26 16 25 6 20 24 72 7 65 467

Utah ....................... 4,235 135 805 606 17 37 269 4 5 288 4,579

Virginia..................... 1704 19 90 145 718 842 31 0 7 78 1,752

West Virginia ................ 2,900 -225 315 279 29 32 96 0 26 158 2,678

Wyoming ................... 16,158 306 1,860 1,488 1,845 2,026 2,574 44 49 1,286 18,398

Federal Offshorea ............ 26,748 60 3,682 3,856 1,565 1,519 1,387 2,659 1,359 4,957 27,036

Pacific (California) . . . . . . . . . . 576 1 95 101 0 0 13 0 0 44 540

Gulf of Mexico (Louisiana)a . . . 19,788 40 2,663 2,877 1,309 1,415 1,085 1,471 1,180 3,735 19,721

Gulf of Mexico (Texas)....... 6,384 19 924 878 256 104 289 1,188 179 1,178 6,775

Miscellaneousb . . . . . . . . . . . . . . 42 10 3 4 1 0 37 0 0 5 82

U.S. Total .................. 177,427 2,742 18,358 20,676 11,380 14,010 16,380 3,578 2,800 19,779 183,460

Table 8. Dry Natural Gas Proved Reserves, Reserves Changes, and Production, 2001

(Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 31

8,800

2,681

4,579

540

5,101

18,398

17,414

43,527

12,527

898 443

13,558

661

26,496

9,811

1,616

84

2,976

1,860

3,915

970

2,678

1,752

1,775

318

Dry Gas Proved Reserves

2001, Billions of Cubic Feet

10,000 to 43,527 (6)

1,000 to 10,000 (12)

1 to 1,000 (13)

0 to 0 (20)

Six Areas Contain

71 Percent of U.S.

Dry Natural Gas Proved Reserves

U.S. TOTAL:

183.460 Trillion Cubic Feet

Figure 20. Changes in Dry Natural Gas Proved Reserves by Area, 2000 to 2001

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

Figure 19. 2001 Dry Natural Gas Proved Reserves by Area

Changes in Dry Natural Gas Reserves by Area

2000 to 2001, Billions of Cubic Feet

1,000 to 2,240 (3)

1 1,000 (17)

0 to 0 (20)

-100 to 0 (4)

-437 to -100 (7)

Dry Gas Reserves Increase Significantly in

Wyoming, Colorado, and Texas

Total U.S. Increase: +6,033 Billion Cubic Feet.

-437

92

1,445

324

35

-234

-198

100

344 2,099

-141

2,240

-168

-215

13

-4

-222 48

-36

572

43

10

2

34

247

to
New Mexico still reported higher production than did

Wyoming.

Discussion of Reserves Changes

Figure 20 maps the change in dry gas proved reserves

from 2000 to 2001 by area. Here’s how the top six areas

fared, compared to the total United States:

Change in

U.S. Gas Reserves

Area (billion cubic feet)

Texas +1,445

Gulf of Mexico Federal Offshore +324

Wyoming +2,240

New Mexico +92

Oklahoma -141

Colorado +2,099

Area Total +6,059

U.S. Total +6,033

Figure 4 in Chapter 2 shows the components of change

in dry natural gas proved reserves for 2001 and the

preceding 10 years.

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. Total discoveries of dry natural gas

reserves were 22,758 billion cubic feet in 2001, a 19

percent increase from the level reported in 2000. About

27 percent of the total discoveries were in Texas, 24

percent were in the Gulf of Mexico Federal Offshore, 12

percent were in Wyoming, and 9 percent were in

Colorado.

Extensions were 16,380 billion cubic feet, 11 percent

more than 2000 and more than twice the prior 10-year

average (7,802 billion cubic feet). Areas with the largest

extensions and their percentage of totalextensions were:

 Texas had 4,944 billion cubic feet of extensions

(30 percent of the total)

 Wyoming had 2,574 billion cubic feet (16

percent)

 Colorado had 2,120 billion cubic feet (13 percent)

 Louisiana had 1,427 billion cubic feet (9 percent).

New field discoveries were 3,578 billion cubic feet in

2001—80 percent more than in 2000. The areas with the

largest new field discoveries were the Gulf of Mexico

Federal Offshore (with 2,659 billion cubic feet of new

field discoveries, 74 percent of the total), Texas (603

billion cubic feet, 17 percent), and Alaska (74 billion

cubic feet, 2 percent). In the prior 10 years, U.S.

operators reported an average of 1,471 billion cubic feet

of reserves from new field discoveries per year. Reserves

from new field discoveries in 2001 were more than twice

that average.

New reservoir discoveries in old fields were 2,800 billion

cubic feet, 18 percent higher than 2000. Among the

areas with the largest new reservoir discoveries in old fields

and their percentage of the total were:

 Gulf of Mexico Federal Offshore (1,359 billion

cubic feet, 49 percent)

 Texas (580 billion cubic feet, 21 percent)

 Louisiana (566 billion cubic feet, 20 percent).

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

average of 2,334 billion cubic feet of reserves from new

reservoirs discovered in old fields per year. Reserves from

new reservoirs discovered in old fields in 2001 were 20

percent higher than that average.

Revisions and Adjustments

There were 18,358 billion cubic feet of revision increases,

20,676 billion cubic feet of revision decreases, and 2,742

billion cubic feet of adjustments in 2001. Combined,

there were 424 billion cubic feet of net revisions and

adjustments in 2001, excluding reserves additions from

net sales and acquisitions. This is significantly less than

the average volume of net revisions and adjustments of

the prior 10 years (7,161 billion cubic feet).

Sales and Acquisitions

Sales represents that volume of dry natural gas proved

reserves deducted from an operator’s total through sale

or transfer of operations of an existing gas field or

properties to another operator (not a volume of

production “sold” at the wellhead). Similarly,

acquisitions are that volume of proved reserves added to

an operator’s total by purchase or operations transfer of

an existing gas field or properties.

In 2001, there were 11,380 billion cubic feet of sales

transactions between operators, and 14,010 billion

cubic feet of acquisitions. The net difference of 2,630

billion cubic feet was added to the National total of dry

natural gas reserves in 2001.

Energy Information Administration

32 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 33

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

bIncludes Federal offshore Alabama.

c

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

Note: The prouction 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 2001 contained in the

Natural Gas Annual 2001, DOE/EIA-0131(01).

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

Alaska ..................... 9,331 0 236 338 0 0 60 75 4 467 8,901

Lower 48 States............. 177,179 1849 18943 21279 11885 14,600 17,123 3,593 2,894 20,175 182,842

Alabama.................... 4,269 -39 80 225 1 3 174 43 3 349 3,958

Arkansas ................... 1,584 28 128 88 8 5 120 0 11 161 1,619

California ................... 2,952 22 168 264 7 21 216 0 2 347 2,763

Coastal Region Onshore . . . . . 244 3 15 64 0 0 0 0 0 13 185

Los Angeles Basin Onshore. . . 204 3 18 28 1 0 8 0 0 9 195

San Joaquin Basin Onshore . . 2,413 16 129 166 6 21 206 0 2 317 2,298

State Offshore . . . . . . . . . . . . . 91 0 6 6 0 0 2 0 0 8 85

Colorado ................... 10,837 102 1,945 1,564 2,551 2,888 2,191 4 8 911 12,949

Florida . . . . . . . . . . . . . . . . . . . . . 93 0 9 0 0 0 0 0 0 6 96

Kansas..................... 5,682 50 299 235 277 355 50 3 1 468 5,460

Kentucky ................... 1,837 175 365 417 52 51 44 0 24 77 1,950

Louisiana ................... 9,512 278 1,040 1,737 511 913 1,451 29 582 1,517 10,040

North .................... 3,344 43 302 528 59 191 1,004 1 23 394 3,927

South Onshore............. 5,447 230 668 1,123 381 540 377 18 525 960 5,341

State Offshore . . . . . . . . . . . . . 721 5 70 86 71 182 70 10 34 163 772

Michigan ................... 2,772 675 268 534 25 2 64 51 3 244 3,032

Mississippi . . . . . . . . . . . . . . . . . . 620 53 70 43 34 29 43 0 19 94 663

Montana. . . . . . . . . . . . . . . . . . . . 892 53 82 91 57 60 37 1 4 74 907

New Mexico ................. 18,509 -29 1,712 1,343 341 332 1,310 23 35 1,649 18,559

East ..................... 3,998 92 523 610 224 141 534 22 19 576 3,919

West..................... 14,511 -121 1,189 733 117 191 776 1 16 1,073 14,640

New York . . . . . . . . . . . . . . . . . . . 322 -18 29 51 1 0 47 1 17 28 a318

North Dakota . . . . . . . . . . . . . . . . 487 15 54 36 9 6 3 0 21 46 495

Ohio ....................... 1,186 31 129 287 87 62 9 0 12 84 971

Oklahoma .................. 14,543 181 1,545 2,008 509 711 1,404 14 55 1,570 14,366

Pennsylvania ................ 1,740 9 202 220 11 32 109 34 1 114 1,782

Texas ...................... 45,419 274 3,833 5,550 3,086 4,520 5,268 632 612 5,460 46,462

RRC District 1 ............. 1,106 -9 91 126 31 47 88 8 1 109 1,066

RRC District 2 Onshore ...... 2,045 -237 151 254 96 279 181 15 112 333 1,863

RRC District 3 Onshore ...... 4,042 65 441 521 589 669 432 90 89 775 3,943

RRC District 4 Onshore ...... 10,118 138 841 1,258 700 740 1,335 312 268 1,449 10,345

RRC District 5 ............. 3,217 9 404 659 23 834 789 52 5 339 4,289

RRC District 6 ............. 6,365 74 428 440 930 1,164 423 5 16 676 6,429

RRC District 7B . . . . . . . . . . . . 356 -5 24 49 17 12 28 0 0 59 290

RRC District 7C ............ 4,132 30 322 893 481 509 467 0 27 356 3,757

RRC District 8 ............. 6,136 87 493 650 127 134 389 77 77 609 6,007

RRC District 8A ............ 1,215 -1 89 99 15 14 68 0 1 82 1,190

RRC District 9 ............. 1,854 46 122 141 21 17 880 0 1 206 2,552

RRC District 10 ............ 4,433 52 411 435 50 81 164 1 8 402 4,263

State Offshore . . . . . . . . . . . . . 400 25 16 25 6 20 24 72 7 65 468

Utah ....................... 4,472 66 835 629 18 38 279 4 5 299 4,753

Virginia..................... 1,704 19 90 145 718 842 31 0 7 78 1,752

West Virginia ................ 3,062 -239 333 295 30 33 101 0 27 167 2,825

Wyoming ................... 17,211 151 1,961 1,569 1,946 2,136 2,714 46 51 1,356 19,399

Federal Offshoreb ............ 27,467 -54 3,763 3,944 1,605 1,561 1,421 2,708 1,394 5,071 27,640

Pacific (California) . . . . . . . . . . 576 1 95 101 0 0 13 0 0 44 540

Gulf of Mexico (Louisiana)b . . . 20,466 -66 2,739 2,960 1,347 1,456 1,117 1,514 1,214 3,843 20,290

Gulf of Mexico (Texas)....... 6,425 11 929 883 258 105 291 1,194 180 1,184 6,810

Miscellaneousc . . . . . . . . . . . . . . 42 11 3 4 1 0 37 0 0 5 83

U.S. Total .................. 186,510 1,849 19,179 21,617 11,885 14,600 17,183 3,668 2,898 20,642 191,743

Table 9. Natural Gas Proved Reserves, Reserves Changes, and Production, Wet After Lease Separation,

2001 (Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Energy Information Administration

34 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

aIncludes Federal offshore Alabama.

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

Note: The prouction 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 2001 contained in the

Natural Gas Annual 2001, DOE/EIA-0131(01).

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

Alaska ..................... 2,564 -1 65 206 0 0 40 56 4 213 2,309

Lower 48 States............. 154,113 1,356 15,852 18,179 10,733 13,756 15,947 2,322 2,416 17,238 159,612

Alabama.................... 4,241 -35 77 224 1 2 173 43 0 345 3,931

Arkansas ................... 1,545 28 127 87 3 5 120 0 11 157 1,589

California . . . . . . . . . . . . . . . . . . . 754 9 80 43 5 16 123 0 2 94 842

Coastal Region Onshore ..... 0 0 0 0 0 0 0 0 0 0 0

Los Angeles Basin Onshore. . . 1 0 0 0 0 0 0 0 0 0 1

San Joaquin Basin Onshore . . 748 9 78 42 5 16 123 0 2 93 836

State Offshore ............. 5 0 2 1 0 0 0 0 0 1 5

Colorado ................... 9,877 65 1,882 1,530 2,524 2,865 2,113 4 6 834 11,924

Florida ..................... 0 0 0 0 0 0 0 0 0 0 0

Kansas..................... 5,641 33 290 231 274 304 48 3 1 460 5,355

Kentucky ................... 1,810 176 365 416 52 51 44 0 24 77 1,925

Louisiana ................... 8,704 238 914 1,582 423 782 1,402 26 563 1,379 9,245

North .................... 3,158 39 273 484 23 134 1,002 0 23 363 3,759

South Onshore............. 4,954 197 586 1,021 339 484 345 18 511 876 4,859

State Offshore . . . . . . . . . . . . . 592 2 55 77 61 164 55 8 29 140 627

Michigan ................... 2,558 687 246 493 23 2 61 50 3 218 2,873

Mississippi . . . . . . . . . . . . . . . . . . 585 55 66 36 31 28 41 0 19 90 637

Montana. . . . . . . . . . . . . . . . . . . . 822 48 70 82 52 56 22 1 4 67 822

New Mexico ................. 16,922 -65 1,492 1,071 301 292 1,207 21 30 1,415 17,112

East ..................... 2,526 46 311 349 185 103 435 20 16 352 2,571

West..................... 14,396 -111 1,181 722 116 189 772 1 14 1,063 14,541

New York . . . . . . . . . . . . . . . . . . . 320 -19 25 51 1 0 47 1 17 28 311

North Dakota . . . . . . . . . . . . . . . . 223 5 4 8 1 0 1 0 16 15 225

Ohio . . . . . . . . . . . . . . . . . . . . . . . 717 -51 102 145 12 62 2 0 4 48 631

Oklahoma .................. 13,430 -31 1,417 1,743 423 689 1,271 14 52 1,420 13,256

Pennsylvania ................ 1,583 7 184 212 10 32 100 34 1 105 1,614

Texas ...................... 38,585 255 3,276 4,625 2,634 4,134 4,940 627 594 4,776 40,376

RRC District 1 ............. 1,037 -7 84 120 8 44 88 8 1 103 1,024

RRC District 2 Onshore ...... 1,930 -209 138 230 81 275 161 15 110 311 1,798

RRC District 3 Onshore ...... 3,404 50 358 420 410 504 392 89 83 639 3,411

RRC District 4 Onshore ...... 9,942 137 830 1,227 692 735 1,330 312 266 1,427 10,206

RRC District 5 ............. 3,089 8 398 604 22 828 781 52 5 329 4,206

RRC District 6 ............. 5,901 58 408 423 890 1,152 422 5 16 633 6,016

RRC District 7B . . . . . . . . . . . . 242 1 17 37 13 10 27 0 0 44 203

RRC District 7C ............ 3,439 76 260 791 448 441 406 0 26 286 3,123

RRC District 8 ............. 3,345 26 277 303 22 37 275 73 72 375 3,405

RRC District 8A . . . . . . . . . . . . 69 17 12 8 2 2 2 0 0 10 82

RRC District 9 ............. 1,645 43 104 58 15 15 879 0 1 186 2,428

RRC District 10 ............ 4,143 30 374 379 25 71 153 1 8 368 4,008

State Offshore . . . . . . . . . . . . . 399 25 16 25 6 20 24 72 6 65 466

Utah ....................... 4,125 58 790 554 1 20 279 4 5 276 4,450

Virginia..................... 1,704 19 90 145 718 842 31 0 7 78 1,752

West Virginia ................ 2,929 -218 330 255 6 33 101 0 27 164 2,777

Wyoming ................... 16,559 131 1,872 1,386 1,919 2,120 2,713 46 50 1,275 18,911

Federal Offshorea ............ 20,456 -46 2,150 3,258 1,319 1,421 1,071 1,448 980 3,913 18,990

Pacific (California) . . . . . . . . . . 76 0 0 22 0 0 0 0 0 4 50

Gulf of Mexico (Louisiana)a . . . 15,350 -58 1,473 2,423 1,190 1,319 783 401 809 2,928 13,536

Gulf of Mexico (Texas)....... 5,030 12 677 813 129 102 288 1,047 171 981 5,404

Miscellaneousb . . . . . . . . . . . . . . 23 7 3 2 0 0 37 0 0 4 64

U.S. Total .................. 156,677 1,355 15,917 18,385 10,733 13,756 15,987 2,378 2,420 17,451 161,921

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

Wet After Lease Separation, 2001 (Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 35

aIncludes Federal offshore Alabama.

bIncludes 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 2001 contained in the

Natural Gas Annual 2001, DOE/EIA-0131(01).

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

Alaska ..................... 6,768 0 171 133 0 0 20 19 0 253 6,592

Lower 48 States............. 23,065 499 3,088 3,099 1,145 845 1,174 1,268 477 2,940 23,232

Alabama. . . . . . . . . . . . . . . . . . . . 29 -4 3 1 1 1 1 0 2 4 26

Arkansas . . . . . . . . . . . . . . . . . . . 39 -1 1 1 5 0 0 0 0 3 30

California ................... 2,198 16 87 222 2 5 93 0 0 253 1,922

Coastal Region Onshore . . . . . 244 3 15 64 0 0 0 0 0 13 185

Los Angeles Basin Onshore. . . 203 3 18 28 1 0 8 0 0 9 194

San Joaquin Basin Onshore . . 1,665 9 50 124 1 5 83 0 0 224 1,463

State Offshore . . . . . . . . . . . . . 86 1 4 6 0 0 2 0 0 7 80

Colorado . . . . . . . . . . . . . . . . . . . 960 37 63 34 27 24 78 0 1 77 1,025

Florida . . . . . . . . . . . . . . . . . . . . . 93 0 9 0 0 0 0 0 0 6 96

Kansas. . . . . . . . . . . . . . . . . . . . . 40 19 9 4 3 51 2 0 0 9 105

Kentucky . . . . . . . . . . . . . . . . . . . 27 -2 0 0 0 0 0 0 0 0 25

Louisiana . . . . . . . . . . . . . . . . . . . 807 43 126 155 88 131 49 2 19 138 796

North . . . . . . . . . . . . . . . . . . . . 186 4 29 44 36 57 2 1 0 31 168

South Onshore. . . . . . . . . . . . . 492 35 82 102 42 56 32 0 14 84 483

State Offshore . . . . . . . . . . . . . 129 4 15 9 10 18 15 1 5 23 145

Michigan . . . . . . . . . . . . . . . . . . . 214 -12 22 41 2 0 3 1 0 26 159

Mississippi . . . . . . . . . . . . . . . . . . 35 -3 4 7 3 2 2 0 0 4 26

Montana. . . . . . . . . . . . . . . . . . . . 70 4 12 9 5 4 15 0 1 7 85

New Mexico ............... 1,588 35 220 272 39 39 103 2 5 234 1,447

East ..................... 1,473 46 212 261 39 37 99 2 3 224 1,348

West. . . . . . . . . . . . . . . . . . . . . 115 -11 8 11 0 2 4 0 2 10 99

New York ................... 2 2 4 0 0 0 0 0 0 1 7

North Dakota . . . . . . . . . . . . . . . . 264 10 49 28 7 6 2 0 5 31 270

Ohio . . . . . . . . . . . . . . . . . . . . . . . 469 83 27 143 75 0 7 0 8 36 340

Oklahoma .................. 1,113 211 128 265 86 22 133 0 3 150 1,109

Pennsylvania . . . . . . . . . . . . . . . . 157 3 18 8 1 0 8 0 0 9 168

Texas ...................... 6,833 21 556 924 448 386 328 4 18 685 6,089

RRC District 1 . . . . . . . . . . . . . 69 1 7 6 23 2 0 0 0 7 43

RRC District 2 Onshore . . . . . . 115 -26 13 24 16 4 20 0 1 22 65

RRC District 3 Onshore . . . . . . 638 16 83 101 178 165 39 1 6 136 533

RRC District 4 Onshore . . . . . . 176 2 11 31 8 5 5 0 2 22 140

RRC District 5 . . . . . . . . . . . . . 128 0 6 55 0 6 8 0 0 10 83

RRC District 6 . . . . . . . . . . . . . 464 13 20 16 39 12 1 0 0 43 412

RRC District 7B . . . . . . . . . . . . 114 -4 6 12 4 2 1 0 0 15 88

RRC District 7C . . . . . . . . . . . . 693 -45 62 102 33 67 61 0 1 70 634

RRC District 8 ............. 2,791 62 216 347 105 97 114 3 5 234 2,602

RRC District 8A ............ 1,146 -21 77 91 12 13 67 0 1 72 1,108

RRC District 9 . . . . . . . . . . . . . 209 1 18 83 5 2 2 0 0 20 124

RRC District 10 . . . . . . . . . . . . 289 22 37 56 25 11 10 0 1 34 255

State Offshore ............. 1 0 0 0 0 0 0 0 1 0 2

Utah . . . . . . . . . . . . . . . . . . . . . . . 348 6 46 75 17 18 0 0 0 23 303

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

West Virginia . . . . . . . . . . . . . . . . 98 14 2 39 24 0 0 0 0 3 48

Wyoming . . . . . . . . . . . . . . . . . . . 652 20 89 183 27 16 1 0 1 81 488

Federal Offshorea ............ 7,010 -7 1,613 686 285 140 349 1,259 414 1,158 8,649

Pacific (California) . . . . . . . . . . 500 1 95 79 0 0 13 0 0 40 490

Gulf of Mexico (Louisiana)a . . . 5,115 -7 1,266 537 156 137 333 1,112 405 915 6,753

Gulf of Mexico (Texas)....... 1,395 -1 252 70 129 3 3 147 9 203 1,406

Miscellaneousb . . . . . . . . . . . . . . 19 4 0 2 0 0 0 0 0 2 19

U.S. Total .................. 29,833 499 3,259 3,232 1,145 845 1,194 1,287 477 3,193 29,824

Table 11. Associated-Dissolved Natural Gas Proved Reserves, Reserves Changes, and Production, 2001

(Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Production

The estimated 2001 U.S. dry natural gas production

was 19,779 billion cubic feet, an increase of almost 3

percent from 2000 (Table 8). Areas with the largest

production and their percentage of total production

were:

 Texas produced 5,138 billion cubic feet (BCF) of

dry natural gas (26 percent of the total)

 Gulf of Mexico Federal Offshore produced 4,913

BCF (25 percent)

 New Mexico produced 1,536 BCF (8 percent)

 Oklahoma produced 1,481 BCF (7 percent)

 Louisiana produced 1,479 BCF (7 percent)

 Wyoming produced 1,286 BCF (7 percent).

Wet Natural Gas

U. S. proved reserves of wet natural gas as of December

31, 2001 were 191,743 billion cubic feet, a 3 percent

increase from the volume reported in 2000 (Table 9). At

year-end 2001, proved wet natural gas reserves for the

lower 48 States had increased by 3 percent compared to

2000, while those of Alaska had decreased by 5 percent.

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. A discussion of the methodology

used to generate wet and dry natural gas reserves

tables in this report appears in Appendix F.

Nonassociated Natural Gas

Proved Reserves

Proved reserves of nonassociated (NA) natural gas, wet

after lease separation, in the United States increased by

3 percent (5,244 billion cubic feet) in 2001 to 161,921

billion cubic feet (Table 10). The lower 48 States’ NA

wet natural gas proved reserves increased 4 percent to

a level of 159,612 billion cubic feet, while Alaska had a

10 percent decline to a level of 2,309 billion cubic feet.

Those States with the largest increases in NA wet

natural gas reserves were Wyoming, Colorado, Texas,

and Louisiana.

Discoveries

NA wet natural gas total discoveries of 20,785 billion

cubic feet in 2001 increased 24 percent compared to

2000’s total of 16,741 billion cubic feet. Areas with the

most total discoveries in 2001 were Texas (6,161 billion

cubic feet), the Gulf of Mexico Federal Offshore (3,499

billion cubic feet), Wyoming (2,809 billion cubic feet),

and Colorado (2,123 billion cubic feet).

Production

U.S. production of NA wet natural gas increased 3

percent from an estimated 16,863 billion cubic feet in

2000 to 17,451 billion cubic feet in 2001. The five leading

producing areas were: Texas (27 percent), the Gulf of

Mexico Federal Offshore (22 percent), Oklahoma (8

percent), New Mexico (8 percent), and Louisiana (8

percent).

Associated-Dissolved Natural Gas

Proved Reserves

Proved reserves of associated-dissolved (AD) natural

gas, wet after lease separation, in the United States

declined very slightly (-9 billion cubic feet) to 29,824

billion cubic feet in 2001 (Table 11). Proved reserves of

AD wet natural gas in the lower 48 States increased less

than 1 percent (+167 billion cubic feet) to 23,232 billion

cubic feet, and in Alaska declined 3 percent (-176 billion

cubic feet) to 6,592 billion cubic feet in 2001. The areas

of the country with the largest AD wet natural gas

reserves and their percentage of the total were:

 Gulf of Mexico Federal Offshore (27 percent)

 Alaska (22 percent)

 Texas (20 percent)

 California (6 percent)

 New Mexico (5 percent).

These areas logically correspond to the areas of the

country with the largest volumes of crude oil reserves.

Production

U.S. production of AD wet natural gas decreased

slightly from an estimated 3,299 billion cubic feet in

2000 to 3,193 billion cubic feet in 2001 (Table 11).

Production of AD wet natural gas in the lower 48 States

decreased from 2,987 billion cubic feet to 2,940 billion

Energy Information Administration

36 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 37

0

2

4

6

8

10

12

14

16

18

20

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

U.S. CBM Reserves, Trillion Cubic Feet

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

Figure 21. Coalbed Methane Proved Reserves 1989-2001

Table 12. Coalbed Methane Proved Reserves and Production for 1989–2001

(Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

New Eastern Western United

Year Alabama Colorado Mexico Utah Wyoming Statesa Statesb Othersc States

Reserves

1989 537 1,117 2,022 NA NA NA NA 0 3,676

1990 1,224 1,320 2,510 NA NA NA NA 33 5,087

1991 1,714 2,076 4,206 NA NA NA NA 167 8,163

1992 1,968 2,716 4,724 NA NA NA NA 626 10,034

1993 1,237 3,107 4,775 NA NA NA NA 1,065 10,184

1994 976 2,913 4,137 NA NA NA NA 1,686 9,712

1995 972 3,461 4,299 NA NA NA NA 1,767 10,499

1996 823 3,711 4,180 NA NA NA NA 1,852 10,566

1997 1,077 3,890 4,351 NA NA NA NA 2,144 11,462

1998 1,029 4,211 4,232 NA NA NA NA 2,707 12,179

1999 1,060 4,826 4,080 NA NA NA NA 3,263 13,229

2000 1,241 5,617 4,278 1,592 1,540 1,399 41 -- 15,708

2001 1,162 6,252 4,324 1,685 2,297 1,453 358 -- 17,531

Production

1989 23 12 56 NA NA NA NA 0 91

1990 36 26 133 NA NA NA NA 1 196

1991 68 48 229 NA NA NA NA 3 348

1992 89 82 358 NA NA NA NA 10 539

1993 103 125 486 NA NA NA NA 18 752

1994 108 179 530 NA NA NA NA 34 851

1995 109 226 574 NA NA NA NA 47 956

1996 98 274 575 NA NA NA NA 56 1,003

1997 111 312 597 NA NA NA NA 70 1,090

1998 123 401 571 NA NA NA NA 99 1,194

1999 108 432 582 NA NA NA NA 130 1,252

2000 109 451 550 74 133 58 4 NA 1,379

2001 111 490 517 83 278 69 14 NA 1,562

aIncludes Pennsylvania, Virginia, and West Virginia. bIncludes Kansas, Montana, and Oklahoma.

cIncludes Oklahoma, Pennsylvania, Utah, Virginia, West Virginia, and Wyoming; these states are individually listed or grouped in

Eastern States and Western States after 1999.

NA = Not available.

Source: Energy Information Administration, Office of Oil and Gas.
cubic feet in 2001, a decline of 2 percent. The areas of the

country with the largest AD wet natural gas

production and their percentage of the total were:

 Gulf of Mexico Federal Offshore (35 percent)

 Texas (21 percent)

 Alaska (8 percent)

 California (8 percent)

 New Mexico (7 percent).

Again, these areas logically correspond to the areas of

the country with the largest volumes of crude oil

production.

Coalbed Methane

Proved Reserves

In 2001, proved reserves of coalbed methane increased

to 17,531 billion cubic feet, a 12 percent increase from

2000’s level (15,708 billion cubic feet). Coalbed methane

accounted for 9.6 percent of all 2001 dry natural gas

reserves (Table 12). EIA estimates that the 2001 proved

gas reserves of fields identified as having coalbed

methane are now more than quadruple the volume

reported in 1989 (Figure 21). Five States ( Colorado,

New Mexico, Wyoming, Utah, and Alabama) currently

have the majority (90 percent) of U.S. Coalbed methane

proved reserves. Estimates of proved coalbed methane

reserves increased 11 percent in Colorado, 1 percent in

New Mexico, 49 percent in Wyoming, 6 percent in

Utah, and declined 6 percent in Alabama in 2001.

Production

U.S. coalbed methane production grew by 13 percent in

2001 to 1,562 billion cubic feet. It accounted for about 8

percent of U.S. dry gas production.

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 extracted from various trade

publications and company reports. The citations do not

necessarily reflect EIA’s concurrence, but are

considered important enough to be brought to the

reader’s attention.

Wyoming

Wyoming’s dry natural gas reserves increased by 2,240

billion cubic feet in 2001, the largest increase of any

State. This was the result of development in the

Pinedale and Madden Fields, and in coalbed methane

fields located in the Powder River Basin.

 Powder River Basin: This basin is located in

northeastern Wyoming and southeastern

Montana. The U.S. Geologic Survey (USGS) has

increased its estimate of the basin’s technically

recoverable CBM resources to 14.26 TCF, up

from 1.11 TCF in 1995. The coal beds are near

the surface and are up to 300 feet thick. These

factors tend to make the wells inexpensive to

drill and operate yet highly productive relative

to other CBM wells. Given these fundamentals,

the basin has seen a boom as producers have

increased their understanding of the techniques

needed to produce the gas. The number of

producing wells increased from 515 in July 1998

to 6,469 in July 2001, the latest month for which

statistics were available. Output in July 2001 in

the Wyoming portion of the basin reached 784

million cubic feet per day. This was an almost 40

percent increase over July 2000 and a 190

percent increase over July 1999. Production

would have been even higher if it were not for

the fact that over 2,200 wells were shut in,

dewatering, or awaiting dewatering permits. As

of July 2001 the basin had less than 15 percent of

the 50,000 wells that are believed necessary to

fully tap the resource. Based on the productivity

of the wells drilled to date this would mean that

the basin could produce over 5 billion cubic feet

per day, more than the proposed capacity of the

pipeline that would bring gas from Prudhoe Bay

to the Lower 48 States. A current impediment to

attaining the full potential of the basin is a delay

in the completion of the Powder River Basin

Coalbed Methane Environmental Impact

Statement (EIS). It is not clear that even the

release of the EIS would minimize all of the

Energy Information Administration

38 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
current limitations on drilling in the basin. For

example, the U.S. Environmental Protection

Agency has received complaints of groundwater

well contamination that are alleged to be the

result of the hydraulic fracturing needed to

enhance release of the methane from the

coal.{41}

Colorado

Colorado had a net increase of 2,099 billion cubic feet of

dry natural gas proved reserves in 2001. This was the

result of development of the Wattenberg Field and

coalbed methane fields and gas fields within the San

Juan, Piceance, and Raton Basins.

Texas

Texas had a net increase of 1,445 billion cubic feet of dry

natural gas proved reserves in 2001. Development of

gas fields in the Barnett Shale and the Lobo Trend

boosted reserves additions for this State. Texas could

have had the largest increase in dry gas proved reserves

in 2001, but a decrease in its associated dissolved gas

reserves volume offset reserves additions of

nonassociated gas.

Areas of Note:

Large Reserves Declines

The following areas had large declines in dry natural

gas proved reserves due to downward revisions or

unreplaced production.

Alaska

Alaska’s proved dry natural gas reserves decreased by

5 percent (437 billion cubic feet) in 2001. Production

decreased from 506 billion cubic feet in 2000 to 461

billion cubic feet in 2001.

Alabama

Alabama’s proved dry natural gas reserves decreased

by 6 percent (234 billion cubic feet) in 2001. Production

in Alabama decreased 4 percent in 2001.

West Virginia

West Virginia’s proved dry natural gas reserves

decreased by 8 percent (222 billion cubic feet) in 2001.

Production in West Virginia decreased 10 percent in

2001.

Reserves in

Nonproducing Reservoirs

Nonproducing proved natural gas reserves (wet after

lease separation) of 52,948 billion cubic feet were

reported in 2001, 24 percent more than the 42,834

billion cubic feet reported in 2000 (Appendix D, Table

D10). About 26 percent of the reserves in nonproducing

reservoirs are located in the Gulf of Mexico Federal

Offshore area. Much of the new deepwater reserves are

in the nonproducing category. Wells or reservoirs are

nonproducing due to any of several operational

reasons. These include:

 waiting for well workovers

 waiting for additional development or

replacement wells to be drilled

 production or pipeline facilities not yet installed

 awaiting 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 2001 Annual Report 39
5. Natural Gas Liquids Statistics

Natural Gas Liquids

Proved Reserves

U.S. natural gas liquids proved reserves decreased 4

percent to 7,993 million barrels in 2001 (Table 13).

Reserve additions replaced 60 percent of 2001 natural

gas liquids production.

The reserves of six areas account for 81 percent of the

Nation’s natural gas liquids proved reserves.

Percent of

Area U.S. NGL Reserves

Texas 33

Gulf of Mexico Federal Offshore 12

Utah - Wyoming 11

New Mexico 11

Oklahoma 9

Louisiana 5

Area Total 81

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.

Discoveries

Total discoveries of natural gas liquids reserves were 997

million barrels in 2001, an increase of 19 percent from

2000 (839 million barrels). Areas with the largest total

discoveries were:

 Texas (34 percent)

 Gulf of Mexico Federal Offshore (21 percent)

 Utah & Wyoming (12 percent)

 Louisiana (8 percent)

 Oklahoma (8 percent)

 New Mexico (7 percent).

New field discoveriesin 2001 (138 million barrels) were 50

percent higher than in 2000. Areas with the largest new

field discoveries were the Gulf of Mexico Federal

Offshore (68 percent of 2001 new field discoveries) and

Texas (25 percent).

New reservoir discoveries in old fields (142 million barrels)

were 39 percent higher than they were in 2000. Areas

with the largest new reservoir discoveries in old fields were

the Gulf of Mexico Federal Offshore (40 percent of 2001

new reservoir discoveries in old fields), Louisiana (30

percent), and Texas (22 percent).

Extensions were 717 million barrels in 2001, 11 percent

higher than the 2000 volume of extensions (645

million). Areas with the largest extensions were Texas

(39 percent), Utah & Wyoming (16 percent), and

Oklahoma (10 percent).

Revisions and Adjustments

In 2001, there were 957 million barrels of revision

increases, 1,089 million barrels of revision decreases and

-429 million barrels of adjustments. The net of revisions

and adjustments was 561 million barrels.

Sales and Acquisitions

There were 550 million barrels of acquisitions, and 448

million barrels of sales in 2001. The net of these

transactions added 102 million barrels of natural gas

liquids proved reserves.

Production

Natural gas liquids production was an estimated 890

million barrels in 2001, a decrease of 3 percent from

2000. Alaska production decreased 9 percent to 20

million barrels in 2001, while lower 48 States

production decreased 3 percent to 860 million barrels in

2001.

Six areas accounted for about 87 percent of the Nation’s

natural gas liquids production.

 Texas (33 percent)

 Gulf of Mexico Federal Offshore (22 percent)

 New Mexico (9 percent)

 Oklahoma (8 percent)

 Louisiana (8 percent)

 Utah-Wyoming (7 percent).

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 41
Energy Information Administration

42 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

aIncludes Federal offshore Alabama.

bIncludes 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 2001 contained in the publications Petroleum Supply

Annual 2001, DOE/EIA-0340(01) and Natural Gas Annual 2001 DOE/EIA-0131(01).

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

Alaska . . . . . . . . . . . . . . . . . . . . . 277 0 148 0 0 0 0 0 0 20 405

Lower 48 States............. 8,068 -429 809 1,089 448 550 717 138 142 870 7,588

Alabama. . . . . . . . . . . . . . . . . . . . 150 -71 3 16 0 0 4 1 0 7 64

Arkansas ................... 5 0 1 0 0 0 0 0 0 1 5

California . . . . . . . . . . . . . . . . . . . 101 -18 5 10 0 1 5 0 0 8 76

Coastal Region Onshore . . . . . 27 -6 1 5 0 0 0 0 0 1 16

Los Angeles Basin Onshore. . . 10 -2 1 1 0 0 0 0 0 0 8

San Joaquin Basin Onshore . . 64 -10 3 4 0 1 5 0 0 7 52

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

Colorado . . . . . . . . . . . . . . . . . . . 316 -34 49 38 59 76 60 0 0 25 345

Florida . . . . . . . . . . . . . . . . . . . . . 11 1 1 0 0 0 0 0 0 1 12

Kansas. . . . . . . . . . . . . . . . . . . . . 306 10 17 13 15 20 3 0 0 26 302

Kentucky . . . . . . . . . . . . . . . . . . . 56 18 13 15 2 2 2 0 1 3 72

Louisiana . . . . . . . . . . . . . . . . . . . 436 -29 43 93 42 62 37 2 43 68 391

North . . . . . . . . . . . . . . . . . . . . 61 -4 9 13 2 6 11 0 1 7 62

South Onshore. . . . . . . . . . . . . 337 -39 27 72 35 42 20 1 37 49 269

State Offshore . . . . . . . . . . . . . 38 14 7 8 5 14 6 1 5 12 60

Michigan . . . . . . . . . . . . . . . . . . . 35 14 4 8 0 0 1 1 0 4 43

Mississippi . . . . . . . . . . . . . . . . . . 8 3 2 1 1 1 0 0 0 2 10

Montana.................... 4 1 1 1 0 0 0 0 0 0 5

New Mexico . . . . . . . . . . . . . . . . . 896 -10 90 86 25 18 70 2 2 84 873

East . . . . . . . . . . . . . . . . . . . . . 333 -32 42 52 21 11 38 2 1 43 279

West. . . . . . . . . . . . . . . . . . . . . 563 22 48 34 4 7 32 0 1 41 594

North Dakota . . . . . . . . . . . . . . . . 54 4 6 4 1 1 0 0 2 5 57

Oklahoma . . . . . . . . . . . . . . . . . . 734 -14 74 109 27 35 72 1 3 75 694

Texas ...................... 2,819 -128 246 365 151 187 277 35 31 298 2,653

RRC District 1 . . . . . . . . . . . . . 55 -12 3 6 1 2 3 0 0 4 40

RRC District 2 Onshore . . . . . . 72 -8 7 10 3 10 6 1 4 12 67

RRC District 3 Onshore . . . . . . 209 16 33 29 30 36 24 6 5 44 226

RRC District 4 Onshore . . . . . . 406 -37 32 48 24 25 47 19 11 53 378

RRC District 5 . . . . . . . . . . . . . 49 -6 5 13 0 9 8 1 0 4 49

RRC District 6 . . . . . . . . . . . . . 283 -15 26 24 32 42 16 0 1 28 269

RRC District 7B . . . . . . . . . . . . 34 2 2 5 2 1 3 0 0 6 29

RRC District 7C . . . . . . . . . . . . 434 -95 28 93 38 40 41 0 2 29 290

RRC District 8 . . . . . . . . . . . . . 526 22 49 68 11 11 36 7 7 54 525

RRC District 8A . . . . . . . . . . . . 217 39 19 21 3 3 14 0 0 17 251

RRC District 9 . . . . . . . . . . . . . 161 -22 10 11 2 2 66 0 0 15 189

RRC District 10 . . . . . . . . . . . . 369 -13 32 37 5 6 13 0 1 31 335

State Offshore ............. 4 1 0 0 0 0 0 1 0 1 5

Utah and Wyoming . . . . . . . . . . . 947 -147 104 78 73 87 118 2 2 65 897

West Virginia . . . . . . . . . . . . . . . . 105 1 12 11 1 1 4 0 1 6 106

Federal Offshorea ............ 1,078 -30 137 240 51 59 64 94 57 192 976

Pacific (California) .......... 4 0 0 0 0 0 5 0 0 0 9

Gulf of Mexico (Louisiana)a . . . 921 -27 103 224 50 57 52 47 53 147 785

Gulf of Mexico (Texas). . . . . . . 153 -3 34 16 1 2 7 47 4 45 182

Miscellaneousb .............. 7 0 1 1 0 0 0 0 0 0 7

U.S. Total .................. 8,345 -429 957 1,089 448 550 717 138 142 890 7,993

Table 13. Natural Gas Liquids Proved Reserves, Reserves Changes, and Production,

Wet After Lease Separation, 2001 (Million Barrels of 42 U.S. Gallons)

Changes in Reserves During 2001

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 12/31/00 (+,–) (+) (–) (–) (+) (+) (+) (+) (–) 12/31/01
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 43

Table 14. Natural Gas Plant Liquids Proved Reserves and Production, 2001

(Million Barrels of 42 U.S. Gallons)

2001 2001 2001 2001

State and Subdivision Reserves Production State and Subdivision Reserves Production

Alaska . . . . . . . . . . . . . . . . . . . . . . 405 20

Lower 48 States.............. 6,190 655

Alabama . . . . . . . . . . . . . . . . . . . . 32 3

Arkansas .................... 3 1

California. . . . . . . . . . . . . . . . . . . . 75 8

Coastal Region Onshore . . . . . 16 1

Los Angeles Basin Onshore . . . 8 0

San Joaquin Basin Onshore. . . 51 7

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

Colorado . . . . . . . . . . . . . . . . . . . . 298 22

Florida . . . . . . . . . . . . . . . . . . . . . . 12 1

Kansas . . . . . . . . . . . . . . . . . . . . . 300 26

Kentucky . . . . . . . . . . . . . . . . . . . . 72 3

Louisiana. . . . . . . . . . . . . . . . . . . . 204 35

North. . . . . . . . . . . . . . . . . . . . . 35 3

South Onshore . . . . . . . . . . . . . 128 23

State Offshore. . . . . . . . . . . . . . 41 9

Michigan . . . . . . . . . . . . . . . . . . . . 41 4

Mississippi................... 2 1

Montana .................... 5 0

New Mexico . . . . . . . . . . . . . . . . . 794 77

East . . . . . . . . . . . . . . . . . . . . . 259 38

West . . . . . . . . . . . . . . . . . . . . . 535 39

North Dakota. . . . . . . . . . . . . . . . . 50 5

Oklahoma . . . . . . . . . . . . . . . . . . . 605 66

Texas....................... 2,318 252

RRC District 1. . . . . . . . . . . . . . 35 4

RRC District 2 Onshore . . . . . . 53 9

RRC District 3 Onshore . . . . . . 144 28

RRC District 4 Onshore . . . . . . 281 40

RRC District 5. . . . . . . . . . . . . . 43 3

RRC District 6. . . . . . . . . . . . . . 215 23

RRC District 7B. . . . . . . . . . . . . 28 6

RRC District 7C . . . . . . . . . . . . 271 26

RRC District 8. . . . . . . . . . . . . . 504 52

RRC District 8A. . . . . . . . . . . . . 250 17

RRC District 9. . . . . . . . . . . . . . 182 14

RRC District 10. . . . . . . . . . . . . 311 30

State Offshore.............. 1 0

Utah and Wyoming . . . . . . . . . . . . 782 54

West Virginia. . . . . . . . . . . . . . . . . 105 6

Federal Offshorea . . . . . . . . . . . . . 486 91

Pacific (California)........... 1 0

Gulf of Mexico (Louisiana)a . . . 460 87

Gulf of Mexico (Texas) . . . . . . . 25 4

Miscellaneousb ............... 6 0

U.S. Total ................... 6,595 675

aIncludes Federal Offshore Alabama. bIncludes 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 2001 contained in the publications Petroleum Supply Annual 2001,

DOE/EIA-0340(2001) and Natural Gas Annual 2001, DOE/EIA-0131(2001).

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

44 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table 15. Lease Condensate Proved Reserves and Production, 2001

(Million Barrels of 42 U.S. Gallons)

2001 2001 2001 2001

State and Subdivision Reserves Production State and Subdivision Reserves Production

Alaska ...................... 0 0

Lower 48 States.............. 1,398 215

Alabama . . . . . . . . . . . . . . . . . . . . 32 4

Arkansas .................... 2 0

California.................... 1 0

Coastal Region Onshore ..... 0 0

Los Angeles Basin Onshore . . . 0 0

San Joaquin Basin Onshore. . . 1 0

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

Colorado . . . . . . . . . . . . . . . . . . . . 47 3

Florida ...................... 0 0

Kansas ..................... 2 0

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

Louisiana. . . . . . . . . . . . . . . . . . . . 187 33

North. . . . . . . . . . . . . . . . . . . . . 27 4

South Onshore . . . . . . . . . . . . . 141 26

State Offshore. . . . . . . . . . . . . . 19 3

Michigan .................... 2 0

Mississippi................... 8 1

Montana .................... 0 0

New Mexico . . . . . . . . . . . . . . . . . 79 7

East . . . . . . . . . . . . . . . . . . . . . 20 5

West . . . . . . . . . . . . . . . . . . . . . 59 2

North Dakota................. 7 0

Oklahoma . . . . . . . . . . . . . . . . . . . 89 9

Texas. . . . . . . . . . . . . . . . . . . . . . . 335 46

RRC District 1.............. 5 0

RRC District 2 Onshore . . . . . . 14 3

RRC District 3 Onshore . . . . . . 82 16

RRC District 4 Onshore . . . . . . 97 13

RRC District 5.............. 6 1

RRC District 6. . . . . . . . . . . . . . 54 5

RRC District 7B............. 1 0

RRC District 7C . . . . . . . . . . . . 19 3

RRC District 8. . . . . . . . . . . . . . 21 2

RRC District 8A............. 1 0

RRC District 9.............. 7 1

RRC District 10. . . . . . . . . . . . . 24 1

State Offshore.............. 4 1

Utah and Wyoming . . . . . . . . . . . . 115 11

West Virginia................. 1 0

Federal Offshorea . . . . . . . . . . . . . 490 101

Pacific (California)........... 8 0

Gulf of Mexico (Louisiana)a . . . 325 60

Gulf of Mexico (Texas) . . . . . . . 157 41

Miscellaneousb ............... 1 0

U.S. Total ................... 1,398 215

aIncludes Federal Offshore Alabama. bIncludes 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” 2001.

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

Proved Reserves

Natural gas plant liquids proved reserves decreased in

2001 to 6,595 million barrels, a 4 percent drop from the

2000 level (6,873 million barrels) (Table 14). Six areas

accounted for about 80 percent of the Nation’s natural

gas plant liquids proved reserves:

Percent of

Area U.S. Gas Plant Liquids

Texas 35

Utah-Wyoming 12

New Mexico 12

Oklahoma 9

Gulf of Mexico Federal Offshore 7

Kansas 5

Area Total 80

Production

Natural gas plant liquids production decreased 5

percent in 2001—from 710 million barrels in 2000 to 675

million barrels of production (Table 14). The top six

areas for proved reserves of natural gas plant liquids

accounted for about 84 percent of the Nation’s natural

gas plant liquids production:

 Texas (37 percent)

 Gulf of Mexico Federal Offshore (14 percent)

 New Mexico (11 percent)

 Oklahoma (10 percent)

 Utah and Wyoming (8 percent)

 Kansas (4 percent).

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.

Lease Condensate

Proved Reserves

Proved reserves of lease condensate in the United

States were 1,398 million barrels in 2001 (Table 15). This

was 5 percent less than the volume reported in 2000

(1,472 million barrels). The reserves of five areas

account for about 85 percent of the Nation’s lease

condensate proved reserves.

Percent of U.S.

Area Condensate Reserves

Gulf of Mexico Federal Offshore 34

Texas 24

Louisiana 13

Utah-Wyoming 8

Oklahoma 6

Area Total 85

Production

Production of lease condensate was 215 million barrels

in 2001, an increase of 3 percent from 2000’s production

(208 million barrels). The production of five areas

account for about 92 percent of the Nation’s lease

condensate production.

 Gulf of Mexico Federal Offshore (47 percent)

 Texas (21 percent)

 Louisiana (15 percent)

 Utah and Wyoming (5 percent)

 Oklahoma (4 percent).

Reserves in

Nonproducing Reservoirs

Like crude oil and natural gas, not all lease condensate

proved reserves were contained in reservoirs that were

producing during 2001. Proved reserves of 562 million

barrels of lease condensate, an increase of 13 percent

from 2000, were reported in nonproducing reservoirs

in 2001 (Appendix D, Table D10). About 48 percent of

the nonproducing lease condensate reserves were

located in the Gulf of Mexico Federal Offshore.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 45
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Annual Report. DOE/EIA-0216(77). Washington,

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DOE/EIA-0216(95). Washington, DC.

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1997. U.S. Crude Oil, Natural Gas, and Natural Gas

Liquids Reserves 1996 Annual Report.

DOE/EIA-0216(96). Washington, DC.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 47
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1998. U.S. Crude Oil, Natural Gas, and Natural Gas

Liquids Reserves 1997 Annual Report.

DOE/EIA-0216(97). Washington, DC.

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Liquids Reserves 1998 Annual Report.

DOE/EIA-0216(98). Washington, DC.

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www.chevrontexaco.com/news/archive/chevron_

press/2001/2001-10-09-1.asp)

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(http://www.eia.doe.gov/emeu/aer/contents.html)

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(http://www.shellus.com/news/press_releases/200

1/press-19SEP01.htm)

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Annual Report 2001, pg 10. (http://

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U.S. Geological Survey Circular 1118. Denver, CO,

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OCS Report MMS 94-0045. New Orleans, LA, pp.

5-6.

Energy Information Administration

48 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Appendix A

Operator Data by Size Class
Appendix A

Operator Data by Size Class

Appendix A provides a series of tables of the proved

reserves and production by production size class for

the years 1996 through 2001 for oil and gas well

operators. The tables show the volumetric change and

percent change from the previous year and from 1996.

In addition they show the 2001 average per operator in

each class. All companies that reported to EIA 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 contains 22,019 small operators.

We estimated production and reserves for small

operators for 2001 from a sample of approximately 3

percent.

Class 1–10 contains the 10 highest producing

companies each year on a barrel oil equivalent basis.

These companies are not necessarily the same 10

companies each year.

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.

Natural Gas

Proved Reserves

The wet natural gas proved reserves reported for 1996

through 2001 have changed from 175,147 billion cubic

feet to 191,743 billion cubic feet (Table A1). These

proved reserves are highly concentrated in the larger

companies. In 2001, the top 20 operators (Class 1–10

and Class 11–20) producing companies had 59 percent

of the proved reserves of natural gas. The next two size

classes contain 80 and 400 companies and account for

26 and 10 percent of the U.S. natural gas proved

reserves, respectively. The top 20 operators had an

increase of 16 percent in their natural gas proved

reserves from 1996 to 2001. Tthe rest of the operators in

(Class 21–100, Class 101–500, and Class Other) had an

increase of 5 percent in their reserves. In 2001, the top

20 operators’ natural gas reserves increased by 9

percent from 2000.

Production

Wet natural gas production has increased from 20,164

billion cubic feet in 2000 to 20,642 billion cubic feet in

2001 (Table A2). In 2001, the top 20 producing

companies had 59 percent of the proved reserves and

production of wet natural gas. The next two size classes

have 24 and 13 percent of the wet natural gas

production, respectively. The top 20 operators had an

increase of 16 percent in their wet natural gas

production from 1996 to 2001. The rest of the operators

had a decrease of 9 percent from 1996 to 2001. The top

20 operators’ wet natural gas production had a increase

of 6 percent in 2001 from 2000.

Crude Oil

Proved Reserves

Proved reserves of crude oil are more highly

concentrated in a few companies than those of natural

gas. The 20 largest oil and gas producing companies in

2001 had 73 percent of U.S. proved reserves of crude oil

(Table A3), in contrast to wet natural gas where these

same companies operated 59 percent of the total

proved reserves.

U.S. proved reserves of crude oil increased 2 percent in

2001. The top 20 producing companies proved reserves

of crude oil during 2001 increased 6 percent. The top 20

class had an increase of 7 percent in their crude oil

proved reserves from 1996 to 2001.

Production

Crude oil production reported for 1996 to 2001 has

decreased from 2,173 million barrels to 1,915 million

barrels (Table A4). The 20 largest oil and gas producing

companies had 68 percent of U.S. production of crude

oil in 2001. In 1996 they accounted for 65 percent of

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 49
production. This is in contrast to wet natural gas where

these same companies produced only 59 percent of the

total. U.S. production of crude oil declined by 12

percent from 1996 to 2001. The top 20 operators had a

decline of 7 percent in their oil production during the

same period. U.S. production of crude oil increased by

2 percent from 2000 to 2001, while the top 20 operators

production increased by 3 percent.

Fields

The number of fields in which Category I and Category

II operators were active dropped during the 1996–2001

period (Table A5). From 1996-2001, the number of fields

in which the top 20 operators were active increased by

765 (15 percent), while in 2001 the number increased by

639 (12 percent) from 2000.

Energy Information Administration

50 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 51

Class 1-10 72,606 68,876 64,336 64,320 81,437 88,936 7,499 16,330 8,893.630

Percent of Total 41.5% 39.2% 37.3% 36.5% 43.7% 46.4% 9.2% 22.5%

Class 11-20 25,416 27,705 28,338 24,925 22,590 24,588 1,998 -828 2,458.787

Percent of Total 14.5% 15.8% 16.4% 14.1% 12.1% 12.8% 8.8% -3.3%

Class 21-100 43,300 45,593 47,009 52,160 48,832 50,055 1,223 6,755 625.690

Percent of Total 24.7% 25.9% 27.3% 29.6% 26.2% 26.1% 2.5% 15.6%

Class 101-500 22,483 23,338 24,471 25,967 22,620 19,046 -3,575 -3,437 47.614

Percent of Total 12.8% 13.3% 14.2% 14.7% 12.1% 9.9% -15.8% -15.3%

Class Other (22,019) 11,342 10,209 8,289 8,289 11,030 9,118 -1,912 -2,224 0.414

Percent of Total 6.5% 5.8% 4.8% 5.0% 5.9% 4.8% -17.3% -19.6%

Category I (179) 146,601 147,491 146,458 146,458 162,144 169,056 6,912 22,455 944.445

Percent of Total 83.7% 83.9% 84.9% 82.8% 86.9% 88.2% 4.3% 15.3%

Category II (430) 18,382 17,764 18,033 18,033 13,123 13,346 222 -5,036 31.037

Percent of Total 10.5% 10.1% 10.5% 12.5% 7.0% 7.0% 1.7% -27.4%

Category III (22,519) 10,164 10,467 7,952 7,952 R11,243 9,342 -1,901 -822 0.426

Percent of Total 5.8% 6.0% 4.6% 4.7% R6.0% 4.9% -16.9% -8.1%

Total Published 175,147 175,721 172,443 176,159 186,510 191,743 5,233 16,596 8.515

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 2.8% 9.5%

Table A1. Natural Gas Proved Reserves, Wet After Lease Separation, by Operator Production Size Class,

1996–2001

(Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

2000–2001 1996–2001 2001

Volume and Volume and Average

Percent Percent Reserves

Size Class 1996 1997 1998 1999 2000 2001 Change Change per Operator

Note: There were 21,910 active Category III operators in the 2001 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 1,797 Category III operators (Table E2). The "other" size class represents 22,019 operators in the

2001 frame (22,519 active operators minus the 500 largest operators).

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

52 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Class 1-10 7,448 7,178 6,954 6,881 8,495 9,019 525 1,571 901.934

Percent of Total 37.5% 35.7% 35.4% 34.7% 42.1% 43.7% 6.2% 21.1%

Class 11-20 3,002 3,286 3,317 3,560 2,886 3,064 178 62 306.430

Percent of Total 14.5% 15.8% 16.4% 14.1% 14.3% 14.8% 6.2% 2.1%

Class 21-100 5,316 5,729 5,595 5,523 4,965 4,949 -16 -367 61.865

Percent of Total 24.7% 25.9% 27.3% 29.6% 24.6% 24.0% -0.3% -6.9%

Class 101-500 2,623 2,665 2,721 2,793 2,780 2,609 -171 -14 6.523

Percent of Total 12.8% 13.3% 14.2% 14.7% 13.8% 12.6% -6.2% -0.5%

Class Other (22,019) 1,484 1,276 1,035 1,099 1,038 1,000 -38 -484 0.045

Percent of Total 6.5% 5.8% 4.8% 5.0% 5.1% 4.8% -3.7% -32.6%

Category I (179) 16,381 16,897 16,619 16,248 17,096 17,672 576 1,2919 8.725

Percent of Total 83.7% 83.9% 84.9% 82.8% 84.8% 85.6% 3.4% 7.9%

Category II (430) 2,128 1,979 2,019 2,556 1,921 1,932 11 -196 4.493

Percent of Total 10.5% 10.1% 10.5% 12.5% 9.5% 9.4% 0.6% -9.2%

Category III (22,519) 1,364 1,258 984 1,052 R1,147 1,038 -109 -326 0.047

Percent of Total 5.8% 6.0% 4.6% 4.7% R5.7% 5.0% -9.5% -23.9%

Total Published 19,873 20,134 19,622 19,856 20,164 20,642 478 769 0.917

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 2.4% 3.9%

Table A2. Natural Gas Production, Wet After Lease Separation, by Operator Production Size Class,

1996–2001

(Billion Cubic Feet at 14.73 psia and 60° Fahrenheit)

2000–2001 1996–2001 2001

Volume and Volume and Average

Percent Percent Production

Size Class 1996 1997 1998 1999 2000 2001 Change Change per Operator

Note: There were 21,910 active Category III operators in the 2001 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 1,797 Category III operators (Table E2). The "other" size class represents 22,019 operators in the

2001 frame (22,519 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 2001 Annual Report 53

Class 1-10 13,362 11,434 11,501 11,121 12,367 13,590 1,223 228 1,359.041

Percent of Total 60.7% 50.7% 54.7% 51.1% 56.1% 60.5% 9.9% 1.7%

Class 11-20 2,013 2,977 2,894 2,585 3,172 2,901 -270 888 290.146

Percent of Total 9.1% 13.2% 13.8% 11.9% 14.4% 12.9% -8.5% 44.1%

Class 21-100 3,155 4,384 3,677 4,338 2,505 2,856 351 -299 35.696

Percent of Total 14.3% 19.4% 17.5% 19.9% 11.4% 12.7% 14.0% -9.5%

Class 101-500 1,838 2,111 1,754 2,379 2,286 1,794 -492 -44 4.485

Percent of Total 8.3% 9.4% 8.3% 10.9% 10.4% 8.0% -21.5% -2.4%

Class Other (22,019) 1,649 1,640 1,208 1,342 1,716 1,305 -411 -344 0.059

Percent of Total 7.5% 7.3% 5.7% 6.2% 7.8% 5.8% -24.0% -20.9%

Category I (179) 19,312 19,461 18,819 18,952 19,421 20,325 904 1,013 113.549

Percent of Total 87.7% 86.3% 89.5% 87.1% 88.1% 90.6% 4.7% 5.2%

Category II (430) 1,117 1,400 1,018 1,521 873 794 -78 -323 1.848

Percent of Total 5.1% 6.2% 4.8% 7.0% 4.0% 3.5% -8.9% -28.9%

Category III (22,519) 1,588 1,685 1,197 1,293 R1,751 1,326 -425 -262 0.061

Percent of Total 7.2% 7.5% 5.7% 5.9% R7.9% 5.9% -24.3% -16.5%

Total Published 22,017 22,546 21,034 21,765 22,045 22,446 401 429 0.997

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 1.8% 1.9%

Table A3. Crude Oil Proved Reserves by Operator Production Size Class, 1996–2001

(Million Barrels of 42 U.S. Gallons)

2000–2001 1996–2001 2001

Volume and Volume and Average

Percent Percent Reserves

Size Class 1996 1997 1998 1999 2000 2001 Change Change per Operator

Note: There were 21,910 active Category III operators in the 2001 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 1,797 Category III operators (Table E2). The "other" size class represents 22,019 operators in the

2001 frame (22,519 active operators minus the 500 largest operators).

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

54 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Class 1-10 1,220 1,047 1,025 974 961 1,061 99 -159 106.050

Percent of Total 56.1% 49.0% 51.5% 49.9% 51.1% 55.4% 10.4% -13.1%

Class 11-20 185 262 255 241 304 240 -64 55 24.032

Percent of Total 8.5% 12.3% 12.8% 12.3% 16.2% 12.5% -21.1% 29.9%

Class 21-100 307 373 342 350 214 233 19 -74 2.912

Percent of Total 14.1% 17.4% 17.2% 17.9% 11.4% 12.2% 8.9% -24.1%

Class 101-500 213 237 206 208 211 195 -15 -18 0.488

Percent of Total 9.8% 11.1% 10.3% 10.7% 11.2% 10.2% -7.3% -8.3%

Class Other (22,019) 248 219 163 179 190 186 -4 -62 0.008

Percent of Total 11.4% 10.2% 8.2% 9.2% 10.1% 9.7% -2.1% -25.1%

Category I (179) 1,791 1,760 1,714 1,617 1,572 1,612 40 -179 9.007

Percent of Total 82.4% 82.3% 86.1% 82.8% 83.6% 84.2% 2.6% -10.0%

Category II (430) 143 157 118 160 111 112 1 -31 0.260

Percent of Total 6.6% 7.3% 5.9% 8.2% 5.9% 5.8% 0.9% -21.8%

Category III (22,519) 239 221 159 175 R197 191 -6 -48 0.009

Percent of Total 11.0% 10.3% 8.0% 9.0% R10.5% 10.0% -3.3% -20.1%

Total Published 2,173 2,138 1,991 1,952 1,880 1,915 35 -258 0.085

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 1.9% -11.9%

Table A4. Crude Oil Production by Operator Production Size Class, 1996–2001

(Million Barrels of 42 U.S. Gallons)

2000–2001 1996–2001 2001

Volume and Volume and Average

Percent Percent Production

Size Class 1996 1997 1998 1999 2000 2001 Change Change per Operator

Note: There were 22,519 active Category III operators in the 2001 sample frame. The reserves and production of Category III operators

were estimated from an adjusted sample of 2,136 Category III operators (Table E2). The "other" size class represents 21,910 operators in the

2001 frame (22,019 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 2001 Annual Report 55

Class 1-10 2,800 2,566 2,475 2,559 3,444 3,794 350 994 379.400

Percent of Total 10.7% 10.4% 9.5% 10.0% 13.0% 14.0% 10.2% 35.5%

Class 11-20 2,441 2,257 1,822 1,514 1,923 2,212 289 -229 221.200

Percent of Total 9.3% 9.1% 7.0% 5.9% 7.2% 8.2% 15.0% -9.4%

Class 21-100 7,526 7,159 7,526 8,180 7,084 7,195 111 -331 89.938

Percent of Total 28.7% 28.9% 29.0% 32.0% 26.7% 26.5% 1.6% -4.4%

Class 101-500 12,492 12,878 12,817 12,344 12,580 12,435 -145 -57 31.088

Percent of Total 47.7% 52.0% 49.4% 48.2% 47.4% 45.9% -1.2% -0.5%

Rest a952 1,332 1,524 1,287 1,529 1,480 -49 528 13.578

Percent of Total 3.6% 5.4% 5.9% 5.0% 5.8% 5.5% -3.2% 55.5%

Category I 15,635 15,232 15,666 15,120 16,174 16,196 22 561 90.480

Percent of Total 59.7% 61.5% 60.4% 59.1% 60.9% 59.7% 0.1% 3.6%

Category II 10,576 R9,530 10,271 10,467 10,146 10,764 618 188 25.033

Percent of Total 40.3% 38.5% 39.6% 40.9% 38.2% 39.7% 6.1% 1.8%

Total 26,211 R24,762 25,937 25,587 26,560 27,116 556 905 44.525

Percent of Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 2.1% 3.5%

aThe reduced 1996 survey had fewer operators and fields in the “rest” class.

R = Revised

Note: Includes only data from Category I and Category II operators. In 2001, there were 179 Category I operators and 430 Category II

operators. The “rest” size class had 109 operators in 2001.

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

Table A5. Operator Field Count by Operator Production Size Class, 1996–2001

2000–2001 1996–2001 2001 Average

Number and Number and Number of

Percent Percent Fields per

Size Class 1996 1997 1998 1999 2000 2001 Change Change Operator
Appendix B

Top 100 Oil and Gas Fields for 2001
Appendix B

Top 100 Oil and Gas Fields for 2001

This appendix presents estimates of the proved

reserves and production of the top 100 oil and gas

fields. The oil field production and reserve data include

both crude oil and lease condensate. The gas field

production and reserve data is total wet natural gas

(associated-dissolved natural gas and nonassociated

natural gas, wet after lease separation). Several of the

same fields are in both tables B1 and B2.

Table B1. Top 100 Oil Fields for 2001

The top 100 oil fields in the United States as of

December 31, 2001, had 15,382 million barrels of

proved reserves accounting for 69 percent of the total

United States (Table 6 and Table 14). Although there is

considerable grouping of field–level statistics within

the tables, rough orders of magnitude can be estimated

for the proved reserves and production of most fields.

Many of the fields in the top 100 group are operated by

only one or two operators, therefore, the totals for

proved reserves are grouped as top 10, top 20, top 50,

and top 100 to avoid revealing company proprietary

data.

In the top 20 oil fields for 2001 there are four fields,

Mississippi Canyon Block 778 (Thunder Horse),

Mississippi Canyon Block 807 (Mars), Green Canyon

Block 644 (Holstein), and Mississippi Canyon Block 810

(Ursa) which are in the deep water of the Gulf of

Mexico Federal Offshore.

The top 100 oil fields in the United States as of

December 31, 2001, had 1,030 million barrels of

production, or 54 percent of the total (Table 6 and

Table 14). Many of the oil fields in the top 100 are very

old. The oldest reported field to EIA, Coalinga in

California, was discovered in 1887. The newest

reported field was Mississippi Canyon Block 778 in the

Gulf of Mexico Federal Offshore. The oil fields with

newer discovery dates are typically located in the Gulf

of Mexico Offshore and Alaska.

Table B2. Top 100 Gas Fields for 2001

The top 100 gas fields in the United States as of

December 31, 2001, had 92,354 billion cubic feet of wet

natural gas proved reserves, or 48 percent of the total

(Table 9).

The top 100 gas fields in the United States as of

December 31, 2001, had 6,965 billion cubic feet of

production, or 32 percent of the total (Table 9). Fewer

of the gas fields in the top 100 are as old as the top100 oil

fields. There were 22 gas fields in Table B2 that were

discovered prior to 1950. Gas fields in the top 100 are

newer than the oil fields, 57 gas fields were discovered

after 1967. The oldest, Big Sandy in Kentucky, was

discovered in 1881. The gas fields with newer discovery

dates are located in the Gulf of Mexico Offshore, New

Mexico, and Colorado.

Table B3. Top U.S. Operators Ranked by

Reported 2001 Operated Production Data

Table B3 lists the top U.S. oil and gas operators ranked

by reported 2001 operated production data.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 59
Table B1. Top 100 U.S. Fields Ranked by Oila Proved Reserves from Reported 2001 Field Level Data

(Million Barrels of 42 U.S. Gallons)

Discovery Proved Reserves 2001 Reported

Field Name Location Year Rank Group Production Volume

1 PRUDHOE BAY AK 1967 1-10 167.2

2 MISSISSIPPI CANYON BLK 778 FG 1999 1-10 0.0

3 KUPARUK RIVER AK 1969 1-10 68.4

4 BELRIDGE SOUTH CA 1911 1-10 38.9

5 MIDWAY-SUNSET CA 1901 1-10 51.8

6 WASSON TX 1937 1-10 26.3

7 YATES TX 1926 1-10 8.1

8 KERN RIVER CA 1899 1-10 40.6

9 ELK HILLS CA 1919 1-10 30.3

10 MISSISSIPPI CANYON BLK 807 FG 1989 1-10 58.4

Top 10 Volume Subtotal 7,611.4 490.0

Top 10 Percentage of U.S. Total 31.9% 23.0%

11 ALPINE AK 1994 11-20 31.2

12 MILNE POINT AK 1982 11-20 19.6

13 SPRABERRY TREND AREA TX 1952 11-20 17.6

14 SLAUGHTER TX 1937 11-20 14.8

15 HONDO FP 1969 11-20 10.0

16 GREEN CANYON BLK 644 FG 1999 11-20 0.0

17 CYMRIC CA 1916 11-20 21.4

18 LEVELLAND TX 1945 11-20 9.4

19 ENDICOTT AK 1978 11-20 9.7

20 MISSISSIPPI CANYON BLK 810 FG 1996 11-20 38.7

Top 20 Volume Subtotal 10,050.4 662.2

Top 20 Percentage of U.S. Total 42.2% 31.1%

21 LOST HILLS CA 1953 21-50 10.9

22 PESCADO FP 1970 21-50 5.8

23 NORTHSTAR AK 1984 21-50 1.7

24 WILMINGTON CA 1935 21-50 15.3

25 COWDEN NORTH TX 1930 21-50 8.3

26 HOBBS NM 1928 21-50 3.0

27 SAN ARDO CA 1947 21-50 4.7

28 MISSISSIPPI CANYON BLK 127 FG 2000 21-50 0.0

29 CEDAR HILLS ND & MT & SD 1954 21-50 3.4

30 SHO-VEL-TUM OK 1905 21-50 6.2

31 POINT MCINTYRE AK 1988 21-50 19.0

32 VACUUM NM 1973 21-50 7.4

33 KELLY-SNYDER TX 1948 21-50 3.4

34 WATTENBERG CO 1970 21-50 6.2

35 ALAMINOS CANYON BLK 25 FG 1997 21-50 8.6

36 VENTURA CA 1916 21-50 4.5

37 GREATER ANETH UT 1956 21-50 3.6

38 GREEN CANYON BLK 338 FG 2001 21-50 0.0

39 COALINGA CA 1887 21-50 7.2

40 MCELROY TX 1926 21-50 5.5

41 RANGELY CO 1902 21-50 5.7

42 INGLEWOOD CA 1924 21-50 2.5

43 HAWKINS TX 1940 21-50 3.6

44 MONUMENT BUTTE UT 1964 21-50 1.9

45 VIOSCA KNOLL BLK 990 FG 1981 21-50 10.2

46 MISSISSIPPI CANYON BLK 383 FG 1987 21-50 0.0

47 GREEN CANYON BLK 158 FG 1992 21-50 5.0

48 FULLERTON TX 1971 21-50 4.8

49 GOLDSMITH TX 1935 21-50 4.1

50 ROBERTSON NORTH TX 1956 21-50 3.5

Top 50 Volume Subtotal 13,059.4 828.0

Top 50 Percentage of U.S. Total 54.8% 38.9%
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 61

51 VIOSCA KNOLL BLK 786 FG 1996 51-100 17.7

52 GREEN CANYON BLK 244 FG 1994 51-100 27.2

53 POLARIS AK 1998 51-100 0.5

54 SACATE FP 1970 51-100 3.0

55 ARROYO GRANDE CA 1906 51-100 0.7

56 SALT CREEK TX 1950 51-100 5.5

57 MISSISSIPPI CANYON BLK 773 FG 2000 51-100 0.0

58 WEST SAK AK 1969 51-100 2.0

59 JAY AL & FL 1970 51-100 3.7

60 REDOUBT SHOAL AK 1968 51-100 0.0

61 SEMINOLE TX 1936 51-100 9.5

62 MONUMENT NM 1999 51-100 2.7

63 PENNEL MT 1955 51-100 2.0

64 MISSISSIPPI CANYON BLK 899 FG 1998 51-100 0.0

65 GREEN CANYON BLK 205 FG 1988 51-100 18.5

66 MEANS TX 1934 51-100 3.8

67 GIDDINGS TX 1973 51-100 11.0

68 BEVERLY HILLS CA 1965 51-100 1.3

69 MISSISSIPPI CANYON BLK 582 FG 2000 51-100 0.0

70 WEST DELTA BLK 30 FG 1949 51-100 5.0

71 MISSISSIPPI CANYON BLK 84 FG 1993 51-100 0.0

72 JO-MILL TX 1954 51-100 2.4

73 CEDAR LAKE TX 1939 51-100 2.5

74 MISSISSIPPI CANYON BLK 935 FG 1994 51-100 8.1

75 ANTON-IRISH TX 1944 51-100 3.9

76 TARN AK 1991 51-100 8.1

77 EUGENE ISLAND SA BLK 330 FG 1971 51-100 9.7

78 HOWARD-GLASSCOCK TX 1925 51-100 3.2

79 BELRIDGE NORTH CA 1912 51-100 3.0

80 EAST BREAKS BLK 602 FG 1999 51-100 0.0

81 BOREALIS AK 2001 51-100 0.2

82 WESTBROOK TX 1920 51-100 1.2

83 EWING BANK BLK 873 FG 1991 51-100 10.2

84 KERN FRONT CA 1925 51-100 1.2

85 GOLDEN TREND OK 1947 51-100 2.0

86 EUNICE MONUMENT NM 1929 51-100 1.1

87 GARDEN BANKS BLK 559 FG 1999 51-100 0.7

88 GREEN CANYON BLK 6 FG 1985 51-100 0.0

89 LOOKOUT BUTTE EAST MT 1986 51-100 1.2

90 ALTAMONT-BLUEBELL UT 1949 51-100 2.9

91 GARDEN BANKS BLK 668 FG 2000 51-100 0.0

92 WASSON 72 TX 1940 51-100 1.5

93 DOLLARHIDE NM & TX 1945 51-100 3.0

94 NIAKUK AK 1984 51-100 7.2

95 MAIN PASS BLK 61 LA 2000 51-100 0.0

96 SOUTH PASS EA BLK 62 FG 1974 51-100 2.5

97 GARDEN BANKS BLK 215 FG 1995 51-100 7.9

98 BREA-OLINDA CA 1897 51-100 1.0

99 AURORA AK 1999 51-100 1.8

100 ELWOOD SOUTH OFFSHORE CA 1966 51-100 1.2

Top 100 Volume Subtotal 15,381.6 1,029.8

Top 100 Percentage of U.S. Total 64.5% 48.3%

Table B1. Top 100 U.S. Fields Ranked by Oila Proved Reserves from Reported 2001 Field Level Data

(Continued)

(Million Barrels of 42 U.S. Gallons)

Discovery Proved Reserves 2001 Reported

Field Name Location Year Rank Group Production Volume

aIncludes lease condensate.

Notes: The U.S. total production estimate of 2,130 million barrels and the U.S. total reserves estimate of 23,844 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.

Source: Energy Information Administration, Office of Oil and Gas.
Table B2. Top 100 U.S. Fields Ranked by Gasa Proved Reserves, from Reported 2001 Field Level Data

(Billion Cubic Feet)

Discovery Proved Reserves 2001 Reported

Field Name Location Year Rank Group Production Volume

1 BLANCO / IGNACIO-BLANCO NM & CO 1927 1-10 812.0

2 BASIN NM 1947 1-10 616.9

3 PRUDHOE BAY AK 1967 1-10 192.0

4 HUGOTON GAS AREA KS & OK & TX 1922 1-10 383.1

5 MADDEN WY 1968 1-10 92.0

6 WATTENBERG CO 1970 1-10 143.1

7 CARTHAGE TX 1944 1-10 203.0

8 JONAH WY 1977 1-10 176.5

9 RATON BASIN GAS AREA CO & NM 1999 1-10 40.4

10 NEWARK EAST TX 1981 1-10 114.0

Top 10 Volume Subtotal 41,920.0 2,772.9

Top 10 Percentage of U.S. Total 21.9% 13.4%

11 PRB COALBED WY 1999 11-20 224.0

12 NATURAL BUTTES UT 1952 11-20 76.3

13 PINEDALE WY 1955 11-20 8.4

14 MOBILE BAY FIELDS AL 1979 11-20 133.8

15 FOGARTY CREEK WY 1975 11-20 32.1

16 DRUNKARDS WASH UT 1989 11-20 71.4

17 BIG SANDY KY & WV 1881 11-20 37.9

18 OAKWOOD VA 1990 11-20 49.4

19 PANHANDLE WEST TX 1918 11-20 96.3

20 ANTRIM MI 1965 11-20 68.4

Top 20 Volume Subtotal 56,074.3 3,570.9

Top 20 Percentage of U.S. Total 29.2% 17.3%

21 SPRABERRY TREND AREA TX 1952 21-50 64.3

22 MISSISSIPPI CANYON BLK 778 FG 1999 21-50 0.0

23 RED OAK-NORRIS OK 1910 21-50 63.1

24 ELK HILLS CA 1919 21-50 166.7

25 VERNON LA 1967 21-50 16.2

26 SAWYER TX 1975 21-50 48.4

27 LAKE RIDGE WY 1981 21-50 16.6

28 GOMEZ TX 1977 21-50 55.9

29 OAK HILL TX 1980 21-50 67.1

30 COOK INLET NORTH AK 1962 21-50 54.3

31 BELUGA RIVER AK 1962 21-50 41.6

32 MONTE CHRISTO NORTH TX 1982 21-50 74.1

33 GRAND VALLEY CO 1985 21-50 29.4

34 RULISON CO 1958 21-50 30.5

35 STRONG CITY DISTRICT OK 1966 21-50 65.9

36 MISSISSIPPI CANYON BLK 810 FG 1996 21-50 62.2

37 MOCANE-LAVERNE GAS AREA KS & OK & TX 1947 21-50 69.2

38 VIOSCA KNOLL BLK 956 FG 1985 21-50 91.4

39 WHITNEY CANYON-CARTER CRK WY 1978 21-50 71.5

40 DEW TX 1982 21-50 68.4

41 GOLDEN TREND OK 1947 21-50 44.4

42 PANOMA GAS AREA KS 1956 21-50 55.3

43 KINTA OK 1926 21-50 33.4

44 GIDDINGS TX 1973 21-50 152.5

45 WATONGA-CHICKASHA TREND OK 1962 21-50 50.8

46 EAST BREAKS BLK 945 FG 1994 21-50 72.7

47 FREESTONE TX 1949 21-50 25.7

48 EAST BREAKS BLK 602 FG 1999 21-50 0.0

49 LOWER MOBILE BAY-MARY ANN AL 1979 21-50 28.1

50 MOBILE BLK 823 FG 1983 21-50 58.5

Top 50 Volume Subtotal 76,543.2 5,249.2

Top 50 Percentage of U.S. Total 39.9% 25.4%
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 63

Table B2. Top 100 U.S. Fields Ranked by Gasa Proved Reserves, from Reported 2001 Field Level Data

(Continued)

(Billion Cubic Feet)

Discovery Proved Reserves 2001 Reported

Field Name Location Year Rank Group Production Volume

51 MISSISSIPPI CANYON BLK 807 FG 1989 51-100 68.8

52 NORA VA 1949 51-100 23.9

53 WASSON TX 1973 51-100 20.7

54 BRUFF WY 1969 51-100 40.9

55 MESA UNIT WY 1981 51-100 9.5

56 WAMSUTTER WY 1958 51-100 27.3

57 MAMM CREEK CO 1959 51-100 22.0

58 WILBURTON OK 1960 51-100 81.9

59 ELK CITY OK 1947 51-100 63.0

60 DOWDY RANCH TX 1999 51-100 23.2

61 BLUE CREEK COAL DEGAS AL 1988 51-100 19.2

62 PARACHUTE CO 1985 51-100 9.2

63 STRATTON TX 1981 51-100 21.3

64 GRAND ISLE SA BLK 116 FG 1999 51-100 60.7

65 BOB WEST TX 1990 51-100 37.5

66 BALD PRAIRIE TX 1976 51-100 12.7

67 BELRIDGE SOUTH CA 1911 51-100 19.5

68 ECHO SPRINGS WY 1977 51-100 29.8

69 MIMMS CREEK TX 1978 51-100 24.5

70 LA PERLA TX 1958 51-100 76.6

71 MISSISSIPPI CANYON BLK 731 FG 1987 51-100 75.0

72 OZONA TX 1971 51-100 22.7

73 MCALLEN RANCH TX 1986 51-100 60.9

74 KUPARUK RIVER AK 1969 51-100 26.1

75 VIOSCA KNOLL BLK 915 FG 1993 51-100 68.3

76 WILD ROSE WY 1975 51-100 21.7

77 INDIAN BASIN NM 1971 51-100 130.6

78 VERDEN OK 1948 51-100 30.4

79 DOUBLE A WELLS TX 1980 51-100 33.3

80 GARDEN BANKS BLK 668 FG 2000 51-100 0.0

81 GARDEN BANKS BLK 877 FG 2001 51-100 0.0

82 WILLOW SPRINGS TX 1954 51-100 29.0

83 STANDARD DRAW WY 1979 51-100 25.4

84 MATAGORDA ISLAND BLK 623 FG 1980 51-100 71.3

85 VAQUILLAS RANCH TX 1978 51-100 56.9

86 WONSITS VALLEY UT 1965 51-100 13.2

87 BLANCO SOUTH NM 1952 51-100 16.7

88 FAIRWAY AL 1986 51-100 28.1

89 CEMENT OK 1917 51-100 29.5

90 JUDGE DIGBY LA 1977 51-100 70.2

91 DESOTO CANYON BLK 133 FG 1993 51-100 0.0

92 RIO VISTA CA 1936 51-100 17.4

93 KNOX OK 1916 51-100 53.2

94 MAYFIELD NE OK 1951 51-100 28.9

95 BLOCK 16 TX 1969 51-100 30.6

96 A W P TX 1981 51-100 16.2

97 CEDAR COVE COAL DEGAS AL 1983 51-100 18.7

98 CEDARDALE NE OK 1957 51-100 19.6

99 TABLE ROCK WY 1946 51-100 9.5

100 KENAI AK 1959 51-100 20.0

Top 100 Volume Subtotal 92,354.1 6,964.9

Top 100 Percentage of U.S. Total 48.2% 33.7%

aTotal wet gas after lease separation.

Note: The U.S. total production estimate of 20,642 billion cubic feet and the U.S. total reserves estimate of 191,743 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.

Source: Energy Information Administration, Office of Oil and Gas.
Table B3. Top U.S. Operators Ranked by Reported 2001 Operated Production Data

Total Natural Gas

Crude Oil Production Production

Rank Company Name (thousand barrels/day) Rank Company Name (million cubic feet/day)

1 BP AMOCO PLC . . . . . . . . . . . . . . . . . . . . . . . . . 854 1 BP AMOCO PLC ....................... 5,362

2 CHEVRONTEXACO INC. . . . . . . . . . . . . . . . . . . 649 2 CHEVRONTEXACO INC ................. 3,403

3 SHELL OIL CO . . . . . . . . . . . . . . . . . . . . . . . . . . 463 3 EXXON-MOBIL CORPORATION........... 3,385

4 PHILLIPS PETROLEUM CO . . . . . . . . . . . . . . . . 330 4 SHELL OIL CO......................... 2,388

5 EXXON-MOBIL CORPORATION . . . . . . . . . . . . 305 5 BURLINGTON RESOURCES OIL & GAS CO . 2,114

6 OCCIDENTAL PETROLEUM CORPORATION . . 290 6 EL PASO ENERGY ..................... 2,040

7 AERA ENERGY LLC . . . . . . . . . . . . . . . . . . . . . . 236 7 ANADARKO PETROLEUM CORP ......... 1,944

8 AMERADA HESS CORP. . . . . . . . . . . . . . . . . . . 125 8 UNOCAL CORPORATION................ 1,629

9 MARATHON OIL CO . . . . . . . . . . . . . . . . . . . . . . 108 9 DEVON ENERGY CORP................. 1,605

10 ANADARKO PETROLEUM CORP . . . . . . . . . . . 106 10 PHILLIPS PETROLEUM CO .............. 1,535

Top 10 Volume Subtotal ........................ 3,466 Top 10 Volume Subtotal ........................ 25,405

Top 10 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 59% Top 10 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 45%

11 UNOCAL CORPORATION . . . . . . . . . . . . . . . . . . 98 11 CONOCO INC. . . . . . . . . . . . . . . . . . . . . . . . . . . 984

12 DEVON ENERGY CORP . . . . . . . . . . . . . . . . . . . 76 12 DOMINION RESOURCES INC. . . . . . . . . . . . . . 947

13 APACHE CORP. . . . . . . . . . . . . . . . . . . . . . . . . . . 68 13 EOG RESOURCES INC . . . . . . . . . . . . . . . . . . . 932

14 KERR MCGEE OIL & GAS CORPORATION . . . . 60 14 APACHE CORP . . . . . . . . . . . . . . . . . . . . . . . . . 927

15 NUEVO ENERGY CO . . . . . . . . . . . . . . . . . . . . . . 48 15 OCCIDENTAL PETROLEUM CORPORATION. . 912

16 EL PASO ENERGY . . . . . . . . . . . . . . . . . . . . . . . . 38 16 MARATHON OIL CO. . . . . . . . . . . . . . . . . . . . . . 910

17 CITY OF LONG BEACH . . . . . . . . . . . . . . . . . . . . 35 17 KERR MCGEE OIL & GAS CORPORATION . . . 728

18 BURLINGTON RESOURCES OIL & GAS CO . . . 32 18 AMERADA HESS CORP. . . . . . . . . . . . . . . . . . . 710

19 PIONEER NATURAL RESOURCES USA. . . . . . . 31 19 WILLIAMS ENERGY INC . . . . . . . . . . . . . . . . . . 666

20 OCEAN ENERGY INC. . . . . . . . . . . . . . . . . . . . . . 30 20 XTO ENERGY INC . . . . . . . . . . . . . . . . . . . . . . . 614

Top 20 Volume Subtotal ........................ 3,982 Top 20 Volume Subtotal ........................ 33,735

Top 20 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 68% Top 20 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 60%

21 CONOCO INC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 21 NEWFIELD EXPLORATION COMPANY . . . . . . 564

22 WESTPORT RESOURCES CORPORATION . . . . 29 22 OCEAN ENERGY INC . . . . . . . . . . . . . . . . . . . . 561

23 VINTAGE PETROLEUM INC. . . . . . . . . . . . . . . . . 28 23 CHESAPEAKE ENERGY CORP . . . . . . . . . . . . 534

24 EOG RESOURCES INC . . . . . . . . . . . . . . . . . . . . 26 24 MITCHELL ENERGY & DEVELOPMENT CORP 526

25 MERIT ENERGY CO. . . . . . . . . . . . . . . . . . . . . . . 26 25 SAMSON INVESTMENT COMPANY . . . . . . . . . 392

26 NEWFIELD EXPLORATION COMPANY. . . . . . . . 25 26 PIONEER NATURAL RESOURCES USA. . . . . . 376

27 CITATION OIL & GAS CORP . . . . . . . . . . . . . . . . 22 27 NOBLE AFFILIATES INC . . . . . . . . . . . . . . . . . . 366

28 DENBURY RESOURCES INC . . . . . . . . . . . . . . . 20 28 QUESTAR CORPORATION . . . . . . . . . . . . . . . . 363

29 DOMINION RESOURCES INC . . . . . . . . . . . . . . . 19 29 A E C OIL & GAS (USA) INC . . . . . . . . . . . . . . . 349

30 NOBLE AFFILIATES INC . . . . . . . . . . . . . . . . . . . 19 30 HOUSTON EXPLORATION . . . . . . . . . . . . . . . . 312

31 ENI SPA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 31 FOREST OIL CORP . . . . . . . . . . . . . . . . . . . . . . 301

32 HUNT OIL CO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 32 WALTER OIL & GAS CORP . . . . . . . . . . . . . . . . 292

33 PLAINS RESOURCES INC. . . . . . . . . . . . . . . . . . 18 33 EQUITABLE RESOURCES INC . . . . . . . . . . . . . 281

34 ARGUELLO INC . . . . . . . . . . . . . . . . . . . . . . . . . . 18 34 STONE ENERGY CORPORATION . . . . . . . . . . 269

35 STONE ENERGY CORPORATION. . . . . . . . . . . . 17 35 QUICKSILVER RESOURCES INC . . . . . . . . . . . 253

36 XTO ENERGY INC . . . . . . . . . . . . . . . . . . . . . . . . 17 36 CABOT OIL & GAS CORP . . . . . . . . . . . . . . . . . 251

37 NATIONAL FUEL GAS . . . . . . . . . . . . . . . . . . . . . 16 37 TOTALFINAELF SA . . . . . . . . . . . . . . . . . . . . . . 248

38 FOREST OIL CORP . . . . . . . . . . . . . . . . . . . . . . . 16 38 SPINNAKER EXPLORATION CO LLC . . . . . . . . 239

39 HILCORP ENERGY CO . . . . . . . . . . . . . . . . . . . . 16 39 WESTPORT RESOURCES CORPORATION. . . 229

40 ENCORE OPERATING LP . . . . . . . . . . . . . . . . . . 15 40 HUNT OIL CO . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

41 BERRY PETROLEUM CO. . . . . . . . . . . . . . . . . . . 14 41 TOM BROWN INC . . . . . . . . . . . . . . . . . . . . . . . 225

42 MARINER ENERGY INC. . . . . . . . . . . . . . . . . . . . 14 42 HILCORP ENERGY CO . . . . . . . . . . . . . . . . . . . 220

43 HOWELL CORPORATION . . . . . . . . . . . . . . . . . . 13 43 KAISER-FRANCIS OIL CO . . . . . . . . . . . . . . . . . 211

44 COHO RESOURCES INC. . . . . . . . . . . . . . . . . . . 13 44 YATES PETROLEUM CORP . . . . . . . . . . . . . . . 202

45 WALTER OIL & GAS CORP . . . . . . . . . . . . . . . . . 13 45 VINTAGE PETROLEUM INC . . . . . . . . . . . . . . . 191

46 POGO PRODUCING CO. . . . . . . . . . . . . . . . . . . . 12 46 POGO PRODUCING CO . . . . . . . . . . . . . . . . . . 179

47 PRIZE OPERATING CO . . . . . . . . . . . . . . . . . . . . 12 47 DENBURY RESOURCES INC . . . . . . . . . . . . . . 178

48 SWIFT ENERGY CO . . . . . . . . . . . . . . . . . . . . . . . 11 48 HELMERICH & PAYNE INC . . . . . . . . . . . . . . . . 171

49 CONTINENTAL RESOURCES INC. . . . . . . . . . . . 11 49 MURPHY OIL CORPORATION. . . . . . . . . . . . . . 150

50 CHESAPEAKE ENERGY CORP. . . . . . . . . . . . . . 11 50 NEXEN ENERGY INC. . . . . . . . . . . . . . . . . . . . . 149

Top 50 Volume Subtotal ........................ 4,519 Top 50 Volume Subtotal ........................ 42,545

Top 50 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 77% Top 50 Percentage of U.S. Total . . . . . . . . . . . . . . . . . . . 75%

Note: Crude oil production includes production of lease condensate and total natural gas production is wet after lease separation.

Energy Information Administration

64 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Appendix C

Conversion to the Metric System
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."{43}

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.

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U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 67
Energy Information Administration

68 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table C1. U.S. Proved Reserves of Crude Oil, Dry Natural Gas, and Natural Gas Liquids,

in Metric Units, 1991 – 2001

Revisionsa Net of Sales New Reservoir Provedc Change Net and and New Field Discoveries Totalb 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 cubic meters)

1991 25.9 35.5 61.4 NA 58.0 15.4 14.6 88.0 399.4 3,924.1 -250.0

1992 46.2 116.8 163.0 NA 62.2 1.3 13.5 77.0 388.9 3,775.2 -148.9

1993 43.1 78.7 121.8 NA 56.6 50.7 17.5 124.8 371.9 3,649.9 -125.3

1994 30.1 160.1 190.2 NA 63.1 10.2 17.6 90.9 360.6 3,570.4 -79.5

1995 19.4 163.4 182.8 NA 79.5 18.1 54.5 152.1 351.8 3,553.5 -16.9

1996 28.0 117.1 145.1 NA 86.3 38.6 22.4 147.3 345.5 3,500.4 -53.1

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

Dry Natural Gas (billion cubic meters)

1991 83.82 125.05 208.87 NA 144.13 24.01 45.42 213.56 487.11 4,730.67 -64.68

1992 63.29 172.53 235.82 NA 132.38 18.38 48.82 199.58 493.36 4,672.71 -57.96

1993 27.51 151.47 178.98 NA 172.82 25.46 52.84 251.12 503.73 4,599.08 -73.63

1994 55.08 155.29 210.37 NA 196.55 53.63 98.54 348.72 518.82 4,639.35 40.27

1995 16.42 219.00 235.42 NA 193.77 47.18 69.43 310.38 508.74 4,676.41 37.06

1996 107.18 115.70 222.88 NA 219.65 41.09 88.07 348.81 534.08 4,714.02 37.61

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

Natural Gas Liquids (million cubic meters)

1991 37.1 20.7 57.8 NA 30.0 4.0 8.7 42.7 119.9 1,186.7 -19.4

1992 35.7 41.5 77.2 NA 30.2 3.2 10.2 43.6 122.9 1,184.6 -2.1

1993 16.2 19.7 35.9 NA 39.0 3.8 10.2 53.0 125.3 1,148.2 -36.4

1994 6.9 31.3 38.2 NA 49.9 8.6 20.8 79.3 125.8 1,139.9 -8.3

1995 30.6 44.0 74.6 NA 68.7 8.1 10.7 87.6 125.8 1,176.3 36.4

1996 75.4 27.8 103.2 NA 71.7 10.3 17.3 99.4 135.1 1,243.8 67.4

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

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

bTotal 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, 1991–2001 annual reports, DOE/EIA–0216.{15–24}
Appendix D

Historical Reserves Statistics

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 69
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 71

Appendix D

Historical Reserves Statistics

These are selected historical data presented at the State and National level. All historical statistics included have

previously been published in the annual reports of 1977 through 2001 of the EIA publication U.S. Crude Oil, Natural

Gas, and Natural Gas Liquids Reserves, DOE EIA-0216.{1-24}

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.

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Alabama

1977 85 0 530 NA

1978 *74 0 514 NA

1979 45 NA 652 213

1980 54 NA 636 226

1981 55 NA 648 192

1982 54 NA a648 193

1983 51 NA a785 216

1984 *68 NA a961 200

1985 69 NA a821 182

1986 55 20 b951 177

1987 55 20 b842 166

1988 54 20 b809 166

1989 43 20 b819 168

1990 44 <1 c4,125 170

1991 43 <1 c5,414 145

1992 41 0 c5,802 171

1993 41 0 c5,140 158

1994 44 0 c4,830 142

1995 43 0 c4,868 120

1996 45 0 c5,033 119

1997 47 0 c4,968 93

1998 39 0 c4,604 81

1999 49 0 c4,287 107

2000 34 NA c4,149 150

2001 42 NA c3,915 64

aOnshore only; offshore included in Louisiana. bOnshore only; offshore included in Federal Offshore - Gulf of

Mexico (Louisiana). cIncludes State Offshore: 2,519 Bcf in 1990; 3,191 Bcf in 1991;

3,233 Bcf in 1992; 3,364 Bcf in 1993; 3,297 Bcf in 1994; 3,432 Bcf

in 1995; 3,509 Bcf in 1996; 3,422 Bcf in 1997; 3,144 Bcf in 1998;

2,853 Bcf in 1999; 2,645 in 2000; 1,461 Bcf in 2001.

Alaska

1977 8,413 846 32,243 NA

1978 9,384 398 32,045 NA

1979 8,875 398 32,259 23

1980 8,751 0 33,382 11

1981 8,283 0 33,037 10

1982 7,406 60 34,990 9

1983 7,307 576 34,283 8

1984 7,563 369 34,476 19

1985 7,056 379 33,847 383

1986 6,875 902 32,664 381

1987 7,378 566 33,225 418

1988 6,959 431 9,078 401

1989 6,674 750 8,939 380

1990 6,524 969 9,300 340

1991 6,083 1,456 9,553 360

1992 6,022 1,331 9,638 347

1993 5,775 1,161 9,907 321

1994 5,767 1,022 9,733 301

1995 5,580 582 9,497 306

1996 5,274 952 9,294 337

1997 5,161 832 10,562 631

1998 5,052 832 9,927 320

1999 4,900 464 9,734 299

2000 4,861 NA 9,237 277

2001 4,851 NA 8,800 405

Note: See 1988 Chapter 4 discussion “Alaskan North Slope

Natural Gas Reserves”.

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves
Energy Information Administration

72 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Arkansas

1977 116 17 1,660 NA

1978 111 8 1,681 NA

1979 107 8 1,703 17

1980 107 11 1,774 16

1981 113 11 1,801 16

1982 107 4 1,958 15

1983 120 4 2,069 11

1984 114 6 2,227 12

1985 97 11 2,019 11

1986 88 9 1,992 16

1987 82 0 1,997 16

1988 77 <1 1,986 13

1989 66 1 1,772 9

1990 60 1 1,731 9

1991 *70 0 1,669 5

1992 58 <1 1,750 4

1993 65 0 1,552 4

1994 51 0 1,607 6

1995 48 0 1,563 6

1996 58 0 1,470 4

1997 45 0 1,475 7

1998 47 0 1,328 5

1999 48 0 1,542 5

2000 48 NA 1,581 5

2001 43 NA 1,616 5

California - Total

1977 5,005 1,047 4,737 NA

1978 4,974 968 4,947 NA

1979 5,265 960 5,022 111

1980 5,470 891 5,414 120

1981 5,441 660 5,617 82

1982 5,405 616 5,552 154

1983 5,348 576 5,781 151

1984 5,707 674 5,554 141

1985 d4,810 590 d4,325 d146

1986 d4,734 d616 d3,928 d134

1987 d4,709 d1,493 d3,740 d130

1988 d4,879 d1,440 d3,519 d123

1989 d4,816 d1,608 d3,374 d113

1990 d4,658 d1,425 d3,185 d105

1991 d4,217 d1,471 d3,004 d92

1992 d3,893 d1,299 d2,778 d99

1993 d3,764 d965 d2,682 d104

1994 d3,573 d835 d2,402 d92

1995 d3,462 d823 d2,243 d92

1996 d3,437 d905 d2,082 d92

1997 d3,750 d1,264 d2,273 d95

1998 d3,843 d1,297 d2,244 d72

1999 d3,934 d1,400 d2,387 d98

2000 d3,813 NA d2,849 d101

2001 d3,627 NA d2,681 d76

dExcludes Federal offshore; now included in Federal OffshorePacific (California).

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

California - Coastal Region Onshore

1977 679 NA 334 NA

1978 602 NA 350 NA

1979 578 NA 365 22

1980 652 NA 299 23

1981 621 NA 306 14

1982 580 NA 362 16

1983 559 NA 381 17

1984 628 140 265 15

1985 631 152 256 16

1986 592 164 255 15

1987 625 298 238 13

1988 576 299 215 13

1989 731 361 224 11

1990 588 310 217 12

1991 554 327 216 12

1992 522 317 203 10

1993 528 313 189 12

1994 480 238 194 11

1995 456 234 153 8

1996 425 261 156 9

1997 430 43 164 9

1998 354 40 106 9

1999 491 40 192 31

2000 455 NA 234 27

2001 385 NA 177 16

California - Los Angeles Basin Onshore

1977 910 NA 255 NA

1978 493 NA 178 NA

1979 513 NA 163 10

1980 454 NA 193 15

1981 412 NA 154 6

1982 370 NA 96 6

1983 343 NA 107 6

1984 373 126 156 5

1985 420 86 181 6

1986 330 66 142 8

1987 361 105 148 8

1988 391 106 151 7

1989 342 32 137 4

1990 316 3 106 5

1991 272 4 115 4

1992 236 4 97 5

1993 238 4 102 6

1994 221 4 103 5

1995 227 4 111 4

1996 234 0 109 3

1997 268 0 141 4

1998 207 0 149 5

1999 297 0 168 7

2000 292 NA 193 10

2001 297 NA 187 8
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U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 73

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

California - San Joaquin Basin Onshore

1977 2,965 NA 3,784 NA

1978 3,099 NA 3,960 NA

1979 3,294 NA 3,941 77

1980 3,360 NA 4,344 81

1981 3,225 NA 4,163 57

1982 3,081 NA 3,901 124

1983 3,032 NA 3,819 117

1984 3,197 384 3,685 105

1985 3,258 350 3,574 120

1986 3,270 368 3,277 109

1987 3,208 1,070 3,102 107

1988 3,439 1,029 2,912 101

1989 3,301 1,210 2,782 95

1990 3,334 1,109 2,670 86

1991 3,126 1,139 2,614 75

1992 2,898 977 2,415 83

1993 2,772 648 2,327 85

1994 2,647 593 2,044 75

1995 2,577 585 1,920 80

1996 2,597 644 1,768 80

1997 2,871 1,221 1,912 82

1998 3,127 1,257 1,945 58

1999 2,949 1,330 1,951 60

2000 2,870 NA 2,331 64

2001 2,766 NA 2,232 52

California-State and Federal Offshore

1977 451 NA 364 NA

1978 780 NA 457 NA

1979 880 NA 553 2

1980 1,004 NA 578 1

1981 1,183 NA 994 5

1982 1,374 NA 1,193 8

1983 1,414 NA 1,474 11

1984 1,509 25 1,448 16

1985 1,492 2 1,433 16

1986 1,516 19 1,579 17

1987 1,552 20 1,704 19

1988 1,497 6 1,793 23

1989 1,429 5 1,727 28

1990 1,382 3 1,646 20

1991 1,050 1 1,221 19

1992 971 1 1,181 21

1993 899 0 1,163 26

1994 878 0 1,231 22

1995 773 0 1,324 25

1996 699 0 1,293 23

1997 709 0 600 14

1998 623 0 524 12

1999 750 30 612 4

2000 792 NA 667 4

2001 726 NA 625 9

California - State Offshore

1977 181 NA 114 NA

1978 519 NA 213 NA

1979 632 NA 231 2

1980 604 NA 164 1

1981 NA NA NA NA

1982 NA NA NA NA

1983 NA NA NA NA

1984 NA 25 NA NA

1985 501 0 314 4

1986 542 18 254 2

1987 515 18 252 2

1988 473 6 241 2

1989 442 5 231 3

1990 420 3 192 2

1991 265 1 59 1

1992 237 1 63 1

1993 226 0 64 1

1994 225 0 61 1

1995 202 0 59 0

1996 181 0 49 0

1997 181 0 56 0

1998 155 0 44 0

1999 197 30 76 0

2000 196 NA 91 0

2001 179 NA 85 0

California - Federal Offshore

1977 270 NA 250 NA

1978 261 NA 246 NA

1979 248 NA 322 0

1980 400 NA 414 0

1981 NA NA NA NA

1982 NA NA NA NA

1983 NA NA NA NA

1984 NA 0 NA NA

1985 991 2 1,119 12

1986 974 1 1,325 15

1987 1,037 2 1,452 17

1988 1,024 0 1,552 21

1989 987 0 1,496 25

1990 962 0 1,454 18

1991 785 0 1,162 18

1992 734 <1 1,118 20

1993 673 0 1,099 25

1994 653 0 1,170 21

1995 571 0 1,265 25

1996 518 0 1,244 23

1997 528 0 544 14

1998 468 0 480 12

1999 553 0 536 4

2000 596 NA 576 4

2001 547 NA 540 9
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74 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Colorado

1977 230 73 2,512 NA

1978 194 75 2,765 NA

1979 159 43 2,608 177

1980 *183 46 2,922 194

1981 147 47 2,961 204

1982 169 100 3,314 186

1983 186 113 3,148 183

1984 198 119 *2,943 155

1985 198 119 2,881 173

1986 207 95 3,027 148

1987 272 67 2,942 166

1988 257 67 3,535 181

1989 359 8 4,274 209

1990 305 8 4,555 169

1991 329 33 5,767 197

1992 304 34 6,198 226

1993 284 22 6,722 214

1994 271 22 6,753 248

1995 252 24 7,256 273

1996 231 22 7,710 287

1997 198 22 6,828 264

1998 212 21 7,881 260

1999 203 21 8,987 303

2000 217 NA 10,428 316

2001 196 NA 12,527 345

Florida

1977 213 1 151 NA

1978 168 1 119 NA

1979 128 1 77 21

1980 134 1 84 27

1981 109 1 69 NA

1982 97 1 64 17

1983 78 4 49 11

1984 82 2 65 17

1985 77 2 55 17

1986 67 2 49 14

1987 61 0 49 9

1988 59 0 51 16

1989 50 0 46 10

1990 42 0 45 8

1991 37 0 38 7

1992 36 0 47 8

1993 40 0 50 9

1994 71 0 98 18

1995 71 0 92 17

1996 97 0 96 22

1997 91 0 96 17

1998 71 0 88 18

1999 85 0 84 16

2000 76 NA 82 11

2001 75 NA 84 12

Illinois

1977 *150 1 NA NA

1978 *158 1 NA NA

1979 *136 1 NA NA

1980 113 2 NA NA

1981 129 1 NA NA

1982 150 1 NA NA

1983 135 1 NA NA

1984 153 1 NA NA

1985 136 1 NA NA

1986 135 1 NA NA

1987 153 5 NA NA

1988 143 <1 NA NA

1989 123 <1 NA NA

1990 131 0 NA NA

1991 128 52 NA NA

1992 138 0 NA NA

1993 116 0 NA NA

1994 117 0 NA NA

1995 119 0 NA NA

1996 94 0 NA NA

1997 92 0 NA NA

1998 81 0 NA NA

1999 100 0 NA NA

2000 111 NA NA NA

2001 92 NA NA NA

Indiana

1977 *20 0 NA NA

1978 *29 0 NA NA

1979 *40 0 NA NA

1980 23 0 NA NA

1981 23 0 NA NA

1982 28 1 NA NA

1983 34 3 NA NA

1984 *33 2 NA NA

1985 *35 2 NA NA

1986 *32 2 NA NA

1987 23 2 NA NA

1988 *22 0 NA NA

1989 *16 0 NA NA

1990 12 0 NA NA

1991 *16 0 NA NA

1992 17 0 NA NA

1993 15 0 NA NA

1994 15 0 NA NA

1995 13 0 NA NA

1996 11 0 NA NA

1997 *10 0 NA NA

1998 13 0 NA NA

1999 10 0 NA NA

2000 15 NA NA NA

2001 12 NA NA NA
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 75

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Kansas

1977 *349 3 11,457 NA

1978 303 3 10,992 NA

1979 *377 3 10,243 402

1980 310 2 9,508 389

1981 371 2 9,860 409

1982 378 13 9,724 302

1983 344 13 9,553 443

1984 377 2 9,387 424

1985 423 <1 9,337 373

1986 312 <1 10,509 440

1987 357 <1 10,494 462

1988 327 <1 10,104 345

1989 338 3 10,091 329

1990 321 <1 9,614 313

1991 300 <1 9,358 428

1992 310 0 9,681 444

1993 271 0 9,348 380

1994 260 0 9,156 398

1995 275 <1 8,571 369

1996 266 <1 7,694 338

1997 238 0 6,989 271

1998 246 0 6,402 334

1999 175 0 5,753 358

2000 237 NA 5,299 306

2001 216 NA 5,101 302

Kentucky

1977 30 0 451 NA

1978 *40 0 545 NA

1979 25 0 468 26

1980 *35 12 508 25

1981 29 13 530 25

1982 *36 13 551 35

1983 35 12 554 31

1984 *41 0 613 24

1985 *42 0 766 27

1986 *31 0 841 29

1987 25 0 909 23

1988 *34 0 923 24

1989 33 0 992 16

1990 33 0 1,016 25

1991 *31 0 1,155 24

1992 34 0 1,084 32

1993 26 0 1,003 26

1994 26 0 969 39

1995 24 0 1,044 43

1996 21 0 983 46

1997 *20 0 1,364 48

1998 23 0 1,222 54

1999 24 0 1,435 69

2000 24 NA 1,760 56

2001 17 NA 1,860 72

Louisiana - Total

1977 3,600 139 57,010 NA

1978 3,448 143 55,725 NA

1979 2,780 76 50,042 1,424

1980 2,751 62 47,325 1,346

1981 2,985 50 47,377 1,327

1982 2,728 49 e44,916 1,295

1983 2,707 45 e42,561 1,332

1984 2,661 55 e41,399 1,188

1985 f883 35 f14,038 f546

1986 f826 f47 f12,930 f524

1987 f807 f56 f12,430 f525

1988 f800 f69 f12,224 f517

1989 f745 f63 f12,516 f522

1990 f705 f22 f11,728 f538

1991 f679 f44 f10,912 f526

1992 f668 f35 f9,780 f495

1993 f639 f338 f9,174 f421

1994 f649 f340 f9,748 f434

1995 f637 f475 f9,274 f601

1996 f658 f331 f9,543 f543

1997 f714 f313 f9,673 f437

1998 f551 f316 f9,147 f411

1999 f600 f278 f9,242 f457

2000 f529 NA f9,239 f436

2001 f564 NA f9,811 f391

eIncludes State and Federal offshore Alabama. f

Excludes Federal offshore; now included in Federal OffshoreGulf of Mexico (Louisiana).

Louisiana - North

1977 244 78 3,135 NA

1978 255 78 3,203 NA

1979 216 NA 2,798 96

1980 248 NA 3,076 95

1981 *317 NA 3,270 99

1982 *240 NA 2,912 85

1983 223 NA 2,939 74

1984 165 9 2,494 57

1985 196 5 2,587 65

1986 160 7 2,515 57

1987 175 3 2,306 50

1988 154 23 2,398 56

1989 123 22 2,652 60

1990 120 <1 2,588 58

1991 127 <1 2,384 59

1992 125 <1 2,311 60

1993 108 0 2,325 57

1994 108 0 2,537 69

1995 108 0 2,788 79

1996 128 0 3,105 85

1997 136 <1 3,093 80

1998 101 0 2,898 57

1999 108 0 3,079 61

2000 97 NA 3,298 61

2001 87 NA 3,881 62
Energy Information Administration

76 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Louisiana - South Onshore

1977 1,382 46 18,580 NA

1978 1,242 38 17,755 NA

1979 682 NA 13,994 676

1980 682 NA 13,026 540

1981 642 NA 12,645 544

1982 611 NA 11,801 501

1983 569 NA 11,142 527

1984 585 20 10,331 454

1985 565 16 9,808 442

1986 547 30 9,103 428

1987 505 22 8,693 429

1988 511 35 8,654 421

1989 479 30 8,645 411

1990 435 11 8,171 431

1991 408 33 7,504 417

1992 417 26 6,693 380

1993 382 329 5,932 334

1994 391 331 6,251 337

1995 387 324 5,648 495

1996 382 322 5,704 411

1997 427 309 5,855 333

1998 353 307 5,698 325

1999 384 278 5,535 364

2000 310 NA 5,245 337

2001 341 NA 5,185 269

Louisiana - State Offshore

1977 1,974 15 35,295 NA

1978 1,951 27 34,767 NA

1979 1,882 14 33,250 652

1980 1,821 13 31,223 711

1981 2,026 16 31,462 684

1982 1,877 21 e30,203 709

1983 1,915 15 e28,480 731

1984 1,911 27 e28,574 677

1985 f122 2 f1,643 f39

1986 f119 f10 f1,312 f39

1987 f127 f22 f1,431 f46

1988 f135 f11 f1,172 f40

1989 f143 f11 f1,219 f51

1990 f150 f11 f969 f49

1991 f144 f11 f1,024 f50

1992 f126 f9 f776 f55

1993 f149 f9 f917 f30

1994 f150 f9 f960 f28

1995 f142 f151 f838 f27

1996 f148 f9 f734 f47

1997 f151 f4 f725 f24

1998 f97 f2 f551 f29

1999 f108 f0 f628 f32

2000 f122 NA f696 f38

2001 f136 NA f745 f60

eIncludes State and Federal offshore Alabama. f

Excludes Federal offshore; now included in Federal OffshoreGulf of Mexico (Louisiana).

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Michigan

1977 *233 0 *1,386 NA

1978 *220 9 *1,422 NA

1979 159 23 1,204 112

1980 *205 14 *1,406 112

1981 *240 17 1,118 102

1982 184 34 1,084 97

1983 209 48 1,219 105

1984 180 46 1,112 84

1985 191 37 985 67

1986 146 34 1,139 88

1987 151 27 1,451 111

1988 132 27 1,323 99

1989 128 8 1,342 97

1990 124 3 1,243 81

1991 119 0 1,334 72

1992 102 0 1,223 68

1993 90 0 1,160 57

1994 91 1 1,323 54

1995 76 1 1,294 45

1996 74 0 2,061 53

1997 68 2 2,195 50

1998 44 0 2,328 51

1999 52 0 2,255 48

2000 56 NA 2,729 35

2001 46 NA 2,976 43

Mississippi

1977 241 9 1,437 NA

1978 *250 27 1,635 NA

1979 238 24 1,504 16

1980 202 36 1,769 20

1981 209 93 2,035 18

1982 223 85 1,796 18

1983 205 77 1,596 19

1984 201 50 1,491 15

1985 184 53 1,360 12

1986 199 16 1,300 11

1987 202 12 1,220 11

1988 221 10 1,143 12

1989 218 6 1,104 12

1990 227 8 1,126 11

1991 194 8 1,057 10

1992 165 7 869 9

1993 133 44 797 11

1994 151 40 650 9

1995 140 6 663 8

1996 164 6 631 7

1997 183 0 582 6

1998 141 0 658 8

1999 163 0 677 10

2000 182 NA 618 8

2001 167 NA 661 10
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 77

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Montana

1977 175 27 *887 NA

1978 158 27 926 NA

1979 152 38 825 10

1980 179 13 *1,287 16

1981 186 11 *1,321 11

1982 216 6 847 18

1983 234 8 896 19

1984 224 4 802 18

1985 232 3 857 21

1986 248 27 803 16

1987 246 <1 780 16

1988 241 0 819 11

1989 225 <1 867 16

1990 221 0 899 15

1991 201 0 831 14

1992 193 0 859 12

1993 171 0 673 8

1994 175 0 717 8

1995 178 0 782 8

1996 168 0 796 7

1997 159 1 762 5

1998 167 0 782 5

1999 207 0 841 8

2000 235 NA 885 4

2001 260 NA 898 5

Nebraska

1977 22 0 NA NA

1978 30 1 NA NA

1979 25 0 NA NA

1980 *46 0 NA NA

1981 41 0 NA NA

1982 *32 0 NA NA

1983 44 0 NA NA

1984 *46 0 NA NA

1985 42 0 NA NA

1986 *45 7 NA NA

1987 33 0 NA NA

1988 42 0 NA NA

1989 32 0 NA NA

1990 26 0 NA NA

1991 26 0 NA NA

1992 26 0 NA NA

1993 20 0 NA NA

1994 22 0 NA NA

1995 25 0 NA NA

1996 28 0 NA NA

1997 *21 0 NA NA

1998 18 0 NA NA

1999 17 0 NA NA

2000 18 NA NA NA

2001 15 NA NA NA

New Mexico - Total

1977 605 97 12,000 NA

1978 579 90 12,688 NA

1979 563 77 13,724 530

1980 547 58 13,287 541

1981 555 93 13,870 560

1982 563 76 12,418 531

1983 576 75 11,676 551

1984 660 87 11,364 511

1985 688 99 10,900 445

1986 644 225 11,808 577

1987 654 235 11,620 771

1988 661 241 17,166 1,023

1989 665 256 15,434 933

1990 687 256 17,260 990

1991 721 275 18,539 908

1992 757 293 18,998 1,066

1993 707 211 18,619 996

1994 718 215 17,228 1,011

1995 732 185 17,491 943

1996 744 148 16,485 1,059

1997 735 146 15,514 869

1998 620 168 14,987 929

1999 718 165 15,449 954

2000 719 NA 17,322 896

2001 715 NA 17,414 873

New Mexico - East

1977 576 95 3,848 NA

1978 554 88 3,889 NA

1979 542 77 4,031 209

1980 518 58 3,530 209

1981 522 93 3,598 214

1982 537 76 3,432 209

1983 542 75 3,230 232

1984 625 87 3,197 221

1985 643 98 3,034 209

1986 593 225 2,694 217

1987 608 230 2,881 192

1988 621 235 2,945 208

1989 619 252 3,075 196

1990 633 253 3,256 222

1991 694 275 3,206 205

1992 731 293 3,130 223

1993 688 211 3,034 233

1994 702 215 3,021 234

1995 713 185 2,867 247

1996 731 148 2,790 299

1997 719 146 2,642 273

1998 610 168 2,693 262

1999 705 165 3,037 255

2000 705 NA 3,537 333

2001 703 NA 3,518 279
Energy Information Administration

78 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

New Mexico - West

1977 *29 2 8,152 NA

1978 *25 2 8,799 NA

1979 21 0 9,693 321

1980 *29 0 9,757 332

1981 *33 0 10,272 346

1982 26 0 8,986 322

1983 34 0 8,446 319

1984 35 0 8,167 290

1985 45 1 7,866 236

1986 51 0 9,114 360

1987 46 5 8,739 579

1988 40 6 14,221 815

1989 46 4 12,359 737

1990 54 3 14,004 768

1991 27 0 15,333 703

1992 26 0 15,868 843

1993 19 0 15,585 763

1994 16 0 14,207 777

1995 19 0 14,624 696

1996 13 0 13,695 760

1997 16 0 12,872 596

1998 10 0 12,294 667

1999 13 0 12,412 699

2000 14 NA 13,785 563

2001 12 NA 13,896 594

New York

1977 NA NA 165 NA

1978 NA NA 193 NA

1979 NA NA 211 0

1980 NA NA 208 0

1981 NA NA *264 0

1982 NA NA 229 NA

1983 NA NA 295 NA

1984 NA NA 389 NA

1985 NA NA *369 NA

1986 NA NA *457 NA

1987 NA NA 410 NA

1988 NA NA 351 NA

1989 NA NA 368 NA

1990 NA NA 354 NA

1991 NA NA 331 NA

1992 NA NA 329 NA

1993 NA NA *264 NA

1994 NA NA 242 NA

1995 NA NA 197 NA

1996 NA NA 232 NA

1997 NA NA *224 NA

1998 NA NA 218 NA

1999 NA NA 221 NA

2000 NA NA 322 NA

2001 NA NA 318 NA

North Dakota

1977 155 10 361 NA

1978 162 4 374 NA

1979 211 6 439 47

1980 214 6 537 61

1981 223 8 581 68

1982 237 8 629 71

1983 258 53 600 69

1984 260 54 566 73

1985 255 34 569 74

1986 218 35 541 69

1987 215 33 508 67

1988 216 39 541 52

1989 246 31 561 59

1990 285 0 586 60

1991 232 4 472 56

1992 237 3 496 64

1993 226 7 525 55

1994 226 2 507 55

1995 233 6 463 53

1996 248 6 462 48

1997 279 6 479 47

1998 245 1 447 48

1999 262 1 416 53

2000 270 NA 433 54

2001 328 NA 443 57

Ohio

1977 *74 0 495 NA

1978 69 0 684 NA

1979 *82 0 *1,479 0

1980 *116 0 *1,699 0

1981 *112 0 965 0

1982 111 0 1,141 NA

1983 130 0 2,030 NA

1984 *116 0 1,541 NA

1985 79 0 1,331 NA

1986 72 0 1,420 NA

1987 66 0 1,069 NA

1988 64 0 1,229 NA

1989 56 0 1,275 NA

1990 65 0 1,214 NA

1991 66 0 1,181 NA

1992 58 0 1,161 NA

1993 54 0 1,104 NA

1994 58 0 1,094 NA

1995 53 0 1,054 NA

1996 53 0 1,113 NA

1997 *43 0 985 NA

1998 40 0 890 NA

1999 51 0 1,179 NA

2000 59 NA 1,185 NA

2001 46 NA 970 NA
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 79

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Oklahoma

1977 1,109 69 13,889 NA

1978 979 33 14,417 NA

1979 1,014 35 13,816 583

1980 930 27 13,138 604

1981 950 43 14,699 631

1982 971 25 16,207 745

1983 931 27 16,211 829

1984 940 40 16,126 769

1985 935 37 16,040 826

1986 874 35 16,685 857

1987 788 56 16,711 781

1988 796 79 16,495 765

1989 789 63 15,916 654

1990 734 37 16,151 657

1991 700 54 14,725 628

1992 698 54 13,926 629

1993 680 40 13,289 643

1994 689 47 13,487 652

1995 676 48 13,438 674

1996 632 43 13,074 684

1997 605 20 13,439 685

1998 599 59 13,645 698

1999 621 58 12,543 749

2000 610 NA 13,699 734

2001 556 NA 13,558 694

Pennsylvania

1977 *57 0 769 NA

1978 27 0 899 NA

1979 33 0 *1,515 1

1980 35 0 951 0

1981 32 0 *1,264 0

1982 37 0 1,429 NA

1983 41 0 1,882 NA

1984 *40 0 1,575 NA

1985 *38 0 *1,617 NA

1986 *26 0 *1,560 1

1987 26 0 1,647 NA

1988 *27 0 2,072 NA

1989 26 0 1,642 NA

1990 22 0 1,720 NA

1991 15 0 1,629 NA

1992 16 0 1,528 NA

1993 14 0 1,717 NA

1994 15 0 1,800 NA

1995 11 0 1,482 NA

1996 10 0 1,696 NA

1997 17 0 1,852 NA

1998 15 0 1,840 NA

1999 16 0 1,772 NA

2000 15 NA 1,741 NA

2001 10 NA 1,775 NA

Texas - Total

1977 9,751 637 56,422 NA

1978 8,911 533 55,583 NA

1979 8,284 471 53,021 2,482

1980 8,206 384 50,287 2,452

1981 8,093 459 50,469 2,646

1982 7,616 377 49,757 2,771

1983 7,539 421 50,052 3,038

1984 7,557 735 49,883 3,048

1985 g7,782 609 g41,775 g2,981

1986 g7,152 1,270 g40,574 g2,964

1987 g7,112 1,028 g38,711 g2,822

1988 g7,043 1,099 g38,167 g2,617

1989 g6,966 805 g38,381 g2,563

1990 g7,106 618 g38,192 g2,575

1991 g6,797 756 g36,174 g2,493

1992 g6,441 g612 g35,093 g2,402

1993 g6,171 g581 g34,718 g2,469

1994 g5,847 g491 g35,974 g2,414

1995 g5,743 g395 g36,542 g2,524

1996 g5,736 g358 g38,270 g2,606

1997 g5,687 g479 g37,761 g2,687

1998 g4,927 g400 g37,584 g2,544

1999 g5,339 g426 g40,157 g2,584

2000 g5,273 NA g40,082 g2,819

2001 g4,944 NA g43,527 g2,653

gExcludes Federal offshore; now included in Federal OffshoreGulf of Mexico (Texas).

Texas - RRC District 1

1977 *174 0 1,319 NA

1978 111 2 986 NA

1979 110 0 919 23

1980 *150 0 829 24

1981 127 5 *1,022 26

1982 129 6 892 29

1983 165 6 1,087 43

1984 173 4 838 39

1985 177 8 967 40

1986 144 1 913 35

1987 143 1 812 27

1988 136 1 1,173 30

1989 139 1 1,267 25

1990 252 0 1,048 26

1991 227 0 1,030 28

1992 185 0 933 27

1993 133 0 698 26

1994 100 1 703 26

1995 90 6 712 26

1996 86 1 906 46

1997 83 <1 953 54

1998 61 0 1,104 38

1999 66 0 1,008 167

2000 87 NA 1,032 55

2001 46 NA 1,018 40
Energy Information Administration

80 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Texas - RRC District 2 Onshore

1977 395 80 3,162 NA

1978 334 1 2,976 NA

1979 292 1 2,974 64

1980 252 1 2,502 64

1981 229 1 2,629 88

1982 206 0 2,493 75

1983 192 0 2,534 99

1984 192 <1 2,512 103

1985 168 0 2,358 100

1986 148 <1 2,180 89

1987 137 0 2,273 102

1988 117 0 2,037 92

1989 107 0 1,770 72

1990 91 0 1,737 80

1991 90 0 1,393 75

1992 86 0 1,389 80

1993 77 0 1,321 86

1994 74 0 1,360 86

1995 61 0 1,251 93

1996 63 <1 1,322 93

1997 66 0 1,634 87

1998 45 <1 1,614 85

1999 53 0 1,881 76

2000 54 NA 1,980 72

2001 48 NA 1,801 67

Texas - RRC District 3 Onshore

1977 937 33 7,518 NA

1978 794 22 7,186 NA

1979 630 32 6,315 231

1980 581 11 5,531 216

1981 552 11 5,292 230

1982 509 22 4,756 265

1983 517 27 4,680 285

1984 522 25 4,708 270

1985 471 6 4,180 260

1986 420 3 3,753 237

1987 386 4 3,632 241

1988 360 16 3,422 208

1989 307 11 3,233 213

1990 275 13 2,894 181

1991 300 28 2,885 208

1992 304 27 2,684 211

1993 327 31 2,972 253

1994 330 61 3,366 254

1995 267 27 3,866 272

1996 281 27 4,349 289

1997 259 28 4,172 286

1998 211 28 3,961 246

1999 221 25 3,913 226

2000 213 NA 3,873 209

2001 195 NA 3,770 226

Texas - RRC District 4 Onshore

1977 145 7 9,621 NA

1978 123 3 9,031 NA

1979 113 4 8,326 248

1980 96 3 8,130 252

1981 97 6 8,004 260

1982 87 7 8,410 289

1983 96 3 8,316 292

1984 99 3 8,525 295

1985 98 2 8,250 269

1986 87 2 8,274 281

1987 80 2 7,490 277

1988 65 1 7,029 260

1989 77 <1 7,111 260

1990 67 <1 7,475 279

1991 52 <1 7,048 273

1992 50 <1 6,739 272

1993 59 <1 7,038 278

1994 41 <1 7,547 290

1995 50 <1 7,709 287

1996 51 0 7,769 323

1997 70 <1 8,099 347

1998 40 0 8,429 363

1999 42 0 8,915 422

2000 34 NA 9,645 406

2001 32 NA 9,956 378

Texas - RRC District 5

1977 68 0 931 NA

1978 *68 0 *1,298 NA

1979 55 1 1,155 34

1980 52 0 1,147 44

1981 49 0 1,250 49

1982 45 0 1,308 53

1983 42 0 1,448 73

1984 36 <1 1,874 74

1985 *59 1 2,058 77

1986 *53 1 2,141 86

1987 54 0 2,119 88

1988 48 0 1,996 81

1989 46 0 1,845 80

1990 47 0 1,875 81

1991 46 0 1,863 71

1992 56 0 1,747 71

1993 52 0 1,867 64

1994 49 0 2,011 59

1995 34 0 1,862 54

1996 29 0 2,079 54

1997 54 0 1,710 35

1998 40 0 1,953 35

1999 37 0 2,319 32

2000 44 NA 3,168 49

2001 29 NA 4,231 49
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 81

Texas - RRC District 6

1977 1,568 12 3,214 NA

1978 1,444 3 3,240 NA

1979 1,177 6 3,258 272

1980 1,115 6 4,230 321

1981 1,040 7 4,177 308

1982 947 6 4,326 278

1983 918 5 4,857 342

1984 889 5 4,703 298

1985 851 4 4,822 293

1986 750 2 4,854 277

1987 733 3 4,682 264

1988 685 5 4,961 263

1989 631 4 5,614 266

1990 605 6 5,753 247

1991 504 7 5,233 243

1992 442 7 5,317 251

1993 406 <1 5,508 248

1994 424 <1 5,381 265

1995 409 1 5,726 271

1996 359 1 5,899 290

1997 348 1 5,887 260

1998 308 0 5,949 276

1999 245 4 5,857 223

2000 213 NA 5,976 283

2001 200 NA 6,128 269

Texas - RRC District 7B

1977 250 NA 699 NA

1978 190 NA 743 NA

1979 208 NA *751 64

1980 196 NA *745 85

1981 254 NA 804 102

1982 199 NA 805 105

1983 217 NA 1,027 133

1984 218 62 794 106

1985 239 63 708 104

1986 193 64 684 109

1987 200 46 697 92

1988 205 42 704 98

1989 204 11 459 73

1990 198 8 522 76

1991 184 8 423 82

1992 163 11 455 68

1993 *171 7 477 79

1994 145 5 425 62

1995 126 4 440 70

1996 136 4 520 65

1997 155 3 478 59

1998 115 0 442 51

1999 123 0 416 36

2000 124 NA 312 34

2001 91 NA 252 29

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Texas - RRC District 7C

1977 191 NA 2,831 NA

1978 202 NA 2,821 NA

1979 206 NA 2,842 182

1980 207 NA 2,378 135

1981 230 NA 2,503 186

1982 229 NA 2,659 199

1983 228 NA 2,568 219

1984 240 24 2,866 233

1985 243 21 2,914 256

1986 213 22 2,721 246

1987 220 25 2,708 243

1988 212 31 2,781 238

1989 247 16 3,180 238

1990 274 8 3,514 256

1991 253 9 3,291 241

1992 255 33 3,239 289

1993 199 15 3,215 273

1994 221 14 3,316 265

1995 204 8 3,107 274

1996 219 5 3,655 303

1997 227 4 3,407 327

1998 173 1 3,113 282

1999 209 3 3,178 305

2000 206 NA 3,504 434

2001 188 NA 3,320 290

Texas - RRC District 8

1977 2,915 127 11,728 NA

1978 2,795 102 11,093 NA

1979 2,686 88 10,077 505

1980 2,597 86 9,144 498

1981 2,503 105 8,546 537

1982 2,312 75 8,196 588

1983 2,350 99 8,156 681

1984 2,342 363 7,343 691

1985 2,333 325 7,330 665

1986 2,183 592 7,333 717

1987 2,108 399 6,999 640

1988 2,107 412 7,058 547

1989 2,151 366 6,753 554

1990 2,152 282 6,614 558

1991 2,114 328 6,133 477

1992 2,013 260 5,924 444

1993 2,057 262 5,516 439

1994 2,002 256 5,442 414

1995 2,032 187 5,441 444

1996 2,079 217 5,452 429

1997 2,100 308 5,397 459

1998 1,865 272 4,857 491

1999 2,067 279 5,434 495

2000 2,073 NA 5,388 526

2001 1,880 NA 5,255 525
Energy Information Administration

82 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Texas - RRC District 8A

1977 2,626 291 1,630 NA

1978 2,439 330 1,473 NA

1979 2,371 270 1,055 351

1980 2,504 196 1,057 290

1981 2,538 247 1,071 335

1982 2,481 200 1,041 296

1983 2,366 203 966 262

1984 2,413 217 907 282

1985 2,711 147 958 283

1986 2,618 559 845 331

1987 2,735 525 876 307

1988 2,800 569 832 326

1989 2,754 377 1,074 332

1990 2,847 285 1,036 354

1991 2,763 363 1,073 333

1992 2,599 273 1,239 257

1993 2,435 264 1,043 298

1994 2,223 154 1,219 267

1995 2,233 156 941 284

1996 2,207 99 931 262

1997 2,098 131 847 290

1998 1,895 99 807 226

1999 2,089 115 1,257 223

2000 2,022 NA 1,101 217

2001 2,070 NA 1,085 251

Texas - RRC District 9

1977 260 28 724 NA

1978 190 27 *908 NA

1979 200 30 *700 79

1980 218 37 649 92

1981 225 34 953 86

1982 219 17 *1,103 119

1983 220 18 932 121

1984 214 25 900 119

1985 285 27 892 111

1986 237 19 868 119

1987 206 21 834 115

1988 202 18 783 106

1989 200 16 703 94

1990 193 12 776 104

1991 162 11 738 101

1992 176 1 670 92

1993 168 2 688 92

1994 159 <1 728 98

1995 149 <1 738 94

1996 144 0 705 119

1997 144 0 794 98

1998 111 0 734 93

1999 123 0 1,137 158

2000 131 NA 1,626 161

2001 104 NA 2,289 189

Texas - RRC District 10

1977 *120 4 7,744 NA

1978 90 0 7,406 NA

1979 97 2 6,784 375

1980 89 2 6,435 369

1981 107 2 6,229 364

1982 112 2 6,210 391

1983 105 6 5,919 413

1984 108 6 5,461 440

1985 *140 5 5,469 433

1986 *104 5 5,276 428

1987 102 2 4,962 417

1988 99 4 4,830 363

1989 97 3 4,767 342

1990 99 3 4,490 328

1991 95 2 4,589 356

1992 89 <1 4,409 336

1993 83 <1 4,040 329

1994 75 <1 4,246 326

1995 80 6 4,436 353

1996 74 4 4,391 332

1997 79 4 4,094 382

1998 62 0 4,273 354

1999 61 0 4,424 217

2000 67 NA 4,079 369

2001 55 NA 3,955 335

Texas - State and Federal Offshore

1977 102 0 5,301 NA

1978 131 1 6,422 NA

1979 139 0 7,865 54

1980 149 0 7,510 62

1981 142 0 7,989 75

1982 141 0 7,558 84

1983 123 0 7,562 75

1984 111 0 8,452 98

1985 119 0 8,129 90

1986 103 0 8,176 109

1987 96 0 7,846 98

1988 85 0 7,802 94

1989 75 0 7,573 84

1990 77 0 7,758 87

1991 67 0 7,150 84

1992 197 0 7,344 122

1993 196 0 6,996 119

1994 209 10 6,613 105

1995 257 16 6,838 136

1996 218 5 6,288 133

1997 366 5 6,277 124

1998 311 0 5,996 147

1999 305 0 6,271 165

2000 428 NA 6,782 157

2001 417 NA 7,242 187
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 83

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Texas - State Offshore

1977 NA NA NA NA

1978 NA NA NA NA

1979 NA NA NA NA

1980 NA NA NA 12

1981 NA NA NA 13

1982 NA NA NA 18

1983 NA NA NA 11

1984 NA NA NA 10

1985 7 0 869 10

1986 2 0 732 9

1987 8 0 627 9

1988 7 0 561 5

1989 6 0 605 6

1990 6 0 458 5

1991 7 0 475 5

1992 5 0 348 4

1993 4 0 335 4

1994 4 0 230 2

1995 8 0 313 2

1996 8 0 292 1

1997 4 0 289 3

1998 1 0 348 4

1999 3 0 418 4

2000 5 NA 398 4

2001 6 NA 467 5

Utah

1977 252 6 877 NA

1978 188 7 925 NA

1979 201 NA 948 59

1980 198 NA 1,201 127

1981 190 NA 1,912 277

1982 173 NA 2,161 (h)

1983 187 NA 2,333 (h)

1984 172 8 2,080 (h)

1985 276 13 1,999 (h)

1986 269 14 1,895 (h)

1987 284 22 1,947 (h)

1988 260 21 1,298 (h)

1989 246 50 1,507 (h)

1990 249 44 1,510 (h)

1991 233 66 1,702 (h)

1992 217 65 1,830 (h)

1993 228 54 2,040 (h)

1994 231 70 1,789 (h)

1995 216 50 1,580 (h)

1996 237 46 1,633 (h)

1997 234 70 1,839 (h)

1998 201 56 2,388 (h)

1999 268 42 3,213 (h)

2000 283 NA 4,235 (h)

2001 271 NA 4,579 (h)

hIncluded with Wyoming.

Virginia

1977 NA NA NA NA

1978 NA NA NA NA

1979 NA NA NA NA

1980 NA NA NA NA

1981 NA NA 118 NA

1982 NA NA 122 NA

1983 NA NA 175 NA

1984 NA NA 216 NA

1985 NA NA 235 NA

1986 NA NA 253 NA

1987 NA NA 248 NA

1988 NA NA 230 NA

1989 NA NA 217 NA

1990 NA NA 138 NA

1991 NA NA 225 NA

1992 NA NA 904 NA

1993 NA NA 1,322 NA

1994 NA NA 1,833 NA

1995 NA NA 1,836 NA

1996 NA NA 1,930 NA

1997 NA NA 2,446 NA

1998 NA NA 1,973 NA

1999 NA NA 2,017 NA

2000 NA NA 1,704 NA

2001 NA NA 1,752 NA

West Virginia

1977 21 0 1,567 NA

1978 *30 0 1,634 NA

1979 *48 0 1,558 74

1980 30 8 *2,422 97

1981 30 8 1,834 85

1982 48 8 2,148 79

1983 49 0 2,194 91

1984 *76 0 2,136 80

1985 40 0 2,058 85

1986 37 0 2,148 87

1987 34 0 2,242 87

1988 33 0 2,306 92

1989 30 0 2,201 100

1990 *31 0 2,207 86

1991 26 0 2,528 103

1992 27 0 2,356 97

1993 24 0 2,439 108

1994 25 0 2,565 93

1995 28 0 2,499 62

1996 25 0 2,703 61

1997 26 0 2,846 71

1998 17 0 2,868 72

1999 21 0 2,936 73

2000 12 NA 2,900 105

2001 8 NA 2,678 106
Energy Information Administration

84 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Wyoming

1977 851 31 6,305 NA

1978 845 36 7,211 NA

1979 841 40 7,526 285

1980 928 28 9,100 341

1981 840 53 9,307 384

1982 856 58 9,758 i681

1983 957 61 10,227 i789

1984 954 71 10,482 i860

1985 951 18 10,617 i949

1986 849 126 9,756 i950

1987 854 27 10,023 i924

1988 815 35 10,308 i1,154

1989 825 46 10,744 i 896

1990 794 42 9,944 i812

1991 757 24 9,941 i748

1992 689 18 10,826 i660

1993 624 12 10,933 i600

1994 565 13 10,879 i564

1995 605 12 12,166 i593

1996 603 14 12,320 i727

1997 627 11 13,562 i761

1998 547 10 13,650 i675

1999 590 5 14,226 i615

2000 561 NA 16,158 i947

2001 489 NA 18,398 i897

i

Utah and Wyoming are combined.

Federal Offshore - Total

1985 2,862 11 j34,492 702

1986 2,715 16 j34,223 681

1987 2,639 21 j31,931 638

1988 2,629 21 j32,264 622

1989 2,747 32 j32,651 678

1990 2,805 49 31,433 619

1991 2,620 18 29,448 640

1992 2,569 31 27,767 610

1993 2,745 18 27,143 630

1994 2,780 53 28,388 624

1995 3,089 62 29,182 655

1996 3,085 45 29,096 776

1997 3,477 41 28,466 920

1998 3,261 7 26,902 931

1999 3,297 5 25,987 998

2000 3,770 NA 26,748 1,078

2001 4,835 NA 27,036 976

j

Includes State offshore Alabama.

Note: Data not tabulated for years 1977-1984.

Federal Offshore - Pacific (California)

1985 991 NA 1,119 12

1986 974 2 1,325 15

1987 1,037 2 1,452 17

1988 1,024 0 1,552 21

1989 987 0 1,496 25

1990 962 0 1,454 18

1991 785 0 1,162 16

1992 734 0 1,118 20

1993 673 0 1,099 25

1994 653 0 1,170 21

1995 571 0 1,265 25

1996 518 0 1,244 23

1997 528 0 544 14

1998 468 0 480 12

1999 553 0 536 4

2000 596 NA 576 4

2001 547 NA 540 9

Note: Data not tabulated for years 1977-1984.

Federal Offshore - Gulf of Mexico (Louisiana)

1985 1,759 11 f26,113 610

1986 1,640 14 f25,454 566

1987 1,514 19 f23,260 532

1988 1,527 21 f23,471 512

1989 1,691 32 f24,187 575

1990 1,772 49 k22,679 k519

1991 1,775 18 k21,611 k545

1992 1,643 31 k19,653 k472

1993 1,880 18 k19,383 k490

1994 1,922 43 k20,835 k500

1995 2,269 46 k21,392 k496

1996 2,357 40 k21,856 k621

1997 2,587 36 k21,934 k785

1998 2,483 7 k20,774 k776

1999 2,442 5 k19,598 k833

2000 2,751 NA k19,788 k921

2001 3,877 NA k19,721 k785

f

Includes State and Federal offshore Alabama. kIncludes Federal offshore Alabama.

Note: Data not tabulated for years 1977-1984.
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 85

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Dry Natural

Crude Oil Natural Gas

Crude Oil Indicated Gas Liquids

Proved Additional Proved Proved

Year Reserves Reserves Reserves Reserves

Federal Offshore - Gulf of Mexico (Texas)

1985 112 0 7,260 80

1986 101 0 7,444 100

1987 88 0 7,219 89

1988 78 0 7,241 89

1989 69 0 6,968 78

1990 71 0 7,300 82

1991 60 0 6,675 79

1992 192 0 6,996 118

1993 192 0 6,661 115

1994 205 10 6,383 103

1995 249 16 6,525 134

1996 210 5 5,996 132

1997 362 5 5,988 121

1998 310 0 5,648 143

1999 302 0 5,853 161

2000 423 NA 6,384 153

2001 411 NA 6,775 182

Note: Data not tabulated for years 1977-1984.

Miscellaneous

1977 23 0 102 NA

1978 24 0 109 NA

1979 22 1 *153 2

1980 *38 0 176 3

1981 40 7 191 21

1982 33 0 69 4

1983 30 8 78 5

1984 23 0 75 5

1985 35 0 76 3

1986 33 0 133 2

1987 30 0 65 4

1988 34 0 83 5

1989 39 0 83 5

1990 43 1 *70 3

1991 42 5 75 8

1992 29 0 92 8

1993 34 0 94 8

1994 20 0 65 8

1995 *22 0 *69 7

1996 18 0 67 7

1997 19 0 *43 9

1998 14 0 38 8

1999 15 0 66 10

2000 17 NA 42 7

2001 21 NA 82 7

Note: States included may vary for different report years and

hydrocarbon types.

Lower 48 States

1977 23,367 2,168 175,170 NA

1978 21,971 1,964 175,988 NA

1979 20,935 1,878 168,738 6,592

1980 21,054 1,622 165,639 6,717

1981 21,143 1,594 168,693 7,058

1982 20,452 1,478 166,522 7,212

1983 20,428 1,548 165,964 7,893

1984 20,883 1,956 162,987 7,624

1985 21,360 1,662 159,522 7,561

1986 20,014 2,597 158,922 7,784

1987 19,878 3,084 153,986 7,729

1988 19,866 3,169 158,946 7,837

1989 19,827 2,999 158,177 7,389

1990 19,730 2,514 160,046 7,246

1991 18,599 2,810 157,509 7,104

1992 17,723 2,451 155,377 7,104

1993 17,182 2,292 152,508 6,901

1994 16,690 2,129 154,104 6,869

1995 16,771 2,087 155,649 7,093

1996 16,743 1,924 157,180 7,486

1997 17,385 2,375 156,661 7,342

1998 15,982 2,328 154,114 7,204

1999 16,865 2,400 157,672 7,515

2000 17,184 NA 168,190 8,068

2001 17,595 NA 174,660 7,588

U.S. Total

1977 31,780 3,014 207,413 NA

1978 31,355 2,362 208,033 NA

1979 29,810 2,276 200,997 6,615

1980 29,805 1,622 199,021 6,728

1981 29,426 1,594 201,730 7,068

1982 27,858 1,478 201,512 7,221

1983 27,735 2,124 200,247 7,901

1984 28,446 2,325 197,463 7,643

1985 28,416 2,041 193,369 7,944

1986 26,889 3,499 191,586 8,165

1987 27,256 3,649 187,211 8,147

1988 26,825 3,600 168,024 8,238

1989 26,501 3,749 167,116 7,769

1990 26,254 3,483 169,346 7,586

1991 24,682 4,266 167,062 7,464

1992 23,745 3,782 165,015 7,451

1993 22,957 3,453 162,415 7,222

1994 22,457 3,151 163,837 7,170

1995 22,351 2,669 165,146 7,399

1996 22,017 2,876 166,474 7,823

1997 22,546 3,207 167,223 7,973

1998 21,034 3,160 164,041 7,524

1999 21,765 2,865 167,406 7,906

2000 22,045 NA 177,427 8,345

2001 22,446 NA 183,460 7,993
Energy Information Administration

86 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D1. U.S. Proved Reserves of Crude Oil, 1976–2001

(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

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 2001 annual reports, DOE/EIA-0216.{1-24}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 87

Table D2. U.S. Lower 48 Proved Reserves of Crude Oil, 1976–2001

(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

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 2001 annual reports, DOE/EIA-0216.{1-24}
Energy Information Administration

88 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D3. U.S. Proved Reserves of Dry Natural Gas, 1976–2001

(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

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 2001 annual reports, DOE/EIA-0216.{1-24}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 89

Table D4. U.S. Lower 48 Proved Reserves of Dry Natural Gas, 1976–2001

(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

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 2001 annual reports, DOE/EIA-0216.{1-24}
Energy Information Administration

90 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D5. U.S. Proved Reserves of Wet Natural Gas, After Lease Separation, 1978–2001

(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

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 2001 annual reports, DOE/EIA-0216.{3-24}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 91

Table D6. U.S. Lower 48 Proved Reserves of Wet Natural Gas, After Lease Separation, 1978–2001

(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

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 2001 annual reports, DOE/EIA-0216.{3-24}
Energy Information Administration

92 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D7. U.S. Proved Reserves of Natural Gas Liquids, 1978–2001

(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

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 liquids

contained in the Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2001 annual reports, DOE/EIA-0216.{3-24}
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 93

Table D8. U.S. Lower 48 Proved Reserves of Natural Gas Liquids, 1978–2001

(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

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 natural gas liquids contained

in the Natural Gas Annual, DOE/EIA-0131.

Source: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 1979 through 2001 annual reports, DOE/EIA-0216.{3-24}
Energy Information Administration

94 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D9. Deepwater Production and Proved Reserves of the Gulf of Mexico Federal Offshore, 1992-2001

Gulf of Mexico Depth

Greater than Less than Deepwater

Year Total Louisianaa Texas 200 meters 200 meters Percentage

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

Production

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

Reserves

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

Natural Gas, Wet After Lease Separation

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

Production

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

Reserves

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
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 95

Table D9. Deepwater Production and Proved Reserves of the Gulf of Mexico Federal Offshore, 1992-2000

(continued)

Gulf of Mexico Depth

Greater than Less than Deepwater

Year Total Louisianaa Texas 200 meters 200 meters Percentage

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

Production

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

Reserves

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

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

Production

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

Reserves

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
Energy Information Administration

96 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table D9. Deepwater Production and Proved Reserves of the Gulf of Mexico Federal Offshore, 1992-2000

(continued)

Gulf of Mexico Depth

Greater than Less than Deepwater

Year Total Louisianaa Texas 200 meters 200 meters Percentage

Lease Condensate (million barrels of 42 U.S. gallons)

Production

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

Reserves

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

aIncludes Federal Offshore Alabama.

bRevisions result from reclassing all field depths to match Minerals Management Service assignments.

Source: Based on data reported on Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves.”
Table D10. 2001 Reported Reserves in Nonproducing Reservoirs for Crude Oil, Lease Condensate, and

Natural Gasa

Lease Nonassociated Associated Total

Crude Oil Condensate Gas Dissolved Gas Gas

State and Subdivision (mbbls) (mbbls) (bcf) (bcf) (bcf)

Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 0 584 37 620

Lower 48 States .......................... 4,806 562 45,737 6,591 52,328

Alabama. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 200 8 208

Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 0 247 9 257

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508 0 301 217 518

Coastal Region Onshore . . . . . . . . . . . . . . . . . . . . 148 0 0 54 54

Los Angeles Basin Onshore . . . . . . . . . . . . . . . . . 97 0 0 77 77

San Joaquin Basin Onshore . . . . . . . . . . . . . . . . . 233 0 301 73 373

State Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 0 0 14 14

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 16 3,519 443 3,962

Florida .................................. 7 0 0 0 0

Illinois. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 0 0 1 1

Indiana.................................. 0 0 6 0 6

Kansas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 0 112 4 116

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 56 0 56

Louisiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 77 3,986 330 4,316

North . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 12 1,753 63 1,816

South Onshore. . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 62 2,009 217 2,226

State Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3 223 51 274

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0 468 17 485

Mississippi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 2 109 12 120

Montana. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 0 93 11 104

Nebraska ................................ 0 0 0 0 0

New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 13 3,350 126 3,476

East . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 4 805 125 930

West. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 10 2,546 1 2,547

New York . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 60 0 60

North Dakota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3 43 15 57

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0 102 3 105

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 30 2,731 198 2,929

Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 305 69 374

Texas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 719 110 11,771 1,087 12,858

RRC District 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 305 9 313

RRC District 2 Onshore . . . . . . . . . . . . . . . . . . . . . 12 4 587 20 607

RRC District 3 Onshore . . . . . . . . . . . . . . . . . . . . . 29 29 903 57 961

RRC District 4 Onshore . . . . . . . . . . . . . . . . . . . . . 8 34 3,585 53 3,638

RRC District 5 ............................ 4 1 1,907 35 1,943

RRC District 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 14 1,282 18 1,300

RRC District 7B . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 90 1 91

RRC District 7C . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 6 521 123 644

RRC District 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 6 762 353 1,115

RRC District 8A . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 0 29 371 400

RRC District 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3 1,264 21 1,285

RRC District 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8 465 26 491

State Offshore . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 2 72 1 72

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 1 1,423 155 1,578

Virginia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 776 0 776

West Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 202 0 202

Wyoming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 29 5,817 43 5,860

Federal Offshoreb ......................... 2,595 275 10,060 3,845 13,905

Pacific (California) . . . . . . . . . . . . . . . . . . . . . . . . . 62 8 48 110 158

Gulf of Mexico (Louisiana)b .................. 2,352 178 6,889 3,311 10,200

Gulf of Mexico (Texas). . . . . . . . . . . . . . . . . . . . . . 180 89 3,122 424 3,546

Miscellaneousc

............................ 1 0 0 0 0

U.S. Total ........................... 5,195 562 46,321 6,628 52,948

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

or more (Category I and Category II operators). bIncludes Federal offshore Alabama.

cIncludes Arizona, Maryland, Missouri, Nevada, Oregon, South Dakota and Tennessee.

Source: Form EIA-23, "Annual Survey of Domestic Oil and Gas Reserves," 2001.

Energy Information Administration 97

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Appendix E

Summary of Data Collection Operations
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 2001 by crude oil or

natural gas well operators who were active as of

December 31, 2001. 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 1994 and 2001, and depicts the

number of active operators, with 1994 showing the

largest in the series. The 2001 sampling frame consisted

of 179 Category I, 485 Category II, 559 Category III

Certainty, and 21,296 Category III Noncertainty

operators, for a total of 22,519 active operators. The

survey sample consisted of 1,223 operators selected

with certainty that included all of the Category I and II

Certainty operators, the 559 smaller operators that

were selected with certainty because of their size in

relation to the area or areas in which they operated, and

644 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 2001 survey is

summarized in Table E2. EIA makes a considerable

effort to gain responses from all operators. About 4.3

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 81 nonoperators, 11 had successor operators that

had taken over the production of the nonoperator.

These successor operators were subsequently sampled.

The overall response rate for the 2001 survey was 97.7

percent. For the 42 operators that did not respond,

production data was 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 2001 Annual Report 101
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

Energy Information Administration

102 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table E1. Comparison of the EIA-23 Sample and Sampling Frame, 1994-2001

Number of Operators

Operator Category 1994 1995 1996 1997 1998 1999 2000 2001

Certainty

Category I. . . . . . . . . . . . . 161 161 176 180 178 177 175 179

Category II . . . . . . . . . . . . 482 476 486 461 420 399 436 485

Category III............ 1,694 1,596 3 1,194 862 648 854 559

Sampled ............. 2,337 2,233 665 1,835 1,460 1,224 1,465 1,223

Percent Sampled . . . . . . . 100 100 100 100 100 100 100 100

Noncertainty

Sampled .............. 1,737 1,632 0 1,645 1,459 1,305 1,311 644

Percent Sampled ....... 8 8 0 8 7 6 6 3

Total

Active Operators........ R24,222 22,766 23,410 22,678 23,620 22,089 22,102 22,519

Not Sampled .......... 20,148 18,901 22,745 19,198 20,701 19,560 19,326 20,652

Sampled .............. 4,074 3,865 665 3,480 2,919 R2,529 2,776 1,867

Percent Sampled . . . . . . . 17 17 3 15 12 R11 13 8

R=Revised data.

Table E2. Form EIA-23 Survey Response Statistics, 2001

Original Netb Responding Nonresponding

Sample Successora Category Non-c Adjustedd Operators Operators

Operator Category Selected Operators Changes operators Sample Number Percent Number Percent

Certainty

Category I . . . . . . . 180 0 +2 -10 172 172 100.0 0 0.0

Category II . . . . . . . 484 8 -24 -29 439 439 100.0 0 0.0

Category III . . . . . . . 559 3 +22 -20 564 553 98.0 e

11 2.0

Subtotal......... 1,223 11 0 -59 1,175 1,164 99.1 e

11 0.9

Noncertainty . . . . . . . . 644 0 0 -22 622 591 95.0 e

31 5.0

Total ............ 1,867 11 0 -81 1,797 1,755 97.7 e

42 2.3

aSuccessor operators are those, not initially sampled, that have taken over the production of a sampled operator.

bNet 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. dAdjusted sample equals original sample plus successor operators plus net category changes minus nonoperators.

eFor the 42 operators (11 Category III operators and 31 Noncertainty operators) that did not respond, production data was obtained from State or other sources.

Source: Form EIA-23, “Annual Survey of Domestic Oil and Gas Reserves” 2001.
report year, revision increases and revision decreases,

sales and acquisitions, extensions, new field

discoveries, new reservoirs in old fields, production,

indicated additional reserves of crude oil,

nonproducing reserves, 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

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.

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 2001, in January of 2002, was the 20th annual

report and reflected data collected through November

2001. 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 2001, Form EIA-23 National estimates of

production were 2,130 million barrels for crude oil and

lease condensate or 12 million barrels (1 percent)

higher than that reported in the Petroleum Supply

Annual 2001 for crude oil and lease condensate (2,118

million barrels). Form EIA-23 National estimates of

production for dry natural gas were 19,779 billion cubic

feet, 330 billion cubic feet (2 percent) higher than the

Natural Gas Monthly, October 2002 for 2001 dry natural

gas production (19,449 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 IHS Energy Group, 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 2001 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 14, 2001. Of these, 22,519

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

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 103
nonoperators) exist as a pool of names and addresses

that may be added to the active list if review indicates

activity.

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, 2002. In

addition, plant operators whose plants were shut down

or dismantled during 2001 were required to complete

forms for the portion of 2001 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 516 plants were sent forms. This

number included no new plants, no reactivated plants,

and no successor plants identified after the initial 2001

survey mailing. A total of 9 plants were reported as

nonoperating according to the Form EIA-64A

Energy Information Administration

104 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table E3. Summary of the 2001 Operator Frame

Activity, Form EIA-23

Total 2000 Operator Frame ............. 68,527

Operators....................... 22,102

Nonoperators.................... 46,425

Changes to 2000 Operator Status . . . . . . 690

From Nonoperator to Operatora . . . . . 456

From Operator to Nonoperator . . . . . . 234

No Changes to 2000 Operator Status . . . 67,837

Operators....................... 21,901

Nonoperators.................... 45,936

Additions to 2000 Operator Frame . . . . . 89

Operator . . . . . . . . . . . . . . . . . . . . . . . 88

Nonoperator..................... 1

Total 2001 Operator Frame ............ 68,616

Operators....................... 22,519

Nonoperators.................... 46,097

a

Includes operator frame activity through December 14, 2001.

b

Relatively few additions were made since EIA ID numbers are now being recycled when no useable data is 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.
definition. For the 14th 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

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,

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 105

Wellhead

Lease or Field

Separation

Facilities

Natural Gas

Processing Plant

Lease Condensate

Storage

Wet Gas after

Separation

Dry Gas

Plant Liquids

Production

Lease Condensate

Production

TOTAL

NATURAL GAS LIQUIDS

PRODUCTION

Wet Gas

Figure E1. Natural Gas Liquids Extraction Flows

Source: Energy Information Administration, Office of Oil and Gas.
when found, were reconciled in both sources. For 2001,

the Form EIA-64A National estimates were 2 percent

(11 million barrels) lower than the Petroleum Supply

Annual 2001 volume for natural gas plant liquids

production.

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 2001 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 January 31, 2002.

Energy Information Administration

106 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table E5. Form EIA-64A 2001 Plant Frame Activity

Frame as of 2000 survey mailing . . . . . . . 574

Additions . . . . . . . . . . . . . . . . . . . 98

Deletions ................... –147

Frame as of 2001 survey mailing . . . . . . . 525

Note: Includes operator frame activity through January 31, 2002.

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

Table E4. Natural Gas Processed and Liquids Extracted at Natural Gas Processing Plants, 2001

Volume of Natural Gas Delivered to Processing Plants

State Out of State Natural Gas Total Liquids

Plant Location Production Production Processed Extracted

(million cubic feet) (thousand barrels)

Alaska .................. 2,984,807 0 2,984,807 30,334

Alabama................. 284,569 1,384 285,953 9,880

Arkansas ................ 207,352 0 207,352 296

California ................ 258,271 0 258,271 8,625

Colorado ................ 497,385 0 497,385 21,006

Florida .................. 4,364 2,822 7,186 1,186

Kansas.................. 445,640 130,591 576,231 27,754

Kentucky ................ 36,901 0 36,901 1,097

Louisiana ................ 4,000,748 205,722 4,206,470 108,367

Michigan ................ 50,734 0 50,734 3,316

Mississippi ............... 2,809 237,021 239,830 11,088

Montana................. 5,691 0 5,691 364

North Dakota ............. 58,536 0 58,536 4,712

New Mexico .............. 966,882 0 966,882 77,237

Oklahoma ............... 956,019 1,646 957,665 61,780

Texas ................... 3,833,272 43,127 3,876,399 253,587

Utah . . . . . . . . . . . . . . . . . . . . 160,889 5,616 166,505 7,930

West Virginia ............. 95,870 29,667 125,537 7,774

Wyoming ................ 988,184 411 988,595 45,923

Miscellanousa ............ 11,160 3,337 14,497 617

Total . . . . . . . . . . . . . . . 15,850,083 661,344 16,511,427 682,873

aIncludes Illinois, Ohio, and Pennsylvania.

Source: Form EIA-64A, “Annual Report of the Origin of Natural Gas Liquids Production,” 2001
Ap pen dix F

Statistical Considerations
Ap pen dix F

Statistical Considerations

Survey Methodology

The Form EIA-23 survey is designed to provide reliable 

estimates for reserves and production of crude oil,

natural gas, and lease condensate for the United States.

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.

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. As a result, EIA conducts extensive frame

maintenance activities each year to identify all current

operators of crude oil and natural gas wells in the

country.

Sampling Strategy

EIA publishes data on reserves and production for

crude oil, natural gas, and lease condensate by State for

most States, and by State subdivision for the States of

California, Louisiana, New Mexico, and Texas. To meet

the survey objectives, while minimizing respondent

burden, a random sampling strategy has been used

since 1977. Each operator reporting on the survey is

asked to report production 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.

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 2001 survey for

each product class.

n 1.0 percent for National estimates.

n 1.0 percent for each of the 5 States having

subdivisions: Alaska, California, Louisiana,

New Mexico, and Texas. For selected

subdivisions within these States, targets of 1.0

percent or 1.5 percent as required to meet the

State target.

n 2.5 percent for each State/subdivision having 1

percent or more of estimated U.S. reserves or

production in 2000 (lower 48 States) for any

product class.

n 4 percent for each State/subdivision having less

than 1 percent of estimated U.S. reserves or

production in 2000 (lower 48 States) for all 3

product classes.

n 8 percent for States not published separately.

The combined production from these States was 

less than 0.2 percent of the U.S. total in 2000 for

crude oil and for natural gas.

The volume of production defining the Certainty

stratum, referred to as the cutoff, varies by product or

State/subdivision. The cutoff criteria and sampling

rates are shown in Table F1. The Certainty stratum,

therefore, has three components.

n 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 2000.

n 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

2000.

n Category III - Small Operators: Operators who

produced less than the Category II operators in

2000, but which were selected with certainty.

Category III operators were subdivided into

operators sampled with certainty (Certainty)

and operators that were randomly sampled

(Noncertainty).

n Certainty - A small operators who satisfied

any of the following criteria based upon their

production shown in the operator frame:

• Operators with annual crude oil

production of 200 thousand barrels or

more, or reserves of 4 million barrels or

more; or annual natural gas production of 

1 billion cubic feet or more, or reserves of

20 billion cubic feet or more.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 109
Table F1. 2001 EIA–23 Survey Initial Sample Criteria

Noncertainty Sample

Production Cutoffs Number of

Crude Oil Gas Certainty Single State Multi–State

State and Subdivision (mbbls) (mmcf) Operators Operators Operators

Alabama Onshore. . . . . . . . . . . . . . . . . . . . . 107 1,000 46 1 3

Alaska .............................. - - 5 - -

Arkansas. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1,000 93 13 8

California Unspecified. . . . . . . . . . . . . . . . . . 17 88 - - -

California Coastal Region Onshore . . . . . . . 200 1,000 16 - -

California Los Angeles Basin Onshore . . . . . 200 25 17 - -

California San Joaquin Basin Onshore. . . . . 200 1,000 43 - -

Colorado . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 128 1 16

Florida Onshore . . . . . . . . . . . . . . . . . . . . . . 200 1,000 2 - -

Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 27 29 12 30

Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1 14 2 21

Kansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 1,000 168 50 48

Kentucky . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 1,000 22 11 16

Louisiana Unspecified. . . . . . . . . . . . . . . . . . 73 183 - - -

Louisiana North. . . . . . . . . . . . . . . . . . . . . . . 13 633 138 - 7

Louisiana South Onshore . . . . . . . . . . . . . . . 70 1,000 190 - 4

Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 39 5 3

Mississippi Onshore . . . . . . . . . . . . . . . . . . . 200 1,000 89 3 5

Montana . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 69 1 12

Nebraska . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2 24 - 19

New Mexico Unspecified . . . . . . . . . . . . . . . 10 13 - - -

New Mexico East . . . . . . . . . . . . . . . . . . . . . 200 1,000 178 - 1

New Mexico West . . . . . . . . . . . . . . . . . . . . . 21 1,000 64 - -

New York. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1,000 15 12 3

North Dakota. . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 72 1 8

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 1,000 25 46 5

Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 1,000 306 101 54

Pennsylvania ........................ 4 1,000 32 - 3

Texas Unspecified. . . . . . . . . . . . . . . . . . . . . 7 118 - - -

Texas-RRC District 1 . . . . . . . . . . . . . . . . . . 23 800 142 - -

Texas-RRC District 2 Onshore . . . . . . . . . . . 200 1,000 166 - 1

Texas-RRC District 3 Onshore . . . . . . . . . . . 200 1,000 247 - 3

Texas-RRC District 4 Onshore . . . . . . . . . . . 91 1,000 182 - 1

Texas-RRC District 5 . . . . . . . . . . . . . . . . . . 38 630 96 - 3

Texas-RRC District 6 . . . . . . . . . . . . . . . . . . 200 1,000 176 - 4

Texas-RRC District 7B . . . . . . . . . . . . . . . . . 34 82 136 - 7

Texas-RRC District 7C . . . . . . . . . . . . . . . . . 200 1,000 178 - 4

Texas-RRC District 8 . . . . . . . . . . . . . . . . . . 200 1,000 233 - 5

Texas-RRC District 8A . . . . . . . . . . . . . . . . . 200 1,000 206 - 6

Texas-RRC District 9 . . . . . . . . . . . . . . . . . . 52 1,000 139 - 4

Texas-RRC District 10 . . . . . . . . . . . . . . . . . 200 1,000 161 - 12

Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 48 3 2

Virginia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 12 - -

West Virginia......................... 5 1,000 30 12 6

Wyoming. . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 1,000 140 3 12

Offshore Areas . . . . . . . . . . . . . . . . . . . . . . . - - 273 -

Other Statesa . . . . . . . . . . . . . . . . . . . . . . . . 125 49 24 2 3

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - - b899 277 b137

aIncludes Arizona, Connecticut, Delaware, Georgia, Idaho, Iowa, Massachusetts, Maryland, Minnesota, Missouri, North Carolina, New

Hampshire, Nevada, New Jersey, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Washington, and Wisconsin. bNonduplicative count of operators by States.

Note: Sampling rate was 8 percent except in Alaska, Florida Onshore, Virginia, and Offshore areas where sampling rate was 100 percent.

— = Not applicable.

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

110 Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
− All other operators with production or

reserves in a State/subdivision that exceed 

selected cutoff levels for that

State/subdivision.

− 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.

n Noncertainties - Small operators not in the

certainty stratum were classified in a

noncertainty stratum.

− In most areas, data from the noncertainty

operators were sampled at a rate of 3

percent.

− In these States (Texas, California,

Colorado, Louisiana, Montana, New

Mexico, South Dakota, Utah, and

Wyoming) EIA did not survey the

noncertainty operators in 2001. Instead, an 

imputation function was applied to

estimate reserve volumes. The function

used EIA historic production and reserves 

data, State and commercially available

production data, and the size

classifications of reporting operators. 

In each State/subdivision the balance between the

number of small certainty 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.

At each iteration a small operator, beginning with the

largest of the Category III operators, was added to the

certainty group and the required sample size was again 

calculated. The procedure of adding one operator at a

time stopped when the proportion of operators to be

sampled at random dropped below 3 percent.

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.

An additional complexity is introduced because some

small operators selected for the sample in another

region or regions, sometimes report production

volumes in a region in which EIA has no previous

record of production.

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, State,

and for the U.S. total.

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. Mathematically, this may be stated

as the following sum:

$ $ Vs = Vsc + Vsr

where

V$

s = estimated total volume in the

State/subdivision

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 111
Vsc = total volume in the State/subdivision

reported by Certainty operators

V$

sr

= estimated total volume in the

State/subdivision of Noncertainty

operators.

The total volume of Certainty operators in the

State/subdivision is simply the sum of individual

operator's volumes:

V V sc

m

n

scm

sc

=

=

∑

1

where

nsc = number of Certainty operators reporting

production in the State/subdivision 

Vscm = volume reported by the m-th certainty

stratum operator in the State/subdivision.

The estimated total volume of Noncertainty operators

in the State/subdivision is the weighted sum of the

reports of the noncertainty sample operators: 

$V W V s r

m

n

srm srm

sr

=

=

∑

1

where

nsr = number of Noncertainty operators

reporting production in the

State/subdivision

Vsrm = volume reported by the m-th

Noncertainty sample operator in the

State/subdivision

Wsrm = weight for the report by the m-th

Noncertainty sample operator reporting

production in the State/subdivision.

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 for a State / subdivision 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 for Operator Nonresponse

The nonresponse rate for Certainty operators for the

2001 survey was 2 percent and for the Noncertainty

operators 5 percent. An imputation was made for the

production and reserves for these 42 nonresponding

operators.

Imputation and Estimation for

Reserves Data

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). Finally,

an imputation was required for the natural gas data of

the small operators to estimate their volumes of

associated-dissolved and nonassociated natural gas.

The final manipulation of the data accounts for the

differences caused by different sample frames from

year to year. Each of these imputations generated only a 

small percentage of the total estimates. The methods

used are discussed in the following sections.

The data reported by operator category by Form

EIA-23 respondents for the report year 2001 are

summarized in Tables F2, F3, F4, and F5. The reported

data in Table F2 shows that those responding operators 

accounted for 97.5 percent of the published production

for wet natural gas and 96.0 percent of the reserves

shown in Table 9. Data shown in Table F3 indicate that

those responding operators accounted for 97.7 percent

of the nonassociated natural gas production and 96.0

percent of the reserves published in Table 10. The

reported data shown in Table F4 indicate that those

responding operators accounted for 95.4 percent of

published crude oil production and 95.8 percent of the

reserves shown in Table 6. Additionally, Table F5

indicates that those responding operators accounted

for 99.1 percent of the published production and 96.9

percent of the published proved reserves for lease

condensate shown in Table 15.

Energy Information Administration

112 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration 113

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table F2. Summary of Total Natural Gas, Wet After Lease Separation, Used in Estimation Process,

Form EIA-23 (Million Cubic Feet at 14.73 psia and 60 Degrees Fahrenheit)

Operator Category

Noncertainty Certainty

Level of Reporting I II III III Total

Field Level Reported and Imputed Data

Proved Reserves as of 12/31/00............. 163,533,701 14,123,379 - 55,553 177,712,633

(+) Revision Increases .................... 17,087,596 1,369,692 - - 18,457,288

(–) Revision Decreases ................... 18,559,737 1,935,360 - - 20,495,097

(–) Sales .............................. 9,436,158 1,321,055 - - 10,757,213

(+)Acquisitions ......................... 13,240,881 819,413 - 30,615 14,090,909

(+)Extensions .......................... 14,456,240 2,577,036 - - 17,033,276

(+) New Field Discoveries ................. 3,437,563 239,626 - - 3,677,189

(+) New Reservoirs in Old Fields ............ 2,162,227 631,797 - - 2,794,024

(–) Production with Reserves in 2001 ........ 17,546,614 1,674,533 - 13,554 19,234,701

Proved Reserves Reported as of 12/31/01..... 168,386,067 14,123,379 - 164,833 182,674,279

Production Without Proved Reserves......... 20,192 543,159 - - 563,351

Reserves Imputed for Production

Without Proved Reserves ................ 141,691 3,430,877 - - 3,572,568

Subtotal Production ..................... 17,566,806 2,217,692 - 13,554 19,798,052

Subtotal Proved Reserves 2001 ........... 168,527,758 17,554,256 - 164,833 186,246,847

State Level Reported and Imputed Data

Production with Reported Proved Reserves.... - 6,093 74,952 74,881 155,926

Production without Reported Proved Reserves . 41 9,311 92,938 59,637 161,927

Production Estimated from Auxillary data...... - - 4,728 - 4,728

Subtotal Production. . . . . . . . . . . . . . . . . . . . . . . 41 15,404 172,618 134,518 322,581

Weighted Subtotal Production . . . . . . . . . . . . 41 15,404 177,346 134,518 327,309

Proved Reserves Reported................. - 27,806 763,682 632,394 1,423,882

Reserves Imputed for Reported Production

Without Proved Reserves . . . . . . . . . . . . . . . . 231 40,768 618,141 318,543 977,683

Reserves Estimated from Auxillary data....... - - - 71,617 71,617

Subtotal Proved Reserves . . . . . . . . . . . . . . . . . 231 68,574 1,381,823 1,022,554 2,473,182

Weighted Subtotal Proved Reserves . . . . . . . 231 68,574 1,453,440 950,937 2,473,182

Total Production in 2001.................... 17,566,847 2,233,096 177,346 148,072 20,642,000

Total Proved Reserves as of 12/31/01 ......... 168,527,989 17,622,830 1,453,440 1,115,770 191,743,000

– = 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,” 2001.
114 Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table F3. Summary of Nonassociated Natural Gas, Wet After Lease Separation, Used in

Estimation Process, Form EIA-23 (Million Cubic Feet at 14.73 psia and 60 Degrees Fahrenheit)

Operator Category

Noncertainty Certainty

Level of Reporting I II III III Total

Field Level Detail Report

Proved Reserves as of 12/31/00............. 136,979,364 12,405,232 - 53,492 149,438,088

(+) Revision Increases .................... 14,154,267 1,171,328 - - 15,325,595

(–) Revision Decreases ................... 15,844,085 1,636,258 - - 17,480,343

(–) Sales .............................. 8,841,726 1,084,332 - - 9,926,058

(+)Acquisitions ......................... 12,564,006 715,503 - 30,615 13,310,124

(+)Extensions .......................... 13,458,797 2,406,818 - - 15,865,615

(+) New Field Discoveries ................. 2,161,311 228,662 - - 2,389,973

(+) New Reservoirs in Old Fields ............ 1,735,830 593,702 - - 2,329,532

(–) Production with Reserves in 2001 ........ 14,803,691 1,483,558 - 13,368 16,300,617

Proved Reserves Reported as of 12/31/01..... 141,574,359 12,405,232 - 162,958 154,142,549

Production Without Proved Reserves......... 1,339 472,313 - - 473,652

Reserves Imputed for Production

Without Proved Reserves ................ 9,674 2,998,338 - - 3,008,012

Subtotal Production ..................... 14,805,030 1,955,871 - 13,368 16,774,269

Subtotal Proved Reserves 2001 ........... 141,584,033 15,403,570 - 162,958 157,150,561

State Level Reported and Imputed Data

Production with Reported Proved Reserves.... - 5,161 64,280 65,054 134,495

Production without Reported Proved Reserves . 40 8,118 77,157 52,184 137,499

Production Estimated from Auxillary data...... - - 3,791 - 3,791

Subtotal Production. . . . . . . . . . . . . . . . . . . . . . . 40 13,279 145,228 117,238 275,785

Weighted Subtotal Production . . . . . . . . . . . . 40 13,279 149,019 117,238 279,576

Proved Reserves Reported................. - 22,775 672,559 556,775 1,252,109

Reserves Imputed for Reported Production

Without Proved Reserves . . . . . . . . . . . . . . . . 225 35,167 496,371 274,462 806,225

Reserves Estimated from Auxillary data....... - - - 70,761 70,761

Subtotal Proved Reserves . . . . . . . . . . . . . . . . . 225 57,942 1,168,930 901,998 2,129,095

Weighted Subtotal Proved Reserves . . . . . . . 225 57,942 1,239,691 831,237 2,129,095

Total Production in 2001.................... 14,805,070 1,969,150 546,174 130,606 17,451,000

Total Proved Reserves as of 12/31/01 ......... 141,584,258 15,461,512 1,239,691 994,195 161,921,000

– = 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,” 2001.
Energy Information Administration 115

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table F4. Summary of Crude Oil Used in Estimation Process, Form EIA-23

(Thousand Barrels of 42 U.S. Gallons)

Operator Category

Noncertainty Certainty

Level of Reporting I II III III Total

Field Level Detail Report

Proved Reserves as of 12/31/00............. 19,475,088 955,696 - 316 20,431,100

(+) Revision Increases .................... 1,409,850 96,954 - - 1,506,804

(–) Revision Decreases ................... 1,488,743 104,203 - - 1,592,946

(–) Sales .............................. 293,309 70,370 - 318 363,997

(+)Acquisitions ......................... 330,065 56,993 - 327 387,385

(+)Extensions .......................... 742,781 61,854 - - 804,635

(+) New Field Discoveries ................. 1,403,732 4,317 - - 1,408,049

(+) New Reservoirs in Old Fields ............ 268,259 16,106 - - 284,365

(–) Production with Reserves in 2001 ........ 1,606,681 99,160 - 35 1,705,876

Proved Reserves Reported as of 12/31/01..... 20,241,101 955,696 - 290 21,197,087

Production Without Proved Reserves......... 2,010 31,511 - - 33,521

Reserves Imputed for Production

Without Proved Reserves ................ 15,610 203,086 - - 218,696

Subtotal Production ..................... 1,608,691 130,671 - 35 1,739,397

Subtotal Proved Reserves 2001 ........... 20,256,711 1,158,782 - 290 21,415,783

State Level Reported and Imputed Data

Production with Reported Proved Reserves.... - 1,188 15,268 15,485 31,941

Production without Reported Proved Reserves . - 1,144 35,897 17,584 54,625

Production Estimated from Auxillary data...... - - 1,105 - 1,105

Subtotal Production....................... 0 2,332 52,270 33,069 87,671

Weighted Subtotal Production ............ 0 2,332 53,375 33,069 88,776

Proved Reserves Reported................. - 7,540 171,370 129,198 308,108

Reserves Imputed for Reported Production

Without Proved Reserves ................ - 6,267 173,740 98,575 278,582

Reserves Estimated from Auxillary data....... - - - 60,695 60,695

Subtotal Proved Reserves ................. - 13,807 345,110 288,468 647,385

Weighted Subtotal Proved Reserves ....... 0 13,807 405,805 227,773 647,385

Total Production in 2001.................... 1,608,691 133,003 140,202 33,104 1,915,000

Total Proved Reserves as of 12/31/01 ......... 20,256,711 1,172,589 405,805 228,063 22,446,000

– = 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,” 2001.
116 Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Table F5. Summary of Lease Condensate Used in Estimation Process, Form EIA-23

(Thousand Barrels of 42 U.S. Gallons)

Operator Category

Noncertainty Certainty

Level of Reporting I II III III Total

Field Level Detail Report

Proved Reserves as of 12/31/00............. 1,308,649 119,271 - 99 1,428,019

(+) Revision Increases .................... 169,732 16,747 - - 186,479

(–) Revision Decreases ................... 334,968 42,243 - - 377,211

(–) Sales .............................. 65,180 9,914 - - 75,094

(+)Acquisitions ......................... 104,744 8,738 - 874 114,356

(+)Extensions .......................... 110,739 24,658 - - 135,397

(+) New Field Discoveries ................. 68,495 4,782 - - 73,277

(+) New Reservoirs in Old Fields ............ 55,798 9,296 - - 65,094

(–) Production with Reserves in 2001 ........ 190,036 16,695 - 76 206,807

Proved Reserves Reported as of 12/31/01..... 1,227,998 119,271 - 897 1,348,166

Production Without Proved Reserves. . . . . . . . . 99 3,911 - - 4,010

Reserves Imputed for Production

Without Proved Reserves . . . . . . . . . . . . . . . . 771 19,289 - - 20,060

Subtotal Production ..................... 190,135 20,606 - 76 210,817

Subtotal Proved Reserves 2001 ........... 1,228,769 138,560 - 897 1,368,226

State Level Reported and Imputed Data

Production with Reported Proved Reserves. . . . - 29 448 700 1,177

Production without Reported Proved Reserves . 1 40 523 327 891

Production Estimated from Auxillary data. . . . . . - - 121 - 121

Subtotal Production. . . . . . . . . . . . . . . . . . . . . . . 1 69 1,092 1,027 2,189

Weighted Subtotal Production . . . . . . . . . . . . 1 69 1,213 1,027 2,310

Proved Reserves Reported. . . . . . . . . . . . . . . . . - 104 2,795 4,564 7,463

Reserves Imputed for Reported Production

Without Proved Reserves . . . . . . . . . . . . . . . . 4 136 3,363 1,468 4,971

Reserves Estimated from Auxillary data. . . . . . . - - - 174 174

Subtotal Proved Reserves . . . . . . . . . . . . . . . . . 4 240 6,158 6,206 12,608

Weighted Subtotal Proved Reserves . . . . . . . 4 240 6,332 6,032 12,608

Total Production in 2001.................... 190,136 20,675 3,086 1,103 215,000

Total Proved Reserves as of 12/31/01 ......... 1,228,773 138,800 6,332 6,929 1,398,000

– = 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,” 2001.
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. The production

reported by Noncertainty sample operators and the

corresponding imputed reserves were weighted to

estimate the full noncertainty stratum when calculating 

reserves and production as previously described in the

section “Total U.S. Reserves Estimates” in this

appendix.

R/P Function

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 2001 oil, gas,

and condensate production (in units of

thousand barrels per year).

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.

In 2001, the R/P function was used to estimate the

proved reserves of all noncertainty operators in these

States -- Texas, California, Colorado, Louisiana,

Montana, New Mexico, South Dakota, Utah, and

Wyoming, rather than rely on a weighted sample.

These States were chosen for this new procedure

because of the many years of historical production and

reserves data within EIA and availability of reliable

State government and commercial production data for

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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 117

Ta ble F6. Sta tis ti cal Pa rame ters of Re serves Es ti ma tion Equa tion by Re gion for 2001

Num ber of Non zero Equa tion Co ef fi cients

 Re gion R/P Pairs Oil Gas LC

Num ber Re gion Oil Gas LC Al pha Beta Al pha Beta Al pha Beta

1 Alaska .................. 7 7 0 -0.1331 0.3956 -0.1170 0.3465 -0.0816 0.3921

2 Pa cific Coast States ........... 45 58 4 -0.1331 0.3426 -0.1170 0.4123 -0.0816 0.6527

2A Fed eral Off shore Pa cific ......... 5 5 0 -0.1331 0.2644 -0.1170 0.2979 -0.0816 0.3921

3 West ern Rocky Moun tains ........ 83 131 53 -0.1331 0.3169 -0.1170 0.2873 -0.0816 0.2201

4 North ern Rocky Moun tains ........ 174 150 44 -0.1331 0.3169 -0.1170 0.2873 -0.0816 0.2201

5 West Texas and East New Mex ico .... 529 529 161 -0.1331 0.3127 -0.1170 0.3456 -0.0816 0.3853

6 West ern Gulf Ba sin............ 542 859 555 -0.1331 0.4273 -0.1170 0.4223 -0.0816 0.3541

6A Gulf of Mex ico .............. 70 137 112 -0.1331 0.6948 -0.1170 0.6550 -0.0816 0.5103

7 Mid-Con ti nent .............. 347 438 173 -0.1331 0.3333 -0.1170 0.3201 -0.0816 0.2234

8 + 9 Mich i gan Ba sin and East ern In te rior .... 83 59 11 -0.1331 0.2933 -0.1170 0.1863 -0.0816 0.2595

10 + 11 Ap pa la chians .............. 28 70 4 -0.1331 0.2933 -0.1170 0.1863 -0.0816 0.2595

United States .............. 1,913 2,443 1,117 -0.1331 0.4062 -0.1170 0.3944 -0.0816 0.3921

Source: Based on data filed on Form EIA-23,"An nual Sur vey of Do mes tic Oil and Gas Re serves, 2001".
Imputation of Annual 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: 

n 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

n 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.

Both methods preserved an exact annual reserves

balance of the following form:

The algebraic allocation method used for all but nine

states in the 2001 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

Energy Information Administration

118 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Fig ure F1. Form EIA-23 Re gional Bound aries

Pub lished Proved Re serves at End of Pre vious Re port Year

+ Ad just ments

+ Re vi sion In creases

– Re vi sion De creases

– Sales

+ Acquisitions

+ Ex ten sions

+ New Field Dis cov er ies

+ New Res er voir Dis cov er ies in Old Fields

– Re port Year Pro duc tion

= Pub lished Proved Re serves at End of Re port Year
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 Type Volumes

Operators in the State/subdivision 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 Category I and Category II 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:

n The frame coverage may or may not have

improved between survey years, such that more 

or fewer Certainty operators were included in

2001 than in 2000.

n One or more operators may have reported data

incorrectly on Schedule A in 2000 or 2001, but

not both, and the error was not detected by edit

processing.

n Operation of properties was transferred during

2001 from operators not in the frame or

Noncertainty operators not selected for the

sample to Certainty operators or Noncertainty

operators selected for the sample.

n Respondent changed classification of natural

gas from NA to AD or vice versa.

n The trend in reserve changes imputed for the

small operators, that was based on the trend

reported by the large operators, did not reflect

the actual trend for the small operators.

n Noncertainty operators, who have grown

substantially in size since they were added to

the frame, occasionally cause a larger standard

error than expected.

n 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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 119

Proved Re serves at End of Pre vious Year

+ Re vi sion In creases

– Re vi sion De creases

– Sales

+ Ac qui si tions

+ Ex ten sions

+ New Field Dis cov er ies

+ New Res er voir Dis cov er ies in Old Fields

– Re port Year Pro duc tion 

= Proved Re serves at End of Re port Year
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 V$

s

 and its sampling error by S.E. ( 

V$

s

), the confidence interval can be expressed as:

$

. .(

$ V k S E V )

s ± s

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:

$

. .(

$ V S E V )

s s

± 2

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. (V$

s

) 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 183,460 ± 1,037 billion

cubic feet. The sampling error of V$

s

 is equal to the

sampling error of the noncertainty estimate V$

sr

, 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.

The noncertainty estimate for a given State/subdivision 

had two separately weighted components based on

reports of:

n Type 1 Operators shown in the frame as having

crude oil or natural gas production in the

State/subdivision.

n Type 2 Operators shown in the frame as having

no crude oil or natural gas production in the

State/subdivision.

Correspondingly, the sampling variance had two

components associated with the estimated production

from each component:

Var Vsr Var Vsr Var Vsr(

$

) (

$

) (

$ = + )

1 2

The Var(Vsr) was estimated as the sum of the estimated

variances of the two component estimates. The

variance for any component, say component j, was

estimated from the formula:

Var V n

W

W

S srj srj

srj

srj

srj

(

$

) = ( )

−1 2

In gen eral, V srj

^

 denotes the production estimate from

component j for each of the two types of operator, and

Var Vsrj

^











 denotes its variance where:

nsrj

 = Num ber of op er a tors in sam ple in com po nent j

wsrj

 = Weight for op er a tor re ports in com po nent j

S srj

2

= variance be tween op er a tor re ports in com po -

nent j.

If the subscripts sr are dropped, S srj

2

 can be expressed

as:

S

V V n

n

j

ji

i

n

ji

i

n

j

j

j j

2

2

2

1

=

−

















−

∑ ∑

' '

/

Where

Vji

'

= Weighted pro duc tion or re serves vol ume for

the i-th sam ple op er a tor in the com po nent j.

The variance of the estimated total volume for a State

having subdivisions is the sum of corresponding Type

1 and Type 2 components where the classification of

operators by type is with regard to the State as a whole;

e.g. Type 2 operators at the State level are those that

were not shown in the sample frame as having

production anywhere in the State.

Since there are no operators in the frame who would be

classified as Type 2 at the U.S. level, there would be no

Type 2 components at the U.S. Level. Therefore, at the

U.S. Level, there was only one sample variance

component calculated for Type 1 operators.

Nonsampling Errors

Several sources of possible error, apart from sampling

error, are associated with the Form EIA-23 survey.

These include bias due to nonresponse of operators in

the sample, proved reserve estimation errors, and

reporting errors on the part of the respondents to the

survey. On the part of EIA, possible errors include

inadequate frame coverage, data processing error, and

errors associated with statistical estimates. Each of

these sources is discussed below. An estimate of the

Energy Information Administration

120 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration 121

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

United States . . . . . . . . . . . . . . . . . . 33 5

Alabama...................... 2 0

Alaskaa ...................... 0 0

Arkansas . . . . . . . . . . . . . . . . . . . . . 12 2

Californiab .................... 0 0

Coastal Region Onshoreb...... 0 0

Los Angeles Basin Onshoreb ... 0 0

San Joaquin Basin Onshoreb ... 0 0

State Offshorea .............. 0 0

Coloradob .................... 0 0

Floridaa ...................... 0 0

Kansas. . . . . . . . . . . . . . . . . . . . . . . 15 1

Kentucky . . . . . . . . . . . . . . . . . . . . . 10 1

Louisianab .................... 0 0

Northb ..................... 0 0

South Onshoreb ............. 0 0

State Offshorea .............. 0 0

Michigan ..................... 0 0

Mississippi .................... 4 1

Montanab ..................... 0 0

New Mexicob .................. 0 0

Eastb ...................... 0 0

Westb ..................... 0 0

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

North Dakota . . . . . . . . . . . . . . . . . . 24 5

Ohio ......................... 7 0

Oklahoma . . . . . . . . . . . . . . . . . . . . 12 1

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

Texasb ....................... 0 0

RRC District 1b .............. 0 0

RRC District 2 Onshoreb....... 0 0

RRC District 3 Onshoreb....... 0 0

RRC District 4 Onshoreb....... 0 0

RRC District 5b .............. 0 0

RRC District 6b .............. 0 0

RRC District 7Bb ............. 0 0

RRC District 7Cb............. 0 0

RRC District 8b .............. 0 0

RRC District 8Ab ............. 0 0

RRC District 9b .............. 0 0

RRC District 10b ............. 0 0

State Offshorea .............. 0 0

Utahb ........................ 7 1

Virginiaa ...................... 0 0

West Virginia .................. 1 0

Wyomingb .................... 0 0

Federal Offshorea .............. 0 0

Pacific (California)a ........... 0 0

Gulf of Mexico (Louisiana)a .... 0 0

Gulf of Mexico (Texas)a ....... 0 0

Miscellaneousd . . . . . . . . . . . . . . . . 11 1

aSampling rate was 100 percent in Alaska, Florida Onshore, Virginia, and Offshore areas. bSampling was not used. Estimates for each operator were made using an imputation function.

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

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,” 2001.

Table F7. Factors for Confidence Intervals (2S.E.) for Crude Oil Proved Reserves and Production, 2001

(Million Barrels of 42 U.S. Gallons)

2001 2001 2001 2001

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, 2001 (Billion Cubic Feet at 14.73 psia and 60 Degrees Fahrenheit)

2001 2001 2001 2001

State and Subdivision Reserves Production State and Subdivision Reserves Production

United States . . . . . . . . . . . . . . . . . . 213 22

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

Alaskaa ...................... 0 0

Arkansas . . . . . . . . . . . . . . . . . . . . . 35 6

Californiab .................... 0 0

Coastal Region Onshoreb...... 0 0

Los Angeles Basin Onshoreb ... 0 0

San Joaquin Basin Onshoreb ... 0 0

State Offshoreb .............. 0 0

Coloradob .................... 0 0

Floridaa ...................... 0 0

Kansas. . . . . . . . . . . . . . . . . . . . . . . 58 7

Kentucky . . . . . . . . . . . . . . . . . . . . . 23 3

Louisianab .................... 0 0

Northb ..................... 0 0

South Onshoreb ............. 0 0

State Offshorea .............. 0 0

Michigan . . . . . . . . . . . . . . . . . . . . . 108 11

Mississippi . . . . . . . . . . . . . . . . . . . . 52 6

Montanab ..................... 0 0

New Mexicob .................. 0 0

Eastb ...................... 0 0

Westb ..................... 0 0

New York . . . . . . . . . . . . . . . . . . . . . 102 4

North Dakota . . . . . . . . . . . . . . . . . . 27 7

Ohio . . . . . . . . . . . . . . . . . . . . . . . . . 116 13

Oklahoma . . . . . . . . . . . . . . . . . . . . 70 9

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

Texasb ....................... 0 0

RRC District 1b .............. 0 0

RRC District 2 Onshoreb....... 0 0

RRC District 3 Onshoreb....... 0 0

RRC District 4 Onshoreb....... 0 0

RRC District 5b .............. 0 0

RRC District 6b .............. 0 0

RRC District 7Bb ............. 0 0

RRC District 7Cb............. 0 0

RRC District 8b .............. 0 0

RRC District 8Ab ............. 0 0

RRC District 9b .............. 0 0

RRC District 10b ............. 0 0

State Offshorea .............. 0 0

Utahb ........................ 0 0

Virginiaa ...................... 0 0

West Virginia . . . . . . . . . . . . . . . . . . 55 3

Wyomingb .................... 0 0

Federal Offshorea c ............. 0 0

Pacific (California)a ........... 0 0

Gulf of Mexico (Louisiana)a c ... 0 0

Gulf of Mexico (Texas)a ....... 0 0

Miscellaneousd ................ 1 0

aSampling rate was 100 percent in Alaska, Florida Onshore, Virginia, and Offshore areas. bSampling was not used. Estimates for each operator were made using an imputation function.

cIncludes Federal offshore Alabama. dIncludes 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,” 2001
bias from nonresponse is presented in the section on

adjustment for operator nonresponse.

Assessing the Accuracy of the

Reserve Data

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 statistically selected sample of

operator properties. The results of these reviews are

used to evaluate the accuracy of reported reserve

estimates. Operators are apprized 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.

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.

Reporting Errors 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.

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, 4 

percent of the crude oil proved reserve estimates, 4

percent of the wet natural gas proved reserve estimates, 

and 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.

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 1999 survey is particularly likely to be deficient in

States where a large portion of total reserves and

production is accounted for by small operators. These

States are not likely to allocate sufficient resources to

keep track of all operators on a current basis. Some

under coverage of this type seems to exist, particularly,

Energy Information Administration

122 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
with reference to natural gas operators. EIA is

continuing to work to remedy the under coverage

problem in those States where it occurred.

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.

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 cubic feet per barrel

(where NGL consists primarily of ethane) and 900 cubic 

feet per barrel (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 to base its computation on. 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 2001 Form

EIA-64A survey, the national weighted average gas

equivalents ratio was computed to be 1,397 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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 123
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. The

assumption was made that coalbed methane fields

contained little or 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.

Adjustments of dry natural gas were set equal to the

difference between the end of previous year reserves

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.

Each estimate of end of year reserves and report year

production has associated with it an estimated

sampling error. The standard errors for dry natural gas

were computed by multiplying the wet natural gas

standard errors by these same percentage reduction

factors. Table F7 provides estimates for 2 times the 

S E Vs. .(

$ ) for dry natural gas.

Energy Information Administration

124 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Appendix G

Estimation of

Reserves and Resources
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 structure presented in Figure G1 outlines the total

resource base and its components. 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 into cumulative (i.e., all

past) production, and reserves. Reserves are

additionally subdivided into proved reserves and

“other reserves”.

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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 127

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

Figure G1. Components of the Oil and Gas

Resource Base

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)
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 1,431 trillion cubic feet (Table G1). Adding

the 2001 U.S. proved reserves of 183 trillion cubic feet

yields a technically recoverable resource target of 1,614

trillion cubic feet. This is about 82 times the 2001 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 2000 the PGC mean estimate

of potential gas resources was 1,091 trillion cubic feet,

about 340 trillion cubic feet less than the estimates in

Table G1. Another recent estimate was made by the

National Petroleum Council (NPC), an industry–based

group that serves in an advisory capacity to the U.S.

Secretary of Energy. The NPC's estimate, based on data

available at year–end 1999, was 1,555 trillion cubic feet,

124 trillion cubic feet more than the estimates

summarized 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 2001 oil production (Table

G1) was about 91 to 1, higher than the comparable gas

ratio.

Federal Land Resources

Estimates of technically recoverable resources that

underlie Federal jurisdiction lands are listed in Table

G1. These estimates are based on National assessments

performed by the USGS and the MMS. It is estimated

that 60 percent of the technically recoverable resources

of crude oil, 52.4 percent of the dry gas resources, and

34.7 percent of the natural gas liquids resources

underlie Federal lands.

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

recoverable in the future from known deposits through

the eventual application of present or anticipated

technology.

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,

Energy Information Administration

128 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 129

Table G1. Mean Estimates of Technically Recoverable Oil and Gas Resources by Deposit Type and

Location

Natural Gas

Crude Oila Natural Gas (Dry) Liquids

Area Jurisdiction (billion barrels) (trillion cubic feet) (billion barrels)

Undiscovered Conventionally Reservoired Fields

Alaska Onshore + State Offshore Federal 3.75 33.97 0.54

Alaska Onshore + State Offshore Other 4.68 95.37 0.61

Alaska Federal Offshore Federal 24.90 122.60 0.00

Lower 48 States Onshore + State Offshore Federal 3.79 23.97 1.26

Lower 48 States Onshore + State Offshore Other 17.83 166.41 5.64

Lower 48 States Federal Offshore Federal 50.10 239.60 0.00

Alaska Subtotal 33.33 251.94 1.15

Alaska Percentage Federal 86.0% 62.1% 47.0%

Lower 48 States Subtotal 71.72 429.98 6.90

Lower 48 States Percentage Federal 75.1% 61.3% 18.3%

Technically Recoverable Resources in U.S.

Undiscovered Conventionally Reservoired Fields 105.05 681.92 8.05

Percentage Federal 78.6% 61.6% 22.4%

Ultimate Recovery Appreciation

U.S. Onshore + State Offshore Federal 14.33 118.70 4.94

U.S. Onshore + State Offshore Other 45.67 203.30 8.46

U.S. Federal Offshore Federal 7.70 68.00 0.00

Technically Recoverable Resources in U.S.

from Ultimate Recovery Appreciation in Discovered

Conventionally Reservoired Fields 67.70 390.00 13.40

U.S. Percentage Federal 32.5% 47.9% 36.9%

Continuous Type Deposits

Non-coal bed Federal 0.32 127.08 1.45

Non-coal bed Other 1.75 181.72 0.67

Coal bed Federal 0.00 16.08 0.00

Coal bed Other 0.00 33.83 0.00

Non-coal bed Subtotal 2.07 308.80 2.12

Non-coal bed Percentage Federal 15.5% 41.2% 68.4%

Coal bed Subtotal 0.00 49.91 0.00

Coal bed Percentage Federal 0.0% 32.2% 0.0%

Technically Recoverable Resources in U.S.

from Continuous Type Deposits 2.07 358.71 2.12

Continuous Type Percentage Federal 15.5% 39.9% 68.4%

U.S. Totals All Sources

U.S. Onshore + State Offshore Federal 22.19 319.80 8.19

U.S. Onshore + State Offshore Other 69.93 680.63 15.38

Federal Offshore Federal 82.70 430.20 0.00

Federal Subtotal 104.89 750.00 8.19

U.S. Technically Recoverable Resources 174.82 1,430.63 23.57

Percentage Federal 60.0% 52.4% 34.7%

Notes:

Proved Reserves are not included in these estimates.

Federal Onshore excludes Indian and Native lands even when Federally managed in trust.

Zero (0) indicates either that none exists in this area or that no estimate of this resource has been made for this area.
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.{43} They are similarly defined by the MMS,

although its system also subdivides them by degree of

development and producing status.{44} 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.{43}

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,

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 130

Table G1. Mean Estimates of Technically Recoverable Oil and Gas Resources by Deposit Type and Location (continued)

Notes (continued): Federal Offshore indicates MMS estimates for Federal Offshore jurisdictions (Outer Continental Shelf and deeper water

areas seaward of State Offshore).

Probable and Possible reserves are considered by USGS definition to be part of USGS Reserve Growth, but are separately considered by

the MMS as its Unproved Reserves term. The USGS did not set a time limit for the duration of Reserve Growth; the MMS set the year 2020 as

the time limit in its estimates of Reserve Growth in existing fields of the Gulf of Mexico.

Excluded from the estimates are undiscovered oil resources in tar deposits and oil shales, and undiscovered gas resources in

geopressured brines and gas hydrates.

Data Sources: National Oil and Gas Resource Assessment Team, 1996 National Assessment of United States Oil and Gas Resources,

Circular 1118, United States Geological Survey, Washington DC, 1995.

D.L Gautier, G.L. Dolton, and E.D. Atanasi, 1995 National Oil and Gas Assessment and Onshore Federal Lands, Open File Report

95-75-N, United States Geological Survey, Washington DC, January 1998.

Resource Evaluation Program, Outer Continental Shelf Petroleum Assessment 2000, Brochure 7, Minerals Management Service,

Washington, DC, January 2001 at <http://www.mms.gov/revaldiv/RedNatAssessment.htm>.

Resource Evaluation Program, An Assessment of the Undiscovered Hydrocarbon Potential of the Nation’s Outer Continental Shelf, OCS

Report MMS 96-0034, Minerals Management Service, Washington, DC, 1996.

Minerals Management Service, Mineral Revenues 1996, U.S. Department of the Interior, Washington, DC, 1997, Table 12 on p. 33 and

Table 23 on p. 70.

Energy Information Administration, U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 1996 Annual Report, Washington, DC,

December 1997, Table 15 on p. 39.

Energy Information Administration, Petroleum Supply Annual 1996, Washington, DC, June 1997, Volume 1, Table 14 on p. 96.

Energy Information Administration, Natural Gas Annual 1996, Washington, DC, September 1997, Table 3 on p. 12.
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

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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 131

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.
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.

 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

Energy Information Administration

132 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
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

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.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 133
Appendix H

Maps of Selected State Subdivisions
Appendix H

Figure H1. Subdivisions of Alaska

Source: After U.S. Geological Survey.

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 137

Maps of Selected State Subdivisions
Figure H2. Subdivisions of California

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

Energy Information Administration

138 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Figure H3. Subdivisions of Louisiana

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

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 139
Figure H4. Subdivisions of New Mexico

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

Energy Information Administration

140 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Figure H5. Subdivisions of Texas

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

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 141
Figure H6. Western Planning Area, Gulf of Mexico Outer Continental Shelf Region

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

Energy Information Administration

142 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Figure H7. Central Planning Area, Gulf of Mexico Outer Continental Shelf Region

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

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 143
Figure H8. Eastern Planning Area, Gulf of Mexico Outer Continental Shelf Region

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

Energy Information Administration

144 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
Appendix I

Annual Survey Forms for

Domestic Oil and Gas Reserves
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 147

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

U.S. DEPARTMENT OF ENERGY

ENERGY INFORMATION ADMINISTRATION

Washington, DC 20585

Form Approved

OMB No. 1905-0057

Expiration Date: 12/31/03

(Revised 2000)

FORM EIA-23

ANNUAL SURVEY OF DOMESTIC OIL AND GAS RESERVES

REPORT YEAR 2 0 0 1

This report is mandatory under the Federal Energy Administration Act of 1974 (Public Law 93-275). For the provisions

concerning the confidentiality of information and sanction statements, see Section VII and VIII of the instructions.

Resubmission?

PART I. IDENTIFICATION

Affix mailing label or enter mailing address

0 0 0 0 Complete and return by April 15, 2002 to:

Energy Information Administration

U.S. Department of Energy

P O Box 20907

Silver Spring, MD 20907

Attn: Form EIA-23

OR

Fax to: (202) 586-1076/ATTN: FORM EIA-23

Questions? Call 1-800-879-1470

EIA Identification Number:

Company Name:

Street or P.O Box:

City, State, Zip Code:

EIN:

1. Contact Information (person most knowledgeable about the reported

data)

Contact Person (Please Print):

Phone Number: () - Ext.

Fax Number: () -

E-mail Address:

2. Was your company an oil and gas field operator at any time

during calendar year 2001? (See definition of an operator,

page 1)

(1)  No... Complete only items 3 through15 below and

return this page.

(2)  Yes... Complete rest of form.

3. Company Status, Name, and/or Address Change or Correction. (Check appropriate box.)

 Name and address on mailing label are correct.

 Change company name, contact person, and/or mailing address,as indicated below.

 Company was sold to or merged with company entered below.

 Company went out of business. Operations transferred to company entered below.

4. Change Company Name, Address, Employer Identification Number (EIN), and/or Contact Information to:

Company Name:

Street or P. O. Box:

City, State, Zip Code:

EIN:

Contact Person (Please Print):

Phone Number: ( ) - Ext. Fax number: ( ) - E-Mail Address:

Comments:

PART II. PARENT COMPANY IDENTIFICATION

6. Company Name 7. Parent Company EIN

8. Address

5. Is there a parent company which exercises ultimate

control over your company?

(1)  No... Answer 12 through 15.

(2)  Yes... Answer 6 through 15. 9. City 10. State 11. Zip Code

PART III. ATTESTATION (I hereby swear or affirm that I have reviewed this Form EIA-23 report and am familiar with its contents, and that to

the best of my knowledge, information, and belief, the information provided and appended is true and complete.)

12. Attestor (Please Print) 13. Title

14. Signature 15. Date

Title 18 USC 1001 makes it a criminal offense for any person knowingly and willingly to make to any Agency or Department of the United States any false,

fictitious, or fraudulent statements as to any matter within its jurisdiction.

SAMPLE

Figure I1. Form EIA-23, Cover Page
Energy Information Administration

148 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Figure I2. Form EIA-23, Summary Report – Page 1

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

O

2001

ANNUAL SURVEY OF DOMESTIC OIL AND GAS RESERVES

SUMMARY REPORT

PAGE 1 OF 2

Report All Volumes of Crude Oil and Lease Condensate in Thousands of Barrels [MBbls] at 60°F

Form Approved

OMB No. 1905-0057

Expiration Date: 12/31/03

(Revised 2000)

1.0 OPERATOR AND REPORT IDENTIFICATION DATA Report All Volumes of Natural Gas in Millions of Cubic Feet [MMCF] at 14.73 psia and 60°F

1.1 OPERATOR I.D. CODE 1.2 OPERATOR NAME REPORT DATE 1.3 ORIGINAL 1.4 RESUBMISSION

12 31 01

2.0 PRODUCTION AND RESERVES DATA

CRUDE OIL NATURAL GAS LEASE CONDENSATE

STATE OR RESERVES 2001 PRODUCTION RESERVES 2001 PRODUCTION RESERVES 2001 PRODUCTION

GEOGRAPHIC

SUBDIVISION

Proved

Reserves

Dec. 31, 2001

(MBbls)

(A)

(From properties for

which reserves were

Estimated)

(MBbls)

(B)

(From properties for

which reserves were

Not Estimated)

(MBbls)

(C)

Proved

Reserves

Dec. 31, 2001

(MMCF)

(D)

(From properties for

which reserves were

Estimated)

(MMCF)

(E)

(From properties for

which reserves were

Not Estimated

(MMCF)

(F)

Proved

Reserves

Dec. 31, 2001

(MBbls)

(G)

(From properties for

which reserves were

Estimated)

(MBbls)

(H)

(From properties for

which reserves were

Not Estimated)

(MBbls)

(I)

ALABAMA-ONSHORE AL

ALABAMA-STATE OFFSHORE AL05

ALASKA-NORTH ONSHORE AND OFFSHORE AK50

ALASKA-SOUTH ONSHORE AK10

ALASKA-SOUTH STATE OFFSHORE AK05

ARIZONA AZ

ARKANSAS AR

CALIFORNIA-COASTAL REGION ONSHORE CA50

CALIFORNIA-LOS ANGELES BASIN ONSHORE CA90

CALIFORNIA-SAN JOAQUIN BASIN ONSHORE CA10

CALIFORNIA-STATE OFFSHORE CA05

COLORADO CO

FLORIDA-ONSHORE FL

FLORIDA-STATE OFFSHORE FL05

ILLINOIS IL

INDIANA IN

KANSAS KS

KENTUCKY KY

LOUISIANA-NORTH LA50

LOUISIANA-SOUTH ONSHORE LA10

LOUISIANA-SOUTH STATE ONSHORE LA05

MARYLAND MD

MICHIGAN MI

MISSISSIPPI-ONSHORE MS

MISSISSIPPI-STATE OFFSHORE MS05

MISSOURI MO

MONTANA MT

NEBRASKA NE

NEVADA NV

NEW MEXICO-EAST NM10

NEW MEXICO-WEST NM50

NEW YORK NY

NORTH DAKOTA ND

OHIO OH

SAMPLE
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 149

Figure I3. Form EIA-23, Summary Report – Page 2

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

O

2001

ANNUAL SURVEY OF DOMESTIC OIL AND GAS RESERVES

SUMMARY REPORT

PAGE 2 OF 2 Report All Volumes of Crude Oil and Lease Condensate in Thousands of Barrels [MBbls] at 60°F

Form Approved

OMB No. 1905-0057

Expiration Date: 12/31/03

(Revised 2000)

1.0 OPERATOR AND REPORT IDENTIFICATION DATA Report All Volumes of Natural Gas in Millions of Cubic Feet [MMCF] at 14.73 psia and 60°F

1.1 OPERATOR I.D. CODE 1.2 OPERATOR NAME REPORT DATE 1.3 ORIGINAL 1.4 AMENDED

12 31 01

2.0 PRODUCTION AND RESERVES DATA

CRUDE OIL NATURAL GAS LEASE CONDENSATE

STATE OR RESERVES 2001 PRODUCTION RESERVES 2001 PRODUCTION RESERVES 2001 PRODUCTION

GEOGRAPHIC

SUBDIVISION

Proved

Reserves

Dec. 31, 2001

(MBbls)

(A)

(From properties for

which reserves were

Estimated)

(MBbls)

(B)

(From properties for

which reserves were

Not Estimated)

(MBbls)

(C)

Proved

Reserves

Dec. 31, 2001

(MMCF)

(D)

(From properties for

which reserves were

Estimated)

(MMCF)

(E)

(From properties for

which reserves were

Not Estimated

(MMCF)

(F)

Proved

Reserves

Dec. 31, 2001

(MBbls)

(G)

(From properties for

which reserves were

Estimated)

(MBbls)

(H)

(From properties for

which reserves were

Not Estimated)

(MBbls)

(I)

OKLAHOMA OK

PENNSYLVANIA PA

SOUTH DAKOTA SD

TENNESSEE TN

TEXAS-RRC DISTRICT 1 TX10

TEXAS-RRC DISTRICT 2 ONSHORE TX20

TEXAS-RRC DISTRICT 3 ONSHORE TX30

TEXAS-RRC DISTRICT 4 ONSHORE TX40

TEXAS-RRC DISTRICT 5 TX50

TEXAS-RRC DISTRICT 6 TX60

TEXAS-RRC DISTRICT 7B TX70

TEXAS-RRC DISTRICT 7C TX75

TEXAS-RRC DISTRICT 8 TX80

TEXAS-RRC DISTRICT 8A TX85

TEXAS-RRC DISTRICT 9 TX90

TEXAS-RRC DISTRICT 10 TX95

TEXAS-STATE OFFSHORE TX05

UTAH UT

VIRGINIA VA

WEST VIRGINIA WV

WYOMING WY

FEDERAL OFFSHORE-GULF OF MEXICO (ALABAMA) AL00

FEDERAL OFFSHORE-GULF OF MEXICO (FLORIDA) FL00

FEDERAL OFFSHORE-GULF OF MEXICO (LOUISIANA) LA00

FEDERAL OFFSHORE-GULF OF MEXICO (MISSISSIPPI) MS00

FEDERAL OFFSHORE-GULF OF MEXICO (TEXAS) TX00

FEDERAL OFFSHORE-PACIFIC (ALASKA) AK00

FEDERAL OFFSHORE-PACIFIC (CALIFORNIA) CA00

FEDERAL OFFSHORE-PACIFIC (OREGON) OR00

OTHER STATE (SPECIFY)

TOTAL (SUM EACH COLUMN) US

SAMPLE
Energy Information Administration

150 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Figure I4. Form EIA-23, Detail Report – Schedule A

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

O 

 2001 ANNUAL SURVEY OF DOMESTIC OIL AND GAS RESERVES

SCHEDULE A - OPERATED PROVED RESERVES, PRODUCTION, AND RELATED DATA BY FIELD Report All Liquid Volumes in Thousands of Barrels [MBbls] at 60°F;

Report All Volumes of Natural Gas in Millions of Cubic Feet [MMCF] at 60°F and 14.73 psia

Form Approved

OMB No. 1905-0057

Expiration Date: 12/31/03

(Revised 2000)

1.0 OPERATOR AND REPORT IDENTIFICATION DATA

1.1 OPERATOR I.D. CODE 1.2 OPERATOR NAME REPORT DATE 1.3 ORIGINAL 1.4 AMENDED 1.5 PAGE

12 31 01 ______ OF _____

2.0 FIELD DATA (OPERATED BASIS)

1. STATE

ABBR.

2. SUBDIV.

CODE

3. COUNTY

CODE

4. FIELD

CODE

5. MMS

CODE 6. FIELD NAME 7. PROVED NONPRODUCING RESERVES

8. FOOTNOTE

2.1 CRUDE OIL

(a) (MBbls)

ASSOC-DISSOLVED

(b) GAS (MMCF)

NONASSOCIATED

(c) GAS (MMCF)

LEASE CON-

(d) DENSATE (MBbls)

9. WATER DEPTH 10. FIELD DISCOVERY YEAR 11. INDICATED ADDITIONAL RESERVES OF CRUDE OIL (MBbls)

TYPE OF HYDROCARBON

TOTAL

PROVED RESERVES

DECEMBER 31, 2000

(A)

REVISION

INCREASES

(B)

REVISION

DECREASES

(C)

SALES

(D)

ACQUISITIONS

(E)

EXTENSIONS

(F)

NEW

FIELD

DISCOVERIES

(G)

NEW

RESERVOIRS

IN OLD FIELDS

(H)

CALENDAR

YEAR

PRODUCTION

(I)

TOTAL

PROVED RESERVES

DECEMBER 31, 2001

(J)

12. CRUDE OIL (MBbls)

13. ASSOCIATED-DISSOLVED GAS (MMCF)

14. NONASSOCIATED GAS (MMCF)

15. LEASE CONDENSATE (MBbls)

1. STATE

ABBR.

2. SUBDIV.

CODE

3. COUNTY

CODE

4. FIELD

CODE

5. MMS

CODE 6. FIELD NAME 7. PROVED NONPRODUCING RESERVES

8. FOOTNOTE

2.2 CRUDE OIL

(a) (MBbls)

ASSOC-DISSOLVED

(b) GAS (MMCF)

NONASSOCIATED

(c) GAS (MMCF)

LEASE CON-

(d) DENSATE (MBbls)

9. WATER DEPTH 10. FIELD DISCOVERY YEAR 11. INDICATED ADDITIONAL RESERVES OF CRUDE OIL (MBbls)

TYPE OF HYDROCARBON

TOTAL

PROVED RESERVES

DECEMBER 31, 2000

(A)

REVISION

INCREASES

(B)

REVISION

DECREASES

(C)

SALES

(D)

ACQUISITIONS

(E)

EXTENSIONS

(F)

NEW

FIELD

DISCOVERIES

(G)

NEW

RESERVOIRS

IN OLD FIELDS

(H)

CALENDAR

YEAR

PRODUCTION

(I)

TOTAL

PROVED RESERVES

DECEMBER 31, 2001

(J)

12. CRUDE OIL (MBbls)

13. ASSOCIATED-DISSOLVED GAS (MMCF)

14. NONASSOCIATED GAS (MMCF)

15. LEASE CONDENSATE (MBbls)

1. STATE

ABBR.

2. SUBDIV.

CODE

3. COUNTY

CODE

4. FIELD

CODE

5. MMS

CODE 6. FIELD NAME 7. PROVED NONPRODUCING RESERVES

8. FOOTNOTE

2.3 CRUDE OIL

(a) (MBbls)

ASSOC-DISSOLVED

(b) GAS (MMCF)

NONASSOCIATED

(c) GAS (MMCF)

LEASE CON-

(d) DENSATE (MBbls)

9. WATER DEPTH 10. FIELD DISCOVERY YEAR 11. INDICATED ADDITIONAL RESERVES OF CRUDE OIL (MBbls)

TYPE OF HYDROCARBON

TOTAL

PROVED RESERVES

DECEMBER 31, 2000

(A)

REVISION

INCREASES

(B)

REVISION

DECREASES

(C)

SALES

(D)

ACQUISITIONS

(E)

EXTENSIONS

(F)

NEW

FIELD

DISCOVERIES

(G)

NEW

RESERVOIRS

IN OLD FIELDS

(H)

CALENDAR

YEAR

PRODUCTION

(I)

TOTAL

PROVED RESERVES

DECEMBER 31, 2001

(J)

12. CRUDE OIL (MBbls)

13. ASSOCIATED-DISSOLVED GAS (MMCF)

14. NONASSOCIATED GAS (MMCF)

15. LEASE CONDENSATE (MBbls)

SAMPLE
Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 151

Figure I5. Form EIA-23, Detail Report – Schedule B

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

O

2001

ANNUAL SURVEY OF DOMESTIC OIL AND GAS RESERVES

SCHEDULE B – FOOTNOTES

Form Approved

OMB No. 1905-0057

Expiration Date:12/31/03

(Revised 2000)

1.1 OPERATOR I.D. CODE REPORT DATE 1.3 ORIGINAL 1.4 AMENDED 1.5 PAGE

12 31 01

Page

Number

(a)

Field Designation

(i.e., 2.1, 2.2 or 2.3)

(b)

Item

Number

(c)

Column

Designation

(d) Footnote

(e)

FOR

DOE USE ONLY

SAMPLE
Energy Information Administration

152 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report

Figure I6. Form EIA-64A

U.S. DEPARTMENT OF ENERGY

ENERGY INFORMATION ADMINISTRATION

Washington, DC 20585

Form Approved

OMB No. 1905-0057

Expiration Date: 12/31/03

ANNUAL REPORT OF THE ORIGIN OF NATURAL GAS LIQUIDS PRODUCTION

FORM EIA-64A

CALENDAR YEAR 2001

This report is mandatory under Public Law 93-275. Failure to comply may result in criminal fines, civil penalties and other sanctions as provided by law. For the sanctions

and the provisions concerning the confidentiality of information submitted on this form, see Page 2 of the Instructions.

Complete and return by April 1, 2002 to:

Energy Information Administration

P O Box 8279

Silver Spring, MD 20907

Attn: EIA-64A

OR

Fax to (202) 586-1076 (Attn: EIA-64A)

Questions?: Call 1-800-879-1470

Affix Mailing Label

PART I. PLANT AND PRODUCTION REPORT IDENTIFICATION

1.0 Does this report reflect active natural gas processing at the facility for the entire year? Yes No (indicate number of months below)

Months covered by this report____________ through ____________ , 2001 (Include Explanatory Notes in Section 7.0)

2.0 Submission Status Original Amended

3.0 Label Information (If label is incorrect or information is missing or no label is given, enter correct information below).

3.1 Parent Company’s Name

3.2 Operator’s Name

3.3 Plant Name

3.4 Geographic Location (Use Area of Origin Codes, Page 6)

3.5 Street Address/PO Box

3.6 City 3.7 State 3.8 Zip Code

3.9 Contact Name 3.10 Title 3.11 Date

3.12 Telephone Number ( ) Ext 3.13 Fax Number ( ) 3.14 E-mail Address:

PART II. ORIGIN OF NATURAL GAS RECEIVED AND NATURAL GAS LIQUIDS PRODUCED

Line

Area of Origin

Code

(A)

Natural Gas Received

Report in millions of cubic feet (MMCF)

(B)

Natural Gas Liquids Production

Report in thousands of barrels (MBbl)

(C)

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8 TOTAL

5.0 Gas Shrinkage Resulting from Natural Gas Liquids Extracted (MMCF):

6.0 Natural Gas Used as Fuel in Processing (MMCF):

7.0 Explanatory Notes:

Title 18 USC 1001 makes it a criminal offense for any person knowingly and willingly to make to any Agency or Department of the United States any false, fictitious, or

fraudulent statements as to any matter within its jurisdiction.

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

SAMPLE
Glossary
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)

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 155

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 Discovery Year: The calendar year in which a

field was first recognized as containing economically

recoverable accumulations of oil and/or gas.

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)

Indicated Additional Reserves of Crude

Oil: Quantities of crude oil (other than proved

reserves) which may become economically

recoverable from existing productive reservoirs

through the application of improved recovery

techniques using current technology. These recovery

techniques may:

1. Already be installed in the reservoir, but their

effects are not yet known to the degree

necessary to classify the additional reserves as

proved

2. Be installed in another similar reservoir, where

the results of that installation can be used to

estimate the indicated additional reserves.

Indicated additional reserves are not included in

proved reserves due to their uncertain economic

recoverability. When economic recoverability is

demonstrated, the indicated additional reserves must

be transferred to proved reserves as positive

revisions.

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

Energy Information Administration

156 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
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.

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 Reservoirs: Reservoirs in which

proved liquid or gaseous hydrocarbon reserves 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.

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 Ownershi

p 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

Energy Information Administration

U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 157
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

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

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158 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report
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

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. It is expected to

change over time for any field, group of fields, State,

or Country. Proved Ultimate Recovery does not

represent the maximum recoverable volume of

resources for an area. It is instead a gauge of how

much has already been produced plus proved

reserves. Proved reserves of crude oil or natural gas

are the estimated quantities of petroleum which

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.

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.

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U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report 159
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.

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160 U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves 2001 Annual Report