U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2007−1021

An Evaluation of the USGS World Petroleum

Assessment 2000—Supporting Data
An Evaluation of the USGS World Petroleum 

Assessment 2000—Supporting Data

By T. R. Klett, D.L. Gautier, and T.S. Ahlbrandt

Open-File Report 2007–1021

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Klett, T.R., Gautier, D.L., and Ahlbrandt, T.S., 2007, An Evaluation of the USGS World Petroleum Assessment 2000—

Supporting Data: U.S. Geological Survey Open-File Report 2007–1021, 5 p.
iii

Contents

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

Data Sources..................................................................................................................................................1

References Cited............................................................................................................................................5

Figures

1. Realized additions to crude oil and natural gas reserves compared to volumes

assessed in the World Petroleum Assessment 2000............................................................2

2. Additions to crude oil reserves from January 1996 through December 2003

by regions as identified by the World Petroleum Assessment 2000 .................................3

3. Additions to natural gas reserves from January 1996 through December 2003

by regions as identified by the World Petroleum Assessment 2000 .................................3

Tables

1. Assessed and realized crude oil and natural gas for the 128 provinces

assessed in World Energy Assessment 2000..................................................................4

2. Additions to crude oil reserves and to natural gas reserves for the 128 provinces 

assessed in World Petroleum Assessment 2000................................................................4
Africa (fig. 2). The greatest amount of reserve growth for 

natural gas was in the Middle East and North Africa, whereas 

the greatest contribution from new-field discoveries was 

in the Asia Pacific region (fig. 3). On an energy-equivalent 

basis, volumes of new gas field discoveries exceeded new oil 

field discoveries. The graphs are based on the data listed in 

tables 1 and 2.

Data Sources

Field sizes, or recoverable oil and gas volumes, are the 

sum of cumulative production and remaining reserves. Field 

sizes used for the reserve-growth assessment in the USGS 

World Petroleum Assessment 2000 were from IHS Energy 

(1996). Although this database was released in the second 

quarter of 1996, only fields discovered before 1996 were 

analyzed. Recent field sizes used in the analysis of additions to 

reserves are reported by IHS Energy (2003). Most fields used 

in the World Petroleum Assessment 2000 are reported in the 

2003 database, from which the contribution of reserve growth 

is calculated (see table 1).

Sizes of Canadian fields used in the USGS World Petroleum Assessment 2000 from NRG Associates (1995), which 

contained data for fields discovered through 1993. Additions 

to reserves from newly discovered fields and reserve growth 

are not included in our study because recent (2003) size data 

for these fields are unavailable. This exclusion, however, does 

not significantly affect the final results.

Oil and gas resources of the United States were not reassessed in the 2000 USGS World Petroleum Assessment and 

analysis of those resources is not included in our study.

An Evaluation of the USGS World Petroleum

Assessment 2000—Supporting Data

By T. R. Klett, D.L. Gautier, and T.S. Ahlbrandt1, 

1

U. S. Geological Survey, Box 25046 Denver Federal Center, Mail Stop 

939, Denver, CO 80225; tklett@usgs.gov

2

U. S. Geological Survey, 345 Middlefield Road, Mail Stop 969, Menlo 

Park, CA 94025-2502; gautier@usgs.gov

3

Present address GSL Energy Corporation, 1875 Lawrence Street, Suite 

1400, Denver, CO 80202

Introduction

In June 2000, the U.S. Geological Survey (USGS) published the results of a world petroleum assessment (exclusive 

of the United States), based on data current through 1995 

(U.S. Geological Survey World Energy Assessment Team, 

2000). The assessment included the volumes of undiscovered 

crude oil and natural gas estimated to have the potential to 

be added to reserves in a 30-year time frame (to 2025). Klett 

and others (2005) compared the actual additions to reserves as 

reported from January 1996 to December 2003 (IHS Energy, 

2003) with those estimates, apportioned to the 1996–2003 

period (27 percent of the 30-year time frame). The present 

report (1) provides tabular data, not included in the 2005 

report by Klett and others, that support the graphical displays 

and (2) briefly summarizes the interpretations and conclusions presented in the 2005 report.

Approximately 28 percent of the additions to oil reserves 

by reserve growth and approximately 11 percent of the 

estimated undiscovered oil volumes that were estimated for 

the World Petroleum Assessment 2000 (U.S. Geological 

Survey World Energy Assessment Team, 2000) were realized 

in the 8 years since that assessment. Slightly more than half 

of the estimated additions to gas reserves by reserve growth 

and approximately 10 percent of the estimated undiscovered gas volumes were realized (fig. 1). Between 1995 and 

2003, growth of oil reserves in previously discovered fields 

exceeded new-field discoveries as a source of global additions to reserves of conventional oil by a factor of about 3 to 

1. The greatest amount of reserve growth for crude oil was 

in the Middle East and North Africa, whereas the greatest 

contribution from new-field discoveries was in Sub-Saharan 
0

100

200

300

400

500

600

700

800

778

649

69 76

Recoverable Petroleum (BBOE)

Crude Oil

2025 Estimate

(Data as of 1995)

Crude Oil

(Realized

1996 to 2003)

Natural Gas

2025 Estimate

(Data as of 1995)

Natural Gas

(Realized

1996 to 2003)

A. New-Field Discoveries

Recoverable Petroleum (BBOE)

0

100

200

300

400

500

600

700

Crude Oil

2025 Estimate

(Data as of 1995)

Crude Oil

(Realized

1996 to 2003)

Natural Gas

2025 Estimate

(Data as of 1995)

Natural Gas

(Realized

1996 to 2003)

612

551

171

283

B. Reserve Growth of Discovered Fields

Figure 1. Realized additions to crude oil and natural gas reserves compared to volumes assessed 

in the World Petroleum Assessment 2000 (U. S. Geological Survey World Energy Assessment Team, 

2000). Reserve additions are from January 1996 through December 2003 for the 128 provinces assessed. 

(A) realized volumes added by the discoveries of new fields and volumes assessed through 1995. (B) 

Realized and assessed volumes added by reserve growth. Approximately 28 percent of the assessed 

estimated volume additions to oil reserves by reserve growth and 11 percent of the assessed estimated 

undiscovered oil volumes were realized in the 8 years since the assessment (27 percent of the 30-year 

time frame for the assessment). Approximately 51 percent of the assessed estimated volume additions 

to gas reserves by reserve growth and 10 percent of the assessed estimated undiscovered gas volumes 

were realized. Volumes are shown in billion barrels of oil equivalent (BBOE). The volume of gas in trillion 

cubic feet (TCF) was converted to BBOE by dividing with an energy-equivalent factor of 6. Data for 

graphs are provided in table 1.

   Evaluation of the USGS World Petroleum Assessment 2000
0

10

20

30

40

50

60

70

80

90

100

Former

Soviet

Union

Recoverable Crude Oil (BB)

Middle

East

and North

Africa

Asia

Pacific

Europe North

America

(excl. US,

Canada)

Central

and

South

America

SubSaharan

Africa

South

Asia

New-field discoveries

Reserve growth of discovered fields

Additions to Crude Oil Reserves

Figure 2. Additions to crude oil reserves, in billions of barrels (BB), from January 1996 through 

December 2003 by regions as identified by the World Petroleum Assessment 2000 (U. S. Geological 

Survey World Energy Assessment Team, 2000). The greatest amount of reserve growth was in the 

Middle East and North Africa, whereas the greatest contribution from new-field discoveries was 

in Sub-Saharan Africa. Data for graph are provided in table 2.

0

200

400

600

800

1,000

1,200

New-field discoveries

Reserve growth of discovered fields

Recoverable Natural Gas (TCF)

Former

Soviet

Union

Middle

East

and North

Africa

Asia

Pacific

Europe North

America

(excl. US,

Canada)

Central

and

South

America

SubSaharan

Africa

South

Asia

Additions to Natural Gas Reserves

Figure 3. Additions to natural gas reserves, in trillions of cubic feet (TCF), from January 1996 

through December 2003 by regions as identified by the World Petroleum Assessment 2000 

(U.S. Geological Survey World Energy Assessment Team, 2000). The greatest amount of reserve 

growth was in the Middle East and North Africa, whereas the greatest contribution from new-field 

discoveries was in the Asia Pacific region. Data for graph are provided in table 2.

Introduction   
Table 1. Assessed and realized crude oil, in billions of barrels (BB), and natural gas, in trillions of cubic feet (TCF), for the 128 provinces 

assessed in World Energy Assessment 2000 (U. S. Geological Survey World Energy Assessment Team, 2000). BBOE, billion barrels of oil 

equivalent.

Commodity Reserve growth New-field discoveries

Assessed natural gas (to 2025) BB 612 649

Crude oil realized, 1996 to 2003, BB 171 69

Assessed natural gas (to 2025)

TCF

BBOE

3305

551

4669

778

Natural gas realized,

1996 to 2003

TCF

BBOE

1699

283

458

76

Table 2. Additions to crude oil reserves, in billions of barrels (BB), and to natural gas reserves, in trillions of cubic feet (TCF), from 

January 1996 through December 2003 (8 years, 27 percent of the 30-year time frame for the assessment) for the 128 provinces assessed 

in World Petroleum Assessment 2000 (U. S. Geological Survey World Energy Assessment Team, 2000). Numbers may not precisely add 

to totals due to rounding.

USGS region* Reserve growth New-field discoveries

Crude oil (BB)

Former Soviet Union 18.68 12.40

Middle East and North Africa 83.27 13.54

Asia Pacific 3.09 7.14

Europe 4.57 2.78

North America (excl. U.S. and Canada) 12.37 0.70

Central and South America 36.54 12.07

Sub-Saharan Africa 14.12 20.33

South Asia -1.37 0.37

Total 171.28 69.33

Natural gas (TCF)

Former Soviet Union 357.14 58.54

Middle East and North Africa 1123.56 63.58

Asia Pacific 42.85 164.30

Europe 21.62 42.51

North America (excl. U.S. and Canada) 13.25 2.79

Central and South America 57.59 78.49

Sub-Saharan Africa 79.67 33.81

South Asia 2.99 14.33

Total 1698.66 458.35

*Represents only those geologic provinces assessed in each region

 Evaluation of the USGS World Petroleum Assessment 2000
References Cited

IHS Energy, 1996 [includes data current as of second quarter, 

1996], International petroleum exploration and production 

database: IHS Energy; database available from IHS Energy, 

15 Inverness Way East, Englewood, CO 80112, U.S.A.

IHS Energy, 2003 [includes data current as of December, 

2003], International petroleum exploration and production 

database: IHS Energy; database available from IHS Energy, 

15 Inverness Way East, Englewood, CO 80112, U.S.A.

Klett, T.R., Gautier, D.L., and Ahlbrandt, T.S., 2005, An 

evaluation of the U.S. Geological Survey World Petroleum 

Assessment 2000: American Association of Petroleum 

Geologists Bulletin, v. 89, no. 8, p. 1033–1042.

NRG Associates, 1995 [includes data current as of December 

1993], The significant oil and gas fields of Canada database: 

Colorado Springs, Col., NRG Associates, Inc.; database 

available from NRG Associates, Inc., P.O. Box 1655, Colorado Springs, CO 80901, U.S.A.

U. S. Geological Survey World Energy Assessment 

Team, 2000, U. S. Geological Survey World Petroleum 

Assessment 2000—Description and results: U. S. Geological Survey Digital Data Series DDS-60, 4 CD-ROMs.

References Cited