U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3064

August 2008

Assessment of Undiscovered Oil and Gas Resources of the 

West Siberian Basin Province, Russia, 2008

Printed on recycled paper

Introduction

The U.S. Geological Survey (USGS) recently 

assessed the undiscovered oil and gas potential of the West 

Siberia Basin Province in Russia as part of the USGS 

Circum-Arctic Resource Appraisal program. This province 

is the largest petroleum basin in the world and has an areal 

extent of about 2.2 million square kilometers (fig. 1). It 

is a large rift-sag feature (fig. 2) bounded to the west by 

the Ural fold belt; to the north by the Novaya Zemlya fold 

belt and North Siberian Sill, to the south by the Turgay 

Depression and Altay-Sayan fold belt, and to the east 

by the Yenisey Ridge, Turukhan-Igarka uplift, YeniseyKhatanga Basin, and Taimyr High (fig. 1). The West 

Siberian Basin Province has a total discovered oil and gas 

volume of more than 360 billion barrels of oil equivalent 

(Ulmishek, 2003). Exploration has led to the discovery of 

tens of giant oil and gas fields, including the Urengoy gas 

field with more than 350 trillion cubic feet of gas reserves 

and Samotlar oil field with reserves of nearly 28 billion 

barrels of oil (Ulmishek, 2003). This report summarizes 

the results of a reassessment of the undiscovered oil and 

gas potential of that part of the province north of the Arctic 

Circle; a previous assessment that included the entire 

province was completed in 2000 (Ulmishek, 2000). The 

total petroleum system (TPS) and assessment units (AU) 

defined by the USGS for the assessments in 2000 were 

adopted for this assessment. However, only those parts of 

the AUs lying wholly or partially north of the Arctic Circle 

were reassessed for this study.

Geologic Definition of Assessment Units

Ulmishek (2000) defined the Northern West Siberian 

Mesozoic Composite TPS in the northern part of the West 

Siberian Basin Province (fig. 1). More than 70 fields 

have been discovered in this TPS, most of which are gas 

fields. Several rock units might be potential source rocks, 

including strata of Jurassic and Cretaceous age. However, 

the true source of the gas resources remains unknown 

(Ulmishek, 2003).

Two AUs encompass the northern part of the province (fig. 1). The Northern West Siberian Onshore Gas 

AU includes primarily Cretaceous sandstone reservoirs in 

structural traps. The South Kara Sea Offshore AU, considered to be the offshore geologic extension of the Northern 

Using a geology-based assessment methodology, the 

U.S. Geological Survey (USGS) estimated means of 

3.7 billion barrels of undiscovered oil and 651 trillion cubic 

feet of natural gas north of the Arctic Circle in the West 

Siberian Basin Province.

_ Omsk

Novosibirsk

Kara Sea

Central Kazakhstan

Folded Region

65°

60°

55°

40° 50° 60° 70° 80°

Yenisey-Khatanga

Basin

Taimyr

High

North Siberian Sill

Arctic Circle

NORTHERN 

WEST

SIBERIAN 

ONSHORE GAS AU

 

SOUTH KARA SEA

OFFSHORE AU

Ob Inlet

Yam al

Pen.

Gydan Pen.

0 620 KILOMETERS

Barents Sea

A

A’

Altay-Sayan

fold belt

Yenisey Ridge

Turukhan-lgarka Uplift

Tunguska

Basin

Novaya Zemlya fold belt

Timan-Pechora

Basin

Ural

fold belt

Turgay

Depression

Yenisey River

River

River

Irtysh

Ob

EXPLANATION

Oil field centerpoint 

Gas field centerpoint

Figure 1. West Siberian Basin Province (red line). Two assessment 

units (AU) (yellow lines) were defined in this study: Northern West 

Siberian Onshore Gas AU and South Kara Sea Offshore AU. Dashed 

yellow lines represent the part of the Northern West Siberian Onshore 

Gas AU that extends south of the Arctic Circle. Outermost yellow line 

bounds the Northern West Siberian Mesozoic Composite TPS.

West Siberia Onshore Gas AU, includes similar traps and reservoirs. Each 

AU was evaluated in its entirety for undiscovered, technically recoverable, oil and gas resources, but the assessment results reported here are 

only for those parts that are north of the Arctic Circle. About 75 percent 

of the Northern West Siberian Onshore Gas AU is north of the Arctic 

Circle, and the South Kara Sea Offshore AU lies wholly within the Arctic 

Circle (fig. 1).
Resource Summary

The results of the quantitative assessment of undiscovered, 

technically recoverable, conventional oil and gas resources in 

that part of the Northern West Siberian Mesozoic Composite TPS 

north of the Arctic Circle are given in table 1. The total estimated 

means for undiscovered conventional oil and gas resources are 

3,659 million barrels of oil (MMBO), 651,499 billion cubic feet 

of natural gas (BCFG), and 20,329 million barrels of natural-gas 

liquids (MMBNGL). Of these volumes, the Northern West Siberian 

Onshore Gas AU accounts for 1,152 MMBO, 29,277 BCFG, and 

850 MMBNGL, and the South Kara Sea Offshore AU accounts 

for 2,507 MMBO, 622,222 BCFG, and 19,479 MMBNGL. The 

estimate for undiscovered gas in the South Kara Sea AU reflects 

the exploration immaturity compared to the Northern West Siberian 

Onshore Gas AU.

0 100 KILOMETERS

EXPLANATION

Sandstones and shales Hydrocarbon pool

Quaternary sediments

Fault

Mainly sandstones Pre-Jurassic rocks

Mainly shales

Major unconformity

0

1.0

2.0

3.0

4.0

km, b.s.l.

Pg 2-3

K t-Pg 2 1

K1br-al 

K c

2 K a-K c 1 2

K b-g 1 J3

J1-2

K b

1

K v-br 1

Q

A A'

Figure 2. Line of cross section A-A ́

in the West Siberian Basin Province; 

location of section shown in figure 

1. J, Jurassic; K1b, Berrasian; K1v, 

Valanginian; K1g, Hauterivian; K1br, 

Barremian; K1a, Aptian; K1al, Albian; 

K2c, Cenomanian; K2t, Turonian; Pg1, 

Paleogene; Pg2-3, Eocene-Oligocene; Q, 

Quaternary. b.s.l., below sea level. From 

Ulmishek (2000).

References

Ulmishek, G., 2003, Petroleum geology and resources of the West 

Siberian Basin, Russia: U.S. Geological Survey Bulletin 2201–G, 

49 p.

Ulmishek, G., 2000, West Siberia Basin—Geologic Province 1174, 

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

Geological Survey World Petroleum Assessment 2000—description and results: U.S. Geological Survey Digital Data Series 

DDS–60, four CD–ROM set, Disk 2.

For Further Information

Assessment results are available at the USGS Energy Program 

Web site, http://energy.usgs.gov/arctic, or by contacting Donald 

L. Gautier, Task Leader for the USGS Circum-Arctic Oil and Gas 

Resource Appraisal (gautier@usgs.gov).

West Siberian Basin Province Assessment Team: 

Christopher J. Schenk, Kenneth J. Bird, Ronald R. Charpentier, 

Donald L. Gautier, David W. Houseknecht, Timothy R. Klett, 

Thomas E. Moore, Mark J. Pawlewicz, Janet K. Pitman, and 

Marilyn E. Tennyson.

Total Petroleum Systems 

(TPS) 

and Assessment Units (AU)

AU

Probability

Field 

Type

Largest 

Expected Oil 

Field Size

Total Undiscovered Resources

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

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

Northern West Siberian Mesozoic Composite TPS

Northern West Siberian 

Onshore Gas AU 1.00

Oil 431 223 901 2,930 1,152 1,241 5,304 17,744 6,859 25 109 369 142

Gas 5,560 6,242 18,831 50,642 22,418 194 594 1,613 708

South Kara Sea Offshore AU 1.00

Oil 712 572 2,053 6,023 2,507 3,183 12,064 36,779 14,933 64 248 763 308

Gas 189,354 154,681 513,304 1,372,510 607,289 4,799 16,000 44,090 19,171

Total Conventional

 Resources 3,659 651,499 20,329

Table 1. West Siberian Basin Province assessment results, north of the Arctic Circle. 

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For gas accumulations, all 

liquids are included as NGL (natural gas liquids). Undiscovered gas resources are the sum of nonassociated and associated gas. F95 represents a 95-percent chance of at least the amount 

tabulated; other fractiles are defined similarly. AU probability is the chance of at least one accumulation of minimum size within the AU. Largest expected oil field size in MMBO; largest 

expected gas field size in BCFG. TPS, total petroleum system; AU, assessment unit. Gray shading indicates not applicable; oil field sizes in MMBO; gas field sizes in BCFG]