U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3083

November 2016 Printed on recycled paper

National and Global Petroleum Assessment

Assessment of Undiscovered Continuous Oil and Shale-Gas 

Resources in the Bazhenov Formation of the West Siberian 

Basin Province, Russia, 2016

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean continuous resources of 12 billion 

barrels of oil and 75 trillion cubic feet of gas in the Bazhenov Formation of the West Siberian Basin Province, Russia.

States. Specifically, mean estimated ultimate recoveries from populations of 

continuous oil and shale-gas wells, the mean drainage areas of drilled wells, 

and ranges of average well success ratios were used to estimate the undiscovered continuous oil and shale-gas resources. Principal input data used in 

the assessment are listed in table 1.

Introduction

The U.S. Geological Survey (USGS) quantitatively assessed the potential for undiscovered, technically recoverable continuous oil and 

shale-gas resources in the West Siberian Basin 

Province of Russia (fig. 1). This study focuses 

on the geologic evaluation and assessment 

of oil and gas source-reservoir rock systems 

and potential resources of the Upper Jurassic 

Bazhenov Formation.

For this study, the USGS defined continuous 

oil and shale-gas source-reservoir rock systems. 

These systems (1) contain at least 2 weight 

percent or more total organic carbon, (2) occur 

within the thermal maturity window for oil or 

natural gas generation, (3) have 15 meters or 

more of organic-rich shale, and (4) contain Type I 

or Type II organic matter (Charpentier and Cook, 

2011). Many studies have been published on the 

Bazhenov Formation, providing information on 

source rock characteristics, tectonic history, thermal history, and timing of maturation and generation of hydrocarbons. Several oil fields in the 

southern part of the West Siberian Basin Province 

produce continuous oil from the Bazhenov 

Formation (for example, Salym Field; Clarke 

and Rachlin, 1980). At the time of this study, no 

fields are known to produce shale gas from the 

Bazhenov Formation.

Two assessment units (AUs) were defined 

for this study (fig. 1). The Bazhenov Continuous 

Oil AU was delineated in the southern part of the 

basin where the Bazhenov source rock is thermally mature with respect to oil generation. The 

Bazhenov Shale Gas AU was delineated in the 

northern part of the province where the Bazhenov 

source rock is deeper and is presumably thermally 

mature with respect to gas generation.

Because detailed production data for continuous resources outside of the United States 

are difficult to obtain, the USGS assessment 

methodology uses analogs of continuous oil 

and shale-gas accumulations from the United 

Figure 1. Map showing the Bazhenov Continuous Oil and Bazhenov Shale Gas 

Assessment Units (AU) in the West Siberian Basin Province, Russia.

40° 50° 60° 70° 80° 90° 100°

70°

65°

60°

55°

KARA SEA

Dudinka

Salekhard

Novosibirsk KAZAKHSTAN

RUSSIA

0 100 200 MILES

0 100 200 KILOMETERS

RUSSIA

CHINA

MONGOLIA KAZAKHSTAN

Area

of study

EXPLANATION

West Siberian Basin Province

Bazhenov Continuous Oil AU

Bazhenov Shale Gas AU

Source: U.S. Department of the Interior National Park Service
ISSN 2327-6916 (print) ISSN 2327-6932 (online) http://dx.doi.org/10.3133/fs20163083

Geologic Model

Continuous oil production from fractured Bazhenov Formation in the southern 

part of the basin has been reported. It is a 

self-sourced, organic-rich mudstone (total 

organic carbon content of at least 2 weight 

percent), contains mostly Type II kerogen, and is thermally mature with respect 

to oil generation (Ulmishek, 2003). The 

Bazhenov Continuous Oil AU area does not 

include areas of discovered accumulations 

and areas where undiscovered conventional 

accumulations might be present. Discovered continuous oil accumulations were 

also excluded from the AU. Undiscovered 

continuous oil accumulations most likely 

exist between structural highs.

No shale-gas production has been 

reported from the Bazhenov Formation. 

However, the part of the Bazhenov 

Formation in the northern part of the 

basin is presumed to be similar to that in 

the southern part of the basin but thermally 

mature with respect to gas generation. As 

with the Bazhenov Continuous Oil AU, 

the Bazhenov Shale Gas AU area does not 

include areas of discovered and undiscovered conventional fields on structural highs. 

Undiscovered shale-gas accumulations 

most likely exist between structural highs.

Undiscovered Resources Summary

The USGS quantitatively assessed 

unconventional oil and gas resource in 

one continuous oil AU and one continuous 

shale-gas AU in the West Siberian Basin 

of Russia (table 2). For total undiscovered resources, the estimated means are 

12,219 million barrels of continuous oil 

(MMBO), or 12 billion barrels of oil, 

with an F95–F5 range from 2,774 to 

26,716 MMBO, 75,156 billion cubic 

feet of natural gas (BCFG), or 75 trillion 

cubic feet of natural gas, with an F95–F5 

range from 17,446 to 159,284 BCFG, and 

1,615 million barrels of natural gas liquids 

(MMBNGL) with an F95–F5 range from 

354 to 3,602 MMBNGL. 

For total continuous oil resources, 

the estimated means for the Bazhenov 

Continuous Oil AU are 12,219 MMBO 

with an F95–F5 range from 2,774 to 

26,716 MMBO, 4,888 BCFG with an 

F95–F5 range from 1,106 to 10,721 BCFG, 

and 69 MMBNGL with an F95–F5 

range from 14 to 158. For total shale-gas 

resources, the estimated means for the 

Bazhenov Shale Gas AU are 70,268 BCFG 

with an F95–F5 range from 16,340 to 

148,563 BCFG and 1,546 MMBNGL 

with an F95–F5 range from 340 to 

3,444 MMBNGL.

Table 1. Key assessment input data for the Bazhenov Continuous Oil and Bazhenov Shale Gas Assessment Units (AUs) in the West Siberian 

Basin Province, Russia.

[AU, assessment unit; %, percent; EUR, estimated ultimate recovery per well; BCFG, billion cubic feet of gas; MMBO, million barrels of oil. EUR, well drainage 

area, and success ratios are from U.S. continuous oil and shale-gas analogs. The average EUR input is the minimum, median, maximum, and calculated mean. Shading 

indicates not applicable]

Table 2. Assessment results for the Bazhenov Continuous Oil and Bazhenov Shale Gas Assessment Units (AUs) in the West Siberian 

Basin Province.

[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 within the NGL (natural gas liquids) category. F95 represents a 95-percent chance of at least the amount tabulated. Other fractiles 

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

Assessment input data

Bazhenov Continuous Oil AU Bazhenov Shale Gas AU

Minimum Mode Maximum Calculated

mean Minimum Mode Maximum Calculatedmean

Potential production area of AU (acres) 1,000 66,500,000 137,500,000 68,000,333 1,000 32,250,000 64,500,000 32,250,333

Average drainage area of wells (acres) 120 180 240 180 80 120 160 120

Success ratios (%) 10 50 90 50 10 50 90 50

Average EUR (oil, MMBO; gas, BCFG) 0.03 0.06 0.15 0.065 0.2 0.5 1.0 0.522

AU probability 1.0 1.0

Total petroleum system (TPS) 

and assessment units (AUs)

AU

probability

Accumulation

type

Total undiscovered resources

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

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

Bazhenov Formation TPS

Bazhenov Continuous Oil AU 1.0 Oil 2,774 10,725 26,716 12,219 1,106 4,286 10,721 4,888 14 58 158 69

Bazhenov Shale Gas AU 1.0 Gas 16,340 63,131 148,563 70,268 340 1,343 3,444 1,546

Total undiscovered resources 2,774 10,725 26,716 12,219 17,446 67,417 159,284 75,156 354 1,401 3,602 1,615

References Cited

Charpentier, R.R., and Cook, T.A., 2011, USGS methodology for 

assessing continuous petroleum resources: U.S. Geological Survey 

Open-File Report 2011–1167, 73 p., accessed September 26, 2016, 

at http://pubs.usgs.gov/of/2011/1167/.

Clarke, J.W., and Rachlin, J., 1980, Salym—Potential W. Siberian oil 

giant: Oil and Gas Journal, v. 78, no. 24 (June 16, 1980), p. 132–135.

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

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

49 p.

West Siberian Basin Province Assessment Team

Timothy R. Klett, Christopher J. Schenk, Michael E. 

Brownfield, Heidi M. Leathers-Miller, Tracey J. Mercier, 

Janet K. Pitman, and Marilyn E. Tennyson

For More Information

Assessment results are available at the USGS Energy 

Resources Program Web site at http://energy.usgs.gov.