World Petroleum Resources Project Fact Sheet

Introduction

The U.S. Geological Survey (USGS) estimated technically 

recoverable, conventional, undiscovered oil and gas resources 

of the Volga-Ural Region Province in Russia and Kazakhstan as 

part of a program to estimate these resources for priority basins 

around the world. The province encompasses approximately 

725,000 square kilometers (fig. 1), north of the Caspian Sea. 

This assessment was based on published geologic information 

and on commercial data from oil and gas wells and fields, and 

field production records. The USGS approach is to define total 

petroleum systems and assessment units, and assess the potential for undiscovered oil and gas resources. 

Total Petroleum Systems and Assessment Units

Two total petroleum systems (TPS), the Proterozoic-Paleozoic Composite and the Permian Foreland Basin, were defined 

for the Volga-Ural Region Province (table 1). The ProterozoicPaleozoic Composite TPS was defined to include petroleum 

source rocks ranging in age from Late Proterozoic through 

Carboniferous, with Upper Devonian to Lower Carboniferous 

(middle Frasnian to Tournasian) Domanik mudstone being the 

main source of petroleum. Two assessment units (AU) were 

defined geologically within the Proterozoic-Paleozoic Composite TPS — Volga-Ural Clastic and Carbonate Reservoirs and 

Lower Volga (figs. 1 and 2). Reservoirs and seals in these AUs 

are associated with carbonate platforms and reefs, and marine 

clastic rocks. Middle to Upper Devonian sandstones and Lower 

Carboniferous carbonate rocks contain the greatest quantities 

of known oil and gas. Known traps include reefs, drapes over 

reefs, anticlines over inverted rift grabens and basin uplifts, 

and fault-related traps. Pinchout and stratigraphic traps also 

are recognized.

The Permian Foreland Basin TPS was defined to include 

Permian (Asselian to Artinskian) deep-water, organic-rich 

mudstone source rocks. One AU was defined for the Permian 

Foreland Basin TPS — Permian Reefs/Thrust Folds TPS 

(fig. 1). Reservoirs in this AU include Permian carbonate reefs 

and clastic rocks having evaporite seals, primarily the Lower 

Permian (Kungarian) evaporite. Known traps are reefs and 

structures associated with thrust faults and folding.

Assessment Results

Estimates of volumes of technically recoverable, conventional, and undiscovered oil and gas resources are shown 

in table 1. No attempt was made to estimate economically 

recoverable resources because it is beyond the scope of this 

study. The mean volumes and probability ranges (F95 to F05) of 

The U.S. Geological Survey estimated mean volumes of technically recoverable, conventional, undiscovered petroleum resources at 1.4 billion 

barrels of crude oil, 2.4 trillion cubic feet of natural gas, and 85 million barrels of natural gas liquids for the Volga-Ural Region Province, using a 

geology-based assessment methodology.

Figure 1. Location of 3 assessment units (AU) in the Volga-Ural 

Region Province and approximate location of cross section (A-A’) 

shown in figure 2. (Map not definitive for political boundaries.)

Assessment of Undiscovered Oil and Gas Resources of the 

Volga-Ural Region Province, Russia and Kazakhstan, 2010

U.S. Department of the Interior Printed on recycled paper

U.S. Geological Survey

Fact Sheet 2010–3095

November 2010 Printed on recycled paper Printed on recycled paper

Permian Reefs/

Thrust Folds AU

Russia

Iran

Kazakhstan

Iraq

Turkey Turkmenistan

Uzbekistan

Azerbaijan

Georgia

Syria

Armenia

40°E 42°E 44°E 46°E 48°E 50°E 52°E 54°E 56°E 58°E 64°N

62°N

60°N

58°N

56°N

54°N

52°N

50°N

48°N

46°N

44°N

42°N

40°N

38°N

36°N

34°N

Caspian 

 Sea

Black 

 Sea

Aral 

 Sea

EXPLANATION

Volga-Ural Region Province

AFRICA

RUSSIA

Arabian

Sea

Barents Sea

0 250 500 MILES

0 250 500 KILOMETERS

Volga-Ural

Clastic and Carbonate

Reservoirs AU

Lower 

Volga

AU

A

A'

60°E

Cross Section
undiscovered petroleum are approximately 1,417 million barrels 

(MMB) of crude oil, with a range of 567 to 2,674 MMB; 2,377 

billion cubic feet (BCF) of natural gas (both associated and dissolved, and nonassociated), with a range of 644 to 5,641 BCF; 

and 85 MMB of natural gas liquids, with a range of 22 to 

209 MMB.

References Cited

Peterson, J.A., and Clarke, J.W., 1983a, Geology of the VolgaUral Province and detailed description of the Romashkino 

and Arlan oil fields: U.S. Geological Survey Open-File 

Report 83–711, 90 p.

Peterson, J.A., and Clarke, J.W., 1983b, Petroleum geology and 

resources of the Volga-Ural Province, U.S.S.R.: U.S. Geological Survey Circular 885, 27 p.

For Further Information

Publications detailing the geology and the methodology 

for the Volga-Ural Region Province and assessment results are 

available at the USGS Energy Program Web site, http://energy.

cr.usgs.gov/oilgas/.

Volga-Ural Region Province Assessment Team

T.R. Klett (tklett@usgs.gov), Christopher J. Schenk, 

Ronald R. Charpentier, Michael E. Brownfield, Janet K. Pitman, 

Troy A. Cook, and Marilyn E. Tennyson.

Acknowledgments

Geographic Information Systems support by Christopher P. 

Anderson, ATA Services. Graphic support by Wayne Husband, 

ATA Services.

6.0

5.0

4.0

3.0

2.0

1.0

0.5

0

0.5

1.0

1.5

W EURAL MOUNTAINS

URAL

FOREDEEP VOLGA-URAL CARBONATE AND

CLASTIC RESERVOIRS AU

LOWER VOLGA

AU

0 100 200 KILOMETERS

Kilometers (Datum Mean Sea Level)

0 50 100 MILES

EXPLANATION

1

2

3

4

5

6

Fault

Unconformity

A A'

Table 1. Volga-Ural Region Province assessment results (technically recoverable, conventional undiscovered resources). 

[MMB, million barrels; BCF, billion cubic feet. Results shown are fully risked estimates. For gas fields, all liquids are included under the natural gas liquids 

(NGL) category. F95 denotes 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. TPS, total petroleum system; AU, assessment unit. Gray shading indicates not applicable.]

Figure 2. Schematic geologic cross section of the Volga-Ural Region Province illustrating 

the geologic delineations of two of the three assessment units (AU) in this study (red line). 

The third AU, Permian Reefs/Thrust Folds, is out of the plane of the cross section. Location 

of cross section is shown in figure 1. Modified from Peterson and Clarke (1983a, b). Rock 

units: 1, Pliocene, mostly continental clastic rocks; 2, Mesozoic, mostly continental clastic 

rocks; 3, Permian, continental clastic rocks and marine carbonate rocks; 4, Carboniferous, 

mostly marine carbonate rocks; 5, Devonian, marine clastic and carbonate rocks; 

6, Proterozoic, marine clastic and carbonate rocks. 

Total undiscovered resources Total Petroleum Systems

(TPS)

and Assessment Units (AU)

Field

type

Oil (MMB) Gas (BCF) NGL (MMB)

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

Mean (expected)

largest

field size

(MMB or BCF)

Gas

Oil Volga-Ural Clastic and

Carbonate Reservoirs AU

Gas

Oil

Lower Volga AU

Volga-Ural Region Province, Proterozoic-Paleozoic Composite TPS

493 1,104 2,220 1,198

64 154 332 170

210 571 1,503 680

84 202 437 224

9

1

25

2

67

5

30

2

156 558 1,840 717 6 23 76 29

158 432 1,150 512 5 13 35 15

168

47

316

196

Gas

Oil

Permian Reefs/Thrust Folds AU

49 66 3

178 6

10 39 122 11 49 180 <1 2 8

25 120 531 1 4 18

Total Undiscovered Petroleum

Resources 567 1,297 2,674 1,417 644 1,932 5,641 2,377 22 69 209 85

17

96

Volga-Ural Region Province, Permian Foreland Basin TPS