U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2017–3085

February 2018

National and Global Petroleum Assessment

Assessment of Undiscovered Continuous Oil and Gas Resources in the 

Domanik-Type Formations of the Volga-Ural Region Province, Russia, 2017

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable 

continuous resources of 2.8 billion barrels of oil and 34 trillion cubic feet of gas in the Domanik-type formations of the Volga-Ural Region 

Province, Russia.

Introduction

The U.S. Geological Survey (USGS) quantitatively assessed 

the potential for undiscovered, technically recoverable continuous oil and gas resources in the Volga-Ural Region Province of 

Russia (fig. 1). This study focused on the geologic evaluation and 

assessment of oil and gas source-reservoir rock systems (petroleum 

systems) and potential resources of the Upper Devonian–Lower 

Carboniferous (Tournaisian) Domanik-type formations. These 

include the Domanik Formation and Domanikoids (younger rocks 

overlying the Domanik Formation).

For this assessment, the USGS defined continuous oil and 

gas systems that (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 thick (15 meters or more) 

organic-rich shale, and (4) contain Type I or Type II organic matter 

(Charpentier and Cook, 2011). Many studies have been published 

on the Domanik-type formations, providing information on sourcerock characteristics, tectonic history, thermal history, and timing 

of the maturation and generation of hydrocarbons (Zaydelson and 

others, 1991; Fadeeva and others, 2016). Several conventional oil 

and some gas fields or accumulations have been discovered in the 

Volga-Ural region that produce from reservoirs, commonly in structural traps and reefs (Ulmishek, 1988). Reports on the number of 

wells that produce directly from Domanik-type formations but not 

from conventional accumulations were unavailable for this study.

The Domanik Total Petroleum System and three assessment 

units (AUs) were defined for this assessment (fig. 1). The Domanik 

Formation Continuous Oil AU was delineated over much of the 

eastern part of the province. The Domanik Formation source rock 

was deposited during a maximum transgression of sea level during 

the Late Devonian (early Frasnian) above older nearshore sediments (Ulmishek, 1988). The Domanikoid Continuous Oil AU 

was deposited above the Domanik Formation in elongated areas 

(troughs) between reefs and carbonate platforms. The Domanikoid 

Continuous Oil AU is younger than the Domanik Formation 

Continuous Oil AU (Peterson and Clarke, 1983). Both the 

Domanik Formation Continuous Oil and Domanikoid Continuous 

Oil AUs are thermally mature with respect to oil generation. The 

Domanik Formation Foredeep Continuous Gas AU was delineated 

in the eastern part of the region in a foredeep basin along the 

Ural Mountains where the Domanik source rock is deeper and 

presumably thermally mature with respect to gas generation.

Detailed production data for continuous resources outside of 

the United States are difficult to obtain, so the USGS assessment 

methodology uses production data of continuous oil and gas 

accumulations from the United States, which serve as analogs. 

Specifically, mean estimated ultimate recoveries from populations 

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

wells, and ranges of average well success ratios were used to estimate undiscovered continuous oil and gas resources. Principal input 

data used in the assessment are listed in table 1.

Geologic Model

Continuous oil production has been reported from the fractured 

Domanik Formation in the southern part of the basin. The Domanik 

Formation 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, 1988). Undiscovered continuous oil accumulations 

most likely exist between structural highs. The Domanik Formation 

Figure 1. Location of the three assessment units (AUs) in the VolgaUral Region Province, Russia.

Base map from U.S. Department of the Interior National Park Service

40° 50° 60°

60°

55°

50°

RUSSIA

KAZAKHSTAN

UKRAINE

Yaroslavl′

Rostov-na-danu

Orenburg

Ufa

Perm′

CASPIAN SEA

Volga River

Volgograd

Izevsk

Ural Mountains Ural Mountains

Don River

Tobol River

Ural

River

Volga River

0 250 KILOMETERS

0 250 MILES

RUS

KAZ

CHN

MNG

UKR

Map

area

EXPLANATION

Domanik Formation Continuous Oil AU

Domanikoid Continuous Oil AU

Domanik Formation Foredeep Continuous Gas AU

Volga-Ural Region Province boundary
ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20173085

Volga-Ural Region Province Assessment Team

Timothy R. Klett, Michael E. Brownfield, Thomas M. Finn, Stephanie B. Gaswirth, Phuong A. Le, Heidi M. Leathers-Miller, Kristen R. Marra, 

Tracey J. Mercier, Janet K. Pitman, Christopher J. Schenk, Marilyn E. Tennyson, and Cheryl A. Woodall

For More Information

Assessment results are also available at the USGS Energy Resources Program website at https://energy.usgs.gov.

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/.

Fadeeva, N.P., Kozlova, E.V., Poludetkina, E.N., Shardanova, T.A., 

Pronina, N.V., Stupakova, A.V., Kalmykov, G.A., and Khomyak, A.N., 

2016, The hydrocarbon-generation potential of the Domanik rocks in the 

Volga-Ural petroliferous basin: Moscow University Geology Bulletin, 

v. 71, no. 1, p. 41–49.

Table 1. Key assessment input data for three continuous assessment units in the Volga-Ural Region Province, Russia.

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

minimum, median, maximum, and calculated mean. Shading indicates not applicable]

Assessment input data—Continuous AUs

Domanik Formation Continuous Oil AU Domanikoid Continuous Oil AU

Minimum Mode Maximum Calculated 

mean Minimum Mode Maximum Calculated mean

Potential production area of AU (acres) 1,000 15,936,500 31,873,000 15,936,833 1,000 7,484,000 14,967,000 7,484,000

Average drainage area of well (acres) 120 180 240 180 120 180 240 180

Success ratio (%) 10 30 70 36.7 10 25 60 31.7

Average EUR (MMBO) 0.03 0.06 0.15 0.065 0.02 0.05 0.1 0.052

AU probability 1.0 1.0

Assessment input data—Continuous AU

Domanik Formation Foredeep Continuous Gas AU

Minimum Mode Maximum Calculated 

mean

Potential production area of AU (acres) 1,000 14,755,000 29,510,000 14,755,333

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

Success ratio (%) 10 50 90 50

Average EUR (BCFG) 0.2 0.5 1.0 0.522

AU probability 1.0

Table 2. Assessment results for three continuous assessment units in the Volga-Ural Region Province, Russia.

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

estimates. For gas accumulations, all liquids are included in the NGL 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]

Total petroleum system 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

Domanik Total Petroleum System

Domanik Formation Continuous Oil AU 1.0 Oil 494 1,831 4,599 2,098 236 899 2,364 1,049 9 35 98 42

Domanikoid Continuous Oil AU 1.0 Oil 169 612 1,473 689 81 300 757 344 3 12 32 14

Domanik Formation Foredeep Continuous Gas AU 1.0 Gas 7,506 28,875 68,334 32,165 296 1,145 2,754 1,287

Total undiscovered continuous resources 663 2,443 6,072 2,787 7,823 30,074 71,455 33,558 308 1,192 2,884 1,343

Peterson, J.A., and Clarke, J.W., 1983, Geology of the Volga-Ural petroleum province and detailed description of the Romashkino and Arlan oil 

fields: U.S. Geological Survey Open-File Report 83–711, 90 p.

Ulmishek, G.F., 1988, Upper Devonian-Tournaisian facies and oil resources 

of the Russian Craton’s eastern margin: Canadian Society of Petroleum 

Geologists Memoir 14, p. 527–549.

Zaydelson, M.I., Surovikov, E.Ya., Vaynbaum, S.Ya., Bellerova, V.A., and 

Ashirov, K.B., 1991, Oil and gas potential of the Domanikoid associations of the Volga-Ural Province: International Geology Review, v. 33, 

no. 3, p. 243–262.

Continuous Oil AU area does not include areas of discovered conventional fields (and [or] accumulations).

No continuous gas production has been reported from the Domanik 

Formation Continuous Oil AU or Domanikoid Continuous Oil AU. The 

Domanik Formation Foredeep Continuous Gas AU is thermally mature 

with respect to gas generation, but few gas fields have been discovered.

Undiscovered continuous gas accumulations most likely exist between 

structural highs. The Domanik Formation Foredeep Continuous Gas AU 

area does not include areas of discovered conventional fields on structural 

highs.

Undiscovered Resources Summary

The USGS quantitatively assessed oil and gas resources in three AUs 

in the Volga-Ural Region Province of Russia (table 2). For undiscovered, 

technically recoverable oil and gas resources, the estimated means are 

2,787 million barrels of continuous oil (MMBO), or 2.8 billion barrels of 

oil, with an F95–F5 range from 663 to 6,072 MMBO; 33,558 billion cubic 

feet of natural gas (BCFG), or 34 trillion cubic feet of natural gas, with 

an F95–F5 range from 7,823 to 71,455 BCFG; and 1,343 million barrels 

of natural gas liquids (MMBNGL) with an F95–F5 range from 308 to 

2,884 MMBNGL.