U.S. Department of the Interior

U.S. Geological Survey

Bulletin 2204−D

Total Petroleum Systems of the North Carpathian

Province of Poland, Ukraine, Czech Republic,

and Austria
Total Petroleum Systems of the

North Carpathian Province of Poland, 

Ukraine, Czech Republic, and Austria

By Mark Pawlewicz 

Bulletin 2204–D

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Pawlewicz, Mark, 2006, Total Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, 

and Austria: U.S. Geological Survey Bulletin 2204–D, 26 p.; available at <http://pubs.usgs.gov/b/2204d>.
iii

Contents

Foreword .........................................................................................................................................................1

Abstract...........................................................................................................................................................2

Introduction.....................................................................................................................................................2

North Carpathian Province ..........................................................................................................................2

Province Boundaries............................................................................................................................2

Structural Setting..................................................................................................................................6

Stratigraphy ...........................................................................................................................................6

Geochemistry of Oil in Poland and Ukraine ..............................................................................................9

Miocene Gas.................................................................................................................................................11

Potential Source Rocks...............................................................................................................................11

Oligocene and Miocene Potential Source Rocks .........................................................................11

Menilite Shale ............................................................................................................................11

Krosno Formation and Menilite Shale Equivalents ..............................................................12

Cretaceous Potential Source Rocks................................................................................................13

Spas and Shypot Formations ...................................................................................................13

Other Potential Source Rocks .................................................................................................13

Jurassic Potential Source Rocks.....................................................................................................13

Paleozoic Potential Source Rocks...................................................................................................14

Other Potential Source Rocks ..........................................................................................................14

Reservoir Rocks ...........................................................................................................................................14

Seals...............................................................................................................................................................15

Assessment Units .......................................................................................................................................15

Isotopically Light Gas Total Petroleum System .............................................................................15

Mesozoic–Paleogene Composite Total Petroleum System.........................................................15

Paleozoic Reservoirs Assessment Unit of the Paleozoic Composite Total Petroleum

System.....................................................................................................................................19

Assessment Results and Summary ..........................................................................................................21

References....................................................................................................................................................25

Figures

1–4. Maps showing:

 1. Location of North Carpathian Province and outlines of total petroleum

systems in Eastern Europe...................................................................................................3

 2. Location of Carpathian Mountains and other features in Eastern Europe..................4

 3. Main flysch nappes in Poland.............................................................................................5

 4. Main flysch nappes in Ukraine ...........................................................................................7

5. Stratigraphic column for the flysch belt in Ukraine................................................................8

6. Stratigraphic chart of flysch strata in Polish nappes...........................................................10

7. Map showing location of Isotopically Light Gas Total Petroleum System within the

North Carpathian Province of Eastern Europe. .....................................................................16
iv

8. Events chart for the Foreland Basin Assessment Unit of the Isotopically Light Gas

Total Petroleum System.............................................................................................................17

9. Map showing location of the Mesozoic–Paleogene Composite Total Petroleum

System in the North Carpathian Province of Eastern Europe.............................................18

10. Events chart for the Deformed Belt Assessment Unit of the Mesozoic–Paleogene

Composite Total Petroleum System.........................................................................................19

11. Map showing location of the Paleozoic Composite Total Petroleum System within

the North Carpathian Province of Eastern Europe................................................................20

12. Events chart for the Paleozoic Reservoirs Assessment Unit of the Paleozoic

Composite Total Petroleum System.........................................................................................21

13. Diagram showing estimated number and size of undiscovered oil fields in the

North Carpathian Province .......................................................................................................24

14. Diagram showing estimated number and size of undiscovered gas fields in the

North Carpathian Province .......................................................................................................24

Tables

1. Summary of allocated oil and gas resources, North Carpathian Province,

as evaluated per assessment unit...........................................................................................22

2. Summary of allocated oil and gas resources, North Carpathian Province ......................23

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

gram (g) 0.03527 ounce, avoirdupois (oz)

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)
v

Abbreviations

API American Petroleum Institute

BCFG billion cubic feet of gas

MMBNGL million barrels of natural gas liquids

MMBO million barrels of oil

MMCFG million cubic feet of gas

°C/km degrees Celsius per kilometer

g/cm

3 grams per cubic centimeter

g/m

3

 grams per cubic meter

HC/g TOC Hydrocarbon/gram of total organic carbon

km kilometer m meters

mD millidarcies

mg milligrams

ppt parts per thousand Ro vitrinite reflectance

wt percent weight percent
Total Petroleum Systems of the North Carpathian Province 

of Poland, Ukraine, Czech Republic, and Austria

By Mark Pawlewicz 

An assessment unit is a mappable part of a total petroleum 

system in which discovered and undiscovered fields constitute a single relatively homogenous population such that 

the chosen methodology of resource assessment based on 

estimation of the number and sizes of undiscovered fields 

is applicable. A total petroleum system might equate to a 

single assessment unit or it may be subdivided into two or 

more assessment units such that each is sufficiently homogeneous in terms of geology, exploration considerations, and 

risk to assess individually. Assessment units are considered 

“established” if they contain more than 13 fields, “frontier” 

if they contain 1–13 fields, and “hypothetical” if they contain no fields. 

A graphical depiction of the elements of a total petroleum 

system is provided in the form of an events chart that shows 

the times of (1) deposition of essential rock units; (2) processes, such as trap formation, necessary to the accumulation 

of hydrocarbons; (3) the critical moment in the total petroleum 

system; and (4) the preservation of hydrocarbons. 

A numeric code identifies each region, province, total petroleum system, and assessment unit; these codes are uniform 

throughout the project and will identify the same item in any 

of the publications. The code is as follows:

Example

Region, single digit 4

Province, three digits to the right of the region code 4047

Total petroleum system, two digits to the right of

province code 404701

Assessment unit, two digits to the right of petroleum

system code 40470101

The codes for the regions and provinces are listed in Klett 

and others (1997).

Foreword

This report was prepared as part of the World Energy Project 

of the U.S. Geological Survey. In the project, the world was 

divided into 8 regions and 937 geological provinces. The 

provinces have been ranked according to the volumes of discovered oil and gas within each (Klett and others, 1997). Then, 

76 “priority” provinces (exclusive of the United States and 

chosen for their high ranking) and 26 “boutique” provinces 

(exclusive of the United States and chosen for their anticipated 

petroleum richness or special economic importance to a 

region) were selected for appraisal of oil and gas resources. 

The petroleum geology of these priority and boutique provinces is described in this series of reports. A detailed report 

containing the assessment results is available separately (U.S. 

Geological Survey, 2000). 

The purpose of this effort is to aid assessment of the 

quantities of oil, gas, and natural gas liquids that have the 

potential to be added to reserves within the next 30 years. 

These volumes either reside in undiscovered fields whose 

sizes exceed the stated minimum-field-size cutoff value for 

the assessment unit (variable, but at least 1 million barrels 

of oil equivalent), or they occur as reserve growth in fields 

already discovered.

The total petroleum system constitutes the basic geologic 

unit of the oil and gas assessment. The system includes 

all genetically related petroleum that occurs in shows and 

accumulations (discovered and undiscovered) that have been 

generated by a pod or by closely related pods of mature 

source rock, and that exist within a limited mappable geologic space, together with the essential mappable geological 

elements (source, reservoir, seal, and overburden rocks) that 

control the fundamental processes of generation, expulsion, migration, entrapment, and preservation of petroleum 

(Magoon and Dow, 1994). The minimum petroleum system 

is that part of a total petroleum system encompassing discovered shows and accumulations together with the geologic 

space in which the various essential elements have been 

proved by these discoveries.
Oil and gas reserves quoted in this report are derived from 

Petroleum Exploration and Production database (Petroconsultants, 1996) and other area reports from Petroconsultants, Inc., 

unless otherwise noted.

Boundaries of total petroleum systems, assessment units, and 

pods of active source rocks were compiled by using geographic information system software. Political boundaries 

and cartographic representations were taken, with permission, 

from Environmental System Research Institute’s ArcWorld 1:3 

million digital coverage (1992), have no political significance, 

and are displayed for general reference purposes only. Oil 

and gas center points are reproduced, with permission, from 

Petroconsultants (1996). 

Abstract

Three total petroleum systems were identified in the 

North Carpathian Province (4047) that includes parts of 

Poland, Ukraine, Austria, and the Czech Republic. They 

are the Isotopically Light Gas Total Petroleum System, the 

Mesozoic–Paleogene Composite Total Petroleum System, 

and the Paleozoic Composite Total Petroleum System. The 

Foreland Basin Assessment Unit of the Isotopically Light Gas 

Total Petroleum System is wholly contained within the shallow sedimentary rocks of Neogene molasse in the Carpathian 

foredeep. The biogenic gas is generated locally as the result 

of bacterial activity on dispersed organic matter. Migration is 

also believed to be local, and gas is believed to be trapped in 

shallow stratigraphic traps. 

 The Mesozoic–Paleogene Composite Total Petroleum 

System, which includes the Deformed Belt Assessment 

Unit, is structurally complex, and source rocks, reservoirs, 

and seals are juxtaposed in such a way that a single stratigraphic section is insufficient to describe the geology. The 

Menilite Shale, an organic-rich rock widespread throughout 

the Carpathian region, is the main hydrocarbon source rock. 

Other Jurassic to Cretaceous formations also contribute to oil 

and gas in the overthrust zone in Poland and Ukraine but in 

smaller amounts, because those formations are more localized 

than the Menilite Shale. 

The Paleozoic Composite Total Petroleum System is 

defined on the basis of the suspected source rock for two oil 

or gas fields in western Poland. The Paleozoic Reservoirs 

Assessment Unit encompasses Devonian organic-rich shale 

believed to be a source of deep gas within the total petroleum 

system. East of this field is a Paleozoic oil accumulation 

whose source is uncertain; however, it possesses geochemical 

similarities to oil generated by Upper Carboniferous coals.

The undiscovered resources in the North Carpathian Province are, at the mean, 4.61 trillion cubic feet of gas 

and 359 million barrels of oil. Many favorable parts of the 

province have been extensively explored for oil and gas. The 

lateral and vertical variability of the structure, the distribution 

and complex geologic nature of source rocks, and the depths 

of potential exploration targets, as well as the high degree of 

exploration, all indicate that future discoveries in this province 

are likely to be numerous but in small fields.

Introduction

In this report the petroleum systems that compose 

the North Carpathian Province, which includes parts of 

Poland, Ukraine, Czech Republic, and Austria (fig. 1), are 

discussed. In the Carpathian overthrust belt of southeastern 

Poland, the first oil well was drilled in 1854 and gas production began in 1921 (Karnkowski, 1996). As of 1993 in 

that part of the province, 67 oil fields and 15 gas fields had 

been discovered. 

North Carpathian Province

Province Boundaries

The North Carpathian Province within Poland, Austria, 

and the Czech Republic is part of the western Carpathian 

Mountains, whereas the Ukraine part of the province lies 

within the eastern Carpathian Mountains (fig. 2). The western 

Carpathian Mountains are part of the Alpine chain (Winkler 

and Slaczka, 1992). The region is bounded by the Central 

European platform to the north and northeast and by the Eastern European platform to the east. The Pieniny klippen belt is 

a salient forming the boundary south of the province (figs. 2, 

3), and the Carpathian–Balkanian basin lies southwest of the 

province. The Pannonian basin to the south of Austria and the 

Czech Republic delimits the province. The North Carpathian 

Province comprises two of the three segments of the Carpathian fold and thrust belt, the western Carpathian Mountains 

and the eastern Carpathian Mountains; the third segment, the 

southern part of the Carpathian Mountain chain, is part of the 

Carpathian–Balkanian Province. The North Carpathian Province is also divided into an inner and an outer segment. The 

inner segment encompasses thrust sheets that involve basement strata, and the outer segment consists of allochthonous 

Cretaceous and Paleogene terrigenous sequences (flysch) that 

were thrust northeastward onto the European foreland (Roca 

and others, 1995). 

The north edge of the North Carpathian Province 

straddles the tectonically disturbed southern boundaries of the 

Eastern and Central European platforms. This northern margin marks the limit of undisturbed, or autochthonous, Miocene marine deposits (that is, molasse). The Pieniny klippen 

belt (figs. 2, 3), a composite unit of continental and oceanic 

crust covered by Jurassic and Cretaceous sedimentary rocks 

folded and thrusted during the Late Cretaceous (Winkler and 

Slaczka, 1992), forms the south edge of the province. This 

 Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
Figure 1. Map showing location of North Carpathian Province and outlines of total petroleum systems in 

Eastern Europe (from U.S. Geological Survey World Energy Assessment Team, 2000).

Paleozoic Composite Total Petroleum System (404703)

North Carpathian Province (4047)

Mesozoic-Paleogene Composite Total Petroleum System (404702)

Isotopically Light Gas Total Petroleum System (404701)

EXPLANATION

POLAND

UKRAINE

ROMANIA

HUNGARY

SLOVAKIA

CZECH

REPUBLIC

AUSTRIA

CROATIA

SERBIA

 AND 

MONTENEGRO

BOSNIA AND

HERZEGOVINA

WARSAW

LVIV

BUDAPEST

BRATISLAVA

VIENNA

BRNO

KRAKOW

0 250 KILOMETERS

45°

50°

20° 25°

International boundary

North Carpathian Province 
0 100 KILOMETERS

50°

49°

48°

47°

46°

44°

16° 18° 20° 22° 24° 26° 28°

45°

51°

VIENNA

KRAKOW

CLUJ

BELGRADE

ZAGREB

BRATISLAVA

BUDAPEST

LVIV

BUCHAREST

AUSTRIA

POLAND

SLOVAKIA UKRAINE

HUNGARY

SERBIA

CROATIA

MOLDAVIA

ROMANIA

BULGARIA

CZECH

REPUBLIC

Inner zones

Ophiolites

Pieniny klippen belt

Alpine units Alpine outer units

Magura and Trans-Carpathian

 flysch units

Outer Carpathian

 flysch units

Carpathian foredeep Buried flysch units

Neogene volcanic rocks

EXPLANATION

Thrust faults, teeth in upper unit

Thrust fault, contact hidden

CENTRAL

EUROPEAN

PLATFORM

EASTERN

EUROPEAN

 PLATFORM

MOESIAN PLATFORM

TRANSYLVANIAN

BASIN

DINARIDES

MIESCHOW

DEPRESSION

LUBLIN-LVIV DEPRESSION

INNER

CARPATHIANS

APUSENI

MTNS

SOUTHERN CARPATHIANS

InnerCarpathians

PANNONIAN

BASIN Stebnik

Stebnik

Borislav-Pokuttia

Skole

Silesian

Magura

Dukla

Carpathian Foredeep

International boundary

Contact

Figure 2. Map showing location of Carpathian Mountains and other features in Eastern Europe (after Roca and others, 1995).

 Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
RZESZOW

TARNOW KRAKOW

ZAKOPANE

19°50’ 20°20’ 20°50’ 21°20’ 21°50 22°20’ 

Miocene molasse

Mesozoic

Pieniny klippen belt

International boundaryContact

Unconformable Miocene

Stebnik and coeval units

Borislav-Pokuttia unit

Skole unit

Sub-Silesian unitSilesian unitFore-Dukla unit

Dukla unit

Magura unit

Autochthon Allochthon (Outer Carpathians)

EXPLANATION

SLOVAKIA

49°15’49°30’49°45’50°00’50°15’

0 30 KILOMETERS

Magura

Skole

Silesian

Stebnik

Miocene Molasse

Fore-Dukla

Unconformable Miocene

Sub-Silesian

Sub-Silesian

Mesozoic

Pieniny Klippen Belt

Unconformable Miocene

Dukla

Figure 3. Main flysch nappes in Poland (from Bessereau and others, 1996).
feature separates the inner Carpathian Mountains from the 

outer Carpathian Mountains, the former being outside the 

assessment region. The western end of the province contains 

gas fields on an extension of the foredeep molasse depositional environment in Austria and the Czech Republic. The 

eastern end of the North Carpathian Province is the geographic boundary between Ukraine and Romania, where, as 

of 2005, oil and gas production has been limited.

Structural Setting

In the northern and eastern parts of the North Carpathian Province during Devonian to Permian time, the Western 

and Eastern European platforms were altered by widespread 

Variscan deformations that produced a series of northwestsoutheast-trending horsts and grabens. Late Permian to Jurassic rifting and Late Cretaceous to Paleocene inversions altered 

these structural features (Bessereau and others, 1996). Thick 

Paleozoic and Mesozoic sequences were deposited in the 

grabens, which became individual flysch depositional basins. 

The rocks in each basin later were thrust north and northeast 

over the stable European platforms during Cretaceous through 

Miocene time (figs. 2–4). Additionally, the flysch nappes 

overrode molasse deposits that were filling, from the north, a 

foreland basin (the Carpathian foredeep) created in response 

to the thrusting. The disturbed part of the molasse zone, 

referred to as the “allochthonous Miocene zone,” is located 

at the point where the molasse deposits are stratigraphically 

integrated with the flysch units, near the middle of the province. Molasse deposition persisted through Neogene time, and 

Neogene deposits unconformably overlie the nappes on their 

northern edge (fig. 3).

The outer Carpathian Mountains (also known as the 

Flysch Carpathians; figs. 2–4), which form the next major 

tectonostratigraphic assemblage south of the autochthonous, 

undisturbed Miocene molasse, consist of major Cretaceous 

through Oligocene flysch nappes. These nappes are a succession of sandstone and shale units thrust to the north over 

Miocene rocks of the Carpathian foredeep (northern boundary 

delimited by the extent of the Miocene marine deposits and 

southern boundary by the Carpathian overthrust; Karnkowski, 

1994). The flysch strata show highly variable lateral and 

vertical facies and large thickness changes because the basin 

floor was segmented into highlands and subbasins during 

successive compressional events (Bessereau and others, 1996; 

Karnkowski, 1999). These variations result from the diachronous nature of the Carpathian Mountains, which formed 

during the collision of Africa with southern Europe during 

Cretaceous through Miocene time. The collision deformed 

the Carpathian Mountains from southwestern Poland through 

Ukraine and into Romania and Bulgaria in a clockwise 

direction. The flysch strata overlie Paleozoic–Mesozoic and 

Precambrian rocks (Karnkowski and Ozimkowski, 1998).

The loading of the European foreland by a succession of 

thrust nappes caused its progressive flexural subsidence and 

the development of the Paleocene Carpathian foreland basin 

(Oszczypko, 1997). In places this north-northeast thrusting 

resulted in as much as 180 km of crustal shortening (Ellouz 

and Roca, 1993; Roure and others, 1993). From the late Oligocene onward, the tectonic pattern was modified by progressive 

emplacement of the outer Carpathan nappes and emergence of 

structural highs, which supplied sediments to adjacent basins. 

In middle Miocene time, the foredeep was formed and filled 

from the north with molasse, a fine and coarse clastic series 

deposited in a marine environment (Bessereau and others, 

1996). Postorogenic uplift and erosion prevailed in the outer 

Carpathan Mountains from late Miocene time. 

In western Poland, flysch overthrusts generally take a lowangle structural attitude, but near the Poland-Ukraine border a 

prominent Precambrian basinal high interfered with overthrusting and deflected several of the thrust sheets, impeding their 

northeasterly directed progress and forming thick, complex, 

stratigraphic packages in which beds are repeated and source 

and reservoir rocks of different ages are juxtaposed. 

In Austria and the Czech Republic, the molasse units 

of the outer Carpathan Mountains rest upon autochthonous 

Paleogene to Neogene rocks, which in turn overlie Mesozoic 

strata. The molasse, consisting of sandstones, shales, and 

conglomerates, is younger than the molasse of Poland and 

Ukraine owing to the asynchronous nature of the thrusting and 

resulting foredeep development. 

Stratigraphy

The Carpathian foreland basin is divided into two major 

units: the folded and thrusted flysch belt and the Carpathian 

foredeep (fig. 2). Within Poland, Upper Cambrian–Permian 

sedimentary rocks overlie a Precambrian metamorphic and 

crystalline basement. The Paleozoic strata contain thick 

Devonian red clastic and carbonate rocks overlain by Lower 

Carboniferous carbonate rocks and several hundred meters of 

Namurian clastic rocks that accumulated in grabens partially inverted during the Paleocene (Bessereau and others, 

1996). At the southern edge of the area underlain by Miocene 

molasse, the flysch interfingers with and is folded into the 

molasse, which it also partly overthrusts. 

In the western part of the region, the foredeep is a narrow, relatively shallow basin (about 500 m deep); it widens 

and deepens to the east (fig. 2). It is filled with autochthonous 

Miocene molasse sediments (Winkler and Slaczka, 1992; 

Bessereau and others, 1996; Koster and others, 1998a) consisting mainly of a fine to coarse clastic series deposited in a 

marine environment. 

The autochthonous molasse is divided into three major 

lithological units, which are mainly of middle Miocene age 

(Badenian and Sarmatian) (fig. 5): (1) a lower unit of red 

algal limestone, sandstone, and shale as much as 70 m thick, 

which originated mainly as deltaic and turbidite sediments; (2) 

a middle unit, as much as 45 m thick, of evaporates, gypsum, anhydrites, and rock salts; and (3) an upper siliciclastic 

unit that contains gray-green claystones in the lower part, 

30–180 m thick, overlain by a thick (as much as 1,800 m) 

 Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
claystone–sandstone sequence of Sarmatian age (Karnkowski 

and Ozimkowski, 1998).

 Much of the flysch is a complex of submarine fan facies 

consisting of interbedded, predominantly terrigenous, gravityflow and hemipelagic deposits (Izotova and Popadyuk, 1996). 

In Poland, the flysch nappes, named in order from north to 

south (figs. 2–4), are (1) the Skole nappe, in the eastern part 

of the Polish outer Carpathan Mountains and in Ukraine, 

composed of Lower Cretaceous to lower Miocene sediments; 

(2) the sub-Silesian nappe, a thin sequence of Cretaceous and 

Paleogene strata; (3) the Silesian nappe, present in the entire 

outer Carpathan Mountains and composed of uppermost 

48°

49°

50°

Porkulets

Dukla

Krosno

Chornogora

Skiba

Trans-Carpathian depression

Pieniny klippen belt

Boryslav-Pokuttia

Sambir

Bilche-Volytsia

Eastern European Platform

Marmarosh

Rakhiv

EXPLANATION

0 100 KILOMETERS

23° 24° 25° 26°

POLAND

ROMANIA

LVIV

BORYSLAV

UZHGOROD

EASTERN EUROPEAN

 PLATFORM

Sambir

Skiba

Krosno

Chornogora

Pieniny Klippen Belt

Dukla

Porkulets

Marmarosh

Rakhiv

Boryslav-Pokuttia

Bilche-Volytsia

TRANS-CARPATHIAN

DEPRESSION

Figure 4. Main flysch nappes in Ukraine (from Koltun and others, 1998).

North Carpathian Province 
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

Sandstone

Siltstone, mudstone

Black shale

Evaporites

Limestone

Chert

Unconformity

Oil reservoir interval

EXPLANATION

Lithology Formations

(thickness in meters) Age Ma Mediterranean

 Central

Peri-Tethys

 

SW NE ? ?

?

Molasse

(0–2,000)

Bystrytsia (250)

Vygoda (200)

Maniava (250)

Yamna (100–250)

Stryi

(1,000–2,000)

Spas/Shypot

(250–500)

Cretaceous Miocene

Lower Upper

Eocene

Oligocene Egerian Eggenburgian

Krosno Beds

Lower

M Upper

Menilite

(250−

600)

(0−

250) (0−1,200)

Main Organic-rich Facies

Aquitanian

Burdigalian

Langhian

Serravallian

Tortonian

Messinian

Quat.

Romanian

Dacian

Pontian

Pannonian

Sarmatian

Badenian

Karpatian

Ottnangian

Eggenburgian

Egerian

Plio. Miocene Early Middle Late

Paleocene

Figure 5. Stratigraphic column for the flysch belt in Ukraine (from Koltun and others, 1998). Plio., Pliocene; 

Quat., Quaternary.

Jurassic to Oligocene rocks; (4) the Dukla nappe, the 

uppermost tectonic unit of the outer Carpathian Mountains, 

which is composed of thick, highly deformed Cretaceous to 

Paleogene deep-water flysch and late Oligocene and earliest 

Miocene (Aquitanian) molasse sequences; and (5) the Magura 

nappe, which comprises the Cretaceous to middle Miocene 

flysch succession. 

In Ukraine, the flysch nappes forming the external 

Carpathian Mountains are Early Cretaceous to early Miocene. 

The Boryslav–Pokuttia nappe, the northeastern most nappe 

(fig. 4), which is present only in Ukraine, consists of a stack 

of duplexes made up of Upper Cretaceous to lower Miocene 

flysch overlain by molasse. To the southeast are the Skiba 

(equivalent to the Skole nappe in Poland), Krosno (equivalent 

to the Silesian nappe in Poland), Chornogora, Dukla, Porkulets, 

Rakhiv, and Marmarosh nappes (fig. 4). Located northeast of 

the Boryslav–Pokuttia nappe are two molasse units the Sambir, 

composed of folded molasse strata of early Miocene (Eggenburgian to Ottnangian) age (Koltun and others, 1998), and the 

Bilche–Volytsia (Koltun and others, 1998). A zone of deformation marks the contact between the nappes and molasse.

 Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
Geochemistry of Oil in Poland

and Ukraine 

The Carpathian foredeep and the Carpathian nappe 

complex are part of one of the largest petroleum provinces in 

central Europe (Ulmishek and Klemme, 1990). Four potential 

hydrocarbon source rocks, ranging in age from Devonian to 

Miocene, are identified within the North Carpathian Province. 

Owing to the complex geologic structure, the diachronous 

emplacement of the thrust sheet, and extensive erosion, a 

given source rock can be immature in one place and overmature in another as a function of its stratigraphic position 

or its position in an individual thrust sheet. ten Haven and 

others (1993) recognized two oil families within the Carpathian nappes and the Polish part of the foredeep. Reservoir oils 

and seeps from Cretaceous to Oligocene reservoirs within the 

Carpathian nappes were sampled, as were reservoir oils from 

Carboniferous to Miocene in the foredeep. In addition, rock 

samples from Lower Cretaceous rocks and Menilite Shale 

(fig. 6) in the nappes were examined for correlations between 

oil and source rock. 

The first oil family is represented by a sample from 

the Nosowka-1 well, which penetrates a Lower Carboniferous carbonate reservoir in the foredeep (fig. 11). To date, no 

source rock is specifically associated with this oil. The second 

oil family includes all nappe oils and a number of foredeep 

samples except for Nosowka-1. Oleanane and other biomarkers derived from angiosperms (land plants) indicated a probable Cretaceous or Tertiary source. Further divisions were 

made within the second oil family on the basis of biomarkers 

and sulfur content. Sulfur content of these samples ranged 

from <0.1 to 2.27 percent, and the foredeep oils had sulfur 

content higher than that of oils from the nappes. The lateral 

and vertical variations in the types of organic matter in the 

Menilite Shale likely cause these differences. 

To determine petroleum-generation potential of the main 

organic-rich sequences that extend across a basin in the flysch 

belts, Koltun and others (1995) examined Lower Cretaceous 

strata and the Oligocene–Miocene Menilite Shale from the 

Skole unit of the Polish Carpathian Mountains (figs. 3, 6) 

and the Boryslav–Pokuttia and Skiba units of the Ukrainian 

Carpathian Mountains (fig. 4). Rock-Eval results showed that 

the Menilite Shale had favorable source-rock properties on a 

basin-wide scale: total organic carbon values were as much as 

18.5 percent and were commonly 4–6 percent in the Ukrainian samples. Samples from the Polish Carpathian Mountains 

were as much as 7.35 percent and were commonly 2–4 percent. The Cretaceous Spas beds in Polish samples contained 

favorable total organic carbon values that were as much as 

4.13 percent and were commonly 1–2 percent; in Ukrainian 

samples, total organic carbon values were as much as 4.87 

percent and were generally 2–4 percent. 

ten Haven and others (1993) analyzed rock samples 

from the Oligocene–Miocene Menilite Shale and from Lower 

Cretaceous rocks. They measured total organic carbon values 

that ranged from 2.15 to 22.15 percent and hydrogen index 

values that ranged from 300 to 650 milligrams of hydrocarbon per gram of total organic carbon (mg HC/g TOC). The 

Cretaceous sample had a TOC value of 3.47 percent and a 

hydrogen index of 53 mg HC/g TOC. From these data they 

determined that the Menilite Shale is a good potential source 

rock. The Cretaceous sample did not show similar promise 

as a source rock, even though it contained organic matter of 

type II (marine origin) and type III (terrigenous origin). In 

light of the biomarkers and total organic carbon values, the 

Menilite Shale (the source for the second oil family) appears 

to be the major source for the hydrocarbons in the nappe 

sequence. 

Koster and others (1998b) recorded total organic carbon 

values as high as 18 percent in the Menilite Shale; more than 

80 percent of the organic matter was present in the black 

shale unit. A mean total organic carbon value of 3.5 percent 

was calculated for all rock types in the formation in southeastern Poland (black and gray shale, sandstone, gray mudstone, chert, and siliceous shale) (Koster and others, 1998a). 

Koster and others (1998b) examined facies differences 

between the upper and lower Menilite Shale and suggested 

that differences in the depositional sites explain variations 

in the organic matter. That is, continental slopes that receive 

organic matter but little clastic material tend to accumulate 

sediments in which the organic matter has a higher hydrogen 

index. In contrast, samples from the upper Menilite that had 

a higher clastics content would result in a correspondingly 

lower hydrogen index produced by a mix of organic matter that contained larger amounts of recycled, or previously 

deposited, organic matter. 

The hydrogen index was observed to differ among the 

various thrust sheets in southeastern Poland. Values as high 

as 350 mg HC/g TOC were measured in black shale samples 

from the lower Menilite Shale in the Skole and the ForeDukla units (fig. 3), whereas lower hydrogen index values, 

<300 mg HC/g TOC, were measured in samples from the 

upper part of the sequence in the Skole unit (Koster and 

others, 1998b). Variation in hydrocarbon index is related to 

differences in the type and concentration of organic matter in 

different locations.

Thermal maturity is measured by Tmax (a laboratoryderived thermal maturity indicator) and vitrinite reflectance. The Menilite Shale is generally thermally immature 

to marginally mature in southeastern Poland, depending 

on the thrust sheet. Tmax values for samples from the Skole 

unit ranged from 400° to 418°C and the Ro was 0.3–0.35 

percent—a value that is well below the generally accepted 

threshold of oil generation of about 0.7 percent. The low 

maturity values show that the various units did not undergo 

sedimentary or tectonic burial during Neogene overthrusting (Koster and others, 1998a). In contrast, samples from the 

Fore-Dukla and the Dukla nappe near the Ukraine border had 

Tmax values in the overmature range for oil generation. ten 

Haven and others (1993), in an analysis of isotopic composition of 33 oils from the foredeep and overthrust region in 

Geochemistry of Oil in Poland and Ukraine 
Figure 6. Stratigraphic chart of flysch strata in Polish nappes (from Slaczka, 1996). Fm, Formation; Ss, sandstone. Color blocks in Explanation refer 

Burdigalian

Aquitanian

Chattian

Rupelian

Priabonian

Bartonian

Lutetian

Ypresian

Maastrichian

Campanian

Santonian

Coniacian

Turonian

Cenomanian

Albian

Aptian

Barremian

Hauterivian

Valanginian

Berriasian

Tithonian

Kimmeridgian

Ma Epoch Age Skole Sub-Silesian Silesian Dukla Mag

Weglowka 

Marls

Krosno Beds

Kliwa Ss Menilite Shale

Menilite Chert

Globigerina Marls

Popiele Beds Green Shales

Hieroglyphic

Beds

Hieroglyphic

Beds

Babica

Clay

Wegierka

Marl

Inoceramian

Beds

Ciezkowice Ss

Upper Istebna Shale

Upper Istebna Ss

Lower Istebna Shale

Lower Istebna Sandstone

Variegated

Shales Godula Beds

Grodziszcze Ss

Grodziszcze Ss Verovice Shales

Lgota Beds

Galze Beds

Spongiolites

Mazanka Ss

Cergowa Beds

Przybyszow Ss

Hieroglyphic Beds

Majdan Beds

Cisna Beds

Lupkow Beds

Supra Magura Magura Beds Glauco 

Pasierbiec Ss

H

Ciezkowice Ss

Inocerami

Vari

? Green and Radio?

?

?

?

?

?

Green and Radiolarian Shales

Spas Shales

Siliceous Marls

Kuzmina Ss

Belwin Marls

Upper Cieszyn Beds

Cieszyn Limestones

Lower Cieszyn Beds

Jurassic Cretaceous Paleocene Eocene Oligocene Miocene

?

20

30

40

50

60

70

80

90

100110

120

130

140150

Formation information uncertain

EXPLANATION

Thick-bedded sandstones and conglomerates

Thick-bedded sandstones

Thin- to thick-bedded sandstones, shales

Thin- to medium-bedded sandstones, shales

Medium- to thin-bedded sandstones, shales

Thin- to medium-bedded sandstones, black shales

Green shales

?
Poland, found that all but one sample plot within a group that 

is associated with an algal origin and that contains oleanane, 

an indicator of an angiosperm origin. The exception is an oil 

from the Nosowka-1 well that has a notably lighter isotopic 

signature.

Oil in the Lower Cretaceous–Oligocene flysch units is 

aliphatic and sulfur-free and contains 3.5–7.0 percent paraffin. Density ranges from 0.75 to 0.93 g/cm3

. The Carpathian 

foreland oils in Upper Cretaceous sandstones and Jurassic 

limestone and Carboniferous rocks are light to medium in 

weight. Density ranges from 0.81 to 0.86 gm/cm3, sulfur 

content from 0.45 to 0.85 percent, and paraffin content from 

2.32 to 9.37 percent (Gorecki and Weil, 1998) oil contains 

0.5–0.7 percent paraffin by weight and as much as 7 percent 

sulfur by weight (Slaczka, 1996).

In the Bilche-Volytsia zone, oil in small oil fields 

producing from Jurassic limestones has a specific gravity 

of 0.973–1.014. The gravity of oil samples from southeastern Poland ranged from 14° to 60° API; the majority of the 

samples lay between 31° and 44° API. The lower values 

are believed to be due to biodegradation. Sulfur in the same 

Carpathian samples ranged from <0.1 to 2.27 percent. Oils 

sampled from the foredeep generally had higher sulfur content than oils from the overthrust units (ten Haven and others, 

1993).

Miocene Gas

Early studies of Miocene gas in Poland and Ukraine 

reported its source to have been Paleozoic–Mesozoic strata 

(Kotarba and others, 1987), but later studies demonstrated 

that Miocene rocks themselves (mainly autochthonous Badenian and lower Sarmatian) were the actual source (Bessereau 

and others, 1996; Kotarba and others, 1987, 1998). Kotarba 

(1992, 1998) assigned a biogenic origin to all of the gas 

in the Miocene molasse of Poland, and Koltun and others 

(1995) reached the same conclusion for gas in the Ukrainian 

molasse. In the molasse area of Austria, most of the produced gas is also of biogenic origin (Ladwein, 1988). 

Kotarba and others (1987) report high wet gas (methane content) values of 0.992 and carbon isotope values in 

the –62.8 to –70.8 range. The combination of these values, 

along with a lack of correlation of these values with depth, is 

evidence for an anaerobic microbial source for the gases. 

Analyses of 80 samples of marine shale from the 

autochthonous Miocene molasse from the western, central, 

and eastern Polish Carpathian Mountains recorded low values of total organic carbon (0.5–0.8 percent) and of hydrogen 

index (<120). Additional tests indicated a probable terrigenous source for the organic matter. Gas in the Carpathian 

foredeep has a high methane and low nitrogen content. 

Potential Source Rocks

Oligocene and Miocene Potential Source Rocks

In Poland, gas fields are found only in Miocene 

molasse. West of Krakow these strata are of Badenian and 

Karpatian age (figs. 5, 6), whereas to the east they are 

lower Sarmatian and Badenian. The lower Sarmatian and 

upper Badenian sediments are a clayey-sandy facies of 

mostly deltaic sediments, and the lower Badenian sequence 

comprises chemical deposits and shallow-water detrital clay 

sediments (Kotarba and others, 1987). The thickness on 

the western side approaches 1 km and on the eastern side 

exceeds 3.5 km.

Concentrations of kerogen in Sarmatian and Badenian 

strata attain as much as 2.1 percent (average 0.82 percent) 

and 3.4 percent (average 0.88 percent) total organic carbon, 

respectively (Kotarba, 1992). These concentrations indicate 

potential for hydrocarbon generation. Petrographic analyses determined that the organic matter was terrigenous type 

III. A Tmax produced by pyrolysis was 435°C and vitrinite 

reflectance ranged from 0.40 to 0.68 percent; these values 

indicate a level of maturity representing the beginning the 

oil window. The geothermal gradient of 34°C/km is low, and 

temperatures measured 2.5 km north of the edge of the overthrust were a maximum of 90°C (Kotarba and others, 1987). 

Low Tmax values indicate that the Miocene rocks at depths 

of 3.2–3.3 km are immature. Below 3.3 km, strata lie at the 

onset of thermogenic processes under the Carpathian flysch 

overthrust (Kotarba and others, 1998).

The isotope carbon values appear to indicate that generation conditions are consistent with depth and that gases 

were generated mainly as a result of anaerobic microbial 

action on the organic matter (Kotarba and others, 1987).

The sources of isotopically light gas in Poland are 

upper Badenian and lower Sarmatian rocks of the autochthonous Miocene sequence in the Carpathian foredeep. These 

rocks contain type III organic matter in concentrations of 

0.02–3.22 wt percent, concentrations that indicate probable 

immaturity to a depth of 3.2 km. Insignificant changes in 

other geochemical parameters (total organic carbon, hydrogen index, and vitrinite reflectance) laterally and with depth 

indicate a consistent depositional environment (Kotarba and 

others, 1998). Carbon isotope values of methane range from 

–70.8 to –62.8 ppt (parts per thousand). 

Menilite Shale 

In the flysch Carpathian region, the Oligocene Menilite 

Shale (identified as Oligocene–lower Miocene in Koltun and 

others, 1998) is the principal source of hydrocarbons. The 

formation is at the top of the flysch complex and is unconformably overlain by molasse. Source rocks in Ukraine are 

primarily in the Boryslav–Pokuttia and Skiba units (fig. 4), 

but in the Polish Carpathian Mountains they are only within 

Potential Source Rocks 11
the Skole flysch unit (Koltun and others, 1995). The thickness and organic content of the Skole are variable across 

the region owing, at least in part, to a northeasterly shifting 

depositional basin. The lower facies of the Menilite Shale 

was slowly replaced by the Krosno Formation in southeast 

Poland and southwest Ukraine, as marked by the changing 

volume and type of organic matter. Mainly amorphous type 

II matter, which contains little terrestrial plant material, was 

diluted as pelagic and hemipelagic, anoxic, depositional 

regions began receiving increasing amounts of clastic material. The boundary between the Menilite Shale and Krosno 

Beds (fig. 6) is diachronous owing to the easterly shift of the 

basin depocenter (Koltun, 1992). (The age designation of the 

Krosno Beds (fig. 5) and Menilite Shale is variable, apparently by location. For example, the Krosno Beds are identified as Oligocene near eastern Poland by Karnkowski and 

Ozimkowski (1998) and as Oligocene-lower Miocene near 

western Ukraine by Koltun and others (1998)).

The Menilite Shale in Poland is characterized by dark 

gray and black, mostly laminated, noncalcareous shales with 

intercalated chert and siliceous shales (Koster and others, 

1998b). The formation is as much as 100 m thick in the 

Silesian thrust sheet and 900 m thick in the Dukla basin; 

combined with the Krosno Formation, thickness ranges from 

1,200 m in the Skole basin to 4,000 m in the Dukla basin. In 

Ukraine, the Menilite Shale reaches a maximum thickness of 

more than 1,500 m in the Skole nappe but is only a few tens 

of meters thick in the innermost part of the outer Carpathian 

Mountains. Subsequent overthrusting and folding of much 

of the Carpathian region led to the development of packages 

of source, reservoir, and seal rocks over a wide area. The 

formation is mature in some places but immature in others; 

in southeast Poland, it is immature to marginally mature at 

outcrop. The thermal maturity of the organic matter in outcrop 

increases from the outer flysch nappe units toward the inner 

units. Lateral variations also exist within individual inner units 

(Koster and others, 1998b).

In Poland, total organic carbon values for the Menilite 

Shale are as much as 22.15 percent, and hydrogen indices 

are as much as 700 mg HC/g TOC (ten Haven and others, 

1993; Bessereau and others, 1996). Koltun and others (1995) 

reported total organic carbon values as high as 7.35 percent 

(mainly in the 2–4 percent range) in surface and subsurface 

samples of Menilite Shale near the Ukraine border. Koster 

and others (1998a) listed 3–10 wt percent for the black shales 

in southeastern Poland. On the basis of three sample sites 

in Poland (two from the Silesian basin and one from the 

Skole basin), the highest values of total organic carbon and 

hydrogen index consistently are from the lowest part of the 

formation, just above a marl facies interval. Organic matter 

is predominantly amorphous marine, but there is also a slight 

amount of terrigenous material (Bessereau and others, 1996). 

As in Ukraine, both total organic carbon and hydrogen index 

decrease higher in the stratigraphic section. In Poland and 

Ukraine, type II organic matter from a marine, sapropelic 

source predominates. Kruge and others (1996) analyzed 

Menilite Shale and mudstone samples from southeast Poland 

and found total organic carbon values from 0.6 to 10.7 

percent; hydrogen indices from 400 to 860 mg pyrolyzate/g 

TOC, and oxygen indices from 18 to 197, indicative of a type 

I/II kerogen. Rock-Eval values indicated immature samples 

north of the Ukraine border; they increased in maturity toward 

the border. Predominant alginite organic matter but minimal 

vitrinite was visible in a petrographic examination. 

Koster and others (1998b) reported, on the basis of RockEval analyses, that Menilite Shale samples from the Skole 

flysch nappe and the Silesian flysch nappe in southeastern 

Poland were thermally immature. The thermal maturity of 

exposed Menilite Shale is at a pretectonic (immature) level 

because the rocks did not undergo deep sedimentary burial. 

Burial owing to overthrusting, however, caused the general 

increase in maturation levels (Koltun and others, 1995).

In Ukraine, the Menilite Shale extends across the entire 

flysch belt (external Carpathian Mountains), though it is 

primarily in the Boryslav–Pokuttia and Skole (equivalent to 

Skiba unit in Ukraine) flysch nappes (fig. 4). This formation 

is the youngest part of the Carpathian flysch sequence and 

is overlain unconformably by the Neogene molasse (Koltun, 

1992). The Menilite Shale reaches a maximum thickness of 

1,500 m in the outer Skole nappe. Owing to thrusting, the 

formation crops out in some places and is buried as deeply 

as 6 km in others. It is differentiated into lower, middle, and 

upper units that differ in areal extent, thickness, and content 

of organic material. The lower unit, because of its basin-wide 

extent and high organic matter content (exceeding 20 percent 

locally; average 4–8 percent) in the outermost tectonic units, 

is considered the principal source rock in the flysch zone and 

in the foredeep (Koltun and others, 1998). The other two units 

are deficient as source rocks. Organic matter is sparse in the 

middle unit and of only local extent in the upper unit. The 

Menilite Shale is immature to a depth of about 4 km, and it 

appears to maintain petroleum potential to about 6 km (Koltun 

and others, 1995, 1998). 

Krosno Formation and Menilite Shale Equivalents

In Poland, the Oligocene-Miocene Krosno Formation 

had low total organic carbon (<1 percent) and a low hydrogen index (<200) at all sampled localities. As compared with 

the Menilite Shale, it is interpreted to have been deposited in 

deeper, more oxygenated water (Koltun, 1992). Its type III 

organic matter is low in quality and quantity, which probably 

makes this formation a substandard source rock. 

In Ukraine, as one moves to the southwest within the 

flysch units, the lower, organic-rich section of the Menilite 

Shale is systematically replaced by the Oligocene Krosno 

Beds (figs. 4, 5), a shale and sandstone unit with organic carbon content commonly <1 percent. The diminishing organic 

content from northeast to southwest across the basin accounts 

for the variability of the Krosno Beds as a source rock and 

limits its potential to generate hydrocarbons. 

12  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
Cretaceous Potential Source Rocks

Spas and Shypot Formations

In Ukraine and Poland, the Lower Cretaceous (Barremian to Albian) Spas Formation lies at the base of the flysch 

complex in the outer part of the Carpathian Mountains (figs. 

5, 6). This formation is present only within the Skiba (Skole) 

nappe (fig. 3), where the lower part consists of more than 

200 m of black shale with minor sandstones and siltstones; 

in that lower part the total organic carbon is generally greater 

than 2 percent and may exceed 7 percent. Organic matter is 

types II and III, mostly from a terrestrial source. Although 

burial through time by overthrusts increased the maturation levels (Koltun and others, 1995), outcrop samples were 

thermally immature, and at a depth of more than 4.4 km 

the rocks are still within the oil window (Koltun and others, 1998). In Ukraine, the Lower Cretaceous (Barremian to 

Albian) Shypot Formation (fig. 5) lies in the more internal 

nappes­—the Chornogora, Dukla, and Krosno (fig. 4). The 

formation has 300 m of black shale and minor sandstones 

and siltstones at its base. Total organic carbon values are 

as much as 8 percent but average 2– 4 percent of mostly 

types II and III organic matter. On the basis of Tmax thermal 

maturity values of 454°– 458°C, samples as deep as 3.6 km 

corresponded with the beginning of the oil window. The two 

formations are considered to have potential as petroleum 

source rocks (Koltun and others, 1998).

In Poland, the Lower Cretaceous Spas Formation is 

predominantly black shale with thin interbedded sandstones 

in the lower part. It is present throughout the Skole basin in 

eastern Poland (figs. 2, 3) and also at the base of the flysch 

zone in the outer Carpathian Mountains. Total organic carbon 

values ranged from 1.5 to nearly 4 percent and average 2 percent; hydrogen indices ranged from 90 to 180. A Tmax value 

of 442°C placed the organic matter in the early oil window 

range. Koltun and others (1995) reported total organic carbon 

values as high as 7.35 percent, but generally they are in the 

2– 4 percent range; organic matter is type II and III kerogen 

and thus more apt to produce gas. Kruge and others (1996) 

reported vitrinite reflectance values of 0.45 and 0.47 percent 

(immature to marginally mature) in two shale samples from 

southeastern Poland. The measurements were apparently 

made on recycled organic matter and therefore may represent a higher maturity than actually exists. Because type III 

kerogen predominates, this formation may be a viable source 

rock within the Skole basin.

Other Potential Source Rocks

Another potential source rock in Poland is in the upper 

part of the lower Neocomian Cieszyn Shale, though geochemical analyses indicated that its potential is much lower 

than that of the Menilite Shale (fig. 6). The upper Cieszyn 

unit is as much as 300 m thick, has total organic carbon 

values of 1.5–3 percent (average 2 percent from type III 

organic matter), and a hydrogen index of 100 mg HC/g TOC. 

The hydrogen index is considered too low for the Cieszyn 

Shale to be a high-quality source rock, and it is unlikely that 

this unit has contributed hydrocarbons to oil and gas pools 

(Bessereau and others, 1996).

The Upper Cretaceous–Paleocene Istebna beds (fig. 6), 

in the eastern Polish Carpathian Mountains, have a gross 

thickness of 50–1,800 m and are composed of thick-bedded 

sandstones separated by thin-bedded sandstones and black 

shales. Two major depositional facies are present in the 

formation: channel-fill and lobe deposits, and channel-fill 

submarine mudflow deposits (Klecker and others, 2001). 

Samples from the Istebna and Inoceramian strata (fig. 6) 

yielded low average total organic carbon (0.6 percent) and 

low hydrogen indices (<130 mg HC/g TOC) that indicate 

minimal source-rock potential.

A single sample of lower Neocomian (Lower Cretaceous) shale showed more favorable results: total organic 

carbon was as high as 1.5 percent and the hydrogen index 

was 120. These findings were balanced by a Tmax > 455, 

which represents the high end of the oil window. This rock 

unit’s source potential appears to be limited (Bessereau and 

others, 1996). 

The Lgota Formation covers a wide area of the Silesian 

and sub-Silesian basins and the Fore-Dukla zone in Poland 

(fig. 3). In this formation (on the basis of limited sampling), 

average total organic carbon was 1 percent and hydrogen 

index was 100 mg HC/g TOC; these values are low and indicate limited potential as a source rock.

Jurassic Potential Source Rocks

In Ukraine, the Middle Jurassic Kokhanivka Formation, organic-rich shale about 500 m thick, is present in the 

northwest part of the foredeep. In samples from 2.3 to 2.5 km 

depths, analyzed by Rock-Eval, total organic carbon values 

exceeded 12 percent locally and a type II kerogen was present, which indicates excellent petroleum potential. Thermal 

maturity parameter Tmax ranged from 434° to 438°C, values 

that indicate maturity at the beginning of the oil window 

(Koltun and others, 1998).

In southeastern Poland, an Upper Jurassic carbonate 

rock is believed to be the source of a thermogenic gas in an 

area that otherwise would be expected to produce only biogenic gas. A cross section by Kotarba (1998) shows Jurassic 

rocks lying beneath a thin sequence of lower Badenian rocks, 

presumably containing oil-prone, marine organic matter at a 

maturation level of 1.1–1.6 percent. Although production is 

unusual for this area of the Carpathian foredeep, some oil is 

produced from this interval (Kotarba, 1998).

A nearly 500-m-thick Middle Jurassic organic-rich shale 

sequence (with minor sandstones and siltstones) is present in the northwestern part of the foredeep. Locally these 

rocks have a high total organic carbon content, greater than 

Potential Source Rocks 13
(<130 mg HC/g TOC), indicating minimal source-rock 

potential.

A single sample of a lower Neocomian (Lower Cretaceous) shale showed more favorable results: total organic 

carbon as high as 1.5 percent, and a hydrogen index of 120. 

These findings are mitigated by a Tmax > 455, which equates 

to the high end of the oil window. This rock unit’s source 

potential appears to be limited (Bessereau and others, 1996). 

The Lgota Formation covers a wide area of the Silesian 

and sub-Silesian basins and the Fore-Dukla zone in Poland 

(fig. 3). In this formation (on the basis of limited sampling), 

average total organic carbon is 1 percent and hydrogen index 

is 100 mg HC/g TOC; these values are low and indicate limited potential as a source rock.

Reservoir Rocks

Biogenic gas forms the main hydrocarbon accumulation in the Carpathian foredeep, which includes the 

Bilche-Volytsia zone (in the little-deformed Carpathian 

foredeep) and in the frontal Carpathian structures of the 

Sambir unit (in the Carpathian thrust belt; figs. 2, 3). Reservoir potential of the autochthonous foreland is restricted 

to Upper Jurassic carbonate rocks and Lower Cretaceous, 

Paleogene, and Neogene sandstones (Sovchik and Vul, 1996). 

In the Bilche-Volytsia zone (fig. 4), commercial oil flow rates 

were obtained from Paleogene sandstones in several fields at 

depths ranging from 4,080 to 5,796 m. 

Upper Cretaceous and Upper Jurassic rocks in the southeast part of the foredeep host oil accumulations beneath the 

flysch that are sealed by Miocene molasse. 

Cretaceous and Eocene sandstones are highly productive 

within the Silesian nappe of eastern Poland (fig. 6). Eocene–

Oligocene sandstones are productive in the Skole (Poland) 

and Skiba (Ukraine) units, and sandstones within the Krosno 

Beds are the youngest productive horizons of Oligocene age 

(Karnkowski, 1996). In the Carpathian Mountains, oil is present in narrow, predominantly steep, overthrust and imbricated 

folds as much as 30 km long. These folds are commonly 

dissected by transverse and longitudinal faults that bound 

numerous blocks (Karnkowski, 1996). 

The Kliwa Sandstone, enclosed within the Menilite 

Shale, the Ciezkowice Sandstone, and both Lower and 

Upper Cretaceous sandstone (fig. 6) are the most productive reservoir rocks in the flysch Carpathian Mountains. The 

most productive structural unit is the Silesian nappe (fig. 6) 

(Karnkowski and Ozimkowski, 1998, Karnkowski, 1999). 

The Paleozoic and the Mesozoic basement are considered to have the best potential for reservoirs after the flysch 

sequences. 

12 percent, and Rock-Eval showed a type III kerogen with 

excellent petroleum potential. Tmax values of 434°– 438°C 

indicated that the formation is in the initial stages of oil generation (Koltun and others, 1998).

Paleozoic Potential Source Rocks

Because of limited drilling, not much is known about 

the source-rock potential of older rocks in the North 

Carpathian Province. Data indicate that Lower Carboniferous 

black shale or silty shale in the northernmost Skole nappe 

have total organic carbon values of about 1.5 percent but 

low hydrogen indices (near 100 mg HC/g TOC). Additionally, these data indicate that Lower Carboniferous coal from 

the west end of the Polish Carpathian Mountains showed 

good petroleum potential—total organic carbon values of 47 

percent and hydrogen index values of 450 (Bessereau and 

others, 1996). In western Poland, southwest of Krakow, drilling also revealed a Devonian source rock beneath the folded 

and thrusted flysch nappes. The Lachowice-1 well was 

drilled through 3.2 km of flysch and 750 m of autochthonous 

Miocene rocks to Devonian carbonate rocks to establish the 

first gas field in the western Carpathian Mountains (Pietsch 

and others, 1997) (fig. 11). Oil from the isolated Nosowka 

area appears to be from Devonian or Carboniferous shales 

(fig. 11).

More than 500 m of Silurian rocks are present in the 

autochthonous foreland, partially overthrust by the Carpathian allochthon. Rock-Eval analyses found total organic 

carbon values from 0.24 to 0.68 percent but no S2 peak. The 

rocks appear to have no generative potential (Koltun and 

others, 1998). 

Other Potential Source Rocks

Another potential source rock in Poland is in the upper 

part of the lower Neocomian Cieszyn Shale, though geochemical analyses indicate that its potential is much lower 

than that of the Menilite Shale (fig. 6). The Cieszyn unit is as 

much as 300 m thick, has total organic carbon values of 1.5 

to 3 percent (average of 2 percent from organic matter type 

III), and a hydrogen index of 100 mg HC/g TOC. The hydrogen index is considered low for it to be a high-quality source 

rock, and whether it has contributed hydrocarbons to oil and 

gas pools is questionable (Bessereau and others, 1996).

The Upper Cretaceous-Paleocene Istebna beds (fig. 6), 

in the eastern Polish Carpathians, have a gross thickness 

of 50 to 1,800 m and are composed of thick-bedded sandstones separated by thin-bedded sandstones and black shales. 

Two major depositional facies are present in the formation: 

channel-fill and lobe deposits, and channel-fill submarine 

mudflow deposits (Klecker and others, 2001). Samples from 

the Istebna/Inoceramus strata (fig. 6) yielded low average 

total organic carbon (0.6 percent) and hydrogen indexes 

14  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
Seals 

In Ukraine, shale units at the base of the major nappes 

are the seals for traps in the allochthonous Carpathian 

flysch. In addition, the subthrust autochthonous sedimentary 

sequence contains Lower Cretaceous and Neogene seals such 

as the Menilite Shale (Sovchik and Vul, 1996).

 Shale units within the various flysch units also provide 

seals for numerous oil and gas fields in Poland. Internal 

nappes are characterized by greater structural complexity than 

the external nappes, lower relief, and large anticlinal rollovers. In contrast, the frontal thrust sheets of external nappes 

are generally steep and depend on fault closure to complete 

the reservoir compartment (Sovchik and Vul, 1996). In western Poland, Devonian reservoirs are sealed by thick, flat-lying 

flysch nappes. Lower Cretaceous shales provide a subregional 

seal for Upper Jurassic carbonate reservoirs. 

Assessment Units 

Isotopically Light Gas Total Petroleum System 

The Isotopically Light Gas Total Petroleum System is 

contained wholly in Miocene strata of Poland, Ukraine, and 

Austria (fig. 7). In Poland, the main stratigraphic package 

that generates gas is the clayey and sandy, predominantly 

deltaic facies within strata of the upper Badenian and lower 

Sarmatian. East of Krakow, the thickness of this package 

ranges from 0 to 1,700 m and 0 to 2,900 m, respectively 

(Kotarba and others, 1998). The autochthonous Miocene 

rocks of the Neogene Carpathian foredeep in Poland contain only biogenic gas (Koltun and others, 1995), which is 

generally 98 percent methane and 2 percent higher gaseous 

hydrocarbons, such as ethane and propane. Most of the gas 

lies within the autochthonous reservoirs of the undeformed 

Miocene molasse; the lower Sarmatian contains 90 percent of 

the identified resources (Karnkowski, 1996). Folded Miocene 

rocks of the Stebnik unit from the inner part of the Polish 

Carpathian foredeep (fig. 2) are thought to be unimportant 

for petroleum exploration (Kotarba, 1998). In Austria, the 

gas from the molasse is mostly biogenic (Ladwein, 1988). 

Gas accumulation in the outer (northern) parts of the 

Carpathian foredeep was facilitated by a high sedimentation 

rate (Kotarba and Jawor, 1993), typified by the rhythmic and 

cyclic deposition of clays and sands as well as by methane 

hydrate. The gas was trapped in stratigraphic and in structural traps, especially in the overthrusted areas. Reservoir 

rocks (mostly sandstones) are present throughout the autochthonous Miocene sequence, which ranges from about 200 m 

to more than 3,000 m thick (Zagorski, 1996). 

Generation of gas started almost contemporaneously 

with deposition. Primary migration of the gas was limited 

but increased as the compaction of the Miocene sediments 

increased. Secondary, longer-range migration resulted from 

the synsedimentary interaction of the flysch overthrusts and 

the Miocene sediments, such that structural traps formed in the 

northward-dipping Miocene strata at the edge of the overthrust 

(Kotarba and others, 1987). 

Reservoir properties differ greatly. Porosity values 

range from 3 to 23 percent (commonly 5–20 percent), and 

permeability ranges from 0 to 4,000 millidarcies (mD) but 

is most commonly a few tens of millidarcies. Permeability 

and porosity both decrease with depth (Zagorski, 1996). 

Sandstone content can be 5–95 percent, though commercial 

production is from horizons containing 5–20 percent sandstone (Zagorski, 1996).

Seals for the Miocene gas accumulations are primarily shale and claystones that overlie coarser sediments, but 

seals are also formed by shale interbeds or massive anhydrite 

in places. The autochthonous Miocene contains numerous 

structural traps in the zone in contact with the nappes; it also 

contains stratigraphic traps related to wedging-out of the 

reservoirs or to the facies changes that are common north 

of the Carpathian overthrust margins (Kotarba and Jawor, 

1993). Generation of biogenic gas began contemporaneously 

with deposition of the molasse and has continued since, but 

likely only on a local scale and in minimal amounts. Figure 8 

shows the timing of critical geologic events during the evolution of the Foreland Basin Assessment Unit. On the basis 

of this assessment, an estimated 141 gas fields and 78 oil 

fields remain to be discovered; these fields have calculated 

mean resources of 2,321 billion cubic feet of gas (BCFG) 

and 9 million barrels of natural gas liquids (MMBNGL) 

respectively.

Mesozoic–Paleogene Composite Total 

Petroleum System

Most of the petroleum fields in the Ukrainian Carpathian Mountains are in the Paleogene flysch nappes of the 

outer tectonic units (figs. 2, 4, 9). In Poland, the main oil 

fields were discovered in both the Paleogene and in the Cretaceous flysch units and in the Paleozoic–Mesozoic basement 

(figs. 2, 3, 9). 

The most important oil and gas fields in western Ukraine 

are in the Boryslav–Pokuttia unit of the foredeep and in 

the flysch sequence of the outer Carpathan belt, primarily 

the Skole nappe (fig. 3). Both settings involve deep-seated 

folds from which hydrocarbons are produced by combined 

Paleocene, Eocene, and Oligocene sandstone reservoirs in 

structural traps that are mostly sealed by Miocene molasse. 

A few oil and gas accumulations lie within the pre-Miocene 

foreland sequence that was overridden by the Carpathian 

nappes. In the foreland of the Carpathian Mountains, and 

beneath the external nappes, two oil fields, one gas field, and 

one gas and condensate field produce from Upper Jurassic 

carbonate rocks. These four fields also include pay sections 

in Cretaceous and Miocene sandstones where karstification 

created good reservoir porosities and permeabilities in parts 

Assessment Units 15
16  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria

Figure 7. Map showing location of Isotopically Light Gas Total Petroleum System within the North Carpathian Province 

of Eastern Europe.

North Carpathian Province (4047)

Gas field center point

Isotopically Light Gas Total Petroleum System (404701)

International boundary

EXPLANATION

POLAND

UKRAINE

ROMANIA

HUNGARY

SLOVAKIA

CZECH

REPUBLIC

AUSTRIA

CROATIA

SERBIA

 AND 

MONTENEGRO

BOSNIA AND

HERZEGOVINA

WARSAW

LVIV

BUDAPEST

BRATISLAVA

VIENNA

BRNO

KRAKOW

0 250 KILOMETERS

45°

50°

20° 25°
of the Jurassic reef core. In back-reef areas, the best reservoirs are associated with friable limestones characterized by 

textures that range from mudstones to grainstones (Izotova 

and Popadyuk, 1996). The oil fields producing from Upper 

Cretaceous sandstone and Upper Jurassic limestone reservoirs 

are also sealed by Miocene molasse. Turbidites throughout 

the Lower Cretaceous into the Oligocene–lower Miocene 

sequence in the eastern Silesian and Skole nappes contain 

traces of oil (Slaczka, 1996).

Lower Cretaceous shales seal Upper Jurassic carbonate reservoirs of northwest Ukraine (fig. 5). In other locations, Miocene shales and evaporites, or shales of the flysch 

nappes, provide the reservoir seal. Hydrocarbon accumulations are contained in two types of trap: erosional highs and 

low-amplitude rollover structures. These two trap styles are 

associated with the Paleogene erosional phase and subsequent development of the Carpathian foredeep, which, in 

turn, modified the structural configuration of the Upper 

Jurassic carbonate shelf in western Ukraine (Izotova and 

Popadyuk, 1996). 

In Poland, the principal oil fields were discovered 

in the Paleogene flysch, the Cretaceous flysch, and in the 

Paleozoic–Mesozoic basement (Koltun and others, 1995). 

Oil accumulated within narrow, predominantly steep, imbricated folds, some with lengths as much as 30 km, that were 

thrust over one another. Lower Cretaceous through Oligocene 

formations have the most prolific hydrocarbon accumulations 

as well as the best seals. The most productive beds are Lower 

Cretaceous sandstones (Karnkowski, 1996). Most of the gas 

fields produce from Miocene rocks, but some also produce 

from Mesozoic strata. In the Polish molasse autochthon, the 

Cretaceous and most Jurassic reservoirs are sealed by the 

shaly and evaporitic basal series of the Badenian molasse 

(Bessereau and others, 1996). 

Traps within the northern Carpathian Mountains are 

associated primarily with folds and fault blocks, but stratigraphic traps are also abundant. Accumulations sealed by 

thrust sheets are the most prospective traps for hydrocarbon 

exploration in the region (Slaczka, 1996).

Oil was generated in the Carpathian Mountains mostly during the Neogene, but the distribution of and variations in sulfur 

content of the oils suggest limited generation in the Paleogene 

before thrust loading of the foredeep by the flysch nappes.

Hydrocarbon in Poland migrated mainly to the north 

early in the evolution of the nappe basins. Later migration 

was influenced by the shape of the basins and the shifting of 

depocenters and by tectonic movements. In the Silesian basin, 

hydrocarbon initially migrated mainly north. Later, migration 

direction changed to the south after the axis of deposition 

shifted to the north, and the southern part of the basin was 

folded and uplifted (Slaczka, 1996). Short-­­­distance migration 

directly from juxtaposed source and reservoir rock characterized accumulations in the structural complexes and imbrications along the Carpathian front as well as along numerous 

fault zones in this tectonically disturbed region.

The events chart in figure 10 summarizes the relation of 

timing and source rock, reservoir rock, seal rock, overburden 

rock, trap formation, generation, migration, accumulation, and 

preservation in the Deformed Belt Assessment Unit. Calculated 

resources (mean value) are 344 million barrels of oil (MMBO), 

2,345 million cubic feet of gas (MMCFG), and 75 MMBNGL.

Figure 8. Events chart for the Foreland Basin Assessment Unit 

of the Isotopically Light Gas Total Petroleum System of the North 

Carpathian Province. Chart shows the relative timing of critical 

geologic events in the evolution of the assessment unit. E, Early; 

M, Middle; L, Late; Pal., Paleocene; Eoc., Eocene; Olig., Oligocene; 

Mio., Miocene; Plio., Pliocene.

PRESERVATION

CRITICAL MOMENT

GENERATIONROCK UNIT SOURCE ROCK RESERVOIR ROCK SEAL ROCK OVERBURDEN ROCK TRAP FORMATION

PETROLEUM

SYSTEM

EVENTS

GEOLOGIC

TIME

SCALE

ACCUMULATION

MIGRATION0

100

200

50

150

250

Paleogene

Cretaceous

Jurassic

Triassic

Permian

65

141

195

230 E

E

E

E

M

M

L

L

L

L

Neogene

22.5

Pal.

Eoc.

Olig.

Mio.

Plio.

Assessment Units 17
18  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria

Figure 9. Map showing location of the Mesozoic–Paleogene Composite Total Petroleum System in the North 

Carpathian Province of Eastern Europe.

Oil field center point

Gas field center point

North Carpathian Province (4047)

Mesozoic–Paleogene Composite Total Petroleum System (404702)

EXPLANATION

POLAND

UKRAINE

ROMANIA

HUNGARY

SLOVAKIA

CZECH

REPUBLIC

AUSTRIA

CROATIA

SERBIA

 AND 

MONTENEGRO

BOSNIA AND

HERZEGOVINA

WARSAW

LVIV

BUDAPEST

BRATISLAVA

VIENNA

BRNO

KRAKOW

0 250 KILOMETERS

45°

50°

20° 25°

International boundary
Figure 10. Events chart for the Deformed Belt Assessment Unit 

of the Mesozoic–Paleogene Composite Total Petroleum System 

of the North Carpathian Province. Chart shows the relative timing 

of critical geologic events in the evolution of the assessment unit. 

E, Early; M, Middle; L, Late; Pal., Paleocene; Eoc., Eocene; Olig., 

Oligocene; Mio., Miocene; Plio., Pliocene.

PRESERVATIONCRITICAL MOMENT

GENERATIONROCK UNIT SOURCE ROCK RESERVOIR ROCK SEAL ROCK OVERBURDEN ROCK TRAP FORMATION

PETROLEUM

SYSTEM

EVENTS

GEOLOGIC

TIME

SCALE

ACCUMULATION

MIGRATION0

100

200

50

150

250

Paleogene

Cretaceous

Jurassic

Triassic

Permian

65

141

195

230 E

E

E

E

M

M

L

L

L

L

Neogene

22.5

Pal.

Eoc.

Olig.

Mio.

Plio.

Paleozoic Reservoirs Assessment Unit

of the Paleozoic Composite Total

Petroleum System

The Paleozoic Reservoirs Assessment Unit is a gas unit 

encompassing Paleozoic rocks that lie beneath molasse and 

flysch in the area extending from the eastern Czech Republic 

along the southwest border of Poland and into southwestern 

Ukraine (fig. 11). Devonian rocks rest directly on the Precambrian basement or on erosional remnants of pre-Devonian 

strata. Lower Devonian rocks are predominantly variegated 

sandstone and red shale with variable thicknesses as much as 

200 m; Middle and Upper Devonian rocks are mostly carbonate (Pietsch and others, 1997).

The assessment unit was defined on the basis of two 

wells. The Lachowice-1 well, southwest of Krakow, was 

drilled into Devonian strata lying beneath the west Carpathian 

fold and thrust belt; gas was discovered in carbonate reservoirs. The Nosowka-1 well east of Krakow produces oil, also 

from Devonian strata (fig. 11).

The oil in the Nosowka field has an isotopically light 

signature and lacks the biomarker oleanane, which excludes a 

Cretaceous or younger source (such as the Menilite Shale). A 

Paleozoic source is therefore considered likely.

Lower Carboniferous black shale and silty shale from 

the foredeep have a total organic carbon value of about 1.5 

percent but a low hydrogen index of 100 mg HC/g TOC that 

is considered insufficient for a good source rock. An Upper 

Carboniferous coal, however, has favorable geochemistry of 

47 percent TOC and a hydrogen index of 450 mg HC/g TOC. 

The geochemical fingerprints of the shale and coal samples 

show some similarities (Bessereau and others, 1996). In 

western Poland, a 246-m-thick section (Numurian A) at the 

boundary between upper Lower Carboniferous and Upper 

Carboniferous is composed of fine-grained sandstone overlain by shales and mudstones interbedded with sapropelic 

shales and coals. Above that section are gray mudstones and 

shales with coal and some sandstone (Pietsch and others, 

1997), a possible source of hydrocarbons within the Devonian reservoirs in this western region. A reported higher 

hydrocarbon content (C3–C7) = 66.8 g/m3 indicates that 

Devonian rocks may have reached the wet gas stage (Pietsch 

and others, 1997). 

In western Poland, the Precambrian–Paleozoic platform 

sedimentary rocks are strongly deformed and are overlain by 

Neogene molasse (lower Miocene and Badenian age). The 

molasse, which has a maximum thickness of 2.6 km, is in 

turn is overlain by Carpathian flysch, which comprises the 

Skole, sub-Silesian, Dukla, and Magura units (fig. 3) (Paul 

and others, 1996).

Flat-lying overthrust sheets of folded Carpathian flysch 

provide a tectonic seal for possible gas and oil reservoirs 

in deeper Carboniferous and Devonian strata (Pietsch and 

others, 1997). The Lachowice gas field is considered to 

be a combined structural and stratigraphic trap associated 

Assessment Units 19
Figure 11. Map showing location of the Paleozoic Composite Total Petroleum System within the North Carpathian 

Province of Eastern Europe.

Paleozoic Composite Total Petroleum System (404703)

North Carpathian Province (4047)

Oil field center point

Gas field center point

EXPLANATION

POLAND

UKRAINE

ROMANIA

HUNGARY

SLOVAKIA

CZECH

REPUBLIC

AUSTRIA

CROATIA

SERBIA

 AND 

MONTENEGRO

BOSNIA AND

HERZEGOVINA

WARSAW

LVIV

BUDAPEST

BRATISLAVA

VIENNA

BRNO

KRAKOW

LACHOWICE

NOSOWKA

0 250 KILOMETERS

45°

50°

20° 25°

20 Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
Figure 12. Events chart for the Paleozoic Reservoirs Assessment 

Unit of the Paleozoic Composite Total Petroleum System of the 

North Carpathian Province. Chart shows the relative timing of 

critical geologic events in the evolution of the assessment unit. 

E, Early; M, Middle; L, Late; Pal., Paleocene; Eoc., Eocene; Olig., 

Oligocene; Mio., Miocene; Plio., Pliocene.

0

100

200

300

400

500

600

50

150

250

350

450

550

Paleogene

Cretaceous

Jurassic

Triassic

Permian

Precambrian

Cambrian

Ordovician

Silurian

Devonian

E

E

E

E

E

E

M

M

M

L

L

L

L

L

L

Mississippian

Pennsylvanian

Neogene

Pal.

Eoc.

Olig.

Mio.

Plio.

PRESERVATION

CRITICAL MOMENT

GENERATIONROCK UNIT SOURCE ROCK RESERVOIR ROCK SEAL ROCK OVERBURDEN ROCK TRAP FORMATION

PETROLEUM

SYSTEM

EVENTS

GEOLOGIC

TIME

SCALE

ACCUMULATION

MIGRATIONwith a posterosional surface and fracture zone sealed on the 

south by a longitudinal fault. The pay zone is thought to be 

about 10 km2 and 100 m thick and to contain an estimated 

reserve of 175–350 MMCFG (Pietsch and others, 1997). 

Longitudinal faults formed during the Variscan orogeny and 

transformed into reverse faults during Carpathian compression; these faults bound narrow grabens to form potential 

hydrocarbon traps, such as in the Lachowice field and in 

others places.

In Carboniferous rock units, sandstones of the same age 

may also be a reservoir facies, as indicated by porosity of 14 

percent in one well (Potrojna IG 1). Upper Carboniferous 

rocks have had oil and gas shows at a depth of 4,858 m in this 

western part of Poland. Possible Cambrian sandstone in the 

Stryszawa area near Lachowice also possesses good reservoir 

qualities (Pietsch and others, 1997). 

Pietsch and others (1997) believe that gas accumulations 

in Carpathian autochthonous rocks in the Lachowice area 

are confined to fractured, cavernous zones of weathering in 

Devonian dolomite and to a diagenetically altered carbonate, 

which is separated from the dolomite by an erosional surface. 

Gas traps are formed by small fault-confined anticlines sealed 

by longitudinal strike-slip faults. Gas may accumulate on 

the downthrown side of the fault, as at Lachowice, or in the 

upthrown wall of the fault, as at Stryszawa. Structural and 

stratigraphic conditions within autochthonous Miocene rocks 

provide trap seals. 

Present-day maturation patterns mainly postdate nappe 

emplacement. Source rocks probably matured initially 

during the precompressional stages in the southern part of 

the Silesian basin and the Dukla-equivalent basins, owing 

to accumulation of thick sediment sequences (Bessereau 

and others, 1996). Hydrocarbons migrated relatively short 

distances from the source into fault-bound traps that were 

sealed by the flysch units. Figure 12 shows the critical geological aspects of the Paleozoic Composite Total Petroleum 

System. Calculated resources for the Paleozoic Reservoirs 

Assessment Unit (mean value) are 47 MMBO, 383 BCFG, 

and 19 MMBNGL.

Assessment Results and Summary

Tables 1 and 2 summarize the allocated oil and gas 

resources in the North Carpathian Province. Assessment units 

are listed for each total petroleum system. The resources are 

grouped into fractals, which are a means of assigning a risk 

factor to the actual discovery of these resources; that is, the 

“F” value represents that chance of the amount tabulated being 

discovered. Although the Carpathian region of Poland and 

Ukraine presents a difficult challenge for future petroleum 

exploration and production, owing to its complex geologic 

structure and stratigraphic variability, the potential exists for 

the discovery of additional large amounts of oil and gas, but 

most probably in small fields (figs. 13, 14).

Assessment Results and Summary  21
Table 1. Summary of allocated oil and gas resources, North Carpathian Province (4047), as evaluated per assessment unit.

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. MFS, minimum field size assessed (MMBO or BCFG). Probgeologic and accessibility probabilities) of at least one field equal to or greater than the MFS. Results shown are fully risked estimates. For gas fields, all liquads are included uliquids) category. F95 represents a 95 percent chance of at lease the amount tabulated. Other fractiles are defined similarly. Fractiles are additive under the assumption of perfecindicates not applicable]

Code Undiscovered Resources

and Field MFS Prob. Oil (MMBO)

Type (0-1) F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 

Gas (BCFG) NGL 

404701 Isotopically Light Gas Total Petroleum System40470101

Oil Fields 1 0 0 0 0 0 0 0 0 0 

Gas Fields 6 852 2,129 4,420 2,321 6 

Total 1.00 0 0 0 0 852 2,129 4,420 2,321 6 

404702 Mesozoic/Paleogene Composite Total Petroleum System40470201

Oil Fields 1 111 316 660 344 306 925 2,105 1,032 17 

Gas Fields 6 405 1,211 2,526 1,313 4 

Total 1.00 111 316 660 344 711 2,136 4,631 2,345 21 

404703 Paleozoic Composite Total Petroleum System40470301

Oil Fields 1 12 42 96 47 25 91 223 103 1 

Gas Fields 6 71 254 576 280 3 

Total 1.00 12 42 96 47 95 345 800 383 4 

1.00

Foreland Basin Assessment Unit (100% of undiscovered oil fields and 100% of undiscovered gas fields allocated to ONSHORE provinDeformed Belt Assessment Unit (100% of undiscovered oil fields and 100% of undiscovered gas fields allocated to ONSHORE provinPaleozoic Reservoirs Assessment Unit (100% of undiscovered oil fields and 100% of undiscovered gas fields allocated to ONSHORE 

1.001.00
Table 2. Summary of allocated oil and gas resources, North Carpathian Province (4047).

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. MFS, minimum field size assessed (MMBO or BCFG). Prob.geologic and accessibility probabilities) of at least one field equal to or greater than the MFS. Results shown are fully risked estimates. For gas fields, all liquids are included undcategory. 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 not applicable]

Code Undiscovered Resources

and Field MFS Prob. Oil (MMBO)

Type (0-1) F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 

4047 Total: Assessed onshore portions of North Carpathian Basin Province

Oil Fields 123 359 756 391 331 1,016 2,328 1,135 18 

Gas Fields 1,328 3,594 7,523 3,914 13 

Total 1.00 123 359 756 391 1,659 4,610 9,851 5,049 31 

4047 Total: Assessed offshore portions of North Carpathian Basin Province

Oil Fields 0 0 0 0 0 0 0 0 0 

Gas Fields 0 0 0 0 0 

Total 0.00 0 0 0 0 0 0 0 0 0 

4047 Grand Total: Assessed portions of North Carpathian Basin Province

Oil Fields 123 359 756 391 331 1,016 2,328 1,135 18 

Gas Fields 1,328 3,594 7,523 3,914 13 

Total 1.00 123 359 756 391 1,659 4,610 9,851 5,049 31 

Gas (BCFG) NGL 

1.000.001.00
Figure 13. Diagram showing estimated number and size of undiscovered oil fields in the North Carpathian Province of Eastern 

Europe. 

0

5

10

15

20

25

30

1 to <2 2 to <4 4 to <8 8 to <16 16

to

<32

32

to

<64

64

to

<128

128

to

<256

256

to

<512

512

to

<1,024

OIL-FIELD SIZE (MILLION BARRELS OF OIL)

UNDISCOVERED OIL FIELDS (NUMBER)

Figure 14. Diagram showing estimated number and size of undiscovered gas fields in the North Carpathian Province of Eastern Europe.

0

10

20

30

40

50

60

6 to <12 12 to <24 24 to <48 48 to <96 96

to

<192

192

to

<384

384

to

<768

768

to

<1,536

1,536

to

<3,072

3,072

to

<6,144

GAS-FIELD SIZE (BILLION CUBIC FEET OF GAS)

UNDISCOVERED GAS FIELDS (NUMBER) 

24  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria
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26  Petroleum Systems of the North Carpathian Province of Poland, Ukraine, Czech Republic, and Austria

Published in the Central Region, Denver, Colo.

Manuscript approved for publication April 29, 2005

Graphics by the author

Photocomposition by Mari L. Kauffmann (Contractor, ATA Services)

Edited by Mary-Margaret Coates (Contractor, ATA Services)