GeolCarp_Vol63_No4_319

www.geologicacarpathica.sk

GEOLOGICA CARPATHICA

, AUGUST 2012, 63, 4, 319—333 doi: 10.2478/v10096-012-0025-3

Assessment of hydrocarbon potential of Jurassic and

Cretaceous source rocks in the Tarnogród—Stryi area

(SE Poland and W Ukraine)

PAWEŁ KOSAKOWSKI

, DARIUSZ WIĘCŁAW

, ADAM KOWALSKI

and YURIY V. KOLTUN

AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of

Environmental Analyses, Cartography and Economic Geology, Al. Mickiewicza 30, 30-059 Kraków, Poland;

kosak@agh.edu.pl; wieclaw@agh.edu.pl; akowalsk@agh.edu.pl

National Academy of Sciences of Ukraine, Institute of Geology and Geochemistry of Combustible Minerals, Naukova 3-a, 79053 Lviv, Ukraine

(Manuscript received November 22, 2011; accepted in revised form March 13, 2012)

Abstract: The Jurassic/Cretaceous stratigraphic complex forming a part of the sedimentary cover of both the eastern
Małopolska Block and the adjacent Łysogóry—Radom Block in the Polish part as well as the Rava Rus’ka and the
Kokhanivka Zones in the Ukrainian part of the basement of the Carpathian Foredeep were studied with geochemical
methods in order to evaluate the possibility of hydrocarbon generation. In the Polish part of the study area, the Mesozoic
strata were characterized on the basis of the analytical results of 121 core samples derived from 11 wells. The samples
originated mostly from the Middle Jurassic and partly from the Lower/Upper Cretaceous strata. In the Ukrainian part of
the study area the Mesozoic sequence was characterized by 348 core samples collected from 26 wells. The obtained
geochemical results indicate that in both the south-eastern part of Poland and the western part of Ukraine the studied
Jurassic/Cretaceous sedimentary complex reveals generally low hydrocarbon source-rock potential. The most favourable
geochemical parameters: TOC up to 26 wt. % and genetic potential up to 39 mg/g of rock, were found in the Middle
Jurassic strata. However, these high values are contradicted by the low hydrocarbon index (HI), usually below 100 mg
HC/g TOC. Organic matter from the Middle Jurassic strata is of mixed type, dominated by gas-prone, Type III kerogen.
In the Polish part of the study area, organic matter dispersed in these strata is generally immature (T

max

below 435 °C)

whereas in the Ukrainian part maturity is sufficient for hydrocarbon generation.

Key words: Jurassic, Cretaceous, Poland, Ukraine, petroleum geochemistry, source rock characteristics.

Introduction

The Jurassic/Cretaceous stratigraphic complex forming a part
of the sedimentary cover of the eastern Małopolska Block and
the adjacent Łysogóry-Radom Block (SE Poland) were stud-
ied with geochemical methods in order to evaluate the possi-
bility  of  hydrocarbon  generation.  Both  the  blocks  extend
southeast,  towards  the  territory  of  Ukraine,  where  these  are
named  the  Rava  Rus’ka  and  the  Kokhanivka  Zones,  respec-
tively (Buła & Habryn 2011). In both areas the Jurassic/Creta-
ceous  complex  vary  in  the  degree  of  geological  and
geochemical  recognition.  In  the  Polish  part  the  complex  is
well-recognized geologically but geochemical and petrophysi-
cal  data  are  insufficient  (Kotarba  et  al.  2003;  Kotarba  2004;
Moryc  2004;  Buła  &  Habryn  2008,  2011;  Kosakowski  et  al.
2012a). In the Ukraine its geological and petrophysical recog-
nitions are poor and geochemical data do not exist (e.g. Dulub
et  al.  2003;  Gutowski  et  al.  2005;  Krajewski  et  al.  2011;
Kurovets  et  al.  2011).  The  available  analytical  results  origi-
nate mostly from Middle Jurassic strata and  partly from Up-
per  Jurassic  and  Lower  Cretaceous  rocks.  The  population  of
samples collected from Mesozoic strata in the Ukrainian part
of  the  Carpathian  Foredeep  is  more  numerous  and  the  core
samples represent all the stratigraphic units involved.

Geochemical characterization of organic matter in the

analysed, Jurassic/Cretaceous complex from the Polish and

Ukrainian part of the Carpathian Foredeep includes: organic
carbon content (TOC), petroleum potential, genetic type of
kerogen and its maturity.

Outline of geology and stratigraphy of the

Mesozoic strata

The study area is located in the border part of the Polish

and  Ukrainian  segments  of  the  Carpathian  Foredeep  and
covers  an  area  between  Tarnogród  and  Lubaczów  towns  in
Poland,  and  Stryi  town  in  Ukraine  (Fig. 1).  The  geology  of
this  part  of  the  Carpathian  Foredeep  was  extensively  dis-
cussed  e.g.  by  Oszczypko  et  al.  (2006),  Buła  &  Habryn
(2011) and Krajewski et al. (2011).

In the study area several structural complexes were distin-

guished. The lower structural complex, which forms an un-
continuous  cover  of  the  older  basement  of  the  foredeep  is
composed  of  incomplete,  Ordovician  and  Silurian  succes-
sions (Figs. 2, 3). This succession fills tectonic troughs cut-
ting  the  crystalline  basement  (Buła  &  Habryn  2008,  2011).
The next structural complex is formed of Jurassic and Creta-
ceous strata. These strata constitute a fragment of a larger ba-
sin,  which  extends  to  the  Polish-Ukrainian  state  border  and
which  is  a  continuation  of  the  Carpathian  Foredeep  outer
zone (Figs. 2, 3; Kisłow 1966). The total thickness of Juras-

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GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

Espitalié & Bordenave 1993). The basic parameters mea-
sured with Rock-Eval are: free hydrocarbons content (S

residual hydrocarbons content (S

), T

max

temperature, carbon

dioxide produced during pyrolysis (S

) and residual organic

carbon content (S

). The above parameters are the basis for

calculation of indices used for quantitative and qualitative
evaluation of organic matter in the analysed rock, namely to-
tal organic carbon (TOC) content, S

ratio, production in-

dex (PI), hydrogen index (HI) and oxygen index (OI). Both
the measured and calculated values provide a basis for char-
acterization of organic matter, its quantity, genetic type and
transformation degree (Espitalié et al. 1985; Hunt 1996).

After removal of carbonates with hydrochloric acid and ex-

traction  of  bitumens,  rock  samples  selected  for  stable  carbon
isotope analysis of kerogen were combusted in an on-line sys-
tem.  Preparation  of  previously  extracted  bitumens  and  their
fractions for stable carbon isotope analyses was carried on with
the same procedure. Stable carbon isotopes were analysed with
the  Finnigan  Delta  Plus  mass  spectrometer.  The  stable  carbon
isotope  data  were  presented  in  the  -notation  relative  to  the
PDB standard, at an estimated analytical precision  ± 0.2 ‰.

The isolation of kerogen for elemental analysis was carried

on  with  the  SOXTEC™  extraction  of  pulverized  samples,
decalcification  of  solid  residue  with  HCl  at  room  tempera-
ture,  removal  of  silicates  with  concentrated  HF,  removal  of
newly  formed  fluoride  phases  with  hot,  concentrated  HCl,
heavy  liquid  separation  (aqueous  ZnBr

solution, density

2.1 g/ml) and repeated extraction with dichloromethane:
methanol (93: 7 v/v) (Więcław et al. 2010). The elemental

(C, H, N and S) analysis of isolated kerogen  was done with
the Carlo Erba EA 1108 elemental analyser. The quantity of
pyrite contaminating the kerogen was analysed as iron with
the  Perkin-Elmer  Plasma  40  ICP-AES  instrument  after  di-
gesting  the  ash  from  the  combusted  kerogen  (815 °C,
30 min.)  with  HCl.  The  organic  sulphur  content  in  kerogen
was  calculated  as  the  difference  between  total  and  pyritic
sulphur. The oxygen content was calculated as the difference
to  100 %,  taking  into  account  the  C,  H,  N,  S,  moisture  and
ash contents.

The saturated hydrocarbon fractions isolated from the bitu-

mens were diluted in isooctane and analysed with the GC-MS
for  biomarker  determination.  The  analysis  was  carried  out
with the Agilent 7890A gas chromatograph equipped with the
Agilent  7683B  automatic  sampler,  an  on-column  injection
chamber and a fused silica capillary column (60 m 0.25 mm
i.d.)  coated  with  95%  methyl/5%  phenylsilicone  phase
(DB-5MS, 0.25 µm film thickness). Helium was used as the
carrier  gas.  The  GC  oven  was  programmed:  80 °C  held  for
1 min, then increased to 120 °C at the rate of 20 °C/min, fur-
ther  increased  to  300 °C  at  the  rate  of  3 °C/min  and  finally
held at 300 °C for 35 min. The gas chromatograph was cou-
pled with the 5975C mass selective detector (MSD). The MS
operated at ion source temperature 230 °C, ionization energy
70 eV, and a cycle time of 1 s in the mass range from 45 to
500 Daltons.

The aromatic hydrocarbon fractions were analysed with

the GC-MS for phenanthrene, dibenzothiophene and their
derivatives. The analysis was carried out using the same

Table 1: Geochemical characterization of Mesozoic strata in the Polish and Ukrainian parts of the Carpathian Foredeep.

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GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

equipment as for the saturate hydrocarbon fraction. The GC
oven was programmed from 40 to 300 °C at the rate of
3 °C · min

—1

. The MS operated with a cycle time of 1 s in the

mass range from 40 to 600 Daltons.

Measurements of mean random vitrinite reflectance (R

)

were carried out with the Zeiss-Opton microphotometer at
546 nm wave length in oil. Sample preparation and point
countings were carried out in accordance with the ICCP pro-
cedure (Taylor et al. 1998).

Geochemical characteristics of organic matter

The Lower Jurassic rocks

The samples from Lower Jurassic strata reveal very low

total organic carbon (TOC) contents, much below 0.5 wt. %
(Table 1, Fig. 4). The median of TOC is 0.08 wt. %. Only in
one sample genetic potential (Rock-Eval S

+ S

) of 0.33 mg/g

of rock was measured (Table 1, Fig. 4). Despite the limited
number and sampling area of analysed samples, it is con-
cluded that the Lower Jurassic rocks cannot be considered as
hydrocarbon source rocks in the study area.

The Middle Jurassic rocks

The highest TOC contents in the whole

Mesozoic  succession  from  the  study  area  was
recorded in the Middle Jurassic strata (Table 1,
Fig. 2). The TOC contents in these strata vary
significantly:  from  0  up  to  25.9 wt. %.  De-
spite  the  similar  variability  range  the  lower
TOC  values  were  measured  in  samples  com-
ing from the Ukrainian part. In about 40 % of
analysed samples the TOC contents were low-
er  than  0.2 wt. %,  and  in  about  45 %  these
were below 1 wt. % (Fig. 4). In samples from
the  Polish  part  TOC  was  below  1 wt. %  in
about  30 %  of  analysed  samples  and  below
0.2 %  in  a  few  cases  (Figs. 4,  5A).  The  maxi-
mum TOC value was measured in the Lubliniec
9/858.6  sample  (Fig. 5A).  The  Mosty  2/2521—
2529  sample  also  revealed  an  excellent  hydro-
carbon potential (Fig. 5B). The median of TOC
values  for  the  whole  population  of  samples
was 0.83 wt. % (Fig. 4); however, for samples
from  the  Polish  part  this  value  was  twice  as
high  as  for  samples  from  the  Ukrainian  part
(Table 1).  The  hydrocarbon  content  in  the
analysed  samples  varied  in  a  similarly  broad
range: from 0.09 up to 39.1 mg/g of rock with
the  median  value  for  all  studied  samples
0.77 mg HC/g of rock. No significant differenc-
es  were  observed  between  the  Polish  and  the
Ukrainian  parts  of  the  study  area  (Table 1,
Figs. 4,  5A,B).  The  contents  of  extractable  hy-
drocarbons  indicate  moderate  to  very  good  oil
sourcing  potential  of  the  analysed  rocks
(Fig. 6A,B).  Despite  relatively  high  TOC  and
genetic potential, the analysed samples indicate

very low hydrocarbon potential, as documented by hydrogen
index values (HI) which range from 13 to 289 mg HC/g TOC,
with a median of merely 57 mg HC/g TOC (Table 1, Figs. 4,
7A,B). Such HI values found in the Middle Jurassic strata in-
dicate the domination of terrigenous material (Type III kero-
gen) in the Polish part (Fig. 7A) and local inputs of marine
Type II kerogen in the Ukrainian part (Fig. 7B) of the study
area. These same Type III and III/II kerogens were observed
in the western part of the Małopolska Block (Kosakowski et
al. 2012b) and in central Poland (Marynowski et al. 2007).
The maceral composition also indicates the presence of both
terrestrial and marine materials. Their proportions vary from
similar percentages of vitrinite and liptinite maceral groups,
as in the Lubliniec 4 well, to predominance of terrestrial ma-
terial, as in the Markowice 2 well (Table 2). Distribution of
n-alkanes and isoprenoids in bitumens from Middle Jurassic
rocks in the Polish part of the study area (Table 3, Fig. 8A)
indicates domination of long-chain hydrocarbons (LTS

ratio

above 2, C

max

from 25 to 29), which suggests domination of

the  gas-prone,  terrestrial  organic  matter  (e.g.  Peters  et  al.
2005).  In  the  Ukrainian  part  of  the  study  area  admixture  of
the  oil-prone  Type II  kerogen  is  documented  by  the  LTS

ratio from 0.7 to 6.4 and C

max

from 20 to 27 (Table 3,

Fig. 2. Sketch map of the bottom surface of Middle Jurassic strata in the study area.

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GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

Figs. 8B, 9). Moreover, the strong domination of C

regular

steranes  (Table 4)  supports  this  interpretation.  Values  of
pristane/phytane  ratio  (Table 3)  usually  above  one  point  to
sub-oxic  conditions  during  deposition  of  organic  matter
(Didyk et al. 1978; Moldowan et al. 1985; Peters et al. 2005).
Low  values  of  diasterane/regular  sterane  ratio  (Table 4)  re-
flect low maturity of organic matter rather than the influence
of clay minerals (Seifert & Moldowan 1978).

The results of stable carbon isotope and elemental analy-

ses are consistent with the above discussed data and indicate
domination of the gas-prone kerogen in the Polish and mixed
kerogen in the Ukrainian parts of the study area (Tables 5, 6,
Figs. 10, 11). Highly generative Type IIS kerogen was re-
corded in only two samples collected from the Korolyn 6
and the Chornokuntsi 1 wells (Table 6).

The low maturity of organic matter dispersed in the Middle

Jurassic strata is indicated by a number of analytical results
and calculated geochemical indices: T

max

values below

430 °C (Table 1, Figs. 4, 7), vitrinite reflectance varying
from 0.51 to 0.65 % (Table 2), high values of CPI (Table 3),
values of biomarker ratios (Table 4, Figs. 12, 13), results of
elemental composition of kerogen (Table 6, Fig. 11) and val-
ues of indices calculated from methylphenantrenes and

dibenzothiophenes distribution (Table 7). All these
results indicate somewhat higher maturity of organ-
ic matter in the Ukrainian part in comparison with
the Polish part of the study area. Anyhow, the mea-
sured maturity fits into the early phase of the “oil
window” (Kosakowski et al. 2011). In that case, the
measured TOC and hydrocarbon contents could be
regarded as initial or close to initial values. In the
light of these facts, the Middle Jurassic clastic rocks
in both the Ukrainian and Polish parts show moder-
ate to high, and locally very high, oil-prone poten-
tial (Figs. 5A,B, 6A,B).

The Upper Jurassic rocks

Characterization of Upper Jurassic strata was

based  on  the  results  of  analyses  of  samples  col-
lected  mostly  in  the  Ukrainian  part  of  the  Car-
pathian  Foredeep  (Table 1,  Fig. 4).  In  the  Polish
part  of  the  study  area  only  16  core  samples  were
taken from two wells: Tymce 1 and Sucha Wola 1
(Table 1,  Fig. 1).  The  TOC  values  in  the    latter
samples are very low, (namely less than 0.5 wt. %
with  median  value  0.07 wt. %  (Table 1,  Figs. 4,
5B).  Hydrocarbons  are  practically  absent  from
these  samples.  Despite  a  much  denser  sampling
grid,  the  TOC  contents  in  Upper  Jurassic  rocks
from the Ukrainian part of the study area are usu-
ally  as  low  as  in  those  from  the  Polish  part,  al-
though  horizons  showing  increased  organic
carbon  contents  were  encountered,  as  well
(Figs. 4, 5B). The TOC contents range from 0.0 to
12.1 wt. %,  with  very  low  median  value
(0.08 wt. %,  Table 1,  Fig. 4).  The  genetic  poten-
tial  (S

+ S

) are also very low in most samples

(Figs. 4, 5B) and hydrocarbons were measured

Fig. 3. Sketch map of the bottom surface of Upper Jurassic strata in the study area.

only in about 40 % of analysed samples. They ranged from
0.18  to  14.0 mg/g  of  rock  (Table 1,  Fig. 5B).  Despite  such
variability, low-hydrocarbon samples prevail and the median
for  the  entire  population  is  0.67 mg/g  of  rock  (Table 1).
Most of the samples show low HI values and median value is
up  to  105 mg  HC/g  TOC  (Table 1,  Fig. 4).  This  low  back-
ground  contrasts  with  the  results  obtained  in  samples  from
the  Voloshcha 1  and  Korolyn 6  wells  (Fig. 1),  where  both
TOC contents, hydrocarbon contents and hydrocarbon index
HI values are much higher. The TOC values measured in the
Voloshcha 1  well,  at  the  depth  interval  2650—3300 m,  are
over 1.0 wt. % and locally reach up to 12.1 wt. % (Table 1).
Genetic potential is also high, although the HI index values
differ only slightly from the average ones. In samples from
the  Korolyn 6  well  both  the  TOC  and  genetic  potential  is
equally high and the HI values reach up to 557 mg/g of TOC
(Table 1,  Fig. 7B).  In  the  remaining  wells  TOC  contents,
genetic  potential  values  and  HI  are  significantly  lower
(Fig. 5B). The probable presence of epigenetic hydrocarbon
(Fig. 6B)  indicates  possible  initiation  of  the  hydrocarbon
generation process.

In this stratigraphic unit organic matter is a mixture of

Type II and Type III kerogens. In comparison to Middle

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GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

reflectance  (Table 2),  biomarker
indices  (Table 4,  Figs. 12,  13B)
and  elemental  analysis  (Fig. 11)
suggest  higher  maturity,  corre-
sponding  to  the  early  and  main
phase of the “oil window”. Hence,
these strata are the effective source
rocks,  especially  in  the  areas
where  highly  generative,  Type IIS
kerogen was recorded.

The Lower Cretaceous rocks

The Lower Cretaceous strata are

represented by only a few samples.
The  TOC  ranges  from  0.01  up  to
2.03 wt. %  and  the  median  is
0.40 wt. %  (Table 1,  Fig. 4).  Rela-
tively  moderate  TOC  contents  are
accompanied  by  very  low  genetic
potential with median value of only
0.14 mg  HC/g  of  rock  (Table 1,
Fig. 5C).  Therefore,  we  can  con-
clude  that  TOC  value  2.03 wt. %
confronted with the low genetic po-
tential  and  low  maturity  cannot  be
regared  as  a  reliable  result.  Proba-
bly,  the  carbonate  matrix  influ-
enced

this

analytical

value.

Alternatively,  it  is  possible  that
syn-sedimentary  oxidation  of  or-
ganic  matter  (Marynowski  et  al.

Table 2: Maceral composition and vitrinite reflectance of organic matter from Jurassic strata in the Tarnogród—Stryi area.

Macerals (%)

Well Depth

(m)

Stratigraphy

Pyrite

(%)

V L I

(%)

Range

No. of

meas.

Oredep.

(%)

Polish part
Lubliniec 4

730.4

M. Jurassic

5.5

3.2

3.1

1.0

7.3 0.54 0.46–0.76

0.90–1.20

Lubliniec 4

796.5

M. Jurassic

2.4

7.0

3.3

0.8

11.1 0.57 0.51–0.78

1.00–1.10

Lubliniec 4

837.5

M. Jurassic

2.1

4.0

1.0

0.2

5.2 0.65 0.52–0.90 115 1.00–1.20

Markowice 2

753.0

M. Jurassic

0.8

13.1

2.4

4.5

20.0 0.51 0.43–0.65 102 n.m.

Markowice 2

800.0

M. Jurassic

5.0

14.0

4.3

5.0

23.3 0.52 0.40–0.66

1.10–1.50

Ukrainian part
Rudky 300

3241.0–3246.0

L. Jurassic

2.4

0.1

ab.

0.1 1.74 1.44–2.00

n.m.

Rudky 300

3491.9–3495.5

L. Jurassic

1.7

<0.1

ab.

<0.1 1.84 1.59–2.20

n.m.

Rudky 300

3902.0–3905.0

L. Jurassic

2.8

<0.1

ab.

<0.1 1.99 1.74–2.30

n.m.

Bortyatyn 1

2846.0–2857.0

M. Jurassic

2.5

3.5

5.0

1.2

9.7 0.61 0.53–0.77

0.90–1.20

Podiltsi 1

3303.0–3306.1

M. Jurassic

5.2

1.7

0.6

0.4

2.7 0.65 0.57–0.73

1.10–1.55

Podiltsi 1

3475.0–3482.0

M. Jurassic

tr.

3.3

3.5

0.3

7.1 0.61 0.50–0.77

0.90–1.20

Bortyatyn 1

1820.0–1830.0

U. Jurassic

4.0

1.9

2.0

0.1

4.1 0.47 0.37–0.59

0.62–0.73

Bortyatyn 1

2522.0–2529.0

U. Jurassic

0.5

1.2

0.1

1.4 0.57 0.53–0.68

1.00–1.50

Moryanti 1

2263.0–2270.0

U. Jurassic

tr.

ab.

n.m. n.m.

n.m. n.d. n.m.

Moryanti 1

2576.0–2582.0

U. Jurassic

0.1

ab.

0.1 0.78 0.71–0.88

1.0–1.20

Moryanti 1

3055.0–3063.0

U. Jurassic

0.1

0.3

ab.

tr.

0.3 0.9

0.68–1.10

1.10–1.25

Voloshcha 1

2255.0–2265.0

U. Jurassic

3.0

2.2

0.3

n.d.

2.5 0.54 0.42–0.67

0.86–1.25

Voloshcha 1

2500.0–2508.0

U. Jurassic

1.3

2.5

0.5

0.2

3.2 0.57 0.45–0.69

n.m.

Voloshcha 1

2651.0–2659.0

U. Jurassic

1.1

7.3

3.5

0.6

11.4 0.58 0.46–0.73

0.90–1.20

Voloshcha 1

2850.5–2860.5

U. Jurassic

2.7

25.0

5.1

4.2

34.3 0.65 0.52–0.77

1.00–1.20

Voloshcha 1

3296.0–3305.0

U. Jurassic

0.1

1.6

0.4

0.1

2.1 0.67 0.55–0.87

n.m.

Voloshcha 1

3547.0–3557.0

U. Jurassic

3.5

<0.1

tr.

<0.1 1.41 1.10–1.50

n.m.

In the Ukrainian part the depth of the sample is impossible to be accurately identified. M. – Middle; U. – Upper; V – vitrinite; L – liptinite; I – iner-
tinite; OM – organic matter; R

– vitrinite reflectance; meas. – measurements; R

Oredep

– vitrinite reflectance of redeposited organic matter; tr. – traces;

n.m. – not measured; ab. – absence; n.d. – no data.

Fig. 7. Hydrogen index versus Rock-Eval T

max

temperature for (A and C) Polish and (B and D)

Ukrainian parts of study area. Maturity paths of individual kerogen types after Espitalié et al. (1985).

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2011)  or  post-sedimentary  oxidation  related  to  erosion
caused that kerogen recently observed in analysed rocks rep-
resents  a  non-generative  residuum.  The  low  hydrocarbon
source potential of this kerogen, is revealed by the hydrocar-
bon  index  below  20 mg  HC/g  TOC  (Table 1,  Figs. 4,  7C).
The low TOC content precludes detailed determination of its
type and maturity but the obtained single values of T

max

sug-

gest its immaturity (Table 1, Figs. 4, 7C).

The overall assessment of Lower Cretaceous strata allows

us to conclude that these sediments do not meet the criteria
of hydrocarbon source rocks, mainly due to their low hydro-
carbon content and immaturity (Figs. 4, 5C, 7C).

The Upper Cretaceous rocks

The characterization of Upper Cretaceous strata was also

based  on  a  small  number  of  samples  collected  only  in  the
Ukrainian part of the Carpathian Foredeep. Similarly to the
Lower  Cretaceous  strata,  the  TOC  range  is  also  wide:  from
0.01  to  1.77 wt. %,  with  nearly  identical  median  value
(0.44 wt. %, Table 1). The relatively high TOC content is as-
sociated with low genetic potential (S

) (Table 1, Figs. 4,

5D). This potential measured only for half the analysed sam-
ples reaches up to 3 mg HC/g of rock (Fig. 5D). The analy-
sed samples point to the existence of very good oil potential,

Table 3: Indices calculated from distribution of n-alkanes and isoprenoids in bitumens extracted from Jurassic and Cretaceous strata.

Pr – pristane; Ph – phytane; CPI

(17—31)

= [(C

+...+C

)+(C

+...+C

)]/2*(C

+...+C

); CPI

(17—23)

=[(C

)

+(C

)]/2*(C

); CPI

(25—31)

=[(C

)+(C

)]/2*(C

+C30); LTS

=(C

)/(C

);

n.c. – not calculated due to partial evaporation of hydrocarbons; values typed in italic are estimated due to co-elution of crocetane.

Well Depth

(m)

Stratigraphy

CPI

(17–31)

CPI

(17–23)

CPI

(25–31)

Pr/Ph Pr/n-C

Ph/n-C

LTS

max

Polish part
Księżpol 18

869.6

M. Jurassic

n.c.

1.80

n.c.

0.62

5.54

Lubliniec

730.4 M.

Jurassic n.c. n.c. 2.58 n.c. n.c. 0.41 8.85 27

Łukowa 2

731.8 M.

Jurassic n.c. n.c. 3.52 n.c. n.c. 0.40 9.79 29

Łukowa 4

982.5 M.

Jurassic n.c. n.c. 1.69 n.c. n.c. 1,00 7.26 27

Markowice 2

800.0

M. Jurassic

n.c. n.c. 2.86 n.c. n.c. 0.52 9.33 27

Markowice 2

902.8

M. Jurassic

n.c. n.c. 1.96 n.c. n.c. 1.48 2.48 27

Ukrainian part
Bortyatyn

1 2846.0–2857.0

Jurassic 1.23 1.00 1.55 1.39 4.93 0.71 1.8 25

Chornokuntsi

1 2096.0–2102.0

Jurassic 1.15 0.84 1.70 0.81 3.18 0.89 1.8 20

Korolyn 6

3421.8–3429.7

M. Jurassic

n.c.

1.29

n.c.

0.44

1.9

Korolyn 6

3517.3–3523.0

M. Jurassic

n.c.

1.17

n.c.

0.30

0.7

Mosty 2

2360.3–2364.4

M. Jurassic

n.c.

1.99

n.c.

1.01

3.0

Mosty

2521.0–2529.0

Jurassic 1.39 1.18 1.67 2.19 1.77 0.23 1.4 23

Mosty

2543.0–2549.0

Jurassic 1.29 0.93 1.75 1.51 3.42 0.59 3.1 27

Podiltsi 1

3214.8–3221.0

M. Jurassic

n.c.

1.42

n.c.

6.4

Podiltsi

3316.0–3323.0

Jurassic 1.22 1.12 1.35 0.87 1.22 1.42 3.6 27

Korolyn

2144.0–2146.7

Jurassic 0.93 0.90 1.19 0.33 0.64 0.59 0.2 19

Korolyn

2293.0–2308.0

Jurassic 0.97 0.95 1.01 0.35 0.51 0.70 0.3 19

Lanivka

1590.0–1597.0

Jurassic n.c. n.c. 2.15 n.c. n.c. n.c. 4.0 22

Mosty

1790.0–1800.0

Jurassic 1.16 0.98 1.47 0.87 4.03 1.32 1.3 23

Voloshcha 1

2659.0–2667.0

U. Jurassic

n.c.

1.64

n.c.

14.6

Voloshcha

1 2870.5–2880.0

Jurassic n.c. n.c. 1.66 n.c. n.c. 0.81 1.9 23

Voloshcha 1

2903.7–2912.0

U. Jurassic

n.c.

1.51

n.c.

10.3

Voloshcha 1

2952.0–2959.0

U. Jurassic

1.17

1.00

1.43

n.c.

1.06

1.7

Voloshcha

1 3126.0–3134.0

Jurassic n.c. n.c. 1.57 n.c. n.c. 0.53 1.9 25

Verchany 1

1811.0–1825.3

U. Jurassic

n.c.

0.98

0.22

n.c.

2.74

0.9

Yuriyiv 1

2016.0–2025.0

U. Jurassic

n.c.

1.20

0.99

n.c.

0.98

2.0

Chornokuntsi

1 1866.0–1871.0

Jurassic? 0.95 0.82 1.27 0.32 1.56 1.97 1.7 24

Didushychi

2 1100.0–1108.0

Cretaceous

n.c. n.c. 3.23 n.c. n.c. 2.99 2.1 22

Didushychi

2 1706.0–1712.0

Cretaceous

n.c. n.c. 2.15 n.c. n.c. 2.57 5.9 29

Pivn. Girs'ke 1

1391.2–1405.2

U. Cretaceous

n.c.

3.11

< 1

n.c. 4.29 1.6 27

Pivn. Girs'ke 1

1405.0–1414.0

U. Cretaceous

n.c.

2.52

< 1

n.c. 7.03 3.1 29

as  revealed  by  relatively  high  efficiency  of  extractable  hy-
drocarbons (Fig. 6C), which may be connected with the be-
ginning of hydrocarbon generation process. All the analysed
samples  indicate  low  HI  values  (median  121 mg  HC/g
TOC), suggesting domination of gas-prone Type III kerogen
(Figs. 4, 7D). This suggestion is supported by n-alkane dis-
tribution showing domination of long-chain hydrocarbons in
the majority of analysed samples (Table 3, Fig. 8E). Regular
sterane distribution (Table 4), stable carbon isotope compo-
sition (Fig. 10) as well as the elemental composition of kero-
gen (Fig. 11) indicate the input of oil-prone Type II kerogen.
Increased concentrations of phytane in samples derived from
the  Pivnichno  Girs’ke 1  well  (Fig. 8E)  may  be  connected
with co-elution of crocetane (2, 6, 11, 15-tetramethylhexade-
cane),  a  biomarker  of  methanogenic  and  methanotrophic
archea  (Peters  et  al.  2005).  In  these  samples  the  highly-
branched  isoprenoid  C

[2,6,10,14-tetramethyl-7-(3-methyl-

penthyl)  pentadecane]  (HBI)  was  also  detected  (Fig. 8E).
According  to  Volkman  et  al.  (1994,  1998),  this  biomarker
occurs in diatoms and is an indicator of diatoms’ contribution
to  organic  matter.  In  the  Pivnichno  Girs’ke  1/1405—1414
sample, the presence of 2, 6, 10, 15, 19-pentamethylicosane
(PMI) was recorded (Fig. 8E). This isoprenoid is a common
crocetane  marker  of  methanogens  in  immature  sediments
(Noble  &  Henk  1998).  The  presence  of  all  the  above  dis-

329

HYDROCARBON POTENTIAL OF JURASSIC AND CRETACEOUS SOURCE ROCKS (SE POLAND AND W UKRAINE)

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

Well Depth

(m)

Stratigraphy

ster

Mor/Hop

S/(S+R)

SR C

Ts/

Ts/Tm Dia/Reg

Polish part
Księżpol 18

869.6

M. Jurassic

21 20 58 2.72

0.79

0.34

0.23

0.12

0.42

0.03

0.05

0.14

Lubliniec

730.4

M. Jurassic 45 20 35 0.77

1.23

0.18 0.27 0.23

0.42

0.15 0.05 0.24

Łukowa 2

731.8

M. Jurassic

20 28 52 2.59

0.85

0.17 0.21 0.13

0.38

0.10 0.12 0.04

Łukowa 4

982.5

M. Jurassic

24 28 48 1.97

0.90

0.31 0.26 0.13

0.44

0.05 0.05 0.10

Markowiece 2

800.0

M. Jurassic

28 21 51 1.83

0.94

0.22

0.26

0.19

0.39

0.16

0.17

0.13

Markowiece 2

902.8

M. Jurassic

23 19 58 2.48

0.96

0.20

0.26

0.49

0.08

0.23

0.17

Ukrainian part
Bortyatyn 1

2846.0–2857.0

M. Jurassic

25 21 54 2.21

0.46

0.56

0.36

0.32

0.11

0.03

0.24

Chornokuntsi

1 2096.0–2102.0 M. Jurassic 35 14 51 1.44

0.67

0.47 0.40 0.21

0.37

0.12 0.05 0.20

Korolyn 6

3421.8–3429.7

M. Jurassic

23 20 58 2.56

0.31

0.58

0.59

0.32

0.01

0.03

0.16

Korolyn 6

3517.3–3523.0

M. Jurassic

33 19 48 1.45

0.22

0.57

0.59

0.65

0.47

0.05

0.06

0.74

Mosty 2

2360.3–2364.4

M. Jurassic

33 26 42 1.28

0.48

0.54

0.44

0.16

0.40

0.10

0.07

0.26

Mosty 2

2521.0–2529.0

M. Jurassic

22 28 50 2.33

0.55

0.57

0.59

0.34

0.27

0.04

0.01

0.07

Mosty 2

2543.0–2549.0

M. Jurassic

36 20 44 1.21

0.42

0.57

0.56

0.31

0.45

0.09

0.07

0.44

Podiltsi 1

3214.8–3221.0

M. Jurassic

32 13 55 1.69

0.50

0.57

0.56

0.33

0.32

0.03

0.18

Podiltsi 1

3316.0–3323.0

M. Jurassic

25 27 48 1.91

0.41

0.58

0.59

0.45

0.34

0.01

0.03

0.14

Korolyn 6

2144.0–2146.7 U. Jurassic 33 22 44 1.33

0.08

0.52 0.60 0.52

0.53

0.10 0.14 0.19

Korolyn 6

2293.0–2308.0 U. Jurassic 35 22 42 1.21

0.09

0.57 0.60 0.52

0.57

0.11 0.27 0.08

Lanivka

1590.0–1597.0 U. Jurassic 23 34 43 1.84

0.19

0.33 0.41 0.07

n.c.

0.24 0.51 0.03

Mosty 1

1790.0–1800.0 U. Jurassic 31 27 42 1.36

0.22

0.59 0.57 0.34

0.29

0.28 0.40 0.18

Voloshcha

2659.0–2667.0 U. Jurassic 34 18 48 1.40

0.54

0.47 0.41 0.20

0.36

0.04 0.06 0.30

Voloshcha

2870.5–2880.0 U. Jurassic 21 28 51 2.45

0.44

0.54 0.50 0.28

0.33

0.02 0.02 0.19

Voloshcha

2903.7–2912.0 U. Jurassic 23 25 52 2.22

0.45

0.54 0.52 0.27

0.35

0.01 0.02 0.12

Voloshcha

2952.0–2959.0 U. Jurassic 18 22 60 3.39

0.47

0.52 0.49 0.34

0.65

0.09 0.04 0.29

Voloshcha

3126.0–3134.0 U. Jurassic 19 17 64 3.44

0.41

0.55 0.57 0.42

0.32

0.07 0.09 0.11

Verchany 1

1811.0–1825.3 U. Jurassic 31 22 47 1.50

0.22

0.45 0.49 0.29

0.35

0.07 0.20 0.15

Yuriyiv 1

2016.0–2025.0 U. Jurassic 32 18 51 1.61

0.67

0.41 0.30 0.15

0.43

0.08 0.04 0.42

Chornokuntsi

1 1866.0–1871.0 U. Jurassic? 38 20 42 1.12

0.09

0.54 0.56 0.16

0.25

0.12 0.28 0.05

Didushychi

2 1100.0–1108.0 U. Cretaceous 24 35 41 1.72

0.31

0.58 0.40 0.22

n.c.

0.37 0.40 0.04

Didushychi

2 1706.0–1712.0 U. Cretaceous 24 32 44 1.85

0.33

0.36 0.41 0.09

n.c.

0.32 0.32 0.03

Pivn. Girs'ke 1 1391.2–1405.2 U. Cretaceous 27 33 40 1.51

0.22

0.40

0.43

0.10

0.31

0.35

0.41

0.08

Pivn. Girs'ke

1 1405.0–1414.0 U. Cretaceous 47 26 28 0.60

0.09

0.35 0.36 0.08

n.c.

0.30 0.37 0.03

Table 4: Selected biomarker characterization of bitumens from Jurassic and Cretaceous strata.

= C

20R sterane/(C

+ C

)

20R steranes; C

= C

20R sterane/(C

)

20R steranes; C

= C

20R sterane/

+ C

)

20R steranes; C

ster = C

20R sterane/C

20R sterane; Mor/Hop = moretane/17 hopane; H

S/(S+R) = homohopane 22S/

(22S + 22R); H

S/(S+R) = bishomohopane 22S/(22S + 22R); C

SR = epimerisation of regular steranes C

ratio; C

= ratio of

-epimeres of regular stera-

nes C

to sum of

steranes; C

Ts/C

H = C

18 norneohopane/C

norhopane; Ts/Tm = C

18 trisnorhopane/C

17 trisnorhopane; Dia/Reg = C

20S diasterane/C

20R sterane; n.c. – not calculated due to low intensities of biomarkers; M. – Middle; U. – Upper.

Fig. 11. Genetic characterization of organic matter from Jurassic
and Cretaceous strata in the analysed part of the Carpathian Fore-
deep. Fields representing natural maturity paths for individual kero-
gens after Hunt (1996).

cussed biomarkers in the study area has already been
described by Kotarba et al. (2011) for the overlying Miocene
strata of the Carpathian Foredeep.

The immaturity of organic matter dispersed in analysed

strata is evidenced by low T

max

temperatures (below 430 °C,

Table 1, Figs. 4, 7D), high CPI values (Table 3) and sterane
ratios (Table 4, Fig. 13B). Moreover, hopane ratios also indi-
cate low maturity of analysed organic matter, comparable to
that from the Upper Jurassic rocks but higher than that from
the Middle Jurassic sediments (Fig. 12).

The low maturity of analysed organic matter indicates that

both the Upper and the Lower Cretaceous strata did not meet
the criteria of hydrocarbon source rocks (Table 1, Figs. 5, 7).

Conclusions

The analysis of both the Jurassic and Cretaceous rocks

from the south-eastern part of Poland and the western part of
Ukraine, between Tarnogród and Stryi towns, generally re-
veals their low hydrocarbon source-rock potential. The low-
est petroleum potential characterizes the Lower Jurassic and
the Cretaceous strata where TOC contents, genetic potential

330

KOSAKOWSKI, WIĘCŁAW, KOWALSKI and KOLTUN

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

and  hydrocarbon  index  values  prove  that
these stratigraphic horizons were not signif-
icant  sources  of  hydrocarbons.  However,
our  results  demonstrate  the  increasing  val-
ues of these quantitative parameters as well
as  local  enrichment  in  organic  carbon  and
hydrocarbon content within the Upper Cre-
taceous  strata  in  the  eastern  part  of  the
study area. Unfortunately, the effective hy-
drocarbon sourcing in these horizons is sig-
nificantly  limited  by  low  maturity  of
organic  matter,  which  does  not  guarantee
its  transformation  into  hydrocarbons.  In
conclusion,  the  above-mentioned  strati-
graphic  horizons  are  of  minor  importance
as  potential  source  rocks  of  hydrocarbons
in the study area.

Table 5: Stable carbon isotope compositions of bitumens, their individual fractions and kerogen from Jurassic and Cretaceous strata.

Fractions (wt. %)

C (‰)

Well Depth

(m)

Stratigraphy

Sat Aro Res Asph Sat

Bit

Aro

Res Asph Ker

Polish part
Księżpol 18

869.6

M. Jurassic

–27.4

–24.4

–25.0

–24.6

–23.7

–23.1

Lubliniec 4

730.4

M. Jurassic

–27.8

–25.5

–26.6

–26.3

–24.9

–23.9

Łukowa 2

731.8

M. Jurassic

–29.3

–26.2

–27.0

–26.5

–25.2

–24.1

Łukowa 4

982.5

M. Jurassic

–27.1

–24.1

–24.7

–24.5

–23.6

–22.9

Markowice 2

800.0

M. Jurassic

–28.5

–26.2

–27.2

–26.5

–25.3

–23.7

Markowice 2

902.8

M. Jurassic

–28.3

–24.5

–25.7

–24.8

–23.7

–22.8

Ukrainian part
Bortyatyn 1

2846.0–2857.0

M. Jurassic

–28.0 –24.3

–24.8

–24.7

–23.4

–23.8

Chornokuntsi 1

2096.0–2102.0

M. Jurassic

–30.2

–29.7

–30.1

–29.7

–29.4

–29.1

Korolyn 6

3421.8–3429.7

M. Jurassic

–27.5

–24.7

–24.6

–25.1

–24.1

–23.7

Korolyn 6

3517.3–3523.0

M. Jurassic

–27.4

–24.6

–24.7

–24.8

–24.3

–23.5

Mosty 2

2360.3–2364.4

M. Jurassic

–28.2

–25.0

–25.1

–25.5

–24.5

–23.5

Mosty 2

2521.0–2529.0

M. Jurassic

–30.3

–26.2

–27.7

–26.2

–25.1

–24.5

Mosty 2

2543.0–2549.0

M. Jurassic

–29.0

–25.6

–26.4

–25.9

–25.0

–24.4

Podiltsi 1

3214.8–3221.0

M. Jurassic

–27.1

–24.2

–24.3

–23.8

–23.2

Podiltsi 1

3316.0–3323.0

M. Jurassic

–27.1

–24.4

–24.9

–24.7

–24.4

–23.8

Korolyn 6

2144.0–2146.7

U. Jurassic

–29.0

–29.6

–28.7

–29.1

–28.4

Korolyn 6

2293.0–2308.0

U. Jurassic

–30.2

–29.7

–30.1

–29.7

–29.4

–29.1

Lanivka

1590.0–1597.0

Jurassic

12 9 36 43 –26.9 –26.3 –26.0 –25.6 –26.7 –23.4

Mosty 1

1790.0–1800.0

U. Jurassic

–27.6

–26.5

–28.3

–27.3

–25.1

Voloshcha 1

2659.0–2667.0

U. Jurassic

–28.9

–25.9

–26.2

–26.0

–25.3

–24.2

Voloshcha 1

2870.5–2880.0

U. Jurassic

–26.9

–23.9

–24.2

–24.1

–23.7

–22.6

Voloshcha 1

2903.7–2912.0

U. Jurassic

–27.5

–24.3

–24.7

–24.4

–23.8

–23.4

Voloshcha 1

2952.0–2959.0

U. Jurassic

–27.3

–23.7

–24.0

–24.1

–23.4

–22.6

Voloshcha 1

3126.0–3134.0

U. Jurassic

–28,0

–25.1

–25.4

–24.8

–24.3

Verchany 1

1811.0–1825.3

U. Jurassic

–28.7

–26.9

–26.8

–26.9

–26.7

–24.3

Yuriyiv 1

2016.0–2025.0

U. Jurassic

–28.2

–24.5

–25.1 –25.0 –23.8

–23.5

Chornokuntsi

1866.0–1871.0

Jurassic? 17 17 37 29 –26.6 –25.6 –25.6 –25.4 –25.3 –24.9

Didushychi

1100.0–1108.0 U.

Cretaceous 13 6 40 41 –28.1 –27.3 –27.4 –27.2 –27.2 –24.6

Didushychi 2

1706.0–1712.0

U. Cretaceous

–28.3

–26.9

–27.2

–27.0

–26.5 –25.0

Pivn. Girs'ke 1

1391.2–1405.2

U. Cretaceous

–27.7

–26.5

–26.7

–26.6

–26.0

–24.8

Pivn. Girs'ke 1

1405.0–1414.0

U. Cretaceous

–28.0

–26.2

–26.6

–25.8

–25.6

–25.0

In the Ukrainian part the depth of the sample is impossible to be accurately identified. M. – Middle; U. – Upper; Sat – saturated hydrocarbons; Aro – aro-
matic hydrocarbons; Res – resins; Asph – asphaltenes; Bit – bitumen; Ker – kerogen.

Fig. 12. Plots of moretane/17 hopane ratio versus
(A) Ts/Tm and (B) C

Ts/C

H ratios.

Fig. 13. Plots of sterane C

20S/(20S + 20R) ratio

versus C

) ratio for organic matter

from Jurassic strata in the (A) Polish and (B)
Ukrainian parts of the Carpathian Foredeep. Ma-
turity fields after Peters & Moldowan (1993).

Fig. 12.

Fig. 13.

331

HYDROCARBON POTENTIAL OF JURASSIC AND CRETACEOUS SOURCE ROCKS (SE POLAND AND W UKRAINE)

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

Table 6: Elemental composition of kerogen from Jurassic and Cretaceous strata.

Elemental composition

(daf, wt. %)

Atomic ratio

Mole fraction

Well Depth

(m)

Stratigraphy

C H O N S H/C

O/C N/C S/C

H/(H+C) O/(O+C) N/(N+C) S/(S+C)

Polish part
Księżpol 18

869.6

M. Jurassic 75.0 4.1 16.5 1.6 1.9 0.65 0.16 0.018 0.009

0.39

0.14

0.017

0.009

Łukowa 2

982.5

M. Jurassic 73.1 3.8 20.1 1.4 1.6 0.63 0.21 0.016 0.008

0.38

0.17

0.016

0.008

Markowice 2

902.8

M. Jurassic 74.5 4.0 19.3 1.6 0.6 0.64 0.19 0.018 0.003

0.39

0.16

0.017

0.003

Ukrainian part
Bortyatyn 1

2846.0–2857.0

M. Jurassic 79.9 4.6 12.6 2.1 0.8 0.70 0.12 0.022 0.004

0.41

0.11

0.022

0.004

Korolyn 6

3517.3–3523.0

M. Jurassic 81.4 4.4 11.7 2.1 0.4 0.65 0.11 0.023 0.002

0.39

0.10

0.022

0.002

Mosty 2

2521.0–2529.0

M. Jurassic 80.7 5.0 11.9 1.7 0.7 0.74 0.11 0.018 0.003

0.42

0.10

0.018

0.003

Podiltsi 1

3214.8–3221.0

M. Jurassic 82.1 3.9 11.0 1.9 1.1 0.57 0.10 0.020 0.005

0.36

0.09

0.019

0.005

Korolyn 6

2293.0–2308.0

U. Jurassic

75.8 7.2 4.8 1.3 10.8 1.13 0.05 0.015 0.054

0.53

0.05

0.015

0.051

Kokhanivka 26 1090.9–1095.0

U. Jurassic

68.8 5.9 18.6 1.6 5.1 1.03 0.20 0.020 0.028

Lanivka 1

1590.0–1597.0

U. Jurassic

70.3 7.2 14.7 2.5 5.3 1.23 0.16 0.030 0.028

0.55

0.14

0.029

0.028

Voloshcha 1

2659.0–2667.0

U. Jurassic

78.8 5.3 12.6 1.9 1.4 0.81 0.12 0.021 0.007

0.44

0.11

0.021

0.007

Voloshcha 1

2903.7–2912.0

U. Jurassic

81.6 3.7 12.2 1.8 0.6 0.55 0.11 0.019 0.003

0.35

0.10

0.019

0.003

Yuriyiv 1

2016.0–2025.0

U. Jurassic

79.6 4.1 13.4 1.6 1.3 0.62 0.13 0.017 0.006

0.38

0.11

0.017

0.006

Chornokuntsi 1 1866.0–1871.0 U. Jurassic? 68.2 6.0 13.9 1.3 10.6 1.05 0.15 0.016 0.059

0.51

0.13

0.016

0.055

Pivn. Girs’ke 1 1405.2–1414.0 U. Cretaceous 44.6 4.6 51.5 1.2 1.1 1.17 0.13 0.023 0.009

0.55

0.46

0.022

0.009

max(DBT)

Well Depth

(m)

Stratigraphy

MPI1

MPR

MPR1

cal

(%)

cal(MPR)

(%)

MDR R

cal(DBT)

(%)

(

Polish part
Księżpol 18

869.6

M. Jurassic

0.57

0.72

0.39

0.72

0.71

1.0

0.6

428

Lubliniec

730.4

Jurassic

0.55 0.58 0.34 0.70 0.60 1.1 0.6

429

Łukowa 2

731.8

M. Jurassic

0.70 0.61 0.35 0.79 0.63 0.3 0.5

425

Łukowa 4

982.5

M. Jurassic

0.66 0.58 0.36 0.77 0.65 0.5 0.5

425

Markowice 2

800.0

M. Jurassic

0.67

0.63

0.37

0.77

0.67

1.2

0.6

429

Markowice 2

902.8

M. Jurassic

0.79

0.89

0.44

0.84

0.83

1.2

0.6

429

Ukrainian part
Bortyatyn 1

2846.0–2857.0

M. Jurassic

0.49

0.57

0.36

0.66

0.65

0.9

0.6

428

Chornokuntsi

1 2096.0–2102.0 M.

Jurassic 0.49

0.50

0.34

0.66

0.60

0.8

0.6 427

Korolyn 6

3421.8–3429.7

M. Jurassic

0.63

0.88

0.43

0.75

0.79

1.8

0.6

432

Korolyn 6

3517.3–3523.0

M. Jurassic

0.79

0.99

0.46

0.84

0.87

2.0

0.7

433

Mosty 2

2360.3–2364.4

M. Jurassic

0.61

0.82

0.43

0.74

0.80

1.5

0.6

431

Mosty 2

2521.0–2529.0

M. Jurassic

0.47

0.39

0.30

0.65

0.52

0.6

426

Mosty 2

2543.0–2549.0

M. Jurassic

0.70

0.63

0.38

0.79

0.68

1.1

0.6

428

Podiltsi 1

3214.8–3221.0

M. Jurassic

0.72

0.67

0.38

0.80

0.69

1.2

0.6

429

Podiltsi 1

3316.0–3323.0

M. Jurassic

0.51

0.77

0.40

0.68

0.72

1.0

0.7

433

Korolyn 6

2144.0–2146.7

U. Jurassic

0.59

0.85

0.41

0.73

0.76

0.7

0.6

426

Korolyn 6

2293.0–2308.0

U. Jurassic

0.60

0.83

0.39

0.73

0.70

0.8

0.6

427

Lanivka

1590.0–1597.0

Jurassic

0.67 0.73 0.38 0.77 0.68 1.4 0.6

430

Moryanti

1848.2–1853.1

Jurassic

0.65 0.71 0.39 0.76 0.71 1.0 0.6

428

Mosty 1

1790.0–1800.0

U. Jurassic

0.57

0.66

0.39

0.71

1.1

0.6

429

Voloshcha

2659.0–2667.0

Jurassic

0.79 0.68 0.36 0.85 0.65 0.6 0.6

426

Voloshcha

2870.5–2880.0

Jurassic

0.44 0.40 0.31 0.64 0.54 0.4 0.5

425

Voloshcha

2903.7–2912.0

Jurassic

0.50 0.45 0.31 0.67 0.52 1.1 0.6

428

Voloshcha

2952.0–2959.0

Jurassic

0.49 0.65 0.39 0.66 0.71 1.7 0.6

431

Voloshcha

3126.0–3134.0

Jurassic

0.55 0.57 0.38 0.70 0.69 1.9 0.6

433

Verchany 1

1811.0–1825.3

U. Jurassic

0.83

0.89

0.43

0.87

0.81

1.0

0.6

428

Yuriyiv 1

2016.0–2025.0

U. Jurassic

0.56

0.58

0.38

0.70

0.69

1.1

0.6

429

Chornokuntsi

1866.0–1871.0 U.

Jurassic? 0.40 0.68 0.30 0.61 0.50 0.5 0.5

426

Didushychi

1100.0–1108.0 U.

Cretaceous 0.81 0.78 0.39 0.85 0.72 1.0 0.6

428

Didushychi

1706.0–1712.0 U.

Cretaceous 0.81 0.68 0.35 0.86 0.63 0.6 0.6

426

Pivn. Girs’ke 1

1391.2–1405.2

U. Cretaceous

0.49

0.47

0.31

0.66

0.54

0.7

0.6

426

Pivn. Girs’ke 1

1405.0–1414.0

U. Cretaceous

0.52

0.55

0.34

0.68

0.60

0.3

0.5

424

Table 7: Maturity indices calculated from distribution of phenanthrene and dibenzothiophene, and their methyl derivatives in bitumens
from Jurassic and Cretaceous strata.

MPI1 = 1.5(2-MP + 3-MP)/(P + 1-MP + 9-MP); P – phenanthrene; MP – metylphenanthrene; MPR = 2-MP/1-MP; MPR1 = (2-MP + 3-MP)/(1-MP + 9-
MP + 2-MP + 3-MP); R

cal

= 0.60MPI1 + 0.37 for MPR < 2.65 (Radke 1988); R

cal(MPR)

= —0.166 + 2.242MPR1 (Kvalheim et al. 1987); MDR = 4-MDBT/1-

MDBT; MDBT – methyldibenzothiophene; R

cal(DBT)

= 0.51 + 0.073MDR; Tmax(DBT) = 423 + 5.1MDR; (Radke & Willsch 1994); M. – Middle; U. – Upper.

In the Ukrainian part the depth of the sample is impossible to be accurately identified. daf – dry, ash – free basis. M. –Middle, U. – Upper.

332

KOSAKOWSKI, WIĘCŁAW, KOWALSKI and KOLTUN

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 4, 319—333

Both the Middle and Upper Jurassic strata reveal different

geochemical  characterizations.  The  Middle  Jurassic  strata
show relatively the best source rock parameters. This is par-
ticularly  evident  from  the  Polish  part  of  the  study  area,
where  nearly  all  analysed  samples  meet  the  quantitative
hydrocarbon sourcing criteria. In the Ukrainian part one can
observe equally high TOC content and genetic potential, al-
though in about 40 % of analysed samples TOC contents are
below  the  threshold.  Good  quantitative  sourcing  character-
ization is reduced by low HI values, generally below 100 mg
HC/g TOC. Organic matter in the Middle Jurassic strata is of
mixed  type,  dominated  by  gas-prone  Type III  kerogen.  The
Rock-Eval T

max

temperature together with the biomarker ra-

tios and vitrinite reflectance indicate that the organic matter
is immature. Hence, despite positive hydrocarbon sourcing
properties, the Middle Jurassic sediments are mature enough
to be the effective hydrocarbon source rocks only in the
Ukrainian part of the study area.

Similar geochemical characteristics were found for the

Upper Jurassic rocks in which highly variable TOC contents
and  genetic  potential,  very  low  medians  and  low  hydrocar-
bon  index  were  observed.  This  indicates  that  the  Upper  Ju-
rassic  strata  are  poor  source  rock  although  horizons  with
high  TOC  contents  and  high  genetic  potential  may  locally
exist. The Middle Jurassic strata reveal the low thermal ma-
turity,  which  makes  them  rather  poor  hydrocarbon  source
rocks except for some isolated horizons found in the vicinity
of  the  Korolyn 6  and  Chornokuntsi 1  wells  where  highly
generative, high-sulphur Type IIS kerogen was recorded.

The overall assessment of both the Jurassic and Cretaceous

rocks  reveals  that  these  are  poor,  ineffective  hydrocarbon
source  rocks.  Horizons  capable  of  generating  hydrocarbons
contain  Type  IIS  kerogen  and  occur  only  locally  within  the
Upper Jurassic strata. In the Polish part of the Upper Jurassic
basin this type of organic matter was not observed.

Acknowledgments:  The  research  was  undertaken  as  Project
No. UKRAINE/193/2006  of  the  Ministry  of  Science  and
Higher Education carried out at the AGH University of Sci-
ence and Technology in Kraków and at the Polish Geologi-
cal Institute – National Research Institute in Warsaw in the
years 2007—2010. Analytical work by Mr. Hieronim Zych and
Mr.  Tomasz  Kowalski  from  the  AGH  University  of  Science
and  Technology  in  Kraków  is  gratefully  acknowledged.  The
authors  are  indebted  to  Ms.  Izabella  Grotek  from  the  Polish
Geological Institute – National Research Institute in Warsaw
for  measurements  of  vitrinite  reflectance  and  maceral  com-
position. The authors want to express their sincere thanks to
Tadeusz  Peryt  (Polish  Geological  Institute  –  National
Research Institute), and to the anonymous reviewers for their
valuable comments, which helped to prepare the final text.

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