25th International Meeting on Organic Geochemistry IMOG 2011

P-374
Bulk geochemical characterisation of the source rocks for shale
gas in Poland
Irena Matyasik, Wojciech Bieleń, Tomasz Słoczyński
Oil and Gas Institute, Cracov, Poland (corresponding author:matyasik@inig.pl)
This paper presents the general geochemical
characteristics of Silurian shale with the aim to
constrain its shale gas potential.
Detailed biomarker and light hydrocarbons
geochemistry confirms that the marine Silurian Shale
is the primary source rock for exploration shale gas in
Poland. Study of the area has been divided into four
parts: Baltic Basin, NE part of Poland (EEC), Lublin
Area and Carpathian Foredeep.
In the Baltic Basin source rocks richest in organic are
observed within Llandovery section. Organic matter of
the shale is characterized by II type of kerogen.
Average TOC contents of Silurian shale are very
different, and vary from less than 0,5 wt. % to 12
wt.%. In the Baltic Basin lateral changes of thermal
maturity correspond to changes of present day burial
[2]. Maturity increases to the west, as the burial does,
and there thermal maturity reaches the value above
3,5 %Ro at the depth 4300m.
In the NE part of Poland the Silurian Shale were not
buried to deep so they are relatively of low mature
(0,6 – 0,75%Ro) and could be considered as source
for both oil and gas generation due to high Hydrogen
Index (above 300 mg HC/g TOC).
Other shale – gas system in Poland is located in
Lublin area where Silurian has been recognized as
good source rocks with II type kerogen. Average
organic matter content is usually in range of 0,25
wt.% to 7,92wt.%. Thermal maturity increases
towards the southeast thus TOC would be expected
to show a general decrease in this direction as
hydrocarbons are generated and expelled (Fig.1).
Organically enriched Silurian Shale with lower thermal
maturity occurs in the last of investigated basins -
Foredeep Carpathian. Most of the samples have HI
values (at present day) between 350 and 500mg
HC/g TOC with S2 values up to 20,5mg HC/g of rock
indicating oil-prone source rock potential. Organic
maturity parameters and modelling indicate that this
formation is at the peak maturity for hydrocarbon
generation.
Remaining Hydrocarbon Potential [mg HC/g Rock]
0 2 4 6 8 10 12 14 16
60
55
Lublin Area
Carpathian Foredeep
Type II
Oil Prone
60
55
50
Baltic Basin
50
45
40
35
30
25
20
15
10
East European Craton
Mixed Type II/III
Oil/Gas Prone
Type II
Gas Prone
5
Dry Gas Prone
5
0
0
0 2 4 6 8
TOC [%]
10 12 14 16
Fig.1. Present-day kerogen type of Silurian Shale in
Poland
Taking into consideration the American expierence in
exploration and exploitation, the most favourable
condition for shale gas exploration in Poland can be
expected in Baltic Basin.
References:
[1] Hill, R. J., Jarvie D.M., Pollastro R.,M., Mitchel H.
and King J.D. 2007. Oil and gas geochemistry and
petroleum systems of the Fort Worth Basin. AAPG
Bull. , Vol. 91, No.4, pp.437- 444.
[2] Poprawa.P.,2010. Shale gas potential of the Lower
Paleozoic Complex in the Baltic Basin and Lublin-
Podlasie Basin (Poland). Geological Review, 58, 226-
249.
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40
35
30
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10