25th International Meeting on Organic Geochemistry IMOG 2011

P-119
Generation potential of Togur Formation rocks in the south-east
of Western Siberia (Russia)
Ivan Goncharov, Nikolay Oblasov, Vadim Samoylenko, Svetlana Fadeeva
TomskNIPIneft, Tomsk, Russian Federation (corresponding author:goncharoviv@nipineft.tomsk.ru)
Togur Formation is considered to be the major source
rock among Lower Jurassic depositions of Western
Siberia. Its formation was the result of early Toarcian
transgression, while sedimentation developed under
conditions when large lakes periodically
communicated with open seas [1]. This resulted in the
unstable formation distribution continuity in area, as
well as, unstable rock composition and properties,
which in its turn, created significant difficulty in
studying this formation.
102 Togur Formation rock samples from 12 well
areas in East of Khanty-Mansiysk autonomy and
Tomsk region were studied (Fig. 1).
The most low-content Togur Formation rock organic
matter was discovered in the wells of Archinskaya,
Elleyskaya, Kolpashevskaya, Stolbovaya,
Urmanskaya and Voskresenskaya fields. The organic
carbon content in these rocks was not more than
1.0% (in separate samples up to 2-3%). Organic
matter in these rocks have a low generation potential
(HI ranges from 13 to 178 mg HC/g TOC, and even
higher).
Togur Formation rocks with a rich TOC content was
discovered in Duklinskaya, Prikoltogorskaya and
Sutiginskaya areas. Organic carbon content in most
investigated rock samples changes from 0.3 to 5.2%,
however, there were samples with a rather high
content (TOC 7.9-20.6%). Nevertheless, organic
matter in these rocks is not of high quality and HI is
usually not more than 300-320 mg HC/g TOC.
The most significant results were obtained in
investigated rock samples from Kulginskaya, Yuzhno-
Tabaganskaya and Lar‘igolkuskaya areas. In these
areas the Togur Formation rocks contain organic
matter with high generation potential. The average HI
is 400-500 mg HC/g TOC, where maximum value is
about 600 mg HC/g TOC. The rocks in Kulginskaya
and Yuzhno-Tabaganskaya areas (in south-western
Tomsk oblast) have rather low carbon content (TOC
0.6-4.9%). Togur Formation rock samples with rather
rich organic matter content were found in wells of
Lar‘igolkusk field (TOC 0.3-17.6%), located in East
Khata-Mansisk autonomy. Togur Formation rocks,
rich in TOC (2.7-19.7%), were earlier discovered in
wells of Vatinskaya, Severo-Orekhovskaya and
Sugmutskaya fields, Khanty-Mansiysk and Jamalo-
Nenechk autonomies, [2], though highly mature
(Tmax=445-466 o C, HI=101-164 mg HC/g TOC).
Different sedimentation conditions of the Togur
Formation significantly affected the extract
hydrocarbon composition of these rocks. Pr/Ph ratio
ranges from 1.0 to 5.0, while Sterane C29/C27 ratio–
from 1.0 to 3.0, which in its turn, reflects the wide
variation of sedimentation oxidation-reduction
environment and bioproducer composition. However,
it can be stated that the oil generation of Togur
Formation played a significant role in the formation of
Verkhekolik-Eganskaya and Suslikovskaya fields in
Eats of Khanty-Mansiysk autonomy. The oil biomarker
composition in these fields is about the same as that
of the rock extract composition in the Togur
Formation, located near Lar‘igolkuskaya area.
Fig.1. Characteristic feature of the generation
potential of Togur Formation.
References
[1] Shurygin B.N. et al. Stratigraphy of oil and
gas basins of Siberia. Jurassic System. Novosibirsk:
Publ. House SB RAS, Department ―GEO‖, 2000.
480p.
[2] Lopatin N.V., et al. (1997) Oil source ,
discovered in crust weathering and mantle of
Paleozoic base in Sredne Pre-Ob areas \\ Geology,
geophysics and oil field development. 7, 7-22p.
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