25th International Meeting on Organic Geochemistry IMOG 2011

P-335
Geochemistry of aqua-bitumoids from deposits in the West
Siberian sedimentary basin
Valentina Danilova, Alexey Kontorovich
Trofimuk Institute of Petroleum Geolodgy and Geophysics SB RAS, Novosibirsk, Russian Federation
(corresponding author:DanilovaVP@ipgg.nsc.ru)
A systematic study of aqua-bitumoids (AB)
(bitumoids -chloroform extractable bitumens) from
West Siberian sedimentary basin have been
conducted for several years in the Organic
Geochemistry laboratory, SB RAS IPGG, which
allowed us to developed a method for their extraction
and schematics for their study.
It‘s been established that the concentration
of bitumoids in reservoir waters varies widely - from 4
to 390 mg / l (litre), reaching in some waters 1-3 g / l
and more. Based on the geological setting of waters
localization, and the concentration and composition of
bitumoids there were defined two types of groups in
the West Siberian basin. The first group characterizes
regional background of primary and secondary
migrations of dispersed bitumoids. Whereas the
second one describes the anomalies associated with
dispersion of oil components from the reservoirs. For
both the generations of AB the analysis was given to
the changes in their content, as well as element,
group and hydrocarbon composition through the area
and in the context of the increasing age of
hydrogeological complexes [1].
Applying cluster analysis method, on the
base of a large set of biomarker parameters, each of
the AB groups was divided into three families, with
their biomarkers specific features and stratigraphic
confinement being established therewith [2].
In each water aggregate entity, aquabitumoids
from the first family by their biomarker
parameters are assigned to the continental type,
which is likely to have sourced from DOM with a
significant portion of terragenous constituent, and the
dissipated from reservoirs oil components,
genetically related to higher terrestrial vegetation.
The third family of AB from the both groups
based on biomarker characteristics was diagnosed as
marine. Thereby, this family in both AB groups I and II
is believed to have originated from DOM of marine
facies and scattered components of oil of marine type.
The second family of AB from both the
groups is closer to the marine family in the context of
biomarker parameters. Their source might have been
dispersed OM mixed with a small portion of
terragenous constituent and scattered components of
oil mixed from the reservoirs.Genetic relations
established at the molecular level between HC
DOM→ AB → oils showed that the source of AB in
the West Siberian basin including its northern areas at
present stage of its history, appeared to have been
not only DOM from the Lower-Middle Jurassic
horizons with different proportions of terragenous and
aquagenous constituents (the Tyumen and Togur
Fms and their analogues), but inherently aquagenous
OM of the Bazhenovo Fm and its analogs. With
regard to northern parts of the basin, there has been
not sufficient information, even enough to make
assumptions of this kind, which leaves the fact
obscure from the point of view of sedimentarymigration
theory of oil formation.
In the issue, the comprehensive studies of
AB have shown that the possibility of hydrocarbons
migration, including hydrocarbons-biomarkers, resins
and asphaltenes, together with waters in natural
systems appear to have been much greater than
anticipated by some researchers [3].
It is shown that the extent of bitumoids‘ comigration
with waters is enormous. Given the large
number of cycles of expelled water exchange in the
basin, even being significantly scattered, they could
have provided established at present oil and gas
resources.
By AB content and composition there have
been developed criteria for prognosis evaluation of
the poorly explored sedimentary basins.
This work was supported by RFBR (10-05-00705), the
Interdisciplinary Integration Project of SB RAS N 36.
References
[1] Kontorovich, A.E. Aquabitumoids // Gubkin‘s Scientific Inheritance
in Petroleum Geology of Siberia. Novosibirsk, Nauka, 1980, pp. 73-
85.
[2] Danilova, V.P. Geochemistry of Aquabitumoids // Geologia I
geofizika, 2004, v. 45, № 7, pp. 803-814.
[3] Uspenskii, V.A. Introduction to Petroleum Geochemistry.
Leningrad, Nedra, 1969, p. 307.
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