25th International Meeting on Organic Geochemistry IMOG 2011

P-283
Correlation between composition of naphthenoarenes and their
saturated analogues in oils from different geological age
deposits
Natalya Voronetskaya, Galina Pevneva, Anatoly Golovko
Institute of Petroleum Chemistry SB RAS, Tomsk, Russian Federation (corresponding
author:voronetskaya@ipc.tsc.ru)
Now hydrocarbons of hybrid structure containing
simultaneously aromatic and naphthenic cycles –
naphthenoarenes are the least studied class of oil
compounds. The structure of naphthenearene
molecules determined in oils is similar to that of
saturated cyclic compounds (cyclanes). The aim of
the present work was to study compositions and
distributions of naphthenoarenes and cyclanes in oils
of multihorizon fields. The oils recovered from
multihorizon oil fields Sirakovo (5 samples) and
Bradarac-Maljurevac (3 samples) (Serbia) occurring
in Cainozoic deposits, as well as oils from Usinskoye
oil field (5 samples), Paleozoic deposits (Russia) were
used as the objects of investigation.
The oils in Sirakovo oil field occur in the depths
ranging from 1400 to 1800 m and oils in Bradarac-
Maljurevac oil field - from 1800 to 2200 m. The depth
of occurrence of Paleozoic oils in Usinskoye oil field
ranges from 1190 to 1400 m.
Concentrates of saturated, mono-, bi- and
triaromatic hydrocarbons were isolated by a column
liquid-adsorption chromatography. The concentrates
of arenes were divided into fractions of alkyl- and
naphthenoarenes by extraction with methanol.
Carbamide dewaxing was used to separate cyclanes
from acyclic alkanes.
Compositions of cyclanes, naphthenobenzenes,
naphthenonaphthalenes and
naphthenophenanthrenes were determined by a
mass-spectrometry method via direct introduction of
the sample into an ionization chamber. The energy of
ionizing electrons was 12 eV.
Cyclanes contain from 1 to 5 saturated cycles in
a molecule. Naphthenoarenes are presented by the
compounds with a number of aromatic cycles from 1
(naphthenobenzenes) to 3
(naphthenophenanthrenes). Total number of cycles in
a molecule of naphthenoarenes does not exceed five.
The content of compounds with two cycles in a
molecule – mononaphthenobenzenes and their
saturated analogues bicyclanes – symbately
decreases with the depth of oil occurrence.
Tricyclic compounds are presented by
naphthenobenzenes, mononaphthenonaphthalenes
and their saturated analogues – tricyclanes. The
content of dinaphthenobenzenes decreases with the
depth of oil occurrence. The content of
naphthenonaphthalenes increases in oils from
Cainozoic deposits with the depth of occurrence and
decreases in Paleozoic oils. The concentration of
tricyclanes in oils from Cainozoic deposits decreases
with the depth of occurrence, while in Paleozoic oils it
increases.
Among tetracyclic compounds we have studied
distributions of trinaphthenobenzenes,
dinaphthenonaphthalenes,
mononaphthenophenanthrenes and their saturated
analogues – tetracyclanes. The content of
trinaphthenobenzenes decreases with the depth of oil
occurrence. The contents of
dinaphthenonaphthalenes and
mononaphthenophenanthrenes increase in Cainozoic
oils with the depth of occurrence and decrease in
Paleozoic oils. The content of tetracyclanes increases
in deeper occurring oils both from Cainozoic and
Paleozoic deposits.
Pentacyclic compounds are presented by
tetranaphthenobenzenes, trinaphthenonaphthalenes,
dinaphthenophenanthrenes and their saturated
analogues – pentacyclanes. The contents of both
naphthenoarenes and their saturated analogues –
pentacyclanes increase in Cainozoic and Paleozoic
oil with the depth of occurrence. One observes slope
opposition in the changes of
trinaphthenonaphthalenes and pentacyclanes
concentrations with the depth.
Based on the investigations it was shown that the
content of naphthenonaphthalenes and
naphthenophenanthrenes with total number of cycles
3-4 increases in Cainozoic oils with the depth of
occurrence, whereas in Paleozoic oils it decreases.
In spite of the age of deposits the content of
cyclanes (4-5 cycles) and naphthenoarenes with total
number of cycles in a molecule 5 increases with the
depth of occurrence, whereas the content of
naphthenobenzens with a number of cycles in a
molecule from 2 to 4 decreases.
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