25th International Meeting on Organic Geochemistry IMOG 2011

P-337
Application of electrospray ionization fourier transform ion
cyclotron resonance mass spectrometry on formation
mechanism of high acidity oils
Cheng Dingsheng 1 , Dou Lirong 2 , Shi Quan 3 , Hou Dujie 4
1 RIPED, Petrochina, CNPC, Beijing, China, 2 CNODC, Petrochina, CNPC, Beijing, China, 3 China University
of Petroleum, Beijing, China, 4 China University of Geosciences, Beijing, China (corresponding
author:chengdingsheng@petrochina.com.cn)
Although content of NSO-compounds in crude oils is
very low, they can seriously affect the processing
technology and product property of crude oils. The
composition of heteroatom compounds, especially the
heteroatom compounds with big molecular weight, is
the key and difficult aspect domain in petroleum
geochemistry for a long time. During the recent years,
great advancements have been achieved on the
composition analysis of heteroatom compounds of
heavy oils by the Electrospray Ionization (ESI)
coupled with Fourier Transform Ion Cyclotron
Resonance Mass Spectrometry (FT-ICR MS).
In order to study the genetic mechanism of high
acidity oils, the authors sampled 58 oil samples from
three rift basins (18 oil samples from Muglad Basin &
Melut Basin in Sudan, 40 samples from Bohai Bay
Basin in China) to compare the compositional
characteristics of crude oils in different basins by ESI
coupled with FT-ICR MS, and probed into the
formation mechanism of high acidity oils in different
rift basins.
Using ESI coupled with FT-ICR MS on 58 crude oils
with different total acid number (TAN), 7 heteroatom
types have been identified in these oil samples,
namely, N, NO, NO2, O1, O2, O3 and O4,
corresponding carbazole compounds, phenolic
compounds containing N, carboxylic acid containing
N, phenolic compounds, carboxylic acid compounds,
carboxylic acid with hydroxyl, dicarboxylic acid,
respectively. Relatively, N1- and O2- compounds
have abundant content in high acidity oils, which
occupied more than 80% in NSO-compounds.
Different types of heteroatom compounds are different
in the degree of ring condensation, for example, O2compounds
range in the degree of ring condensation
between 0 to -34 and N-compounds range between -9
to -27.
Further analysis indicated that the organic acids of
crude oil consist mainly of naphthenic acids with the
TANs increasing gradually with the increment of
biodegradation degree. The naphthenic acids of high
TAN oils consist mainly of mono-cyclic, bi-cyclic, tricyclic
naphthenic acids. With increasing of intensity of
biodegradation, the ratio of the content of naphthenic
acids to fatty acids and the content of multicyclic
naphthenic acids will be increased among the
naphthenic acids, especially the bi-cyclic, tri-cyclic
naphthenic acids. The degree of ring condensation of
carbazole will be increased during biodegradation,
and the relative molecular weight of benzocarbazole
and dibenzocarbazole have good relationship with the
intensity of biodegradation. The average molecular
weight of benzocarbazole and dibenzocarbazole will
be reduced with the increment of the intensity of
biodegradation, that is, the alkyl chain of
benzocarbazole and dibenzocarbazole will be shorter.
The authors conclude that FT-ICR MS is a powerful
analysis technology for petroleum geochemistry,
which can provide very wide applications in petroleum
and petroleum chemical industry. The only origin of
high TAN oils is biodegradation.
References
[1] Shi Q, Deng ZY, Zhang YH et al. 2008. Data
processing of crude components by negative ion
electrospray Fourier transform ion cyclotron resonance mass
spectrometry. Journal of Instrument Analysis, 27(1) (in
Chinese with English abstract)
[2] Shi Q, Zhou YC, Hou DJ et al. 2007. Analyses on
naphthenic acids of Liao He crude oils by negative ion
electrospray Fourier transform ion cyclotron resonance mass
spectrometry. Journal of Instrument Analysis, 26(1):317-320
(in Chinese with English abstract)
[3] Shi Q, Zhao SQ, Xu CM and Hou DJ. 2008. Fourier
transform ion cyclotron resonance mass spectrometry and
its application in petroleum analysis. Journal of Chinese
Mass Spectrometry Society, 29(6): 367-378 (in Chinese with
English abstract)
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