25th International Meeting on Organic Geochemistry IMOG 2011

P-011
Rapid geochemical typing using infrared spectroscopy
Andrew Bishop, Amy Kelly, Patrick Killough
Shell Projects & Technology, Houston, United States of America (corresponding
author:andrew.bishop@shell.com)
Prior to the advent of capillary gas
chromatography, infrared spectroscopy was
commonly used to provide typing information on oil
samples. However, the complexity of sample
preparation and data interpretation, plus the lack of
the type of detailed information available with capillary
GC, led to the abandonment of this method of
analysis. Improvements in this technology mean that
the instrumentation available today is vastly superior
and offers advantages of speed, ease of use and
portability which behove a revisit of infrared
spectroscopy for applications in geochemistry.
Several studies have documented geochemical
applications of Near-infrared (NIR) Spectroscopy, e.g.
Bement et al. 1996, Mullins et al. 2006, Leach et al.
2008. Mid-infrared (MIR) spectroscopy has received
less attention, thought it offers the advantage over
NIR in that functional group information is discernible,
and this may provide geochemical typing information.
Permanyer et al. (2005) describe the use of MIR for
oil-oil correlation in a group of fields in the Ebro delta,
offshore Spain. They conclude that MIR spectral
characteristics can be used for the assessment of
maturity, in-reservoir mixing and
compartmentalization. Abbas et al. (2006) showed
that oils from several different petroleum systems can
be successfully discriminated using MIR.
The objective of this investigation has been to
assess the suitability of MIR for the geochemical
interpretation of oil and condensate samples.
Approximately 350 oils have been analysed by this
method. The samples represent a range of source
ages, types, levels of maturity and extent of
biodegradation.
The analysis was performed on a Nicolet 6700
Response
1.8
1.6
1.5
1.4
Response
1.2
1.0 1.0
0.5
0.8
0.6
0.4
0.2
0.0
0.0
3650
CH3
CH3, CH2
CH3, CH2
Full Data-2
3037.383057 2073.134521 1108.885864
3150
2650
Variable
2150
1650
1150
Wavenumber cm -1
CH3, CH2
CH3
Aromatic
Figure 1. Example crude oil mid-range infrared
spectrum, with key bands identified.
C=O
S=O
650
Figure 2. Relationship of an example IR parameter
with Pristane/Phytane, illustrating response of IR
spectra to specific geochemical signatures.
FTIR spectrophotometer, with a trough plate ATR
interface. This enables the analysis of a dead oil
sample in about 5 minutes, with virtually no sample
preparation. The data has been interpreted using
peak heights, ratios and chemometrics on specific
spectral windows.
The results show that infrared spectra can be used
to rapidly assess the source type, maturity and level
of biodegradation of an oil sample. This method does
not offer the specificity of contemporary molecular
analysis, but it does offer a means to rapidly screen
large sample sets and identify unusual outlier
compositions. This method can also be used to
generate data fast in locations where sample export
restrictions and lack of local infrastructure, may
preclude timely analysis using standard petroleum
geochemistry procedures.
References
Abbas et al. (2006) Applied Spectroscopy 60, 304-
314.
Bement et al. (1996) Organic Geochemistry 24, 1173-
1178.
Leach et al. (2008) Organic Geochemistry 39, 910-
914.
Mullins et al. (2006) Energy and Fuels 20, 2448-2456.
Permanyer et al. (2005) Fuel 84, 159-168.
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