25th International Meeting on Organic Geochemistry IMOG 2011

P-070
Characterisation of biodegraded Australian oils via catalytic
hydropyrolysis
Robert S Lockhart 1 , Minh Tam Le 2 , Kliti Grice 1 , Will Meredith 3
1 WA Organic and Isotope Geochemistry Centre, Curtin University, Bentley, WA, Australia, 2 Clermont
Université, Ensemble Scientifique des Cézeaux, Aubière Cedex, France, 3 Nottingham Fuel and Energy
Centre, University of Nottingham, Nottingham, United Kingdom (corresponding
author:R.Lockhart@curtin.edu.au)
Asphaltene fractions isolated from a series of
biodegraded crude oils, reservoired in Australian
sedimentary basins (Gippsland and Carnarvon
Basins), have been subjected to catalytic
Hydropyrolysis (Hypy) in order to investigate the
characterisation potential of the ―bound‖ hydrocarbon
product. Hypy is pyrolysis assisted by high hydrogen
pressure (~150 Bar) and a dispersed sulfidic Mo
catalyst. Developed as a rapid characterisation
technique, Hypy possesses proven ability to release
high yields (>65%) of covalently-bound biomarkers
from petroleum source rocks and high volatile coals,
with overall conversions of organic matter >85%
(Love et al., 1995; Love et al., 1996). Owing to a
unique hydrogen gas sweep mechanism,
Hydropyrolysates benefit from superior carbon
skeletal preservation where compared with more
conventional pyrolysis methods (Lockhart et al., 2008;
Love et al., 1996; Murray et al., 1998).
Results support the findings of previous workers, who
have consistently demonstrated the ability of Hypy to
maximise yield of the significant pool of highly
informative biomarkers covalently-bound within the
complex macromolecular structures of a range of
solvent insoluble organic fractions (Bowden et al.,
2006; Russell et al., 2004; Sonibare et al., 2009). The
crude oils examined range in severity of
biodegradation, from non-biodegraded oils to those
lacking straight-chain, branched and cyclic alkanes,
while the most strongly altered samples display
depletion of polycyclic aromatic compounds and large
unresolved complex mixtures (Grice et al., 2000).
Figure 1, illustrates a typical example, where Hypy
has generated a ―bound‖ oil from the isolated
asphaltene, which is believed to be representative of
the original parent source rock. Findings further
illustrate the potential application of Hypy as a
powerful correlation technique, in conjunction with
compound specific isotope analyses.
Relative response
(b) Asphaltene “Bound”
nC17
UCM
nC18
nC26
(a) “Free” crude oil
nC30
nC35
Relative retention time
Figure 1. Total Ion Chromatograms (TIC) showing (a)
the saturate fraction of a biodegraded Australian
crude oil (Gippsland Basin) and (b) corresponding
results obtained following Hypy of the asphaltene
fraction. UCM = unresolved complex mixture.
References
Bowden, S. A. et al., (2006) Org. Geochem., 37:369-
383.
Grice, K. et al., (2000) Org. Geochem., 31:67-73.
Lockhart, R. S. et al., (2008) Org. Geochem., 39:
1119-1124.
Love, G. D. et al., (1995) Org. Geochem., 23:981-986.
Love, G. D. et al., (1996) Energy & Fuels, 10:149-157.
Murray, I. P. et al., (1998) Org. Geochem., 29:1487-
1505.
Russell, C. A. et al., (2004) Org. Geochem., 35:1441-
1459.
Sonibare, O. O., et al., (2009) J. Anal. Appl. Pyrolysis,
86, 135-140.
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