EXHIBIT 27
[CSIRO LOGO]
CSIRO Petroleum Confidential Report No. 04-002 (Part 1)
JANUARY 2004
THE GEOCHEMISTRY AND ORGANIC
PETROLOGY OF OIL SHOWS AND
FINE-GRAINED ROCKS IN MOOSE-1 AND
MOOSE-1ST1, EAST PAPUAN BASIN
PART 1: TEXT AND DIAGRAMS, APPENDICES A TO G
A Report to InterOil Corporation
S. C. George, M. Ahmed, N. R. Sherwood,
R. A. Quezada and N.J. Russell
FOR FURTHER INFORMATION CONTACT:
Dr. Simon C. George
CSIRO Petroleum,
PO Box 136, North Ryde, NSW, Australia 1670
Telephone: +61 2 9490 8718, Facsimile: +61 2 9490 8197
E-mail: Simon.George@csiro.au
THIS IS A CONFIDENTIAL REPORT FOR
RESTRICTED DISTRIBUTION ONLY
Copies to: InterOil Corporation
(4 hard copies, electronic copy)
CSIRO authors
Confidential CSIRO archives (2 hard copies,
electronic copy)
EXECUTIVE SUMMARY
During drilling of the Moose-1 well (and the subsequent sidetrack well Moose-1
ST1), oil shows were identified in the Mendi Formation limestone, which was a
secondary target in PPL 238 of Papua New Guinea. This study uses geochemical
analyses to assess the origin of these oil shows, and in particular to
geochemically correlate the oil shows with other crude oils in the region, and
to establish the contributions of possible drilling contaminants on the oil
shows, including diesel, Aus-Tex additive, and drilling greases. A further
purpose of this study is to use organic geochemical and petrological analyses to
investigate the source potential, including thermal maturity, of fine-grained
mudstones underlying the Mendi Formation limestones in Moose-1 ST1.
Oil shows from 530 m (Moose-1), 675.1 m, 686.2 m, 727 m, 759.5-759.6 m and 840 m
(all Moose-1 ST1) were strongly overprinted by diesel. Carefully application of
high resolution organic geochemistry enabled the indigenous signature of some of
these oil shows to be separated from that of the diesel. The diesel has a
characteristic n-alkane distribution maximising at n-C(16), and also a
distinctive pattern of branched and cyclic alkanes, but contains few biomarkers.
Oil shows from 686.2 m and 759.5-759.6 m (Moose-1 ST1) were also strongly
overprinted by a drilling additive called Aus-Tex, which is characterised by
unusually high abundances of some polycyclic aromatic hydrocarbons, but which
also contains abundant biomarkers that strongly interfere with the natural
geochemistry of these oil shows. The oil shows from 686.2 m and 759.5-759.6 m
were essentially unusable for obtaining information on the natural component. An
oil show from 809.7 m contains no discernible wellbore contaminants and
indicated a mixture of oil signatures.
The main natural component of all the interpretable oil shows is an oil with an
origin from a calcareous source with a high proportion of prokaryotic and a low
proportion of terrestrial organic matter input, which correlates well with the
"Family B" solid bitumens in the Subu wells and the fluid inclusion oil from
Subu-1. Geochemical features of this oil type are high amounts of 2?
- -methylhopanes and 30-norhopanes, high C(29)/C(30) ? ? hopane ratios and lack of
a significant terrestrial signature. The oil show from 809.7 m contains a
mixture of the calcareous sourced oil, and an oil derived from a clay-rich,
marine source rock low in sulphur, which had significant input of terrestrial
organic matter and was deposited in an oxic depositional environment. This
signature correlates with the Jurassic-sourced oils in the Foldbelt and at
Puri-1, and with the "Family A" solid bitumens in the Subu wells. Geochemical
features of this oil type are high amounts of diterpanes and a high [C(24)
tetracyclic terpane/(C(24) tetracyclic terpane + C(23) tricyclic terpane) ratio,
indicative of a strong terrestrial influence, and a moderate to high content of
rearranged hopanes and diasteranes. The oil shows in Moose-1 and Moose-1 ST1
have
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 2
a maturity in the peak oil window (about 0.8 to 0.9% VRE), which is slightly
higher than that indicated by the geochemical signatures for the underlying
fine-grained samples. The difference in maturity, but more importantly the major
difference in source characteristics, indicates that these fine-grained samples
did not source the oil shows in the Mendi Formation limestones.
The fine-grained samples in Moose-1ST1 were deposited in an oxic marine
depositional environment with major terrestrial organic matter input, including
a minor coniferous organic matter component that could be derived from re-worked
Jurassic rocks. They correlate reasonably well with the fine-grained samples
analysed from the Subu wells. C(26) sterane distributions are consistent with
Cretaceous or younger ages for these strata. They have low TOC values (<1.2%)
and low hydrogen indices (mostly <155 mg/g), indicating type III organic matter,
with low liquid hydrocarbon generation potential. On the basis of the maceral
contents, in particular the liptinite contents, the original oil generation
potential ranges from poor to very good. This is better than is apparent from
the Rock-Eval results, probably because of the diluting effect of inertinite on
hydrogen indices, and also the maturity level that this sequence has reached.
Most of the finegrained samples in Moose-1ST1 have measured vitrinite
reflectance values (~0.65 to ~0.70%) that are `suppressed', by at least 0.2%.
The FAMM-derived equivalent vitrinite reflectance, which is free from the
effects of VR suppression, is about 0.9%, indicating full maturity for oil
generation. On the basis of the geochemical data, the best estimate of their
thermal maturity is about 0.7-0.8% (mid oil window), which is consistent with
the Rock Eval data but is somewhat lower than the equivalent vitrinite
reflectance data from FAMM. The anomalously high maturity indicated for the
uppermost sample (vitrinite reflectance value of 1.25%) may be due to
overthrusting, localised thermal effects from igneous activity and associated
hydrothermal fluids, or the complicating effects of reworked material.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 3
TABLE OF CONTENTS
Page number
EXECUTIVE SUMMARY .............................................................. 2-3
TABLE OF CONTENTS .............................................................. 4-7
LIST OF TABLES and FIGURES ..................................................... 8-11
1 INTRODUCTION ................................................................. 12
2.1 Samples .................................................................. 14
2.2 Total organic carbon and Rock Eval ....................................... 14
2.3 Solvent extraction ....................................................... 14
2.3.1 Soxhlet Extraction ................................................... 14
2.3.2 Ultrasonication ...................................................... 14
2.3.3 Separating funnel .................................................... 17
2.4 Asphaltene precipitation ................................................. 17
2.5 Column chromatography .................................................... 17
2.5.1 Long column method ................................................... 17
2.5.2 Short column method .................................................. 18
2.6 Gas Chromatography ....................................................... 18
2.7 Gas Chromatography - Mass Spectrometry (GC - MS) ......................... 18
2.8 Organic petrology ........................................................ 19
2.8.1 FAMM Analyses ........................................................ 19
2.8.2 Conventional Organic Petrology ....................................... 21
3 RESULTS AND DISCUSSION ....................................................... 23
3.1 Total organic carbon and Rock Eval data ................................. 23
3.2 Extractability ........................................................... 23
3.3 Extract gross compositions ............................................... 25
3.4 Overall character of aliphatic and aromatic hydrocarbon fractions,
including n-alkane distributions ............................................. 25
3.5 n-Alkane and isoprenoid parameters ....................................... 28
3.6 Intra n-alkane peaks in EOM .............................................. 29
3.7 Alkylcyclohexanes and methylalkylcyclohexanes ............................ 32
3.8 Terpanes ................................................................. 32
3.8.1 Bicyclic sesquiterpanes .............................................. 36
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 4
3.8.2 Diterpanes ............................................... 36
3.8.3 Tricyclic and tetracyclic terpanes ....................... 37
3.8.4 Methylhopanes ............................................ 38
3.8.5 Hopanes .................................................. 39
3.9 Steranes and Diasteranes ..................................... 42
3.10 Aromatic Hydrocarbons ....................................... 47
3.10.1 Overall aromatic hydrocarbon composition ................ 47
3.10.2 Alkylbenzenes ........................................... 51
3.10.3 Alkylnaphthalenes ....................................... 52
3.10.4 Alkylphenanthrenes ...................................... 55
3.10.5 Alkylbiphenyls .......................................... 57
3.10.6 Alkyldibenzothiophenes .................................. 58
3.11 Organic petrology results ................................... 59
3.11.1 Sample descriptions and maceral contents ................ 59
3.11.2 Thermal maturity: FAMM and vitrinite reflectance
analyses........................................................ 62
4 INTERPRETATION AND SYNTHESIS ..................................... 65
4.1 The fine-grained rocks in Moose-1ST1 ......................... 65
4.1.1 Source potential ......................................... 65
4.1.2 Source characteristics ................................... 65
4.1.3 Thermal maturity characteristics ......................... 70
4.2 Overprinting of oil shows by diesel, Aus-Tex and grease ...... 73
4.2.1 Diesel (Appendices J and K) .............................. 73
4.2.2 Aus-Tex (Appendix L) ..................................... 74
4.2.3 Grease samples: Pipe Dope and Grease Gun (Appendices
M and N) ....................................................... 74
4.2.4 Moose-1 530 m, open hole slurry sample (Appendix B) ...... 74
4.2.5 Moose-1ST1, 675.1 m, core (Appendix C) ................... 75
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 5
4.2.6 Moose-1ST1, 686.2 m, core (Appendices D and E) ...................................... 75
4.2.7 Moose-1ST1,727 m, oil mixed with water (Appendix F) ................................. 75
4.2.8 Moose-1ST1, 759.5 m, core (Appendix G) .............................................. 76
4.2.9 Moose-1ST1, 809.7 m, core (Appendix H) .............................................. 76
4.2.10 Moose-1ST1, 840 m, fluid sample (Appendix I) ....................................... 77
4.3 The source of the natural component of the oil shows at Moose-1 and Moose-1ST1 .......... 78
4.3.1 "Calcareous" source signature ....................................................... 78
4.3.2 "Jurassic" source signature ......................................................... 79
4.4 Distribution of oil shows and contaminants in Moose-1 and Moose-1 ST1 ................... 80
5 CONCLUSIONS ................................................................................. 82
6 ACKNOWLEDGEMENTS ............................................................................ 83
7 REFERENCES .................................................................................. 84
APPENDIX A: Peak assignments and abbreviations ................................................ 9 pages
APPENDIX B: Moose-1 530m (Open Hole Slurry Sample): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX C: Moose-1ST1 675.1 m (Extractable Organic Matter): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX D: Moose-1ST1 686.2m (Extractable Organic Matter): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX E: Moose-1ST1 686.2m (Extractable Organic Matter, Soxhlet Extract):
gas and mass chromatograms and peak identifications ........................................... 6 pages
APPENDIX F: Moose-1ST1 727m (Oil Mixed With Water): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX G: Moose-1ST1 759.5m (Core Sample): gas and mass chromatograms and
peak identifications .......................................................................... 25 pages
APPENDIX H: Moose-1ST1 809.7m (Core Sample): gas and mass chromatograms and
peak identifications .......................................................................... 25 pages
APPENDIX I: Moose-1ST1 840m (Fluid Sample): gas and mass chromatograms and
peak identifications .......................................................................... 25 pages
APPENDIX J: Moose-1ST1 Diesel Sample (Tank): gas and mass chromatograms and
peak identifications .......................................................................... 25 pages
APPENDIX K: Moose-1ST1 Diesel Sample (Line): gas and mass
chromatograms and peak identifications ........................................................ 2 pages
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 6
APPENDIX L: Moose-1ST1, Aus-Tex Sample: gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX M: Moose-1ST1, Grease Gun Sample: gas and mass
chromatograms and peak identifications ........................................................ 2 pages
APPENDIX N: Moose-1ST1, Pipe Dope Sample: gas and mass
chromatograms and peak identifications ........................................................ 2 pages
APPENDIX O: Moose-1ST1 820m (Mudstone Sample): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX P: Moose-1ST1 920m (Mudstone Sample): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX Q: Moose-1ST1 968-971m (Mudstone Sample): gas and mass
chromatograms and peak identifications ........................................................ 25 pages
APPENDIX R: Fluorescence alteration diagrams from Moose-1 ST1 ................................. 3 pages
APPENDIX S: Reflectance histograms for samples from Moose-1 ST1 ............................... 8 pages
The report is presented in two volumes:
Part 1: Text and diagrams, Appendices A to G
Part 2: Appendices H to S
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 7
LIST OF TABLES
Table 1: Sample details. ................................................................ 15
Table 2: Geochemical and organic petrological analyses carried out. ..................... 16
Table 3: Total organic carbon and Rock Eval data. ....................................... 24
Table 4: Extractability and gross compositional data .................................... 24
Table 5: General molecular data and aliphatic hydrocarbon parameters .................... 26
Table 6: Preliminary origin of oil shows, based on overall and gross distributions ...... 28
Table 7a: Terpane parameters (part a).................................................... 33
Table 7b: Terpane parameters (part b).................................................... 33
Table 7c: Terpane parameters (part c) ................................................... 34
Table 7d: Terpane parameters (part d).................................................... 34
Table 7e: Terpane parameters (part e).................................................... 35
Table 7f: Terpane parameters (part f) ................................................... 35
Table 8a: Sterane and diasterane parameters (part a) .................................... 43
Table 8b: Sterane and diasterane parameters (part b) .................................... 43
Table 8c: Sterane and diasterane parameters (part c)..................................... 44
Table 8d: Sterane and diasterane parameters (part d)..................................... 44
Table 8e: Sterane and diasterane parameters (part e)..................................... 45
Table 9b: Aromatic hydrocarbon parameters (part b)....................................... 48
Table 9c: Aromatic hydrocarbon parameters (part c) ...................................... 49
Table 9d: Aromatic hydrocarbon parameters (part d)....................................... 49
Table 9e: Aromatic hydrocarbon parameters (part e) ...................................... 50
Table 9f: Aromatic hydrocarbon parameters (part f) ...................................... 50
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 8
Table 10: Maceral group compositions, vitrinite reflectance data and petrographic
descriptions for samples from Moose-1 ST1 .................................... 60
Table 10 continued: Maceral group compositions, vitrinite reflectance data and
petrographic descriptions for samples from Moose-1 ST1. ........................ 61
Table 11: FAMM-derived equivalent vitrinite reflectance (EqVR) and measured vitrinite
reflectance (VR) data for samples from Moose-1 ST1. ............................. 63
Table 12: Summary of the origin of oil shows, based on all geochemical data ............. 81
LIST OF FIGURES
Figure 1: Location map of Moose-1 relative to the Subu wells and other prospects
in PPL 238 of Papua New Guinea .......................................................... 12
Figure 1a: Fluorescence alteration diagram showing the `normal' calibration
curve and suppression/enhancement iso-correction lines based on a suite of
Indonesian Tertiary coals and source rocks .............................................. 20
Figure 2: Normalised n-alkane profiles of samples ........................................... 27
Figure 3: Cross-plot of two carbon preference indices (defined in Table 5) .................. 29
Figure 4a: Partial gas chromatographs for the n-C(13) and n-C(16) range, comparing
diesel with oil show samples 675.1 m, 686.2 m and 727 m (total EOM). iC15 and
iC16 are acyclic C(15) and C(16) isoprenoids, 2MPD = 2-methylpentadecane, other
significant peaks are numbered. Lines indicate relative abundances between
selected compounds ...................................................................... 30
Figure 4b: Partial gas chromatographs for the n-C(13) and n-C(16) range, comparing
diesel with oil show samples 759.5-759.6 m, 809.7 m and 840 m (total EOM). iC15
and iC16 are acyclic C(15) and C(16) isoprenoids, 2MPD = 2-methylpentadecane, other
significant peaks are numbered. Lines indicate relative abundances between
selected compounds ...................................................................... 31
Figure 5: Cross-plot of C(31) 2? Me/(C(31) 2? Me+C(30)? ? hopane) versus C(32) 2?
Me/(C(32) 2? Me+C(31)? ? hopane). The two families refer to solid bitumens extracted
from the sandstones in the Subu wells, the fluid inclusion oil from Subu-1, the
Puri-1 oil and the Bwata-1 condensate (data shown as black dots, from George et
al., 2003) .............................................................................. 39
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 9
Figure 6: Cross-plot of C(27) sterane ????????????? versus C(29) sterane ?????? ? ? ? ? ? ? ?
ratios. The family refers to solid bitumens extracted from the sandstones in the
Subu wells (data shown as black dots, from George et al., 2003) ................................... 46
Figure 7: Normalised aromatic hydrocarbon compositions of the Moose-1 samples ......................... 51
Figure 8: Cross-plot of the trimethylnaphthalene ratio versus the
tetramethylnaphthalene ratio. The data from the Subu wells are shown as black
dots (from George et al., 2003). .................................................................. 53
Figure 9: Cross-plot of log (1,2,7-TMN/1,3,7-TMN) versus log
(1,2,5-TMN/1,3,6-TMN). The boundaries on this trimethylnaphthalene graph are
taken from Strachan et al. (1988). The data from the Subu wells are shown as
black dots (from George et al., 2003). ............................................................ 54
Figure 10: Cross-plot of methylphenanthrene index
(1.5*[3-MP+2-MP]/[P+9-MP+1-MP]) versus methylphenanthrene distribution fraction
((3-MP+2-MP)/ ? MPs). The data from the Subu wells are shown as black dots (from
George et al., 2003). ............................................................................. 56
Figure 11: Cross-plot of methylphenanthrene ratio (2-MP/1-MP) versus
dimethylphenanthrene ratio (3,5-+2,6-DMP+2,7-DMP)/
(1,3-+3,9-+2,10-+3,10-DMP+1,6-+2,9-+2,5-DMP). The data from the Subu wells are
shown as black dots (from George et al., 2003) .................................................... 57
Figure 12: Cross-plot of dibenzothiophene/phenanthrene ratio versus
dibenzothiophene/1,3,6,7-TeMN ratio. The data from the Subu wells are shown as
black dots (from George et al., 2003) ............................................................. 59
Figure 13: Cross-plot of C(29)Ts/C(29)? ? hopane versus C(30)*/C(30) ? ? hopane for the samples
from this project compared to literature and unpublished data. Solid symbols are
analyses carried out at the CSIRO laboratory. Open symbols are analyses derived
from literature data, some of which were derived from ruler-measured peak heights
from published chromatograms and thus are subject to inaccuracies. Black symbols
are samples in this report from the Moose-1 and Moose-1ST1 well ................................... 67
Figure 14: Cross-plot of C(29) ? ? hopane/C(30) ? ? hopane versus C(31) ? ?
hopane/C(30) ? ? hopane ratios for the samples from this project compared to literature and
unpublished data. Solid symbols are analyses carried out at the CSIRO laboratory.
Open symbols are analyses derived from literature data, some of which were derived
from ruler-measured peak heights from published chromatograms and thus are
subject to inaccuracies. Black symbols are samples in this report from the Moose-1
and Moose-1ST1 well ............................................................................... 68
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 10
Figure 15: Cross-plot of Pr/Ph versus C35??C(35) + C(34) homohopane ratios for the
samples from this project compared to Subu well, literature and unpublished
data. Solid symbols are analyses carried out at the CSIRO laboratory. Open
symbols are analyses derived from literature data, some of which were
derived from ruler-measured peak heights from published chromatograms and
thus are subject to inaccuracies. Black symbols are samples in this report
from the Moose-1 and Moose-1ST1 well .......................................................... 69
Figure 16: Cross-plot of C(29) sterane ? ? ? 20S/(20S+20R) versus C(29) sterane
?????? ? ? ? ? ? ? ? for the samples from this project compared to
literature and unpublished data. Solid symbols are analyses carried out at
the CSIRO laboratory. Open symbols are analyses derived from literature
data, some of which were derived from ruler-measured peak heights from
published chromatograms and thus are subject to inaccuracies .................................. 72
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 11
1 INTRODUCTION
The Moose-1 well was spudded in March 2003, with a cored sidetrack well (Moose-
1ST1) from 650 m commenced in July 2003. The Moose prospect was identified as
the first prospect to be drilled by InterOil in PPL 238 (formerly PPL 230) in
Papua New Guinea (Fig. 1). The well is located at Long 145?11'8.52"E, Lat
06?57'50.96"S. The nearest wells include the Subu stratigraphic wells (27 km)
drilled by InterOil in August 2001 (George et al., 2003), and the Puri-1 well
(26 km) drilled in 1957-9. The nearest commercial production is the South East
Gobe field approximately 166 km to the northwest.
[LOCATION MAP OF MOOSE-1]
Figure 1: Location map of Moose-1 relative to the Subu wells and other prospects
in PPL 238 of Papua New Guinea.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 12
During drilling, oil shows were identified in the Mendi Formation limestone,
which was a secondary target in PPL 238. The limestone reservoir is interpreted
to extend from 610 m to 809.9 m and was fully cored from 664.14 m. There is a 2
m siltstone interval from 756.34 to 758.36 m. On the basis of the cores two
limestone zones (Upper and Lower, separated by the 2m siltstone zone) and three
porosity types (matrix, fracture and fault) have been identified.
The main purpose of this report is to use geochemical analyses to assess the
origin of the oil shows in the Mendi Formation limestone section penetrated by
Moose-1 and Moose-1 ST1. In particular, it is important to geochemically
correlate the oil shows with other crude oils in the region, and to establish
the contributions of possible drilling contaminants on the oil shows, including
diesel, Aus-Tex additive, and drilling greases. The geochemical characteristics
of the oil shows are compared with previously analysed oils, bitumens, oil
inclusions and oil seeps from nearby in Papua New Guinea. A further purpose of
this study is to use organic geochemical and petrological analyses to
investigate the source potential, including thermal maturity, of fine-grained
mudstones underlying the Mendi Formation limestones in Moose-1 ST1.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 13
2 SAMPLES AND EXPERIMENTAL PROCEDURE
2.1 SAMPLES
Details of the 27 samples analysed in this study are provided in Table 1,
including CSIRO code, depth interval, type of sample and a brief description.
Except for the sample from 530 m in Moose-1, all other samples are from
Moose-1ST1, or are additives that were used at the Moose-1 well site which have
been tested for interference with the natural oil show geochemistry. A summary
of the analyses carried out on each samples is provided in Table 2.
2.2 TOTAL ORGANIC CARBON AND ROCK EVAL
Fourteen fine-grained samples (Table 2) were crushed to a fine powder and then
submitted to Geotechnical Services Pty Ltd for total organic carbon (TOC)
analysis and Rock Eval pyrolysis, using standard techniques, including
de-carbonation treatment of the samples. Rock Eval pyrolysis was completed on 13
of the samples with TOC values > 0.5%.
2.3 SOLVENT EXTRACTION
Samples were extracted in three different ways (Table 2).
2.3.1 Soxhlet Extraction
After crushing to a fine powder, samples were solvent extracted with a mixture
of dichloromethane (DCM) and methanol (MeOH) (93:7 vol%) for 72 hours using a
Soxhlet apparatus. An aliquot of the extractable organic matter (EOM) was blown
to dryness to provide a gravimetric weight of the total EOM.
2.3.2 Ultrasonication
Whole core was ultrasonicated in an excess of DCM in a large beaker. Where
possible, an aliquot of the EOM was blown to dryness to provide a gravimetric
weight. For sample 530 m, a combination of both ultrasonication of the slurry
and a separating funnel (see Section 2.3.3) was used.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 14
Table 1: Sample details.
Type of
CSIRO code Appendix Well Depth (m) sample Description
- ---------- -------- ---------- ------------- --------- ------------------
530 m B Moose-1 530.0 m open hole brown slurry
675.1 m C Moose-1ST1 675.1 m core suspected oil show
686.2 m D Moose-1ST1 686.2 m core suspected oil show
686.2 m Sox E Moose-1ST1 686.2 m core matrix Soxhlet extracted
727 m F Moose-1ST1 727.0 m yellow suspected oil mixed with
fluid water
759.5-759.6 m G Moose-1ST1 759.5-759.6 m core (wet) suspected oil show, oil/water
wet sample
809.7 m H Moose-1ST1 809.7 m core suspected oil show
840 m I Moose-1ST1 840.0 m fluid water with oil
Diesel (tank) J - - diesel tank sample
Diesel (line) K - - diesel line sample
Aus-Tex L - - Aus-Tex drilling additive
Grease gun M - - grease Shell grease (grease gun)
Pipe dope N - - grease Shell grease (pipe dope)
811.0 m - Moose-1ST1 811.0 m core mudstone *
820.0 m O Moose-1ST1 820.0 m core mudstone *
861.0 m - Moose-1ST1 861.0 m core mudstone *
870.0 m - Moose-1ST1 870.0 m core mudstone *
880.0 m - Moose-1ST1 880.0 m core mudstone *
890.0 m - Moose-1ST1 890.0 m core mudstone *
901.0 m - Moose-1ST1 901.0 m core mudstone *
909.0 m - Moose-1ST1 909.0 m core mudstone *
920.0 m P Moose-1ST1 920.0 m core mudstone *
930.0 m - Moose-1ST1 930.0 m core mudstone *
937.0 m - Moose-1ST1 937.0 m core mudstone *
950.0 m - Moose-1ST1 950.0 m core mudstone *
960.0 m - Moose-1ST1 960.0 m core mudstone *
968-971.0 m Q Moose-1ST1 968-971.0 m cuttings mudstone *
* The fine-grained samples are generically termed "mudstones" in this Table. A
more detailed lithological description of these predominantly calcareous
siltstones and mudstones is given in Table 10.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 15
Table 2: Geochemical and organic petrological analyses carried out.
CSIRO GC-FID GC-MS GC-FID GC-MS
code Extract EOM EOM CC Fract Fract TOC RE VR FAMM
---- ------- --- --- -- ----- ----- --- -- -- ----
530 m *UP* ** ** No No No No No No No
675.1 m *U* ** ** *S* ** ** No No No No
686.2 m *U* ** ** *S* ** ** No No No No
686.2 m *X* ** ** No No No No No No No
Sox
727 m *P* ** ** *L* ** ** No No No No
759.5-759.6 *U* ** ** *L* ** ** No No No No
m
809.7 m *X* ** ** *S* ** ** No No No No
840 m *P* ** ** *L* ** ** No No No No
Diesel No ** ** *L* ** ** No No No No
(tank)
Diesel No ** No No No No No No No No
(line)
Aus-Tex *X* ** ** *L++* ** ** No No No No
Grease gun *U* ** No No No No No No No No
Pipe dope *U* ** No No No No No No No No
811.0 m No No No No No No ** ** * No
820.0 m *X* No No *L* ** ** ** ** * No*
861.0 m No No No No No No ** ** * *
870.0 m No No No No No No ** ** * No
880.0 m No No No No No No ** ** * No
890.0 m No No No No No No ** ** * No
901.0 m No No No No No No ** No * No
909.0 m No No No No No No ** ** * *
920.0 m *X* No No *L* ** ** ** ** * No*
930.0 m No No No No No No ** ** * No
937.0 m No No No No No No ** ** * No
950.0 m No No No No No No ** ** * No
960.0 m No No No No No No ** ** * No
968-971.0 *X* No No *L* ** ** ** ** * **
m
* = analysis carried out; No = analysis not carried out. Extract = Extracted,
with method used (X = Soxhlet extraction; U = ultrasonication; P = separating
funnel); GC-FID EOM = gas chromatography with flame ionisation detection of
extractable organic matter; GC-MS EOM = gas chromatography-mass spectrometry of
extractable organic matter; CC = Column chromatography, with method used (L =
long column fractionation; S = short column fractionation;++ = additional
asphaltene precipitation); GC-FID Fract = gas chromatography with flame
ionisation detection of aliphatic and aromatic fractions; GC-MS Fract = gas
chromatography-mass spectrometry of aliphatic and aromatic fractions; TOC =
total organic carbon; RE = Rock Eval; VR = vitrinite reflectance; FAMM =
fluorescence alteration of multiple macerals.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 16
2.3.3 Separating funnel
Fluid samples were extracted using a separating funnel, shaking the fluid with a
similar volume (~25 mL) of DCM, followed by decanting the solvent layer
containing the EOM. The separating funnel was then washed with a further three
batches of 25 mL of DCM Where possible, an aliquot of the EOM was blown to
dryness to provide a gravimetric weight.
2.4 ASPHALTENE PRECIPITATION
The EOM of the AUS-Tex (Table 2) was blown down to very small volume to which an
excess of pentane was added for the precipitation of asphaltenes. The suspension
was sonicated for 5 minutes and then allowed to settle in a fridge for at least
2 hours. Solid asphaltenes were separated from the soluble maltene fraction by
centrifuging the suspension. The process was repeated to isolate any of the
remaining maltenes from the asphaltene precipitate.
2.5 COLUMN CHROMATOGRAPHY
Samples were fractionated by column chromatography in two different ways (Table
2).
2.5.1 Long column method
Samples in which sufficient EOM was recovered (>20 mg) were fractionated by a
long column chromatography method. An accurate amount of un-evaporated EOM (or
maltene fraction for Aus-Tex) was adsorbed onto alumina and all solvent was
removed by gently blowing with nitrogen. The extracts were fractionated using
column chromatography on silica gel (C60: 60-210 (Mu)m) below alumina. Elution
with petroleum ether (40-60(degree)C, 100 mL) produced the aliphatic hydrocarbon
fraction, elution with a 4:1 mixture of DCM + petroleum ether (150 mL) produced
the aromatic hydrocarbon fraction and elution by a 1:1 mixture of DCM + MeOH
(100 mL) produced the polar compounds. All solvent was evaporated from 1/10th
aliquots of the aliphatic and aromatic hydrocarbon fractions, and from the whole
polar compound fraction, to give the total weights of the respective fractions.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 17
2.5.2 Short column method
Samples in which only a small amount of EOM was recovered (<20 mg) were
fractionated by a short column chromatography method. The extracts were
fractionated using column chromatography on silica gel (C60: 60-210 (Mu)m) below
alumina in a Pasteur pipette. Elution with petroleum ether (40-60(degree)C, 5
mL) produced the aliphatic hydrocarbon fraction, elution with a 4:1 mixture of
DCM + petroleum ether (5 mL) produced the aromatic hydrocarbon fraction and
elution by a 1:1 mixture of DCM + MeOH (5 mL) produced the polar compounds.
Generally too little of the fractions is recovered using this method to enable
gravimetric weights to be obtained.
2.6 GAS CHROMATOGRAPHY
Gas chromatography (GC) of the aliphatic and aromatic hydrocarbon fractions and
most of the EOM fractions (Table 2) was performed on a Varian 3400 gas
chromatograph equipped with a flame ionisation detector. Chromatography was
carried out on a fused silica column (60 m x 0.25 mm i.d.) coated with DB5MS
(modified 5% phenyl 95% methyl silicone, 0.25 (Mu)m film thickness) or with DB1
(dimethylpolysiloxane, 0.25 (Mu)m film thickness), using a splitless injection
technique. The oven was programmed for an initial temperature of 40(degree)C for
2 min., followed by heating at 4(degree)C min.-1 to 310(degree)C, and a hold for
30 mins.
2.7 GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC-MS)
GC-MS of the aliphatic and aromatic hydrocarbon fractions and most of the EOM
fractions (Table 2) was performed on a Hewlett Packard 5890 gas chromatograph
interfaced to a VG AutoSpecQ Ultima (electron energy 70 eV; electron multiplier
250 V; filament current 200 (Mu)A; source temperature 250(degree)C) tuned to
1000 resolution. Chromatography was carried out on a fused silica column (60 m x
0.25 mm i.d.) coated with DB5MS, using a splitless injection technique. The oven
was programmed in two ways for different GC-MS runs: (a) for an initial
temperature of 40(degree)C for 2 min., followed by heating at 4(degree)C min.-1
to 310(degree)C, and (b) for an initial temperature of 40(degree)C for 2 min.,
followed by heating at 20(degree)C min.-1 to 200(degree)C and then a second
heating ramp at 2(degree)C min.-1 to 310(degree)C.
All the fractions were analysed using a magnet scan programme (m/z 50 to 550;
0.5 s/decade), using GC programme a. The aliphatic fractions were analysed using
a single ion monitoring (SIM) programme (SIRV_INCD), using GC programme b: (m/z
177, 183,
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 18
191, 205, 217, 218, 231.11, 231.21, 253, 259). The aliphatic fractions were also
analysed using two metastable reaction monitoring (MRM) programmes, using GC
programme b:
MRM_HOPS: m/z 370, 384, 398, 412, 426, 440, 454, 468, 482? 191.
MRM_STER: m/z 358, 372, 386, 400, 414? 217; 414? 231.
2.8 ORGANIC PETROLOGY
The samples were prepared as polished mounts using standard techniques and
stored in a vacuum desiccator prior to analysis to minimise any oxidation
effects.
2.8.1 FAMM Analyses
The FAMM (`fluorescence alteration of multiple macerals') analytical technique
was developed by CSIRO Petroleum to provide an objective and accurate method of
determining the thermal maturity of petroleum source rocks, including those
containing vitrinite that exhibits suppressed or enhanced reflectance.
FAMM results, expressed as `equivalent vitrinite reflectance' (EqVR) values, are
free from the effects that hydrogen content exerts on measured vitrinite
reflectance (VR). Perhydrous vitrinites exhibit suppression of reflectance by
comparison with orthohydrous vitrinites, whereas subhydrous vitrinites exhibit
enhancement of reflectance.
The FAMM methodology has been described by Wilkins et al. (1992;1995). The
chemical basis of fluorescence alteration has been discussed in the literature
(Lin and Davis, 1988; Davis et al., 1990; Pradier et al., 1990 and 1991). The
application of FAMM to resolve problems due to complexities in stratigraphy,
structure and organic matter (OM) populations (including reworking, cavings and
drilling mud additives) for SE Asian samples has been discussed by Wilkins et
al. (1997). More recent developments in FAMM methodology and interpretations,
including a discussion on oxidation effects, are presented in Wilkins et al.
(1998).
In the present study, a custom-built, fibre optics-based laser microprobe (488
nm wavelength) was used to collect the fluorescence data at a fixed wavelength,
corresponding to that of the general peak of fluorescence emission intensity
(i.e. 620-630 nm). The fluorescence alteration data are obtained by measuring
the change in fluorescence intensity with time, from a focused ~2 ?m diameter
laser spot on the surface of each analysed maceral grain over a period of 400
seconds. The fluorescence alteration
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 19
ratio is the ratio of the final intensity (F(400)) to initial intensity (F(o)).
The alteration data for grains of liptinite, vitrinite and inertinite group
macerals, where present, are plotted on a `fluorescence alteration diagram'
(Fig. 1a). In this diagram F(400), which is primarily controlled by the OM type,
is plotted against the fluorescence alteration ratio, which, for a given OM
type, is primarily controlled by the thermal maturity.
[FLUORESCENCE ALTERATION RATIO LINE GRAPH]
Figure 1a: Fluorescence alteration diagram showing the `normal' calibration
curve and suppression/enhancement iso-correction lines based on a suite of
Indonesian Tertiary coals and source rocks.
Central to the FAMM technique is a calibration derived from well-characterised,
`normal' (`orthohydrous') telovitrinites which plot on or close to a
sub-vertical line on the diagram (Fig. 1a). This J-shaped curve represents
vitrinites for which EqVR=VR and its lateral position may vary slightly for
different geological provinces due to basic differences in precursor flora
(Wilkins et al., 1998); however, the position of the horizontal iso-EqVR lines
remains constant. Figure 1a shows the `normal' vitrinite curve and corresponding
suppression iso-correction curves for 400s fluorescence alterations based on a
suite of Indonesian Tertiary coals (Teerman et al., 1995). In the present study
the Tertiary calibration has been employed.
Fluorescence alteration data from hydrogen-poor macerals (i.e. subhydrous
vitrinite and most inertinite) plot to the left of the `normal' vitrinite line;
hydrogen-rich macerals (i.e. liptinite and perhydrous vitrinite) plot to the
right. This enables identification of perhydrous vitrinite, which is associated
with VR suppression, and subhydrous vitrinite, which is associated with VR
enhancement. The `normal' vitrinite line is calibrated in
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 20
units of `mean random vitrinite reflectance in oil' (Rm(o)%). Mean maximum
reflectance in oil (Rmax(o)%) = 1.066 x Rm(o)% for the 0.4%-1.2% reflectance
range (Ting, 1978).
For samples containing a suite of iso-metamorphic inertinite, vitrinite and
liptinite, fluorescence alteration data, in general, plot on or near, a
parabolic curve (multimaceral curve) on fluorescence alteration diagrams. The
EqVR for an orthohydrous vitrinite population can be determined from the
intersection between the multimaceral curve and the normal vitrinite curve. For
samples having EqVRs <0.9%, containing perhydrous or subhydrous vitrinites, the
EqVR is generally read from the horizontal tangent to the multimaceral curve.
For samples having EqVRs >0.9% containing perhydrous or subhydrous vitrinites
and for samples where multimaceral curves are poorly constrained or cannot be
drawn, EqVR is generally determined from the mean fluorescence alteration ratio
of the indigenous vitrinite population. In the present study the values read
from multimaceral curves are similar to those determined from the position of
the average vitrinite. Where there are slight differences the values from the
average vitrinite are reported, to facilitate more direct comparisons with the
VR data.
As a cross-check of the EqVR values approximate corrections to measured VR
values can be made from the plotted position of vitrinite on fluorescence
alteration diagrams. For example, vitrinite plotting on the +0.2% line would
require a correction of 0.2% (absolute) to be added to the VR to compensate for
VR suppression. In the FAMM method however the thermal maturity is determined
from the EqVR value, rather than the `corrected VR' as the corrections are
estimated values.
2.8.2 Conventional Organic Petrology
For VR and maceral analyses, reflected white light and incident conventional
fluorescence excitation were employed, with the use of oil immersion on the
samples.
Organic matter abundances were determined by visual estimation and are presented
as percentages by volume of the total sample in Table 10 and Appendix R. The
following ranges of volume percentages apply to the abundance classes used:
ABUNDANCE CLASS VOLUME %
- --------------- --------
rare <0.1
sparse 0.1-0.5
common >0.5-2
abundant >2-10
major >10
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 21
Where possible, at least 25 VR measurements (Rm(o)%) were made on each sample.
The measurements were taken at random orientation of the vitrinite phytoclasts,
in nonpolarised light (cf. `maximum VR', which is measured in plane polarised
light via stage rotation). Zeiss equipment was employed and an interference
filter having a passband peak of 546 nm was used. The photometer was mainly
calibrated against a synthetic garnet standard of 0.92% reflectance. The samples
were measured with an immersion oil having a refractive index of 1.518 at
23(degrees)C +/-1(degree)C.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 22
3 RESULTS AND DISCUSSION
All of the gas chromatograms and mass chromatograms referred to in the text are
provided in Appendices B to Q, with peak identifications in Appendix A.
3.1 TOTAL ORGANIC CARBON AND ROCK EVAL DATA
Fourteen fine-grained samples (mudstones) from Moose-1 ST1 were analysed for
their content in total organic carbon (TOC) and by Rock Eval pyrolysis (Table
3). Most samples (11) have TOC values between 0.8-1.2%, and only one has a TOC
<0.5%. Rock Eval data suggest oil-window maturities and type III organic matter,
with little liquid hydrocarbon generation potential, as shown by hydrogen
indices of 105-155 mg/g for all but two of the samples. One of the exceptions
(811 m) has a very small S(2) peak, despite a reasonable TOC (1.1%), indicating
that most of the organic carbon in this sample is refractory and non-generative.
The most prospective sample is 968-971 m, which has a hydrogen index of 217 mg
S(2) / g TOC. Production indices vary between 0.11 and 0.29, consistent with the
rocks having reached the oil-generative window. T(max) data for these samples
mostly vary from 442-448(Degrees) C, corresponding to a vitrinite reflectance of
ca. 0.7-0.9% when applying a correlation for type III organic matter established
by Teichmuller and Durand (1982). The T(max) value of the 968-971 m sample is
somewhat lower (432(Degrees)C), probably due the different kerogen type of this
sample.
3.2 EXTRACTABILITY
Extractability data are expressed as extractable organic matter (EOM) ppm of
rock (= (Mu)g EOM / g rock) (Table 4). Widely varying amounts of EOM were
recovered from the samples. The 686.2 m sample (Soxhlet extract) contains 1,342
ppm, whereas ultrasonication of this sample produced very little EOM (2 mg).
This indicates that most of the extractable hydrocarbons in this sample reside
deep within the limestone matrix (analysed by crushing and Soxhlet extraction),
rather than in the open porosity or on any fracture surfaces (easily accessible
during ultrasonication). The Aus-Tex additive is very extractable (>10%). The
mudstone samples have extractabilities between 441 and 1,629 ppm (Table 4).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 23
Table 3: Total organic carbon and Rock Eval data.
CSIRO TOC T(max) S(1) S(2) S(3) S(1)+S(2)
code (%) ((Degree)C) (mg/g) (mg/g) (mg/g) (mg/g) S(2)/ S(3) PI HI OI
- ------------- ---- ----------- ------ ------ ------ ---------- ---------- ---- --- ---
811.0 m 1.11 nd 0.04 0.10 0.05 0.14 2.00 0.29 9 5
820.0 m * 0.55 442 0.13 0.85 0.08 0.98 10.63 0.13 155 15
861.0 m 0.84 444 0.15 1.29 0.11 1.44 11.73 0.10 154 13
870.0 m 0.80 443 0.22 1.12 0.09 1.34 12.44 0.16 140 11
880.0 m 0.94 444 0.41 1.34 0.07 1.75 19.14 0.23 143 7
890.0 m 0.51 444 0.08 0.54 0.16 0.62 3.38 0.13 106 31
901.0 m 0.28 nd nd nd nd nd nd nd nd nd
909.0 m 1.13 443 0.25 1.45 0.08 1.70 18.13 0.15 128 7
920.0 m * 0.93 445 0.15 0.99 0.14 1.14 7.07 0.13 106 15
930.0 m 0.90 445 0.16 0.98 0.18 1.14 5.44 0.14 109 20
937.0 m 0.89 455 0.15 0.94 0.16 1.09 5.88 0.14 106 18
950.0 m 0.92 448 0.12 0.97 0.22 1.09 4.41 0.11 105 24
960.0 m 0.99 444 0.15 1.13 0.84 1.28 1.35 0.12 114 85
968-971.0 m * 1.08 432 0.91 2.34 2.19 3.25 1.07 0.28 217 203
TOC = total organic carbon; PI = production index (S(1) / S(1) + S(2)); HI =
hydrogen index (mg S(2) / g TOC); OI = oxygen index (mg S(3) / g TOC); nd = not
determined. * = the three samples selected for more detailed geochemical
characterisation.
Table 4: Extractability and gross compositional data.
Extract Asph. Polars Aliph./ HCs /
recov- Extract recov- Aliph. Arom. + arom. Polars
ered (ppm of ered HCs HCs Asph. HC +
CSIRO code (mg) rock) (%) (%) (%) (%) ratio Asph.
- ------------- ------- --------- ------ ------ ----- ------- ------- ------
675.1 m 19 nd nd nd nd nd nd nd
686.2 m 2 nd nd nd nd nd nd nd
686.2 m Sox 155 1,342 nd nd nd nd nd nd
727 m 348 nd nd 92.4 5.1 2.5 18.0 39.0
759.5-759.6 m 32 nd nd 61.7 23.2 15.1 2.7 5.6
809.7 m 3 36 nd nd nd nd nd nd
840 m 46 nd nd 75.8 11.3 12.9 6.7 6.8
Diesel (tank) nd nd nd 85.6 12.4 1.9 6.9 51.4
Aus-Tex 4,676 102,481 8.6 48.4 17.3 34.3 2.8 1.9
820 m 46 441 nd 33.5 37.9 28.6 0.9 2.5
920 m 48 476 nd 36.7 33.3 30.0 1.1 2.3
968-971 m 87 1,629 nd 26.5 21.2 52.4 1.3 0.9
Asph = asphaltenes; Alip. = aliphatic; Arom. = aromatic; HC = hydrocarbon:
Polars = polar compounds eluted during column chromatography. The fraction
(Polars + Asph.) is the sum of the recovered asphaltenes (if any) and recovered
polar compounds; nd = not determined. Note that quantitation of hydrocarbon
fractions are partially affected by evaporation loss, and quantitation of
asphaltenes and polar compounds are affected by partial recovery of these
fractions.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 24
3.3 EXTRACT GROSS COMPOSITIONS
Extract gross compositions are shown in Table 4. The yield of recovered
asphaltenes from the precipitation procedure for Aus-Tex is 8.6% of the total
extract. For other samples, only total polar compounds were quantified. The 727
m sample is highly aliphatic (aliphatic / aromatic hydrocarbon ratio = 18). Two
other oil show samples contain 13-15% polar compounds and more than 60%
aliphatic hydrocarbons. The diesel is polar-lean (<2%) and dominantly aliphatic
(aliphatic / aromatic hydrocarbon ratio = 6.9), whereas the Aus-Tex is much more
polar (34.3%) and has a greater relative content of aromatic hydrocarbons
(aliphatic / aromatic hydrocarbon ratio = 2.8). The three mudstone samples have
near unity aliphatic / aromatic hydrocarbon ratios (0.9-1.3) and much greater
polar compound contents than the oil show samples (28-52%).
3.4 OVERALL CHARACTER OF ALIPHATIC AND AROMATIC HYDROCARBON FRACTIONS,
INCLUDING N-ALKANE DISTRIBUTIONS
The overall character of the aliphatic and aromatic hydrocarbon fractions is
best judged from the GC traces (Appendix *1) and the TICs (Appendix *2). These
show considerable variation throughout the sample set, mainly due to the
presence / absence and extent of an Unresolved Complex Mixture (UCM) or "hump".
A UCM of varying amount is present in both aliphatic and aromatic hydrocarbon
fractions of many samples. To provide an approximate method of quantifying this,
two UCM / n-alkane ratios were calculated from peak heights measured in GC
traces of total EOM (aliphatic HC fractions of the three mudstone samples),
excluding the effects of the baseline bleed. These ratios were measured at the
position of the C(17) and C(27) n-alkanes (Table 5). Where no n-alkanes could be
clearly distinguished in the GC trace, a small, nominal value was assigned,
based on abundances in mass chromatograms.
n-Alkanes are the most abundant class of compounds in most of the samples, and
their distribution (Fig. 2) defines the overall molecular weight distribution of
each sample.
The diesel has an n-alkane molecular weight distribution that maximises at
n-C(16), with significant amounts of n-alkanes from n-C(8) to n-C(25) (Fig. J1).
Hardly any n-alkanes > n-C(29) are present. The UCM/n-C(17) ratio is low (<0.01)
because only a slight UCM is present at this molecular weight range. The
UCM/n-C(27) ratio is higher (0.2 to 0.7) and variable due to the very low
content of n-C(27) in the diesel (Table 5). There is a distinct UCM in the
aromatic hydrocarbon fraction, which is dominated by alkylnaphthalenes,
alkylphenanthrenes and alkyldibenzothiophenes (Fig. J2).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 25
Table 5: General molecular data and aliphatic hydrocarbon parameters.
UCM UCM n-C(31)
/ / Pr / Ph / CPI CPI2 n-Alkane / Wax
CSIRO code n-C(17) n-C(27) Pr/Ph n-C(17) n-C(18) 22-32 26-28 maxima n-C(19) Index
- ------------- ------- ------- ----- ------- -------- ----- ----- -------- ------- -----
530 mt 0.17 1.71 1.19 0.27 0.28 nd 0.86 16 nd 32.7
675.1 m 0.03 0.44 1.26 0.33 0.28 nd 0.69 17 nd 145.7
686.2 m 0.06 1.80 1.10 0.27 0.28 nd 0.76 17 nd 50.2
686.2 m Sox 0.07 0.44 1.19 0.26 0.26 nd nd 17 nd nd
727 m 0.10 75 1.93 0.46 0.30 nd nd 17 nd nd
759.5-759.6 0.05 0.31 1.12 0.26 0.28 0.92 0.96 17 0.02 10.4
m
809.7 m 0.08 0.90 1.37 0.26 0.21 1.00 1.02 20 0.06 6.7
840 m 0.06 0.22 1.10 0.27 0.29 0.93 0.81 16 0.002 41.1
Diesel 0.04 0.67 1.75 0.38 0.26 0.92 0.71 16 0.000 69.0
(tank) 2
Diesel (line) 0.06 0.20 1.80 0.31 0.23 nd nd 16 nd nd
Aus-Tex 0.07 nd 0.83 0.40 0.44 0.99 1.11 28 1.10 0.4
Shell grease, >100 >100 nd nd nd nd nd nd nd nd
gun
Shell grease, >100 >100 nd nd nd nd nd nd nd nd
pipe dope
820 m 0.05 0.07 3.03 0.84 0.25 1.06 1.06 19 0.01 8.8
920 m 0.06 0.05 2.75 1.70 0.59 1.16 1.22 23 0.10 3.4
968-971 m 0.03 0.06 2.09 0.75 0.39 1.18 1.31 17 0.07 3.7
UCM / n-C(17) = height of UCM at n-C(17) / height of n-C(17) (measured in GC
traces); UCM / n-C(27) = height of UCM at n-C(27) / height of n-C(27) (measured
in GC traces); Pr = pristane; Ph = phytane. Pr/Ph, Pr/n-C(17) and Ph/n-C(18)
measured in GC traces, other ratios measured in m/z 85 mass chromatograms. CPI =
Carbon Preference Index. nd = not determined.
? 2 * (C(23) ? C(25) ? C(27) ? C(29) ? C(31)) ?
CPI(22?32) ? ? -------------------------------------------------- ?
? C(22) ? 2 * (C(24) ? C(26) ? C(28) ? C(30) ? C(32) ?
? 2 ? C(27) ? ? C(21) ? C(22) ?
CPI 2 (26?28) ? ? ------------- ? Wax Index = ? ? -------------- ?
? C(26) ? C(28) ? ? C(28) ? C(29) ?
Many of the oil show samples have overall distinct similarities to the diesel.
These include 530 m from Moose-1 (the open-hole slurry; Fig. B1), which has a
very similar n-alkane distribution. This sample has a larger UCM hump, with
higher UCM/n-C(17) and UCM/n-C(27) ratios, than the diesel, which is interpreted
to be due to greater biodegradation of this sample. Other oil show samples from
Moose-1ST1 that are similar to diesel (with respect to the n-alkane distribution
and the size of the UCM) include 675.1 m (Figs C1), 686.2 m (Figs C1, D1), 759.5
m (Fig. G1) and to some extent 840 m (Fig. I1). The 686.2 m sample was
ultrasonicated and Soxhlet extracted, and these two analytical approaches showed
very similar n-alkane distributions, so only the
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 26
[PERFORMANCE GRAPH]
Figure 2: Normalised n-alkane profiles of samples.
ultrasonicated sample was analysed in more detail. The 840 m includes a peak
co-eluting with n-C(22), which is not present in the diesel.
The Aus-Tex has a quite different molecular weight distribution (maxima =
n-C(28)) and UCM profile (Fig. L1), and is characterised by unusually high
abundances of some polycyclic aromatic hydrocarbons (PAH; phenanthrene,
fluoranthene, pyrene, chrysene, benzofluoranthene, benzopyrene, and
dibenzochrysene, and related isomers; Fig. L2). These PAH serve as a marker for
a contribution of Aus-Tex to oil shows, even though no oil show samples have a
similar n-alkane distribution as the Aus-Tex. Similar PAH as in Aus-Tex are
apparent in the oil show samples 686.2 m and 759.5-759.6 m.
The 727 m oil show sample contains some n-alkanes, which have a similar
distribution as diesel (Fig. F1), but is characterised by a very marked high
molecular weight UCM hump (UCM/n-C(27) =75). No other oil shows have this
distribution, but two grease samples (pipe dope and grease gun) have no
n-alkanes and a very marked UCM at a similar high molecular weight (Figs M1 and
N1).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 27
The 809.7 m oil show sample contains n-alkanes with a maxima at n-C20, and also
has peaks near the elution position of n-C(22) and n-C(24) which are not present
in the diesel. The n-alkane distribution distinguishes this sample from diesel
(Fig. 2).
The three mudstone samples in Moose-1ST1 have higher n-alkane molecular weight
maximas than the oil show samples or the diesel (Fig. 2; 17-23). The mudstone
samples have virtually no UCM hump in either the aliphatic or aromatic
hydrocarbon fractions.
Thus, based on overall distributions, the oil shows in Moose-1 and Moose-1ST1
have the following gross origins (Table 6). Note that later in the report this
assignment is further refined.
Table 6: Preliminary origin of oil shows, based on overall and gross
distributions.
CSIRO code Description Origin
- ---------- ----------- ------
530 m brown slurry Diesel, minor biodegraded component
675.1 m suspected oil show Diesel
686.2 m suspected oil show Diesel, mix of Aus-Tex (minor)
727 m suspected oil mixed with Minor diesel and major biodegraded component,
water possibly a grease (pipe dope or grease gun??)
759.5-759.6 m suspected oil show, oil/water Diesel, mix of Aus-Tex (minor)
wet sample
809.7 m suspected oil show Natural oil show, slightly biodegraded. Some
contribution of diesel is possible.
840 m water with oil Natural oil show, slightly biodegraded. Some
contribution of diesel is possible.
3.5 N-ALKANE AND ISOPRENOID PARAMETERS
Aliphatic hydrocarbon parameters are given in Table 5. All the oil shows that
contain n-alkanes (except 809.7 m) and the diesel have minor even carbon number
n-alkane predominance over the C(22)-C(32) range, as measured by the
CPI(22)-(32), but this predominance is more marked over the C(26)-C(28) range,
as measured by the CPI(26)-(28) (Fig. 3). This distribution is consistent with
derivation of the diesel and the oil shows from a calcareous source. In
contrast, the fine-grained samples have slight odd predominance in the high
molecular weight n-alkanes, and thus plot closer to many of the Subu samples.
This indicates that the fine-grained samples contain a contribution from
terrestrial organic matter.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 28
[CHART]
Figure 3: Cross-plot of two carbon preference indices (defined in Table 5).
The Pr/Ph ratios of the oil shows mostly varies between 1.1 and 1.4, and are
lower than for the diesel (~1.8) and the fine-grained samples (2.1-3.0). One oil
show sample (727 m) has a higher Pr/Ph ratio (1.9), more similar to the diesel.
The Aus-Tex has a lower Pr/Ph ratio than the other samples (Table 5).
Isoprenoid/alkane ratios are similar for the diesel and the oil shows, but are
mostly higher for the fine-grained samples, consistent with the latter being
less thermally mature than the diesel or the oil shows.
3.6 INTRA N-ALKANE PEAKS IN EOM
In addition to using ratios, similarities and dissimilarities between the diesel
and the oil shows can be demonstrated by examination of the low abundance peaks
that elute between n-C(13) and n-C(16) (Fig. 4). Using this method, and
particularly the correlation lines
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 29
[CHART]
Figure 4a: Partial gas chromatographs for the n-C(13) and n-C(16) range,
comparing diesel with oil show samples 675.1 m, 686.2 m and 727 m (total EOM).
iC15 and iC16 are acyclic C(15) and C(16) isoprenoids, 2MPD =
2-methylpentadecane, other significant peaks are numbered. Lines indicate
relative abundances between selected compounds.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 30
[CHART]
Figure 4b: Partial gas chromatographs for the n-C(13) and n-C(16) range,
comparing diesel with oil show samples 759.5-759.6 m, 809.7 m and 840 m (total
EOM). iC15 and iC16 are acyclic C(15) and C(16) isoprenoids, 2MPD =
2-methylpentadecane, other significant peaks are numbered. Lines indicate
relative abundances between selected compounds.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 31
between pairs of compounds, shows that the diesel is very similar to the oil
shows from 675.1 m, 686.2 m, 759.5-759.6 m and 840 m. These similarities include
the dominance of the C(16) isoprenoid, the low abundance of peaks 22 and 27, and
peak 1 being greater than peak 3. Oil show 727 m also has many similarities to
diesel, but it also contains a very large peak eluting between peaks 20 and 21,
and much larger peaks 22 and 27 than in the diesel (Fig. 4a). For these reasons,
it is likely that the oil show 727 m contains both diesel and another component.
The sample differing the most from the diesel is 809.7 m. In this sample the
C(16) isoprenoid is a less dominant peak, peak 27 is very large, peak 3 is
greater than peak 1, and there is an additional large peak eluting between iC15
and peak 10 (Fig. 4b). These data support the conclusion from the overall
distribution of compounds in this oil show, which is that the 809.7 m oil show
is not strongly affected by diesel and is the closest to a genuine oil signature
in Moose-1ST1.
Interestingly, based on overall composition oil show sample 840m appears quite
dissimilar to diesel, but has a similar n-C(13) and n-C(16) range profile (Fig.
4b). This suggests that diesel, which is recognised to be a contributor to this
sample (Table 5), is dominant in this molecular weight range.
3.7 ALKYLCYCLOHEXANES AND METHYLALKYLCYCLOHEXANES
The distribution of alkylcyclohexanes in the sample set follows that of the
n-alkanes very closely (see Appendix Figure *5). For example, sample 809.7 m has
a higher molecular weight maxima for alkylcyclohexanes than the other oil show
samples or the diesel, and this is also the case of the n-alkanes (Fig. 3).
Alkylcyclohexanes are relatively more abundant in the three finer-grained
samples than in the oil show samples. Methylalkylcyclohexanes have a low
abundance in all samples.
3.8 TERPANES
Terpane distributions are summarised in Tables 7a-f. These biomarkers enable
source and maturity-related information to be deduced, as well as specific
oil-oil correlations to be made. For example, additional contributions of
natural crude oil to the oil shows that are predominantly diesel can be
recognised.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 32
Table 7a: Terpane parameters (part a).
CSIRO Drim./ C(15)BS/ C(14) BS/ 19NIP/ IP/ 19NIP/ IP/ C(26)/C(25) C(23) tri./
code HD D+HD D+HD C(30)? ? C(30)? ? C(23) tri. C(23) tri. tri. C(30)? ?
- -------- ----- -------- --------- -------- -------- ---------- ---------- ------------ -----------
Calc. S123 S123 S123 S191 S191 S191 S191 S191 S191
530 m 0.50 0.42 n.d. n.d. n.d. n.d. n.d. 1.16 0.09
675.1 m 0.59 0.37 n.d. n.d. n.d. n.d. n.d. 0.66 1.33
686.2 m 0.24 0.18 n.d. n.d. n.d. n.d. n.d. 0.81 0.30
727 m 1.17 0.80 n.d. n.d. n.d. n.d. n.d. 1.68 0.02
759.5-7 0.67 0.38 n.d. n.d. n.d. n.d. n.d. 0.87 0.14
59.6 m
809.7 m 0.27 0.22 n.d. 0.35 0.22 1.32 0.84 0.95 0.27
840 m 0.63 0.48 n.d. n.d. n.d. n.d. n.d. 0.88 1.94
Diesel 1.47 0.71 0.17 n.d. n.d. n.d. n.d. 0.46 260
(tank)
Aus-Tex 1.05 0.32 n.d. n.d. n.d. n.d. n.d. 1.56 0.01
820 m 0.33 0.92 0.41 0.03 0.02 3.35 2.65 1.22 0.01
920 m 0.47 0.56 0.35 0.08 0.06 9.15 6.67 1.07 0.01
968-971 0.51 0.54 0.25 0.06 0.05 1.80 1.63 1.18 0.03
m
Terpane abbreviations are listed in Table A1.
Drim./HD = drimane/homodrimane; C(15)BS/D+HD = rearranged C(15) bicyclic
sesquiterpanes/(drimane + homodrimane); C(14) BS/ D+HD = C(14) bicyclic
sesquiterpanes/(drimane + homodrimane); 19NIP/C(30)? ? = 19NIP =
4?(H)-19-isopimarane/C(30)? ? hopane; IP/C(30)? ? = isopimarane/C(30)? ? hopane;
19NIP/C(23) tri. = 19NIP = 4?(H)-19-isopimarane/C(23) tricyclic terpane;
IP/C(23) tri. = isopimarane/C(23) tricyclic terpane; C(26)/C(25) tri. =
C(26)/C(25) tricyclic terpanes; C(23) tri./ C(30)? ? = C(23) tricyclic
terpane/C(30)? ? hopane. Calc. = method used to calculate ratio: S123 = peak
area in m/z 123 mass chromatogram, S191 = peak area in m/z 191 mass
chromatogram; nd = not determined.
Table 7b: Terpane parameters (part b).
CSIRO C24 tet. C(23)/C(21) C(23)-(26)/ C(24) tet. C(24)/C(24) C(19)/C(19) Ts/(Ts+ Tm/
code /C(30)? ? tri. C(19)-(21) /C(23) tri. +C(23) tri +C(23) tri Ts/Tm Tm) C(27)?
- ------- --------- ----------- ----------- ------------ ----------- ----------- ------ ------- -------
Calc. S191 S191 S191 S191 S191 S191 M M M
530 m 0.07 2.5 1.99 0.79 0.44 0.21 1.7 0.64 17
675.1 m 0.43 1.7 0.92 0.32 0.24 0.37 2.0 0.66 n.d.
686.2 m 0.13 1.4 0.73 0.43 0.30 0.50 1.6 0.62 12
727 m 0.04 6.4 16.06 1.83 0.65 n.d. 1.8 0.64 n.d.
759.5-7 0.04 1.3 0.64 0.28 0.22 0.46 1.01 0.50 9
59.6 m
809.7 m 0.51 1.6 1.06 1.90 0.66 0.28 1.2 0.55 18
840 m 0.52 1.5 0.73 0.27 0.21 0.47 1.6 0.61 11
Diesel 68 1.3 0.71 0.26 0.21 0.38 2.3 0.70 11
(tank)
Aus-Tex 0.01 1.3 1.61 1.16 0.54 0.33 0.98 0.50 8
820 m 0.05 0.97 0.44 5.4 0.84 0.79 0.79 0.44 24
920 m 0.05 0.66 0.20 5.3 0.84 0.87 0.68 0.41 19
968-971 0.07 1.10 0.50 2.0 0.67 0.69 0.85 0.46 15
m
Terpane abbreviations are listed in Table A1.
C(24) tet / C(30)? ? ?? ?C(24) tetracyclic terpane/C(30)? ? hopane; C(23)/C(21)
tri. = C(23)/C(21) tricyclic terpanes; C(23)-(26) / C(19)-(21) = C(23)-(26)
/C(19)-(21) tricyclic terpanes; C(24) tet. / C(23) tri.= C(24) tetracyclic
terpane/C(23) tricyclic terpane; C(24)/C(24)+C(23) tri = C(24) tetracyclic
terpane/(C(24) tetracyclic terpane + C(23) tricyclic terpane); C(19)/C(19)+C(23)
tri = C(19) tricyclic terpane/(C(19) tricyclic terpane + C(23) tricyclic
terpane). Calc. = method used to calculate ratio: S191 = peak area in m/z 191
mass chromatogram, M = peak area in metastable reaction monitoring chromatogram;
nd = not determined.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 33
Table 7c: Terpane parameters (part c).
C(29)Ts/ C(29) C(29) C(30)
CSIRO C(29)Ts/ C(29)Ts+ C(30)*/ C(29)*/ C(30)*/ C(30) Section/ 25-nor/ ? ? ??? ? ? ? ??? ?
code C(29)?? C(29)? ? C(29)Ts C(29)? ? C(30)? ? C(30)? ? C(29)? ? ???) ???)
- ---- ------- -------- ------- ------- -------- -------------- --------- --------- ---------
Calc. M M M M M M M M M
530 m 0.19 0.16 0.10 0.02 0.03 n.d. 0.02 0.94 0.94
675.1 m 0.18 0.15 n.d. n.d. n.d. n.d. n.d. 0.97 0.94
686.2 m 0.24 0.20 0.19 0.08 0.04 n.d. n.d. 0.93 0.92
727 m 0.20 0.17 n.d. n.d. n.d. n.d. n.d. 0.95 0.95
759.5-7 0.25 0.20 0.45 0.20 0.06 n.d. n.d. 0.89 0.92
59.6 m
809.7 m 0.43 0.30 0.71 0.19 0.62 0.21 n.d. 0.88 0.75
840 m 0.22 0.18 0.21 0.10 0.05 n.d. n.d. 0.94 0.91
Diesel 0.26 0.20 n.d. n.d. n.d. n.d. n.d. 0.95 0.94
(tank)
Aus-Tex 0.21 0.18 0.48 0.25 0.05 n.d. 0.03 0.89 0.92
820 m 0.36 0.26 0.50 0.12 0.09 n.d. n.d. 0.86 0.90
920 m 0.24 0.19 0.64 0.11 0.09 n.d. n.d. 0.85 0.88
968-971 0.28 0.22 0.56 0.12 0.09 n.d. n.d. 0.88 0.91
m
Terpane abbreviations are listed in Table A1.
C(29)Ts/C(29)? ? ?? ?C(29)Ts/C(29)? ? hopane; C(29)Ts/C(29)Ts+C(29)? ? =
?C(29)Ts/(C(29)Ts+C(29)? ? hopane); C(29)*/C(29)? ? = C(29)*/C(29)? ? hopane;
C(30)*/C(30)? ? = C(30)*/C(30)? ? hopane;C(30)Section/C(30)ab =
C(30)Section/C(30)? ? hopane; C(29) 25-nor/C(29)? ? = C(29) 25-norhopane/C(29)?
? hopane; C(29) ? ? ??? ? ? ? ? ) = C(29) hopanes ? ? ??? ? ? ? ? ); C30 ? ? ???
? ? ? ? ) = C(30) hopanes ? ? ??? ? ? ? ? ).
Calc. = method used to calculate ratio: S191 = peak area in m/z 191 mass
chromatogram, M = peak area in metastable reaction monitoring chromatogram; nd =
not determined. (Deggars) = MRM data.
Table 7d: Terpane parameters (part d).
C(31)? ? ? C(32)? ? C(33)? ? % C(31) % C(32) % C(33) % C(34) % C(35) C(35)/
CSIRO 22S/(22 22S/(22 22S/(22 homo- homo- homo- homo- homo- (C(35)+
code S+22R) S+22R) S+22R) hops hops hops hops hops C(34)
- ---------- ---------- -------- -------- ------ ------- ------- ------- ------- -------
Calc. M M M S191 S191 S191 S191 S191 S191
530 m 0.59 0.62 0.63 36 21 17 13 13 0.51
675.1 m 0.58 0.57 0.56 46 25 14 8 7 0.48
686.2 m 0.57 0.59 0.59 44 24 15 9 9 0.49
727 m 0.57 0.59 0.60 34 21 18 12 15 0.55
759.5-7 0.58 0.55 0.56 45 27 16 8 4 0.36
59.6 m
809.7 m 0.58 0.51 0.64 46 25 12 8 9 0.53
840 m 0.53 0.60 0.59 38 24 16 11 10 0.46
Diesel 0.52 0.63 0.51 100 n.d. n.d. n.d. n.d. n.d.
(tank)
Aus-Tex 0.57 0.56 0.57 36 26 18 12 9 0.42
820 m 0.59 0.59 0.60 48 30 13 7 3 0.28
920 m 0.59 0.58 0.61 53 26 13 7 2 0.23
968-971 0.57 0.58 0.60 47 26 14 8 4 0.32
m
Terpane abbreviations are listed in Table A1.
C(31)? ? ?22S/(22S+22R) = C(31)? ? hopanes (22S/(22S+22R));
C(32)???22S/(22S+22R) = C(32)? ? hopanes (22S/(22S+22R)); C(33)???22S/(22S+22R)
= C(33)? ? hopanes (22S/(22S+22R)); % C(31) homo-hops = C(31) homohopanes, as %
of total (C(31) to C(35)) homohopanes, etc; C(35)/(C(35)+C(34)) = C(35)? ?
hopanes/(C(35)? ? hopanes+C34? ? hopanes).
Calc. = method used to calculate ratio: M = peak area in metastable reaction
monitoring chromatogram; nd = not determined.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 34
Table 7e: Terpane parameters (part e).
Homo- Olean-a Gamm- C(30) C(27) 28,30- 29,30- 28,30- C(29)? ?
CSIRO hops/ ne/ acerane 30-nor/ hops/ BNH/ BNH/ BNH/ /C(30)? ?
code C(30)? ? C(30)? ? /C(30)? ? C(30)? ? C(30)? ? C(30)? ? C(30)? ? Ts hops
- ---------- -------- -------- --------- -------- -------- -------- -------- ------ ---------
Calc. S191 S191 M M S191 M M M S191
530 m 3.5 0.23 0.05 0.18 0.36 0.03 0.09 0.04 1.06
675.1 m 2.0 n.d. 0.08 0.19 0.67 n.d. 0.12 n.d. 1.14
686.2 m 1.9 n.d. 0.16 0.10 0.45 n.d. 0.06 n.d. 0.84
727 m 4.0 n.d. 0.04 0.19 0.36 n.d. 0.10 n.d. 1.08
759.5-7 0.9 0.06 0.23 0.004 0.17 n.d. 0.02 n.d. 0.48
59.6 m
809.7 m 1.3 0.01 0.08 0.14 1.8 0.06 0.08 0.03 1.9
840 m 1.6 0.03 0.17 0.07 0.48 n.d. 0.07 n.d. 0.71
Diesel n.d. n.d. n.d. 0.15 8.4 0.06 0.29 0.02 3.9
(tank)
Aus-Tex 1.4 0.06 0.24 0.02 0.21 0.005 0.02 0.02 0.44
820 m 1.3 n.d. n.d. n.d. 0.33 0.02 0.02 0.08 0.50
920 m 1.1 n.d. n.d. n.d. 0.34 0.03 0.01 0.13 0.55
968-971 1.2 n.d. n.d. n.d. 0.36 0.01 0.01 0.05 0.60
m
Terpane abbreviations are listed in Table A1.
Calc. = method used to calculate ratio: S191 = peak area in m/z 191 mass
chromatogram, M = peak area in metastable reaction monitoring chromatogram; nd =
not determined. (Double Dagger) value probably affected by co-elution.
Table 7f: Terpane parameters (part f).
C(31)? ?/ C(29) ster. C(31) 2? Me/ C(32) 2? Me/ C(33) 2? Me/
C(30)? ? ?? C(29)? ? ?? (C31 2? Me+ (C(32) 2? Me+ (C(33) 2? Me+
CSIRO code hopanes hopanes C(30)? ? C(31)? ? C(32)? ?
- ------------- ----------- ----------- ------------ -------------- --------------
Calc S191 S191,S217 S205 S205 S205
530 m 1.25 0.23 0.82 0.55 0.85
675.1 m 0.94 0.15 0.67 0.48 0.79
686.2 m 0.84 0.23 0.60 0.40 0.74
727 m 1.34 0.22 0.81 0.52 0.86
759.5-759.6 m 0.42 0.48 0.12 0.07 0.39
809.7 m 0.62 0.18 0.56 0.30 0.62
840 m 0.62 0.31 0.40 0.32 0.67
Diesel (tank) 0.51 0.10 n.d. n.d. n.d.
Aus-Tex 0.50 0.78 0.18 0.13 0.39
820 m 0.62 0.73 0.32 0.18 0.48
920 m 0.59 0.56 0.31 0.13 0.40
968-971 m 0.59 0.49 0.33 0.17 0.46
Terpane abbreviations are listed in Table A1.
Calc. = method used to calculate ratio: S191 = peak area in m/z 191 mass
chromatogram, S217 = peak area in m/z 217 mass chromatogram, S205 = peak area in
m/z 205 mass chromatogram; nd = not determined.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 35
3.8.1 Bicyclic sesquiterpanes
Bicyclic sesquiterpanes were detected using the m/z 123 mass chromatogram in all
the samples (Appendix Fig. *6a). In the diesel, bicyclic sesquiterpanes included
drimane (most abundant), with lesser amounts of homodrimane and rearranged C(15)
bicyclic isomers (Fig. J6a). Two C(14) isomers could also be detected. Ratios
based on these distributions are given in Table 7a. In contrast, most of the oil
shows have bicyclic sesquiterpane distributions dominated by homodrimane, with
very small amounts of C(14) isomers detected. Thus, drimane/homodrimane ratios
are lower in most of the oil shows than in the diesel (Table 7a). The one
exception is the 727 m oil show, which is more similar to the diesel (Fig. F6a).
Aus-Tex has a slightly different bicyclic sesquiterpane distribution, with
dominantly drimane and homodrimane (Fig. L6a). The mudstone samples have similar
bicyclic sesquiterpane distributions to most of the oil shows, with dominant
homodrimane.
These variations suggest that in most of the oil show samples the bicyclic
sesquiterpanes are not primarily derived from diesel, but from another
component.
3.8.2 Diterpanes
Most oil show samples and the diesel contain no detectable or very low abundance
diterpanes in the m/z 123 and 191 mass chromatograms. For example, the diesel
just has a very small isopimarane peak (Fig. J6b). This is in contrast to many
typical Jurassic-sourced oils and solid bitumens which contain large amounts of
4?(H)-19-isopimarane, ent-beyerane and isopimarane (George et al., 2003). In
this regard, the oil show sample 809.7 m is different to the diesel and the
other oil show samples, because it contains a significant amount of
4?(H)-19-isopimarane, ent-beyerane and isopimarane (Fig. H6b). The 19NIP/C(30)?
? hopane and IP/C(30)? ? hopane ratios of sample 809.7 m in Moose-1ST1 (Table
7a) are similar to those of Puri-1 crude oil, and solid bitumens CN249 and CN250
from Subu-1 (George et al., 2003). This is further supporting evidence that this
sample contains a genuine oil show not substantially affected by diesel. These
diterpenoids are probably derived from conifer resins (Noble et al., 1985,
1986). Thus it can be concluded that sample 809.7 m was derived from a rock
containing significant amounts of coniferous organic matter, which based on the
Subu work may well be a Jurassic-age source rock.
The fine-grained samples from Moose-1ST1 contain low amounts of
4?(H)-19-isopimarane, ent-beyerane and isopimarane relative to hopanes, with
19NIP/C(30)? ? hopane and IP/C(30)? ? hopane ratios of 0.02-0.08 (Table 7a).
However,
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 36
relative to tricyclic terpanes 4?(H)-19-isopimarane and isopimarane are
moderately abundant. In this respect these samples are similar to the
fine-grained samples from Subu. Thus, the fine-grained samples from Moose-1ST1
contain low amounts of coniferous organic matter.
3.8.3 Tricyclic and tetracyclic terpanes
All of the C(19) to C(26) (not C(22)) tricyclic terpanes and C(24) tetracyclic
terpane were detected in all of the samples. The overall abundance of these
terpanes could most conveniently be measured against the relative abundance of
the C(30) ? ? hopane in the m/z 191 mass chromatogram (Tables 7a and 6b; C(23)
tri./C(30)? ? and C(24) tet./C(30)? ?). These two ratios are very low (<0.1) in
the Aus-Tex and the fine grained samples, reflecting the low relative abundance
of tricyclic and tetracyclic terpanes in these samples. These ratios are very
high in the diesel, due to the very low abundance of hopane in the diesel. The
oil shows have variable ratios, from very low (e.g. 727 m) to moderately high
(840 m). This variability is consistent with varying contributions to the oil
shows of diesel and another, probably natural, component.
Two other terpane ratios [C(24) tetracyclic terpane/(C(24) tetracyclic terpane +
C(23) tricyclic terpane) and C(19) tricyclic terpane/(C(19) tricyclic terpane +
C(23) tricyclic terpane)] can be used to gain a broad approximation of the
relative amounts of terrestrial and marine organic matter in a source rock
(Preston and Edwards, 2000; George et al., 2002a). The three fine-grained
samples have high ratios (>0.65; Table 6b), suggesting significant terrestrial
organic matter input. In this respect they are similar to the fine-grained
samples from the Subu wells (George et al., 2003). In contrast, these ratios are
mostly relatively low for the diesel and the oil shows, although samples 727 m
and 809.7m have high C(24) tetracyclic terpane/(C(24) tetracyclic terpane +
C(23) tricyclic terpane) ratios. A high terrestrial organic matter input in the
809.7 m sample is consistent with the presence of diterpanes in this sample,
indicating coniferous organic matter. The C(26) tricyclic terpanes are not
significantly more abundant than the C(25) tricyclic terpanes in samples other
than 727 m (where the C(26)/C(25) tricyclic ratio >1 is caused by the
evaporative profile) and in Aus-Tex (Table 7b). This is evidence against the
diesel or any of the oil shows being sourced from a lacustrine source rock
facies (Schiefelbein et al., 1999). The Aus-Tex contains significant amounts of
C(28) and C(29) tricyclic terpanes (similar abundance as C(24) tetracyclic
terpane), which although present in the oil shows, are always of lesser
abundance.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 37
3.8.4 Methylhopanes
Methylhopanes were detected in all the samples, except the diesel, by monitoring
the m/z 205 mass chromatogram (Fig. *7c). Two isomer classes were identified: 2?
- -methylhopanes and 3?-methylhopanes. The 3?-methylhopanes are less abundant than
the 2?-methylhopanes, although are slightly more abundant in the fine-grained
samples. Where 2?-methylhopanes are abundant, notably in oil show samples 530 m
and 727 m, a complete series of the 2?-methylhopanes from C(30) to C(36) is
detectable (e.g. Figs. B7c and F7c).
There is considerable variation across the sample set in the abundance of the 2?
- -methylhopanes compared to hopanes (Table 7f), as shown by the cross-plot of
C(31)2?Me/(C(31)2?Me+C(30)? ? hopane) versus C(32)2?Me/(C(32)2? Me+C(31)?
? hopane) (Fig. 5). These ratios were effective at discriminating two families
of solid bitumens in the sandstone samples from the Subu wells, together with
the fluid inclusion oil from Subu-1, the Puri-1 oil and the Bwata-1 condensate
(George et al., 2003). The "Family A" samples (low amounts of 2?-methylhopanes)
were derived from a Jurassic-age source rock that contained high amounts of
terrestrial organic matter, and in particular coniferous organic matter. The
origin of 2?-methylhopanes is thought to be related to high prokaryotic source
input (Summons and Jahnke, 1990). 2?-methylhopanes are commonly found in high
abundance in oils derived from source rocks deposited in calcareous
environments. Thus the "Family B" solid bitumens were ascribed to having an
origin from a calcareous source with a high proportion of prokaryotic and a low
proportion of terrestrial organic matter input.
The lack of 2?-methylhopanes (and most other hopanes) in the diesel, and the
low abundance of 2?-methylhopanes in the Aus-Tex, indicates that the variable
but generally high amounts of 2?-methylhopanes in most of the oil show samples
are derived from a natural component of the oil show, and not a drilling
contaminant (Fig. 5; Table 7f). On the cross-plot, most of the oil shows cluster
around the Family B Subu population (Fig. 5). This indicates that the most
likely source of the natural component of most of the oil shows is the same or a
similar source as that which sourced the Family B solid bitumens and the fluid
inclusion oil in the Subu wells. The exception is the 759.5-759.6 m oil show,
which has a very low content of 2?-methylhopanes, probably due to overprinting
with Aus-Tex (Fig. 5).
The three fine-grained samples have low 2?-methylhopane/hopane ratios,
consistent with significant terrestrial organic matter input, as deduced by
terpane ratios (Fig. 5). In this respect, they are again similar to the Subu
fine-grained samples (George et al., 2003).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 38
[CHART]
Figure 5: Cross-plot of C(31)2?Me/(C(31)2?Me+C(30)? ? hopane) versus C(32)
2?Me/(C(32)2? Me+C(31)? ? hopane). The two families refer to solid bitumens
extracted from the sandstones in the Subu wells, the fluid inclusion oil from
Subu-1, the Puri-1 oil and the Bwata-1 condensate (data shown as black dots,
from George et al., 2003).
3.8.5 Hopanes
Hopanes and moretanes were monitored using the m/z 191 mass chromatograms. MRM
chromatograms were also run in order to examine the distribution of the C(27) to
C(35) hopanes in greater detail and to provide a cleaner distribution with less
interfering peaks that can complicate the interpretation of m/z 191 mass
chromatograms. Various biomarker parameters related to source and maturity were
calculated from the distribution of the terpanes in the SIM and MRM
chromatograms and are shown in Table 7 (b to f).
The ratio Tm/C(27)? is mainly controlled by maturity, and is most sensitive in
the early part of the oil window, whereas the Ts/Tm ratio is both maturity and
source controlled. The
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 39
ratio Tm/C(27)? varies from 8-24, without any clear correlation between samples.
The Ts/Tm ratio is lower for the fine-grained samples (0.7-0.85) than the oil
show samples (1-2), consistent with the fine-grained samples being of a lower
maturity than the oil shows. The diesel contains some Ts and Tm, with a Ts/Tm
ratio of 2.3. The higher relative amount of these C(27) hopanes in the oil
shows, together with the lower Ts/Tm ratios, indicates that most of the C(27)
hopanes in the oil shows are probably derived from a natural component and not
the diesel. The Ts/Tm ratios for the oil shows are similar to those found for
the Family B solid bitumens in the Subu wells, and are considerably lower than
the Ts/Tm ratios for the Family A solid bitumens in the Subu wells (3-6). This
indicates that the oil shows may have been derived from the same source rock as
the one from which the Family B solid bitumens in the Subu wells were derived.
The C(29)Ts/C(29)? ? hopane ratio varies between 0.18-0.36 for the Moose-1
sample set (Table 7c), except for sample 809.7 m which has a slightly higher
ratio (0.43). Again, these ratios correlate with the Family B solid bitumens in
the Subu wells, and are very different to the Family A solid bitumens (ratios
3.5-6; George et al., 2003). Other rearranged hopanes, including C(29) and C(30)
diahopane and an unidentified C(30) rearranged hopane (C(30)Section) were
detected in higher abundance in oil show sample 809.7 m than the other samples.
Based on C(29)*/C(29) ? ? hopane, C(30)*/C(30) ? ? hopane and C(30)Section
(rearranged hopane)/C(30) ? ? hopane ratios, oil show sample 809.7 m correlates
with the Family A solid bitumens, whereas all the other samples correlate better
with the Family B solid bitumens in the Subu wells. Previous work in Papua New
Guinea has indicated that high abundances of diahopanes are characteristic of
Jurassic, terrestrially-derived, oils (Waples and Wulff, 1996; George et al.,
1997).
Homohopane S/(S+R) maturity ratios are at or near equilibrium values (Table 7d).
The C(29) hopane ? ? ??? ? ? ? ? ) and C(30) hopane ? ? ??? ? ? ? ? ) ratios are
mostly at or near equilibrium values (0.9-0.95) for the Moose-1 sample set
(Table 7c). This implies mid oil window maturities or greater for those samples.
The exceptions are the oil show sample 809.7 m and the fine-grained samples,
which have non-equilibrium ratios and thus probably have lower maturities than
the other samples. This is supported by lower Ts/Tm ratios for these samples.
Homohopane proportions are similar for all samples, and are strongly depleted in
the higher molecular weight components, so provide little correlation
information (Table 7d). Traces of oleanane were detected in four of the oil show
samples (530 m, 759.5-759.6 m, 809.7 m, 840 m). This compound is a biomarker for
angiosperm input into a source rock, and although absent from the diesel is also
present in Aus-Tex. Therefore no conclusion can be drawn regarding the oleanane
present. Gammacerane was detected in low to moderate amounts in all the oil show
samples, is absent from diesel and the fine-grained samples, but is present in
Aus-Tex, in quite high abundance (Fig. L9a). Interestingly, two
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 40
samples with obvious Aus-Tex contamination based on PAH abundance (686.2 m and
759.5-759.6 m) have higher gammacerane/C(30) ?? hopane ratios than other oil
show sample, indicating a likely control on this ratio by Aus-Tex.
Little 25-norhopane (a biomarker for biodegradation) is present in any of the
samples (Table 7c). 29,30-bisnorhopane and C(30) 30-norhopane are present in
significant amounts in most of the oil show samples (low abundance in
759.5-759.6 m sample) These form part of a homologous series (C(28)-C(34)) which
could be partially or completely detected in these samples (e.g. Figs. B8, B9
and B10). However, 30-norhopanes are also present in small amounts in the
diesel. Thus, although these isomers are higher in abundance than in the Family
B solid bitumens in the Subu wells, they may be partially derived from the
diesel and not from a naturally-sourced crude oil with family B affinity.
C(29)/C(30) ?? hopane ratios are quite high for the oil shows (0.71-1.9) except
for samples 759.5-759.6 m which has a lower value. In contrast, diesel has an
even higher value (3.9). These data indicate a component of the hopanes in the
oil shows was not derived from diesel, and was most likely derived from a
calcareous-influenced source rock, similar to that which sourced the Family B
solid bitumens in the Subu wells. The fine-grained samples from Moose-1 ST1 have
much lower values (0.5-0.6), consistent with these not being a local source for
a component of the oil shows
Sterane/hopane ratios are all <1 for the oil shows (Table 7f), consistent with
Family B solid bitumens in the Subu wells, and the fine-grained samples also
have low values, similar to the Subu fine-grained samples (George et al., 2003).
In summary, hopane distributions indicate many differences between the
fine-grained samples from Moose-1ST1 (lower maturity) and the oil shows (mid oil
window maturity or higher). The low abundance of several hopanes in diesel, and
the different distributions compared to the oil shows, are indicative of a
natural component to most of the oil shows, notwithstanding some overprinting
also from Aus-Tex. For most of the oil shows, the natural component correlates
best with Family B solid bitumens in the Subu wells. An exception is the oil
show sample 809.7 m, which also correlates with the Family A solid bitumens
based on abundance of rearranged hopanes, although this sample also contains
some indicators of Family B affiliation, such as 30-norhopanes and strong 2?
- -methylhopanes. Interestingly this sample is the one least affected by diesel
(see Sections 3.4 and 3.6).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 41
3.9 STERANES AND DIASTERANES
Sterane distributions in the samples were monitored by SIM analyses using both
the m/z 217 and m/z 218 mass chromatograms, while the diasteranes (rearranged
steranes) were analysed using the m/z 217 and m/z 259 mass chromatograms. MRM
chromatograms were also run, in order to examine the distribution of the C(27)
to C(30) steranes, diasteranes and methylsteranes in greater detail. The MRM
data provided better quality data than the SIM data, due to co-elutions and some
interfering contaminants in the SIM chromatograms. Sterane and diasterane ratios
are reported in Table 8.
The diesel has a very unusual sterane and diasterane distribution, very strongly
biased towards the C(27) compared to the C(29) isomers (Fig. J11). The
C(29)/C(27) ? ? ? 20R sterane ratio is 0.2 (Table 8a), whereas the oil shows
have ratios from 0.7-1.9. This distribution is unlike any of the oil shows, and
is likely a consequence of the refinery cut causing molecular weight
discrimination. In the same way, the hopanes in the diesel are strongly biased
towards low molecular weight components. Therefore, most of the sterane
signature in the oil shows can be deduced to not be derived from the diesel,
although it is possible that some distortion of the true sterane signature of
the indigenous oil shows has been imparted by the diesel.
Aus-Tex contains abundant steranes, and these strongly dominate over
diasteranes. In this respect, Aus-Tex is different to most of the oil shows, as
shown by the diasterane/sterane ratio, which is 0.17 for the Aus-Tex, 0.21-4.0
for the oil shows. Again there is a correlation between the two oil shows
samples which have obvious Aus-Tex contamination based on PAH abundance (686.2 m
and 759.5-759.6 m), which have lower diasterane/sterane ratios than other oil
show samples (0.21, 0.26), indicating a likely control on this ratio by Aus-Tex
(Table 8c).
Most of the oil shows contain similar amounts of C(27) and C(29) steranes and
diasteranes (Tables 8a and b). The two exceptions are 727 m and 809.7 m, which
are more C(29) biased. Sample 809.7 m contains many more diasteranes relative to
steranes than any other oil show samples (Table 8c), and in this respect has a
greater rearranged signal than even the most diasterane-rich natural sample from
the Subu study (Puri-1 crude oil). This is consistent with the greater amount of
rearranged hopanes in this oil show compared with the others, and is further
indication of at least a contribution of the likely Jurassic,
terrestrially-derived oil that sourced the Family A solid bitumens in the Subu
wells (George et al., 2003) to this oil show, which based on overall
distributions has little diesel contamination. The lower diasterane/sterane
ratios of the other oil shows correlate better with the Family B solid bitumens
in the Subu wells (George et al., 2003).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 42
Table 8a: Sterane and diasterane parameters (part a).
C(27) ? ? ? C(28) ? ? ? C(29) ? ? ? C(29)/C(27) C(28)/C(29) C(30)/(C(27)+
20R 20R 20R ? ? ? 20R ? ? ? 20R C(28)+C(29)
CSIRO code (%) (%) (%) steranes steranes ? ? ? 20R TMI
- ------------- ----------- ----------- ----------- ---------- ----------- ------------- ----
Calc. S217* S217* S217* S217* S217* M M
530 m 36.1 21.2 42.7 1.2 0.50 3.4 0.88
675.1 m 43.8 18.2 38.0 0.9 0.48 2.3 0.54
686.2 m 48.8 19.5 31.7 0.7 0.61 1.6 0.67
727 m 30.8 15.1 54.1 1.8 0.28 10.1 0.90
759.5-759.6 m 37.9 23.0 39.1 1.0 0.59 1.5 0.59
809.7 m 28.9 15.7 55.4 1.9 0.28 19.4 1.19
840 m 41.6 22.7 35.7 0.9 0.64 1.7 0.51
Diesel (tank) 72.6 12.1 15.3 0.2 0.79 nd 0.29
Aus-Tex 33.4 28.7 38.0 1.1 0.75 1.6 0.70
820 m 19.5 24.6 55.8 2.9 0.44 5.7 1.3
920 m 19.0 20.1 60.9 3.2 0.33 4.8 1.7
968-971 m 26.7 23.3 50.0 1.9 0.47 4.6 1.4
Sterane and diasterane abbreviations are listed in Table A2. C(27) ? ? ? 20R (%)
= C(27) ? ? ? 20R sterane (as % of total C(27) to C(29) ? ? ? 20R steranes);
C(28) ? ? ? 20R (%) = C(28) ? ? ? 20R sterane (as % of total C(27) to C(29) ? ?
? 20R steranes); C(29) ? ? ? 20R (%) = C(29) ? ? ? 20R sterane (as % of total
C(27) to C(29) ? ? ? 20R steranes); C(30)/(C(27)+C(28)+C(29)) ? ? ? 20R steranes
(%); TMI = Terrestrial/marine index = (C(27)(??) ?? diasteranes/(C(27) ??
diasteranes + C(30) ?? diasteranes)). Calc. = method used to calculate ratio:
S217 = peak area in m/z 217 mass chromatogram, M = peak area in metastable
reaction monitoring chromatogram; nd = not determined. * MRM used for diesel.
Table 8b: Sterane and diasterane parameters (part b).
C(27) ??? C(28) ??? C(29) ??? C(27) C(28) C(29) C(27) ?? C(28) ?? C(29) ??
CSIRO steranes steranes steranes steranes steranes steranes diaster. diaster. diaster.
code (%) (%) (%) (%) (%) (%) (%) (%) (%)
- ----- --------- --------- --------- -------- -------- -------- -------- -------- --------
Calc. S218 S218 S218 M M M S259 S259 S259
530 m 30.9 21.6 47.5 40.7 18.0 41.3 37.1 22.8 40.2
675.1 m 39.6 20.3 40.1 42.7 18.8 38.4 45.1 28.2 26.6
686.2 m 33.3 25.1 41.5 36.2 25.0 38.7 35.6 27.9 36.6
727 m 26.5 18.1 55.4 37.7 16.1 46.2 28.6 23.0 48.4
759.5-75 27.6 26.6 45.8 41.6 24.7 33.7 33.6 29.7 36.7
9.6 m
809.7 m 32.3 20.9 46.7 37.2 21.9 40.8 21.7 31.1 47.2
840 m 37.7 27.0 35.3 42.2 22.7 35.1 44.6 33.5 21.9
Diesel 70.4 13.4 16.2 62.7 16.7 20.6 60.4 23.5 16.1
(tank)
Aus-Tex 26.0 31.8 42.2 39.9 24.8 35.3 25.3 32.4 42.4
820 m 29.3 22.0 48.7 26.0 22.7 51.2 19.2 29.9 50.9
920 m 31.8 15.7 52.5 24.5 19.6 55.9 17.4 25.7 56.9
968-971 m 30.2 21.7 48.1 30.4 23.3 46.4 20.9 27.6 51.5
Sterane and diasterane abbreviations are listed in Table A2.
C(27) ??? steranes (%) = C(27) ??? steranes 20S+R (as % of total C(27) to C(29)
??? 20R steranes); C(28) ??? steranes (%) = C(28) ??? steranes 20S+R (as % of
total C(27) to C(29) ??? 20R steranes); C(29) ??? steranes (%) = C(29) ???
steranes 20S+R (as % of total C(27) to C(29) ??? 20R steranes); C(27) steranes
(%) = C(27) steranes (% of total C(27) to C(29) regular steranes); C(28)
steranes (%) = C(28) steranes (% of total C(27) to C(29) regular steranes);
C(29) steranes (%) = C(29) steranes (% of total C(27) to C(29) regular
steranes); C(27) ?? diaster. (%) = C(27) ?? diasterane 20S+R (as % of total
C(27) to C(29) ?? 20S+R diasteranes); C(28) ?? diaster. (%) = C(28) ??
diasterane 20S+R (as % of total C(27) to C(29) ?? 20S+R diasteranes); C(29) ??
diaster. (%) = C(29) ?? diasterane 20S+R (as % of total C(27) to C(29) ?? 20S+R
diasteranes). Calc. = method used to calculate ratio: S218 = peak area in m/z
218 mass chromatogram, S259 = peak area in m/z 259 mass chromatogram, M = peak
area in metastable reaction monitoring chromatogram; nd = not determined. * MRM
used for 809.7 m sample.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 43
Table 8c: Sterane and diasterane parameters (part c).
C(27) ?? C(28) ?? C(29) ?? C(27) ? ? ? C(28) ? ? ? C(29) ? ? ?
diaster./ diaster./ diaster./ Diaster./ 20S/(20S 20S/(20S 20S/(20S
CSIRO code steranes steranes steranes steranes + 20R) + 20R) + 20R)
- ---------- --------- --------- --------- --------- ----------- ----------- -----------
Calc. M M M M M M M
530 m 0.47 0.60 0.45 0.48 0.54 0.44 0.42
675.1 m 0.71 0.61 0.45 0.59 0.46 0.42 0.43
686.2 m 0.32 0.24 0.21 0.26 0.39 0.39 0.38
727 m 0.29 0.34 0.22 0.27 0.47 0.48 0.46
759.5-759.6 m 0.24 0.20 0.18 0.21 0.39 0.35 0.39
809.7 m 3.55 4.28 4.28 4.01 0.53 0.56 0.47
840 m 0.54 0.40 0.34 0.44 0.43 0.35 0.36
Diesel (tank) 1.28 1.46 1.13 1.28 0.47 0.61 0.50
Aus-Tex 0.19 0.17 0.15 0.17 0.37 0.34 0.35
820 m 1.22 1.11 0.92 1.04 0.50 0.46 0.49
920 m 1.38 1.40 1.19 1.28 0.50 0.48 0.49
968-971 m 0.82 0.89 0.94 0.89 0.44 0.43 0.42
Sterane and diasterane abbreviations are listed in Table A2.
C(27) ?? diaster./steranes = C(27) ?? diasteranes/?? ? ? +??? steranes); C(28)
?? diaster./steranes = C(28) ?? diasteranes/?? ? ? +??? steranes); C(29) ??
diaster./steranes = C(29) ?? diasteranes/?? ? ? +??? steranes);
Diaster./steranes = C(27)+C(28)+C(29) ?? diasteranes/?? ? ? +??? steranes).
Calc. = method used to calculate ratio: M = peak area in metastable reaction
monitoring chromatogram.
Table 8d: Sterane and diasterane parameters (part d).
C(29) ? ? ? ? VRE from C(27) C(28) C(29) C(29) ??
steranes C(29) ????????? ????????? ????????? diasterane
CSIRO code 20S/20R 20S/20R ? ? ? ? ? ? ? ? ? ? ? ? S/(S+R)
- ------------- ------------- -------- -------- --------- --------- ----------
Calc. M M M M M M
530 m 0.71 0.71 0.45 0.51 0.57 0.59
675.1 m 0.76 0.73 0.41 0.49 0.53 0.64
686.2 m 0.61 0.65 0.28 0.40 0.42 0.65
727 m 0.84 0.77 0.46 0.58 0.57 0.62
759.5-759.6 m 0.64 0.67 0.21 0.32 0.33 0.65
809.7 m 0.87 0.79 0.40 0.43 0.52 0.62
840 m 0.57 0.64 0.29 0.34 0.38 0.63
Diesel (tank) 1.00 0.85 0.48 0.56 0.65 0.78
Aus-Tex 0.53 0.62 0.19 0.29 0.32 0.63
820 m 0.97 0.83 0.34 0.40 0.40 0.60
920 m 0.98 0.84 0.29 0.32 0.34 0.59
968-971 m 0.73 0.71 0.30 0.37 0.40 0.60
Sterane and diasterane abbreviations are listed in Table A2.
VRE from C(29) 20S/20R = Vitrinite reflectance equivalent from C(29) ? ? ?
steranes 20S/20R (Sofer et al., 1993). Calc. = method used to calculate ratio: M
= peak area in metastable reaction monitoring chromatogram.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 44
Table 8e: Sterane and diasterane parameters (part e).
21-nor/ 21-nor/
(21- + (21- +
CSIRO code NDR NCR 24-nor) 27-nor)
- ---------- ---- ---- ------- -------
Calc. M M M M
530 m nd 0.31 0.71 0.58
675.1 m nd 0.49 0.71 0.66
686.2 m 0.48 0.61 0.46 0.58
727 m nd 0.29 0.85 0.77
759.5-759.6 m 0.49 0.66 0.10 0.19
809.7 m 0.32 0.53 0.46 0.56
840 m 0.51 0.61 0.45 0.57
Diesel (tank) nd nd nd nd
Aus-Tex 0.45 0.68 0.09 0.18
820 m 0.38 0.45 0.28 0.27
920 m 0.37 0.37 0.20 0.19
968-971 m 0.41 0.50 0.37 0.42
Sterane and diasterane abbreviations are listed in Table A2.
C(26) steranes distributions (Holba et al., 1998a, 1998b): NDR =
nordiacholestanes ratio: [(24- /(24- + 27-) nordiacholestanes]; NCR =
norcholestanes ratio [(24-/(24- + 27-) norcholestanes]; 21-nor/(21- + 24-nor) =
21-norcholestane/(21-norcholestane + ? ? ? 20R 24-norcholestane); 21-nor/(21- +
27-nor) = 21- norcholestane /(21- norcholestane + ? ? ? 20R 27- norcholestane).
Calc. = method used to calculate ratio: M = peak area in metastable reaction
monitoring chromatogram.
C(30) steranes and diasteranes are present in all the samples, except that they
could not be detected in the diesel (Table 8a). This indicates a marine source
for these oil shows, assuming that Aus-Tex has not been a major overprint. C(30)
steranes and diasteranes are particularly abundant in the oil shows from 727 m
and 809.7 m, which are more C(29) sterane biased and which contain little or no
diesel contamination in this molecular weight fraction. This indicates that
these oil shows are at least in part natural, and derived from a strongly marine
source rock.
The C(27-29) ? ? ? 20S/(20S+20R) sterane ratios are generally close to
equilibrium and do not show any obvious intra-sample variabilities, except that
the diesel has somewhat higher values and the Aus-Tex has somewhat lower values
(Table 8c). Using an equation from Sofer et al. (1993), a vitrinite reflectance
equivalent (VRE) can be calculated from the C(29) ? ? ? steranes 20S/20R ratio.
This indicates maturities in the early to mid oil window (0.65-0.85%) for all
the samples (Table 8d). The C(27)-C(29) ?????? ? ? ? ? ? ? ? sterane ratios
allow more differentiation of the sample set based on thermal maturity, because
these ratios only reach equilibrium at higher maturities (Fig. 6). The following
observations can be made: (1) The fine-grained samples have low thermal
maturities (ratios 0.3-0.4), slightly higher than for the Subu fine grained
samples (0.2-0.3). (2) The Aus-Tex has a low thermal maturity. (3) Oil show
sample 759.5-759.6 m, which is known to be overprinted by Aus-Tex, has a very
similar low thermal maturity, so steranes in this sample are almost certainly
affected significantly by Aus-Tex. (4) The apparent
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 45
(CHART)
Figure 6: Cross-plot of C(27) sterane ????????????? versus C(29) sterane ??????
? ? ? ? ? ? ? ratios. The family refers to solid bitumens extracted from the
sandstones in the Subu wells (data shown as black dots, from George et al.,
2003).
lower thermal maturity of 686.2 m oil show (and possibly 840 m) is also likely
caused by Aus-Tex (see Fig. 6). (5) The diesel has very low amounts of steranes,
and these give a higher maturity than any oil shows, so diesel overprinting has
probably not significantly affected any oil shows. (6) Other oil shows (530 m,
675.1 m, 727 m, 809.7 m) have a similar mid oil window maturity as many of the
solid bitumens from Subu.
All samples except the diesel contain significant amounts of C(26) steranes
(norcholestanes) and diasteranes (nordiacholestanes) (Fig. x14a). The importance
of these compounds is that they can be used as age-diagnostic biomarkers (Holba
et al., 1998a, b). Apart from the 21-norcholestane isomer, which may increase in
relative abundance with maturity, there are two main series of norcholestanes
and nordiacholestanes. The 27-nor series is abundant in older rocks, whereas in
Cretaceous
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 46
and Tertiary rocks the 24-nor series becomes more abundant (Holba et al., 1998a,
b). Two ratios, the NDR (nordiacholestanes ratio) and the NCR (norcholestanes
ratio), quantify this (Table 8e). NDR values above a threshold of 0.25 and NCR
values above a threshold of 0.35 are consistent with Cretaceous or younger
rocks. NDR values above a threshold of 0.5 and NCR values above a threshold of
0.6 are consistent with Tertiary rocks. The NDR ratios for the oil shows in
Moose-1 vary between 0.32-0.51, and the NCR ratios for the oil shows vary
between 0.29-0.66. These values therefore indicate that the oil shows contain
C(26) steranes derived principally from Cretaceous or younger strata. Note the
Aus-Tex also contains C(26) steranes, and these have values in the same range
(Table 8e). Therefore, the age specificity for the samples contaminated by
Aus-Tex (759.5-759.6 m, 686.2 m, and possibly 840 m) is unreliable. Other oil
shows dated using this method are considered to be reliable. The fine-grained
rocks in Moose-1ST1 have NDR ratios varying between 0.37-0.41, and NCR ratios
varying between 0.37-0.5. These values are consistent with Cretaceous or younger
ages for these strata.
3.10 AROMATIC HYDROCARBONS
Eight major classes of aromatic hydrocarbons were monitored to assess variations
in thermal maturity and to characterise source-related geochemical parameters.
These compound classes were the alkylbenzenes, alkylnaphthalenes,
alkylphenanthrenes, alkylbiphenyls, alkylfluorenes, alkylpyrenes,
alkylfluoranthenes and alkyldibenzothiophenes. All chromatograms are included in
the appendices. A wide variety of source and maturity related parameters were
calculated from the integrated SIM mass chromatograms and are reported in Table
9. Abbreviations for aromatic hydrocarbons are defined in Appendix Table A3.
3.10.1 Overall aromatic hydrocarbon composition
The overall aromatic hydrocarbon compositions of the Moose-1 samples are shown
in Figure 7. All samples contain low amounts of alkylbenzenes. The diesel is
strongly dominated by alkylnaphthalenes, whereas Aus-Tex is very strongly
dominated by phenanthrene. The oil shows have quite variable compositions, some
being dominated by alkylnaphthalenes (727 m, 759.5-759.6 m), and some containing
dominantly alkyldibenzothiophenes (675.1 m, 686.2 m, 840 m).
Alkyldibenzothiophenes are also rich in the diesel (Fig. 7), so it is likely
that the high content of sulphur compounds in the oil shows is related to
contamination by diesel. The one oil show (809.7 m) that has a very different
composition (high alkylphenanthrenes and biphenyl) is also the sample that
aliphatic parameters show to have the least contamination from diesel or
Aus-Tex.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 47
Table 9a: Aromatic hydrocarbon parameters (part a).
CSIRO code TMBI- TMBI- MEBI- TeMBI TeMBI MNR N/ ENR DNR-1
1 2 1 -x -y ? MNs
- ------------------------------------------------------------------------------------------------------
530 m 0.38 0.69 0.70 0.53 0.39 1.5 0.27 3.4 3.5
675.1 m nd nd nd nd nd 2.1 0.01 10.2 5.4
686.2 m nd 0.42 nd 0.41 0.07 1.8 0.11 25.2 4.1
727 m nd 0.35 nd 0.28 0.09 2.6 0.02 nd 9.6
759.5-759.6 0.23 0.30 nd 0.54 0.39 1.5 0.26 3.7 4.3
m
809.7 m 0.34 0.60 0.76 0.47 0.27 1.4 0.14 1.4 3.9
840 m nd nd nd 0.47 0.44 1.5 0.11 nd 2.3
Diesel 0.19 0.54 0.44 0.38 0.21 1.5 0.21 3.9 4.4
(tank)
Aus-Tex 0.32 0.84 nd 0.46 0.30 1.5 0.37 6.1 4.6
820 m nd 0.12 nd 0.43 0.24 1.3 0.19 1.5 2.2
920 m 0.11 0.47 nd 0.36 0.23 2.1 0.43 2.2 4.1
968-971 m 0.16 0.50 nd 0.44 0.30 2.4 0.54 1.6 3.7
For compound abbreviations see Table A3. TMBI = trimethylbenzene index; TMBI-1 =
(1,3,5-TMB/[1,3,5-TMB+1,2,3-TMB]); TMBI-2 = (1,2,4-TMB/[1,2,4-TMB+1,2,3-TMB]);
MEBI = methylethylbenzene index, MEBI-1 = (1M3EB+1M4EB)/(1M3EB+1M4EB+1M2EB);
TeMBI = tetramethylbenzene index; TeMBI-x
(1,2,3,5-TeMB/[1,2,3,5-TeMB+1,2,3,4-TeMB]); TeMBI-y
(1,2,4,5-TeMB/[1,2,4,5-TeMB+1,2,3,4-TeMB]); MNR = methylnaphthalene ratio
(2-MN/1-MN); N/? MNs = naphthalene/? methylnaphthalenes: ENR = ethylnaphthalene
ratio (2-EN/1-EN); DNR = dimethylnaphthalene ratio: DNR-1
([2,6-+2,7-DMN]/1,5-DMN).
Table 9b: Aromatic hydrocarbon parameters (part b).
CSIRO code DNR-x DNR-y DNR-z TNR-1 TNR-2 TNRs TNR-x 136-TMN/
137-TMN
- ----------------------------------------------------------------------------------------------
530 m 1.02 0.47 0.52 0.64 0.63 1.17 0.75 1.64
675.1 m 0.95 0.44 0.41 0.98 0.82 1.45 0.79 1.45
686.2 m 0.83 0.42 0.54 0.68 0.66 1.17 0.86 1.58
727 m 1.12 0.49 0.35 0.96 0.73 1.19 0.78 1.73
759.5-759.6 1.13 0.48 0.52 0.67 0.64 1.18 0.75 1.61
m
809.7 m 0.94 0.42 0.33 1.04 0.88 1.71 0.72 1.36
840 m 0.78 0.47 0.58 0.90 0.80 1.38 0.75 1.37
Diesel 1.26 0.52 0.55 0.76 0.68 1.23 0.71 1.60
(tank)
Aus-Tex 1.12 0.43 0.56 1.02 0.89 1.49 0.71 1.25
820 m 0.81 0.42 0.38 0.97 0.87 1.81 0.86 1.30
920 m 0.67 0.42 0.40 0.97 0.85 1.58 0.96 1.33
968-971 m 0.63 0.42 0.47 0.86 0.91 1.71 0.95 1.06
For compound abbreviations see Table A3. DNR = dimethylnaphthalene ratio; DNR-2
= (2,7-DMN/1,8-DMN); DNR-3 = (2,6-DMN/1,8-DMN); DNR-x =
([2,6-+2,7-DMN]/1,6-DMN); DNR-y =
([2,6-+2,7-DMN]/[2,6-+2,7-DMN+1,3+1,7-DMN]); DNR-z = (1,5-/[1,5-+1,2-DMN]); TNR
= trimethylnaphthalene ratio; TNR-1 = (2,3,6-TMN/[1,4,6-+1,3,5-TMN]); TNR-2 =
([2,3,6-+1,3,7-TMN]/[1,4,6-+1,3,5-+1,3,6-TMN]); TNRs =
([1,3,7-+2,3,6-TMN]/1,3,6-TMN); TNR-x = (1,2,5-TMN/[1,2,5-+1,2,4-+1,2,3-TMN]).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 48
Table 9c: Aromatic hydrocarbon parameters (part c).
CSIRO code Log Log TeM- TeM- TMNr TeMNr PMNr HPI %
(1,2,5-/ (1,2,7-/ NR-1 NR-2 IP-iHM
1,3,6-) 1,3,7-) N
- ---------------------------------------------------------------------------------------------------
530 m -0.16 -0.36 0.73 3.4 0.47 0.58 nd 0.26 0
675.1 m -0.12 -0.49 0.68 2.9 0.47 0.59 0.48 0.16 0
686.2 m -0.14 -0.58 0.37 3.9 0.47 0.60 0.52 0.13 0
727 m -0.45 -0.57 0.85 2.5 0.62 0.71 0.58 0.10 0
759.5-759.6 -0.19 -0.41 0.66 2.4 0.49 0.60 0.42 0.26 0
m
809.7 m 0.06 -0.38 0.68 2.5 0.39 0.54 0.54 0.59 0
840 m -0.12 -0.66 0.83 2.7 0.49 0.56 0.38 0.39 0
Diesel -0.40 -0.48 0.94 2.2 0.61 0.71 0.45 0.17 0
(tank)
Aus-Tex -0.47 -0.62 0.40 1.6 0.70 0.77 nd nd nd
820 m 0.49 -0.09 0.44 8.9 0.20 0.24 0.16 1.0 3.8
920 m 0.75 -0.31 0.23 13.5 0.12 0.17 0.14 4.4 2.6
968-971 m 0.45 -0.55 0.30 12.5 0.25 0.21 0.10 2.6 2.8
For compound abbreviations see Table A3. Log (1,2,5-/1,3,6-) = Log
(1,2,5-TMN/1,3,6-TMN); Log (1,2,7-/1,3,7-) = Log (1,2,7-TMN/1,3,7-TMN); TeMNR =
tetramethylnaphthalene ratio; TeMNR-1 = (2,3,6,7-TeMN/1,2,3,6-TeMN); TeMNR-2 =
(1,2,5,6+1,2,3,5-TeMN)/1,2,3,6-TeMN; TMNr = (1,3,7-TMN/[1,3,7-+1,2,5-TMN]);
TeMNr = (1,3,6,7-TeMN/[1,3,6,7+1,2,5,6-TeMN]); PMNr = pentamethylnaphthalene
ratio = PMNr (1,2,4,6,7-PMN/[1,2,4,6,7+1,2,3,5,6-PMN]); HPI = higher plant index
= ([retene + cadalene + IP-iHMN]/1,3,6,7-TeMN); % IP-iHMN = % IP-iHMN of total
(retene + cadalene + IP-iHMN).
Table 9d: Aromatic hydrocarbon parameters (part d).
CSIRO % % HPP MPI-1 %R(c) MPDF 1-MP/ log MPR
code Cad. Retene (MPI-1) 9-MP (1-MP/
9-MP)
- --------------------------------------------------------------------------------------------------------
530 m 79.8 20.2 0.20 0.65 0.79 0.45 0.60 -0.22 1.13
675.1 m 5.0 95.0 0.95 0.70 0.82 0.43 0.74 -0.13 1.00
686.2 m 67.0 33.0 0.33 0.56 0.73 0.44 0.74 -0.13 1.04
727 m 35.9 64.1 0.64 0.74 0.84 0.48 0.53 -0.28 1.3
759.5-759.6 84.3 15.7 0.16 0.44 0.67 0.54 0.62 -0.20 1.3
m
809.7 m 13.2 86.8 0.87 0.68 0.81 0.46 0.78 -0.11 1.12
840 m 53.9 46.1 0.46 0.62 0.77 0.44 0.80 -0.10 0.98
Diesel 63.3 36.7 0.37 0.77 0.86 0.49 0.64 -0.19 1.2
(tank)
Aus-Tex nd nd nd 0.17 0.50 0.65 0.87 -0.06 2.4
820 m 35.6 60.5 0.63 0.54 0.72 0.47 0.80 -0.09 0.82
920 m 9.5 87.9 0.90 0.39 0.63 0.38 1.6 0.21 0.60
968-971 m 11.1 86.2 0.89 0.33 0.60 0.39 1.6 0.20 0.60
For compound abbreviations see Table A3. % Cad. = % cadalene of total (retene +
cadalene + IP-iHMN); % Retene = % Retene of total (retene + cadalene + IP-iHMN);
HPP = higher plant parameter = (retene /[retene + cadalene]); MPI-1=
methylphenanthrene index =1.5*[3-MP+2-MP]/[P+9-MP+1-MP]); %R(c) (MPI-1) =
calculated vitrinite reflectance from MPI-1 (0.6*MPI-1+0.4 (for R(o) <1.35),
from Radke and Welte, 1983); MPDF = methylphenanthrene distribution fraction =
((3-MP+2-MP)/ ? MPs); MPR = methylphenanthrene ratio = (2-MP/1-MP).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 49
Table 9e: Aromatic hydrocarbon parameters (part e).
CSIRO code DPR Log DPR-x Log Fl/(Fl + MPyI2 3-MBp 3-MBp/ MBpR
(1,7-DM (Retene Py) /Bp 4-MBp
P/ /9-MP)
DMP X)
- --------------------------------------------------------------------------------------------------------
530 m 0.23 -0.52 0.23 -1.24 0.19 0.40 1.9 2.4 4.6
675.1 m 0.25 -0.42 0.28 -1.07 0.35 0.39 3.5 2.4 6.8
686.2 m 0.20 -0.47 0.25 -1.56 0.50 0.48 2.5 2.9 8.2
727 m 0.29 -0.51 0.24 -1.26 0.11 0.26 1.9 2.4 5.5
759.5-759.6 0.38 -0.51 0.24 -1.37 0.53 0.64 1.7 2.3 4.6
m
809.7 m 0.30 -0.43 0.27 -0.77 0.51 0.40 0.04 2.0 5.8
840 m 0.29 -0.40 0.28 -0.98 0.46 0.45 2.5 1.8 6.4
Diesel 0.31 -0.43 0.27 -1.08 0.16 0.37 1.4 2.0 3.7
(tank)
Aus-Tex 0.52 -0.49 0.24 nd 0.53 1.09 1.2 5.5 nd
820 m 0.24 -0.06 0.47 -0.63 0.39 0.40 1.7 2.7 25.8
920 m 0.28 0.00 0.50 0.09 0.39 0.37 1.4 2.3 10.8
968-971 m 0.18 -0.07 0.46 -0.24 0.53 0.39 0.91 2.4 4.2
For compound abbreviations see Table A3. DPR = dimethylphenanthrene ratio =
(3,5-+2,6-DMP+2,7-DMP)/(1,3-+3,9-+2,10-+3,10-DMP+1,6-+2,9-+2,5-DMP); Log
(1,7-DMP/DMP X) = Log (1,7-DMP/1,3-+3,9-+2,10-+3,10-DMP); DPR-x =
dimethylphenanthrene ratio-x = (1,7-DMP/1,7-+1,3-+3,9-+2,10-+3,10-DMP); Fl/(Fl +
Py) = fluoranthene/(fluoranthene + pyrene); MPyI2 = methylpyrene index =
(2-MPy/(1-+4-MPy); MBpR = methylbiphenyl ratio = (3-MBp/2-MBp).
Table 9f: Aromatic hydrocarbon parameters (part f).
CSIRO code DMBp DMBp P/DBT DBT/P MDR DMDR DBT/ P/A 2MP/2
R-x R-y 1,3,6,7- MA
TeMN
- ---------------------------------------------------------------------------------------------------
530 m 2.2 3.2 1.2 0.84 2.3 0.68 1.9 nd nd
675.1 m 2.5 4.9 1.9 0.53 2.1 0.61 1.8 56.3 13.5
686.2 m 4.8 nd 2.3 0.44 2.1 0.60 2.4 13.9 53.0
727 m 2.4 4.1 6.4 0.16 5.3 1.10 0.41 nd nd
759.5-759.6 2.4 3.7 4.1 0.24 2.1 0.65 1.9 7.4 2.6
m
809.7 m 2.6 5.5 3.1 0.32 1.7 0.56 2.5 33.8 37.0
840 m 2.6 4.3 2.1 0.47 1.8 0.58 2.2 nd nd
Diesel 2.1 3.0 1.5 0.67 2.3 0.59 1.2 nd 5.3
(tank)
Aus-Tex nd nd 35.4 0.03 14.0 0.42 9.4 7.4 6.2
820 m 10.1 24.5 14.2 0.07 3.0 0.53 0.87 60.7 1.7
920 m 9.7 29.2 20.1 0.05 2.0 0.92 0.97 67.0 11.2
968-971 m 2.0 4.6 47.4 0.02 3.0 0.87 0.73 28.0 9.5
For compound abbreviations see Table A3. DMBpR-x = dimethylbiphenyl ratio =
(3,5-DMBp/2,5-DMBp); DMBpR-y = dimethylbiphenyl ratio = (3,3'-DMBp/2,3'-DMBp);
MDR = methyldibenzothiophene ratio = (4-MDBT/1-MDBT); DMDR =
dimethyldibenzothiophene ratio = (4,6-DMDBT/(3,6-+2,6-DMDBT)); P/A -=
phenanthrene/anthracene; 2MP/2MA = 2-methylphenanthrene/2-methylanthracene.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 50
(CHART)
Figure 7: Normalised aromatic hydrocarbon compositions of the Moose-1 samples.
The fine-grained samples have overall aromatic hydrocarbon compositions
dominated by alkylnaphthalenes.
3.10.2 Alkylbenzenes
Alkylbenzenes, including the xylenes, trimethylbenzenes and tetramethylbenzenes,
were detected in most of the samples (see Appendix *16). These compounds are in
such low abundance in some samples (675.1 m, 686.2 m, 840 m) that their
distribution is not
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 51
interpretable. Low abundances of alkylbenzenes may be due to partial evaporative
loss during sample work-up, or to the effects of biodegradation.
There are at least two potential controls on the distribution of alkylbenzenes.
Firstly, some isomers may be more thermally stable than others, so
maturity-dependent ratios can be configured (TMBI-1, TMBI-2, MEBI-1, TeMBI-x,
TeMBI-y; Table 9a). The Moose-1 samples are not readily separated by thermal
maturity based on these ratios. A second control on alkylbenzene distributions
is biodegradation. Moderate biodegradation of oils has been shown to result in
the preferential retention of 1,2,3-trimethylbenzene and
1,2,3,4-tetramethylbenzene relative to other trimethylbenzene and
tetramethylbenzene isomers (George et al., 2002b). More extensive biodegradation
results in the removal of all alkylbenzenes. Two of the Moose-1 oil show samples
(727 m, 759.5-759.6 m) have alkylbenzene distributions dominated by
1,2,3-trimethylbenzene and/or 1,2,3,4-tetramethylbenzene relative to other
trimethylbenzene and tetramethylbenzene isomers. Furthermore, alkylbenzenes in
the fine-grained samples are also dominated by these two isomers. This is
evidence that the alkylbenzenes in these samples have been affected by
biodegradation.
3.10.3 Alkylnaphthalenes
Alkylnaphthalenes provide information on the thermal maturity, biodegradation
history and source characteristics of the samples analysed.
Biodegradation favours less alkylated isomers, those with ?-substitution
patterns, and those with a 1,6-substitution pattern, whereas aromatic
hydrocarbons with methyl groups on adjacent positions and with greater
alkylation are more resistant to biodegradation (Volkman et al., 1984; Fisher et
al., 1998). There is no evidence that the alkylnaphthalene in any of the samples
from Moose-1 have been affected by biodegradation.
The diesel contains very abundant alkylnaphthalenes (especially C(2) and C(3))
in its aromatic hydrocarbon fraction (Fig. 7). Consequently, oil show samples
that are partially composed of diesel mostly have alkylnaphthalene distributions
that are similar to diesel (Table 9a and b). For example, the DNR-1 of diesel is
4.4, and the oil shows have DNR-1 values of 2.3-5.4, except for oil show sample
727 m which has a higher value (9.6). Therefore, there is little geochemically
meaningful data from alkylnaphthalenes to be derived for the oil shows. Oil show
sample 727 m has consistently more mature MNR, DNR-1, TNR-1 and TNR-2 parameters
than diesel, so it may contain an additional, more mature component, over and
above the diesel that has been identified based on aliphatic distributions.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 52
(CHART)
Figure 8: Cross-plot of the trimethylnaphthalene ratio versus the
tetramethylnaphthalene ratio. The data from the Subu wells are shown as black
dots (from George et al., 2003).
Higher molecular weight alkylnaphthalenes are relatively less abundant in the
diesel, so may be more reliable as maturity indicators (Fig. 8). The
trimethylnaphthalene and tetramethylnaphthalene ratios (Table 9c) for the
fine-grained samples are consistently lower than those of the oil shows, and are
similar to the values for the Subu fine-grained samples. Based on these ratios,
most oil shows are less mature than the diesel or the Aus-Tex, and have similar
mid oil window maturities to many of the solid bitumens from the Subu wells
(Fig. 8). All but one of the samples have 136-TMN/137-TMN ratios (Table 9b)
between 1.1 and 1.6, consistent with the liquid reaction environment (van
Aarssen et al., 2001). This suggests that the fine-grained samples have reached
the oil window, and that the oil shows were generated within it (or are
influenced by diesel which has a value of 1.6). Oil show sample 727 m is the
exception, with high trimethylnaphthalene and tetramethylnaphthalene ratios
(Fig. 8), a high pentamethylnaphthalene ratio, and a high 136-TMN/137-TMN ratio
(1.7). All the
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 53
alkylnaphthalene data suggest that this sample is more mature than the other oil
show samples.
Other alkylnaphthalene ratios provide information on source. The ratio
(1,2,5-TMN/1,3,6-TMN) increases with greater input from higher plants (Strachan
et al., 1988), although clearly this ratio is also influenced by maturity, with
low maturity samples containing greater amounts of 1,2,5-TMN which is a
precursor compound (van Aarssen et al., 1999). The ratio (1,2,7-TMN/1,3,7-TMN)
increases with greater input from angiosperms (Strachan et al., 1988), and thus
is often high in samples with high oleanane. The cross-plot of the logs of these
ratios is shown in Fig. 9, with boundaries on this trimethylnaphthalene graph
taken from Strachan et al. (1988). Both ratios are high for the three
fine-grained samples, reflecting both a likely angiosperm input to these
samples, and also their low maturity. Interestingly, no oleanane was detected in
these samples (see Section 3.8.5). The oil show samples and the diesel have
values for these
(CHART)
Figure 9: Cross-plot of log (1,2,7-TMN/1,3,7-TMN) versus log
(1,2,5-TMN/1,3,6-TMN). The boundaries on this trimethylnaphthalene graph are
taken from Strachan et al. (1988). The data from the Subu wells are shown as
black dots (from George et al., 2003).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 54
two ratios close to the boundary lines, and into the lower left quadrant,
meaning no clear evidence for angiosperm organic matter input.
The higher plant index (HPI) varies from 1.0-4.4 for the fine grained samples,
0.1-0.6 for the oil shows and diesel (Table 9c). The higher values in the fine
grained samples likely reflects increased higher plant contributions compared to
the oil shows. The higher plant fingerprint (varying proportions of retene +
cadalene + IP-iHMN; Table 9c and d) shows that only the fine-grained samples
contain detectable IP-iHMN, and that these samples contain dominantly retene,
not cadalene. Retene is likely to be resin-derived, and this evidence
corroborates the presence of 4?(H)-19-isopimarane and isopimarane in these
samples, which are also resin-derived compounds.
3.10.4 Alkylphenanthrenes
The methylphenanthrene index (MPI-1), the methylphenanthrene distribution
fraction (Fig. 10), the methylphenanthrene ratio and the dimethylphenanthrene
ratio (Fig. 11) are lower for the fine-grained sediments than the oil shows,
suggesting that they have lower thermal maturities (Table 9d and e). The
fine-grained sediments in Moose-1 have similar alkylphenanthrene maturity
indicators as the fine-grained sediments in the Subu wells (George et al.,
2003). Calculated reflectance (Rc) from MPI-1 is 0.60-0.72% for the fine-grained
sediments, suggesting an early oil window maturity.
The alkylphenanthrene ratios of most of the oil shows are somewhat lower than
that of diesel, and very different to that of Aus-Tex (Figs. 10 and 11). The
exception is the 759.5-759.6 m oil show, which has values different to the other
oil shows, trending towards the position of Aus-Tex. This sample is strongly
contaminated by Aus-Tex, and it is likely that the alkylphenanthrene ratios have
been affected by the Aus-Tex. There is no clear sign that other oil show samples
which are known to contain significant amounts of Aus-Tex (686.2 m, and possibly
840 m) have altered alkylphenanthrene distributions. As for the
alkylnaphthalenes, oil show 727 m has the highest maturity of the oil shows.
Calculated reflectance (Rc) from MPI-1 is 0.84% for the 727 m oil show,
suggesting a mid oil window maturity. Other oil shows have calculated
reflectance (Rc) from MPI-1 to as low as 0.73%. These values are less than for
many of the solid bitumens from the Subu wells, which have peak oil window
maturities (0.8-1.1%).
Three alkylphenanthrene ratios can be used to assess the degree of contribution
of coniferous organic matter into a rock, in particular Araucariaceae input
(Alexander et al., 1988). These are 1-MP/9-MP, retene/9-MP and
1,7-DMP/(1,3-+3,9-+2,10-+3,10-DMP) (Table 9d and e). The three fine-grained
samples mostly have values for the logs of these ratios over the threshold
suggested by Alexander et al. (1988). This evidence
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 55
(CHART)
Figure 10: Cross-plot of methylphenanthrene index
(1.5*[3-MP+2-MP]/[P+9-MP+1-MP]) versus methylphenanthrene distribution fraction
((3-MP+2-MP)/ ? MPs). The data from the Subu wells are shown as black dots (from
George et al., 2003).
corroborates the presence of 4?(H)-19-isopimarane and isopimarane in these
samples, which are also resin-derived compounds. All the oil shows have values
for the logs of these ratios below the threshold suggested by Alexander et al.
(1988). This is evidence against any coniferous organic matter input.
Interestingly, oil show sample 809.7 m does have a higher log retene/9-MP ratio
(-0.77) than the other oil shows (although the other ratios are not different to
the other oil shows). This corroborates the significant presence of
4?(H)-19-isopimarane and isopimarane in this sample (see Section 3.8.2).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 56
(CHART)
Figure 11: Cross-plot of methylphenanthrene ratio (2-MP/1-MP) versus
dimethylphenanthrene ratio (3,5-+2,6-DMP+2,7-DMP)/
(1,3-+3,9-+2,10-+3,10-DMP+1,6-+2,9-+2,5-DMP). The data from the Subu wells are
shown as black dots (from George et al., 2003).
3.10.5 Alkylbiphenyls
Alkylbiphenyls provide information about thermal maturity (Alexander et al.,
1986, although these ratios may be only sensitive to variations in the upper
part of the oil window (George and Ahmed, 2002). The methylbiphenyl ratio and
two dimethylbiphenyl ratios (Table 9e and f) are higher for the fine-grained
rocks than the oil shows. This is the complete reverse of what is indicated by
all other maturity parameters. Based on other parameters, the samples from
Moose-2 have maturities in the early to mid oil window, so it is likely that the
alkylbiphenyl ratios are insensitive to maturity variations in this well.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 57
Therefore, as for the Subu work, these ratios are not considered to be effective
tools for this sample set.
3.10.6 Alkyldibenzothiophenes
Alkyldibenzothiophenes can also be used as thermal maturity markers, thus two
ratios (MDR and DMDR) are defined in Table 9f. These ratios were not very useful
for determining thermal maturities in the Subu wells (George et al., 2003), and
the same applies to the Moose-1 samples. The only correlation with other
parameters is that sample 727 m is the most mature of the oil shows, based on
MDR and DMDR. Aus-Tex has an anomalously high MDR, but this is not apparent in
any of the samples suspected to be contaminated by Aus-Tex. Based on a
calibration of MDR to vitrinite reflectance (Radke, 1988), VRE values for the
three fine-grained samples are 0.65-0.73%, which is consistent with other
geochemical ratios.
The relative abundances of dibenzothiophenes to phenanthrene and
1,3,6,7-tetramethylnaphthalene are reported in Table 9f. The three fine-grained
samples have low DBT/P ratios (<0.07) and DBT/1,3,6,7-TeMN ratios (<1.0),
reflecting an overall low sulphur content (Fig. 12). In this respect they are
similar to the Subu fine-grained samples (George et al., 2003). Aus-Tex has a
very high PAH content, and therefore the DBT/P ratio is very low, even though
the overall high relative content of sulphur compounds is reflected by quite a
high DBT/1,3,6,7-TeMN ratio (Fig. 12). No oil show samples trend towards this
composition. Diesel is similar to many of the oil shows, with relatively high
DBT/P ratios (>0.3) and low DBT/1,3,6,7-TeMN ratios. In comparison, all the Subu
data have DBT/P ratios <0.3, and the only oil shows with similar ratios are 727
m and 759.5-759.6 m. It is likely that the sulphur content of diesel is
over-printing these ratios for the oil shows, particularly for samples 675.1 m,
686.2 m, 840 m, as was deduced from the overall high abundance of sulphur
compounds in these samples and in diesel (Fig. 7).
The exception is 809.7 m, which is the least diesel over-printed. The position
of this sample on Fig. 12 is close to that of family B Subu solid bitumens,
providing evidence that this sample has some affinities to the
calcareous-sourced family B Subu solid bitumens, as well as to the
Jurassic-sourced, family A solid bitumens (as was indicated by some of the
hopane and sterane data, and by the terpane data).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 58
(CHART)
Figure 12: Cross-plot of dibenzothiophene/phenanthrene ratio versus
dibenzothiophene/1,3,6,7-TeMN ratio. The data from the Subu wells are shown as
black dots (from George et al., 2003).
3.11 ORGANIC PETROLOGY RESULTS
3.11.1 Sample descriptions and maceral contents
The dominant lithologies of the samples from between 811 m and 971 m are
calcareous siltstones and mudstones, with lesser amounts of sandstone and
claystone (Table 10). Consistent with their marine origin, the samples generally
contain considerable amounts of carbonate and pyrite. The presence of shell
fragments in many samples is also consistent with their marine nature and
numerous samples contain glauconite, which is indicative of a shallow marine
depositional environment (Table 10).
The rocks studied generally contain common to abundant dispersed organic matter
(DOM), which is dominated by liptinite and vitrinite, with lesser amounts of
inertinite
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 59
Table 10: Maceral group compositions, vitrinite reflectance data and
petrographic descriptions for samples from Moose-1 ST1.
DEPTH CSIRO MACERAL GROUP ABUNDANCE MEAN %
(M) SAMPLE NO. RMO
(WHOLE ROCK BASIS)
(* CUTTINGS) LIPTINITE VITRINITE INERTINITE TOTAL
811 55420 <0.1 0.8 0.2 1 1.25
Description: Calcareous siltstone>calcareous mudstone. Rare lamalginite (mo),
rare liptodetrinite (mo). Rare oil droplets (by-bo), generally 1- 3 um in
diameter. Common reworked vitrinite. Rare graphite. Sparse shell fragments. Rare
glauconite. Abundant pyrite (commonly as euhedral crystals up to 0.1 mm in
diameter), common iron oxides.
820 55421 1 0.2 <0.1 1.2 0.63
Description: Calcareous siltstone>sandstone. Rare lamalginite (by-bo), sparse
liptodetrinite (by-mo), sparse sporinite (my-mo), rare cutinite (mo), rare
resinite (mo-mb), rare suberinite (mb). Rare vitrinite fluoresces do-mb.
Sparse oil droplets (by-my), including fluid inclusions, generally 1-3 um in
diameter. Rare bitumen (mo). Sparse reworked vitrinite. Rare graphite. Rare
shell fragments. Sparse glauconite. Sparse reworked rock fragments. Abundant
pyrite, common iron oxides.
861 55422 2 2 0.3 4.3 0.68
Description: Siltstone. Common lamalginite (by-my), common liptodetrinite
(my-mo), sparse sporinite (mo), rare cutinite (mo), rare resinite (mo), rare
suberinite (mb). Rare vitrinite fluoresces do-mb. Rare oil droplets (my), mostly
as fluid inclusions, generally 1-3 um in diameter. Sparse reworked vitrinite.
Rare graphite. Abundant fluorescing carbonate grains. Common pyrite, common iron
oxides.
870 55423 3 0.2 <0.1 3.2 0.63
Description: Calcareous siltstone>mudstone>sandstone. Common lamalginite (by-
bo), common liptodetrinite (by- mo), sparse sporinite (mo), rare cutinite (mo),
rare resinite (mb). Rare vitrinite fluoresces mb. Rare oil droplets (by), mainly
as fluid inclusions, generally 1-2 um in diameter. Sparse reworked vitrinite.
Rare graphite. Rare shell fragments. Common pyrite, common iron oxides.
880 55424 1 1 0.5 2.5 0.65
Description: Calcareous mudstone>calcareous siltstone. Sparse lamalginite
(my-bo), common liptodetrinite (my-mo), sparse sporinite (mo-do), rare cutinite
(mo-do), rare resinite (mb). Rare vitrinite fluoresces mb. Common reworked
vitrinite. Sparse shell fragments. Rare glauconite. Common pyrite, common iron
oxides.
890 55425 1 1.5 0.5 3 0.69
Description: Calcareous mudstone=calcareous siltstone>sandstone. Sparse
lamalginite (my-bo), common liptodetrinite (my-mo), rare cutinite (mo-do), rare
resinite (do), rare suberinite (mb). Rare vitrinite fluoresces db. Rare oil
droplets (by), including fluid inclusions, generally 1-2 um in diameter. Common
reworked vitrinite. Rare graphite. Sparse shell fragments. Rare glauconite.
Common pyrite, common iron oxides.
901 55426 0.1 <0.1 0.1 0.2 0.69
Description: Calcareous siltstone>calcareous sandstone. Rare lamalginite (my-
mo), rare liptodetrinite (my-mo), rare cutinite (mo), rare sporinite (mo).
Rare vitrinite fluoresces db. Rare oil droplets (by), including fluid
inclusions, generally 1-2 um in diameter. Sparse reworked vitrinite. Rare
graphite. Sparse glauconite. Sparse pyrite, common iron oxides.
Continued......
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 60
Table 10 continued: Maceral group compositions, vitrinite reflectance data and
petrographic descriptions for samples from Moose-1 ST1.
DEPTH CSIRO MACERAL GROUP ABUNDANCE MEAN %
(M) SAMPLE NO. RMO
(WHOLE ROCK BASIS)
(* CUTTINGS) LIPTINITE VITRINITE INERTINITE TOTAL
909 55427 3 1 0.5 4.5 0.68
Description: Mudstone>siltstone. Common lamalginite (my-bo), common
liptodetrinite (my-mo), rare cutinite (mo-do), rare resinite (mo-mb). Rare
vitrinite fluoresces mb. Rare oil droplets (by) generally 1-3 um in diameter.
Sparse reworked vitrinite. Abundant fluorescing carbonate grains. Rare shell
fragments. Abundant pyrite, common iron oxides.
920 55428 1 0.5 0.5 2 0.64
Description: Calcareous mudstone>calcareous siltstone>sandstone. Common
lamalginite, including Veryhachium (my-mo), common liptodetrinite (my-mo), rare
cutinite (mo), rare sporinite (mo). Rare vitrinite fluoresces db. Rare bitumen
(mo). Sparse reworked vitrinite. Rare graphite. Sparse shell fragments. Common
pyrite, common iron oxides.
930 55429 1 0.3 1 2.3 0.65
Description: Calcareous mudstone>calcareous siltstone. Sparse lamalginite
(my-mo), common liptodetrinite (my-mo), rare cutinite (mo), sparse sporinite
(mo). Rare vitrinite fluoresces db. Rare reworked vitrinite. Rare graphite.
Sparse shell fragments. Common pyrite, common iron oxides.
937 55430 1 0.4 1 2.4 0.65
Description: Calcareous mudstone. Common lamalginite (my-mo), common
liptodetrinite (my-mo), rare cutinite (mo), rare sporinite (mo). Rare vitrinite
fluoresces db. Rare oil droplets (by), including fluid inclusions, generally 1-2
um in diameter. Sparse reworked vitrinite. Rare glauconite. Sparse shell
fragments. Common pyrite, common iron oxides.
950 55431 1 <0.1 1 2 0.64
Description: Calcareous mudstone>claystone. Common lamalginite (my-mo), common
liptodetrinite (my-mo), rare sporinite (mo). Rare vitrinite fluoresces db. Rare
reworked vitrinite. Rare shell fragments. Common pyrite, common iron oxides.
960 55432 1 0.1 1 2.1 0.63
Description: Calcareous mudstone>>calcareous siltstone. Common lamalginite
(my-mo), common liptodetrinite (my-mo), rare cutinite (do), rare sporinite (mo).
Rare vitrinite fluoresces mb. Rare reworked vitrinite. Rare glauconite. Sparse
shell fragments. Common pyrite, common iron oxides.
969.5 55433* 1 0.5 0.5 2 0.66
Description: Calcareous mudstone>>calcareous siltstone. Sparse lamalginite
(my-mo), common liptodetrinite (my-mo), rare suberinite (mo), sparse sporinite
(mo). Rare vitrinite fluoresces mb. Sparse reworked vitrinite. Rare graphite.
Rare glauconite. Sparse shell fragments. Common pyrite, abundant iron oxides.
Key: All samples core except where noted with an * (969.5 m is the cuttings
interval from 968-971 m).
- -Rmo%- mean vitrinite reflectance value taken on randomly oriented phytoclasts,
in nonpolarised light
- -rare: <0.1%; sparse: 0.1-0.5%; common: >0.5-2%; abundant: >2-10%.
- -fluorescence colours designated as, b- bright; m- moderate; d- dull; y- yellow;
o- orange; g- green; b- brown; nf- non-fluorescing.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 61
(Table 10; Appendix S). Reworked vitrinite, which has higher reflectances than
the indigenous vitrinite and is commonly characterised by blocky form, cracks
and extensive pyritisation, is widespread through the studied section. Liptinite
ranges from rare to abundant and mainly comprises lamalginite derived from
dinoflagellate/acritarch cysts, along with associated liptodetrinite although
higher plant-derived liptinite, including sporinite, cutinite and subcrinite is
also present in most of the rocks. Some of the terrestrially-derived liptinite
occurs within reworked coaly grains.
Small oil droplets (1-3um in diameter) have been identified in numerous
samples and include fluid inclusions as well as trace amounts of `free oil'
occurring between mineral grains. On the basis of the maceral contents of the
samples studied, in particular liptinite contents, the original oil generation
potential of the section ranges from poor to very good.
3.11.2 Thermal maturity: FAMM and vitrinite reflectance analyses
FAMM analyses have been carried out on three samples from the studied section
and vitrinite reflectance (VR) data are available for all samples (Table 11:
Appendix S). The quality of these analyses depends upon the total OM content as
well as on maceral content and maceral characteristics. Because vitrinite is
generally sparse to common in the rocks studied, confidence in the results is
high. Some samples are complicated by the presence of reworked populations of
organic matter but this material has been delineated where possible, such that
confidence in the results remains good. In some cases however delineation of the
reworked macerals is not straightforward and at least some measurements may be
from this population. In particular, vitrinite in the sample from 811 m is
dominated by a reworked population and has anomalously high VR values; the
readings may include measurements from reworked vitrinite.
With the exception of the sample from 811 m, the VR data are similar for all
samples studied, ranging from 0.63%-0.69%. The FAMM-derived equivalent vitrinite
reflectance (EqVR) values, however, are about 0.9% and the vitrinite plots in
the `perhydrous field' of the FAMM diagram, such that considerable VR
suppression is expected.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 62
Table 11: FAMM-derived equivalent vitrinite reflectance (EqVR) and measured
vitrinite reflectance (VR) data for samples from Moose-1 ST1.
SAMPLE EqVR DATA VR DATA
- ------------------------- --------------------------------- ------------------------------------------
CSIRO EqVR RANGE (1)VR
DEPTH (m) SAMPLE NO. (%) (%) SUPPRESSION RM(0) RANGE (%) n ?
- --------- ---------- ----- ---------- ----------- ----- ----------- --- ----
811 55420 1.25 1.05-1.36 27 0.07
820 55421 0.63 0.52-0.78 26 0.07
861 55422 0.93 0.87-1.00 severe 0.68 0.54-0.80 41 0.07
870 55423 0.63 0.53-0.74 26 0.07
880 55424 0.65 0.53-0.80 31 0.07
890 55425 0.69 0.56-0.80 32 0.07
901 55426 0.69 0.58-0.80 14 0.06
909 55427 0.92 0.84-0.98 severe 0.68 0.56-0.80 32 0.07
920 55428 0.64 0.56-0.74 29 0.06
930 55429 0.65 0.57-0.76 30 0.06
937 55430 0.66 0.54-0.78 32 0.06
950 55431 0.64 0.52-0.76 17 0.07
960 55432 0.63 0.52-0.70 25 0.05
969.5 55433* 0.91 0.83-1.00 severe 0.66 0.54-0.76 30 0.06
All samples core except where noted with an * (969.5 m is the cuttings interval
from 968-971 m).
EqVR = FAMM-derived equivalent vitrinite reflectance calibrated against Rm(o)%.
Rm(o)% = Mean vitrinite reflectance measured under oil immersion on randomly
oriented phytoclasts in nonpolarised light.
n = Number of vitrinite reflectance readings; ? = standard deviation.
Readings taken from dispersed organic matter (DOM).
The ranges in EqVR are based on plotted positions of vitrinite data in relation
to iso-EqVR lines on the FAMM diagrams
(1) The degree of vitrinite reflectance suppression/enhancement is based on the
position of the vitrinite data points in relation to iso-correction curves
superimposed on the fluorescence alteration diagram; minimal (0.0-0.1%),
moderate (>0.1-0.2%) and severe (>0.2%); enhancement shown in parentheses n/a =
not available
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 63
Important insights into the quality and consistency of the data set can be made
from a comparison of EqVR and VR values, with consideration of the interpreted
corrections to VR on the basis of the iso-correction curves presented in Fig.
1a. The average plotted position of the vitrinites on the FAMM diagrams indicate
VR suppression of slightly >0.2%. Where the corrections are applied, the EqVR
values for the samples are in general agreement with the VR values, both for the
`spot' measurements (Appendix R) and the average values, although the EqVR
values are slightly higher than the `corrected' VR values in some instances. As
mentioned above, the corrected VR values are approximate and are simply used to
for cross-checking the data; the EqVR values are used to give the thermal
maturity level. Because of the general agreement in the two determinations, a
high degree of confidence exists for both the VR and FAMM data.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 64
4 INTERPRETATION AND SYNTHESIS
4.1 THE FINE-GRAINED ROCKS IN MOOSE-1ST1
4.1.1 Source potential
The low TOC values (<1.2%) and the low hydrogen indices (mostly <155 mg/g)
indicate type III organic matter, with low hydrocarbon generation potential.
This organic matter type is supported by the molecular geochemistry, which
indicate a marine depositional environment with major terrestrial organic matter
input.
One Moose-1ST1 sample (811 m) has a very small S(2) peak, despite a TOC content
of 1.1%, indicating that most of the organic carbon in this sample is refractory
and non-generative. The thermal maturity of this sample may be considerably
greater than the other samples (see Section 4.1.3), indicating that any source
potential has been exhausted. One sample (968-971 m) has a higher hydrogen index
2(17 mg/g), but a moderate TOC (1.1%). This is the most prospective sample,
although based on the Rock-Eval data alone it cannot be considered to be a
potential effective source rock. Note that the fine-grained rocks at Moose-1ST1
have better source potential than the fine-grained rocks at the Subu wells
(George et al., 2003), which have very poor oil generating potential.
On the basis of the maceral contents of the samples studied, in particular the
liptinite contents, the original oil generation potential of the section studied
ranges from poor to very good. This is better than is apparent from the
Rock-Eval results, probably because of the diluting effect of inertinite on
hydrogen indices, and also the maturity level that this sequence has reached
(peak oil window, see Section 4.1.3), resulting in oil generation and reduction
of the residual hydrogen indices.
4.1.2 Source characteristics
A marine depositional environment is indicated by the C(30)/(C(27)+C(28)+C(29))
? ? ? 20R ratios >4, and by the presence of glauconite and lamalginite derived
from dinoflagellate/acritarch cysts (Section 3.11.1). However, major terrestrial
input to this setting is indicated by the common occurrence of higher
plant-derived macerals such as vitrinite, by the slight odd predominance of the
n-alkanes, by two high tricyclic terpane ratios [C(24) tetracyclic
terpane/(C(24) tetracyclic terpane + C(23) tricyclic terpane) and C(19)
tricyclic terpane/(C(19) tricyclic terpane + C(23) tricyclic terpane)], and by
the high higher plant index. There are indications of a coniferous organic
matter component in this mix, notably the presence of relatively high amounts of
retene, 1,7-dimethylphenanthrene, 1-
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 65
methylphenanthrene, 4?(H)-19-isopimarane and isopimarane in these samples,
which are resin-derived compounds. This correlates with the presence of minor
amounts of resinous material in samples 820 m and 968-971 m (Table 10). This
resinous material may be reworked from the Jurassic. The sulphur content was
low. The depositional environment was oxic, as indicated by high Pr/Ph ratios
and low C(35)??C(35) + C(34)) homohopane ratios. In these respects, the
fine-grained samples from Moose-1ST1 have many similarities to the
non-overprinted fine-grained samples from the Subu wells (George et al., 2003).
This is also partly indicated by source-correlation diagrams (Figs. 13-15).
The presence of small amounts of C(26) steranes in the clastics below the Mendi
Formation limestones (below 810m) from Moose-1ST1 enables a degree of age
control to be suggested. The fine-grained rocks in Moose-1ST1 have NDR ratios
varying between 0.37-0.41, and NCR ratios varying between 0.37-0.5. These values
are consistent with Cretaceous or younger ages for these strata (Holba et al.,
1998a, b).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 66
- - Subu fine-grained samples - Bujon-1 1476m FIO - Hovare oil seep
- - Subu family 2 solid bitumens - Barune Sandstone FIO - Chim oil seep
- - Subu family 3 solid bitumens - Koko-1 1162m FIO - Gobe 3X DST3 crude oil
- - Ouha anticline bitumen, CN746 - Koko-1 1163m RFT crude oil - Omati-1 crude oil
- - Subu FIO, CN392 - Kimu-1 1873-79m FIO - Angore-1A crude oil
- - Subu rod grease contaminant, CN679 - Aure Thrust Belt oil seeps - Moose-1ST1 oil shows
- - Puri-1 crude oil - Aure Scarp oil stained rocks - Moose-1ST1 fine grained rocks
- - Bwata-1 condensate - Lufa oil seep - Moose-1 diesel
- - Iagifu, Hedinia and P'nyang FIOs - Puri anticline oil seep - Moose-1 Aus-Tex
- - Iagifu DST crude oils
[CHART]
Figure 13: Cross-plot of C(29) Ts/C(29) ?? hopane versus C(30)*/C(30) ?? hopane
for the samples from this project compared to literature and unpublished data.
Solid symbols are analyses carried out at the CSIRO laboratory. Open symbols are
analyses derived from literature data, some of which were derived from
ruler-measured peak heights from published chromatograms and thus are subject to
inaccuracies. Black symbols are samples in this report from the Moose-1 and
Moose-1ST1 well.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 67
- - Subu fine-grained samples - Bujon-1 1476m FIO Hovare oil seep
- - Subu family 2 solid bitumens - Barune Sandstone FIO - Chim oil seep
- - Subu family 3 solid bitumens - Koko-1 1162m FIO - Gobe 3X DST3 crude oil
- - Ouha anticline bitumen, CN746 - Koko-1 1163m RFT crude oil - Omati-1 crude oil
- - Subu FIO, CN392 - Kimu-1 1873-79m FIO - Angore-1A crude oil
- - Subu rod grease contaminant, CN679 - Aure Thrust Belt oil seeps - Moose-1ST1 oil shows
- - Puri-1 crude oil - Aure Scarp oil stained rocks - Moose-1ST1 fine grained rocks
- - Bwata-1 condensate - Lufa oil seep - Moose-1 diesel
- - Iagifu, Hedinia and P'nyang FIOs - Puri anticline oil seep - Moose-1 Aus-Tex
- - Iagifu DST crude oils
[CHART]
Figure 14: Cross-plot of C(29) ?? hopane/C(30) ?? hopane versus C(31) ??
hopane/C(30) ? ? hopane ratios for the samples from this project compared to
literature and unpublished data. Solid symbols are analyses carried out at the
CSIRO laboratory. Open symbols are analyses derived from literature data, some
of which were derived from ruler-measured peak heights from published
chromatograms and thus are subject to inaccuracies. Black symbols are samples in
this report from the Moose-1 and Moose-1ST1 well.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 68
- - Subu fine-grained samples - Bujon-1 1476m FIO - Hovare oil seep
- - Subu family 2 solid bitumens - Barune Sandstone FIO - Chim oil seep
- - Subu family 3 solid bitumens - Koko-1 1162m FIO - Gobe 3X DST3 crude oil
- - Ouha anticline bitumen, CN746 - Koko-1 1163m RFT crude oil - Omati-1 crude oil
- - Subu FIO, CN392 - Kimu-1 1873-79m FIO - Angore-1A crude oil
- - Subu rod grease contaminant, CN679 - Aure Thrust Belt oil seeps - Moose-1ST1 oil shows
- - Puri-1 crude oil - Aure Scarp oil stained rocks - Moose-1ST1 fine grained rocks
- - Bwata-1 condensate - Lufa oil seep - Moose-1 diesel
- - Iagifu, Hedinia and P'nyang FIOs - Puri anticline oil seep - Moose-1 Aus-Tex
- - Iagifu DST crude oils
[CHART]
Figure 15: Cross-plot of Pr/Ph versus C(35)??C(35) + C(34) homohopane ratios for
the samples from this project compared to Subu well, literature and unpublished
data. Solid symbols are analyses carried out at the CSIRO laboratory. Open
symbols are analyses derived from literature data, some of which were derived
from ruler-measured peak heights from published chromatograms and thus are
subject to inaccuracies. Black symbols are samples in this report from the
Moose-1 and Moose-1ST1 well.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 69
4.1.3 Thermal maturity characteristics
It is possible to assign vitrinite reflectance (VR) boundaries as a general
guide to the level of OM thermal maturity for petroleum generation. Based on the
generally accepted values that appear in the literature, the following VR
boundaries are used:
VR RANGE TYPE OF PETROLEUM GENERATION
- -------- ----------------------------
0.50% Immature with respect to petroleum generation
0.50-0.70% Early stages of thermal maturity for petroleum generation
0.70-1.00% Main stage of oil generation
1.00-1.35% Late stage of oil generation/condensate
1.35-2.00% Wet Gas and methane
2.00% Dry gas only
With the exception of the sample from 811 m, the mean VR for the section studied
ranges from about 0.6% to about 0.7%, indicating early maturity. Largely due to
the limited extent of the sequence analysed, a systematic increase of thermal
maturity with depth is not evident and the sequence is essentially
isometamorphic. The anomalously high maturity indicated for the uppermost sample
(VR of 1.25%) may be due to overthrusting, localised thermal effects from
igneous activity and associated hydrothermal fluids, or, as mentioned above,
complicating effects of reworked material. The FAMM-derived equivalent vitrinite
reflectance (EqVR) indicates that the measured VR considerably underestimates
thermal maturity and that the section studied is within the main zone of oil
generation (about 0.9% EqVR). The perhydrous vitrinite compositions that lead to
VR suppression are likely to be controlled by a combination of the precursor
plant types/plant parts and the Eh/pH conditions of the depositional
environments. Vitrinite reflectance suppression is commonly associated with
sediments from marine or marine-influenced depositional environments (e.g.
Wilkins et al., 1992) and therefore the VR suppression determined in the present
study is not unexpected.
Rock-Eval T (max) data for the fine-grained samples from Moose-1ST1 mostly vary
from 442-448(DEGREE)C, corresponding to a vitrinite reflectance of ca. 0.7-0.9%
when applying a correlation for type III organic matter established by
Teichmuller and Durand (1982).
The molecular geochemical data indicate that the fine-grained samples from
Moose-1ST1 have lower thermal maturities than the oil shows. This is consistent
with the oil shows not being derived from the fine-grained samples in
Moose-1ST1. Parameters that show this maturity difference include Ts/Tm, hopane
????????? ) ratios, sterane maturity-dependent ratios [(20S/(20S+20R), ?????? ?
? ? ? ? ? ?], trimethylnaphthalene ratios,
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 70
tetramethylnaphthalene ratios, and alkylphenanthrene ratios. Note also that most
source parameters also clearly distinguish the fine-grained samples in
Moose-1ST1 from the oil shows in Moose-1ST1, and these parameters are for the
most part not masked by the overprinting effects of diesel and Aus-Tex. These
ratios also show that the fine-grained samples from Moose-1ST1 are slightly more
mature than the fine-grained samples from the Subu wells (e.g. see Fig. 16).
Establishing an absolute maturity from geochemical parameters is more difficult
than the relative maturities described above, as this relies on calibrations
which may or may not be applicable. Vitrinite reflectance equivalent (VRE) from
the C(29) 20S/20R ratio (Sofer et al., 1993) is 0.71-0.84% for the three
samples. VRE values from the methylphenanthrene index (MPI-1; 0.60-0.72%; Radke
and Welte, 1983) are similar to those from the methyldibenzothiophene ratio
(0.65-0.73%; Radke, 1988), but are lower than the values from the
methylphenanthrene ratios (0.72-0.85%; Radke et al., 1984).
Care has to be exercised in the application of any of these calibrations, as
they may not be directly applicable to the type of kerogen in these rocks, or to
basins other than the ones they were originally calibrated on. For example, it
is known that the MPI-1 gives inaccurate results for marine source rocks
containing type II kerogen (Radke et al., 1986).
A different approach for interpreting geochemical maturity ratios is to compare
the various maturity indicators with sequences with known thermal maturities.
This has been carried out for the Proterozoic middle Velkerri member (George and
Ahmed, 2002), and this provides a convenient calibration set, with wells known
to have maturities in the early oil window (Walton-2), the peak oil window
(Shea-1) and the late oil window (McManus-1). For the fine-grained samples in
Moose-1ST1, the DNR-1, TNR-2 and DMPR values are similar to those in Shea-1,
indicating a peak oil window maturity. The MPI-1, MPDF, MPR are similar to those
in Walton-2, indicating an early to peak oil window maturity. The TMNr, TeMNr
and PMNr values are very low (0.1-0.25), indicative of early oil window
maturities (van Aarssen et al., 1999; George and Ahmed, 2002). However, these
latter three ratios may have been influenced by the large proportion of
terrestrial organic matter in these samples.
In summary, the molecular geochemical data for the fine-grained samples from
Moose-1ST1 provides somewhat variable absolute maturities, although these are
undoubtedly less than that of the oil shows in the overlying limestone. On the
basis of the geochemical data, the best estimate of their thermal maturity is
about 0.7-0.8% (mid oil window), which is consistent with the Rock Eval data but
is somewhat lower than the equivalent vitrinite reflectance data from FAMM
(about 0.9%). Undoubtedly, the
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 71
- - Subu fine-grained samples - Bujon-1 1476m FIO - Hovare oil seep
- - Subu family 2 solid bitumens - Barune Sandstone FIO - Chim oil seep
- - Subu family 3 solid bitumens - Koko-1 1162m FIO - Gobe 3X DST3 crude oil
- - Ouha anticline bitumen, CN746 - Koko-1 1163m RFT crude oil - Omati-1 crude oil
- - Subu FIO, CN392 - Kimu-1 1873-79m FIO - Angore-1A crude oil
- - Subu rod grease contaminant, CN679 - Aure Thrust Belt oil seeps - Moose-1ST1 oil shows
- - Puri-1 crude oil - Aure Scarp oil stained rocks - Moose-1ST1 fine grained rocks
- - Bwata-1 condensate - Lufa oil seep - Moose-1 diesel
- - Iagifu, Hedinia and P'nyang FIOs - Puri anticline oil seep - Moose-1 Aus-Tex
- - Iagifu DST crude oils
[CHART]
Figure 16: Cross-plot of C(29) sterane ? ? ? 20S/(20S+20R) versus C(29) sterane
?????? ? ? ? ? ? ? ? for the samples from this project compared to literature
and unpublished data. Solid symbols are analyses carried out at the CSIRO
laboratory. Open symbols are analyses derived from literature data, some of
which were derived from ruler-measured peak heights from published chromatograms
and thus are subject to inaccuracies.
measured vitrinite reflectance values (0.65-0.70%) have been significantly
suppressed, by at least 0.2%. FAMM and VR analyses of additional samples from
above 811 m and from below 971 m would enable a thermal maturity profile to be
established for the Moose-1 sequence and would better constrain the maturity
evaluation for the sample from 811 m.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 72
4.2 OVERPRINTING OF OIL SHOWS BY DIESEL, AUS-TEX AND GREASE
The main issue to consider regarding the observed oil shows in the limestone in
Moose-1 is whether and by how much their identity and their geochemistry has
been influenced by wellbore contaminants, specifically the diesel and the
Aus-Tex which have been analysed in detail in this report, and to some extent
the pipe grease and the grease from the grease gun. To this end, in this Section
the geochemical distinguishing features of each contaminant are briefly
summarised (Sections 4.2.1 to 4.2.3). Then, each oil show is considered in turn,
with respect to how much its geochemical composition has been altered by the
contaminants (Sections 4.2.4 to 4.2.10).
4.2.1 Diesel (Appendices J and K)
Two samples of the diesel, from the line and the tank, were analysed. These have
similar n-alkane compositions, so only the tank diesel sample was analysed in
detail.
The diesel is aliphatic rich (85%), is dominated by n-alkanes (n-C(8) to
n-C(25), maxima n-C(16)), and has an aromatic fraction dominated by
alkylnaphthalenes, alkylphenanthrenes and alkyldibenzothiophenes. It contains
only a minor UCM hump. The pattern of branched and cyclic alkanes in the diesel
is characteristic and was useful for correlating the diesel with oil shows (Fig.
4). Many oil shows have similar n-alkanes and branched and cyclic alkane
distributions as the diesel. The diesel has a higher Pr/Ph ratio than many of
the oil shows, and a maturity based on aromatic hydrocarbons in the peak oil
window. Sulphur compounds in the diesel have strongly influenced the sulphur
compound distribution in several of the oil shows. The diesel contains abundant
tricyclic terpanes, a small amount of isopimarane but no other diterpanes, and
highly unusual hopane, sterane and diasterane distributions, which are skewed
heavily in favour of the low molecular weight homologues. These hopane, sterane
and diasterane distributions are unlike any found in the oil shows. Some of the
diesel biomarker ratios (e.g. Ts/Tm, drimane/homodrimane) are clearly distinct
from the oil shows. Furthermore, the diesel does not contain some biomarkers
that are present in all the oil shows, for example methylhopanes and
4?(H)-19-isopimarane. For these reasons, it can be concluded that most of the
biomarkers in the oil shows are not derived from the diesel.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 73
4.2.2 Aus-Tex (Appendix L)
This drilling additive has a substantially different n-alkane distribution to
the diesel and the oil shows. The Aus-Tex has an n-alkane maxima at n-C(28), a
different UCM profile, and is characterised by unusually high abundances of some
PAH (phenanthrene, fluoranthene, pyrene, chrysene, benzofluoranthene,
benzopyrene, and dibenzochrysene, and related isomers). These PAH serve as a
very useful marker for a contribution of Aus-Tex to the oil shows. The Aus-Tex
contains a small amount of isopimarane but no 4?(H)-19-isopimarane, and contains
significant amounts of C(28) and C(29) tricyclic terpanes and gammacerane, and
traces of 3?-methylhopanes. Aus-Tex contains unusual sterane distributions,
strongly dominated by the ? ? ? R isomers. In other respects, the compounds
present in the oil shows (e.g. hopanes, steranes, aromatic hydrocarbons) are
also usually present in Aus-Tex, albeit sometimes in different distributions.
Therefore, if the presence of PAH in an oil show indicates a likely Aus-Tex
contribution, then great care has to be exercised with many molecular
parameters, as these are very likely influenced by the Aus-Tex. This is clearly
the case for oil show sample 759.5 m, which is strongly overprinted by Aus-Tex,
and for which alkylphenanthrene ratios trend towards the position of Aus-Tex
(Figs. 10 and 11).
4.2.3 Grease samples: Pipe Dope and Grease Gun (Appendices M and N)
These grease samples were not analysed in detail, as they both consist mainly of
a very prominent UCM hump. Most oil show samples do not contain a large UCM
hump. The only exception is sample 727 m, which does have a significant UCM and
therefore potentially could be overprinted by a grease.
4.2.4 Moose-1 530 m, open hole slurry sample (Appendix B)
This sample has a very similar n-alkane distribution to the diesel. It has a
larger UCM hump than diesel, indicating that it has undergone a phase of
biodegradation. It contains no evidence of any overprinting by Aus-Tex or
grease. Alkylnaphthalene and alkylphenanthrene maturity parameters indicate a
lower maturity than the diesel, and a higher maturity than the fine-grained
rocks. It contains a more complete series of biomarkers than the diesel, and
these have a different distribution. This indicates that a portion of this open
hole slurry sample is derived from a natural oil show, particularly higher
molecular weight compounds (>C(27)). Therefore, these compounds can be used with
caution to type the natural portion of this oil show. Other parameters are
likely to be
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 74
partially or completely compromised by the interpreted overprinting of this oil
show by diesel.
4.2.5 Moose-1ST1, 675.1 m, core (Appendix C)
This sample has a very similar n-alkane distribution to the diesel. The pattern
of branched and cyclic alkanes in this sample is very similar to that of diesel.
It contains no evidence of any overprinting by Aus-Tex or grease.
Alkylnaphthalene and alkylphenanthrene maturity parameters indicate a lower
maturity than the diesel, and a higher maturity than the fine-grained rocks. It
contains a more complete series of biomarkers than the diesel, and these have a
different distribution. This indicates that a portion of the extractable organic
matter in this core is derived from a natural oil show, particularly higher
molecular weight compounds (>C(27)). Therefore, these compounds can be used with
caution to type the natural portion of this oil show. Other parameters are
likely to be partially or completely compromised by the interpreted overprinting
of this oil show by diesel.
4.2.6 Moose-1ST1, 686.2 m, core (Appendices D and E)
This sample has a very similar n-alkane distribution to the diesel. Most of the
extract resides deep within the limestone matrix, rather than in the open
porosity and on any fracture surfaces. The pattern of branched and cyclic
alkanes in this sample is very similar to that of diesel. It contains no
evidence of overprinting by grease. However, the presence of substantial amounts
of PAH indicate that is has been overprinted by Aus-Tex. Other effects of the
Aus-Tex overprinting of this sample are the higher relative abundances of ? ? ?
R steranes and gammacerane in this sample. Alkylnaphthalene and
alkylphenanthrene maturity parameters indicate a lower maturity than the diesel,
and a higher maturity than the fine-grained rocks. It contains a more complete
series of biomarkers than the diesel, and these have a different distribution.
However, the biomarkers in this sample have been affected by the overprinted by
Aus-Tex, so it is recommended that these are not used to help type the natural
portion of this oil show.
4.2.7 Moose-1ST1,727 m, oil mixed with water (Appendix F)
This sample has a very similar n-alkane distribution to the diesel, but also
contains a large UCM hump. The pattern of branched and cyclic alkanes in this
sample is similar to that of diesel. The UCM hump could be the product of
biodegradation of a natural oil
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 75
show, but it also has similarities to the grease samples. Therefore, care has to
be exercised in the interpretation of this sample, as biomarkers may be derived
from grease, or from a natural oil show. It contains no evidence of any
overprinting by Aus-Tex. Alkylnaphthalene and alkylphenanthrene maturity
parameters indicate a similar maturity as the diesel, and a higher maturity than
the fine-grained rocks. It contains a more complete series of biomarkers than
the diesel, and these have a different distribution. This indicates that a
portion of the extractable organic matter in this core may be derived from a
natural biodegraded oil show, particularly higher molecular weight compounds
(>C(27)). Therefore, these compounds can be used with caution (because of the
possibility of grease overprinting) to type the natural portion of this oil
show. Other parameters are likely to be partially or completely compromised by
the interpreted overprinting of this oil show by diesel.
4.2.8 Moose-1ST1, 759.5 m, core (Appendix G)
This sample has a very similar n-alkane distribution to the diesel. The pattern
of branched and cyclic alkanes in this sample is very similar to that of diesel.
It contains no evidence of overprinting by grease. However, the presence of
substantial amounts of PAH indicate that is has been overprinted by Aus-Tex.
Other effects of the Aus-Tex overprinting of this sample are the higher relative
abundances of ? ? ? R steranes and gammacerane in this sample, and a trend of
alkylphenanthrene parameters towards the Aus-Tex composition (Figs. 10 and 11).
Alkylnaphthalene maturity parameters indicate a lower maturity than the diesel,
and a higher maturity than the fine-grained rocks. It contains a more complete
series of biomarkers than the diesel, and these have a different distribution.
However, the biomarkers in this sample have been affected by the overprinted by
Aus-Tex, so it is recommended that these are not used to help type the natural
portion of this oil show.
4.2.9 Moose-1ST1, 809.7 m, core (Appendix H)
This sample has a different n-alkane distribution to the diesel, and the pattern
of branched and cyclic alkanes is different to that of diesel. Aromatic
hydrocarbons in this sample are dominated by alkylphenanthrenes and biphenyl,
and thus it has a very different composition compared to diesel and the other
oil shows. Therefore, this oil show sample is regarded as the most natural and
pristine from Moose-1 ST1, and it appears to have not been overprinted
significantly by diesel. It also contains no evidence of any overprinting by
Aus-Tex or grease. Alkylnaphthalene and alkylphenanthrene maturity parameters
indicate a similar maturity as the diesel, and a higher maturity than the
fine-grained rocks
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 76
and the other oil shows. In this respect, these aromatic hydrocarbons may be
dominantly derived from diesel and not from the natural oil show. It contains a
more complete series of biomarkers than the diesel, and these have a different
distribution. This indicates that the hydrocarbon distributions in this sample
are the best for determining the origin and characteristics of the natural oil
shows in Moose-1 ST1.
4.2.10 Moose-1ST1, 840 m, fluid sample (Appendix I)
This sample has a very similar n-alkane distribution to the diesel. The pattern
of branched and cyclic alkanes in this sample is very similar to that of diesel.
It contains no evidence of any overprinting by Aus-Tex or grease.
Alkylnaphthalene and alkylphenanthrene maturity parameters indicate a lower
maturity than the diesel, and a higher maturity than the fine-grained rocks. It
contains a more complete series of biomarkers than the diesel, and these have a
different distribution. This indicates that a portion of the extractable organic
matter in this core is derived from a natural oil show, particularly higher
molecular weight compounds (>C(27)). Therefore, these compounds can be used with
caution to type the natural portion of this oil show. Other parameters are
likely to be partially or completely compromised by the interpreted overprinting
of this oil show by diesel.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 77
4.3 THE SOURCE OF THE NATURAL COMPONENT OF THE OIL SHOWS AT MOOSE-1 AND
MOOSE-1ST1
Two distinct source signatures that are not related to any wellbore overprinting
can be distinguished in the Moose-1 and Moose-1 ST1 oil shows. The oil shows
that were used to make this assessment are: 530 m, 675.1 m, 727 m, 809.7 m, and
840 m.
4.3.1 "Calcareous" source signature
Four of these five oil shows (not 809.7 m) have a dominant source signature that
is similar to that exhibited by the Family B solid bitumens and the fluid
inclusion oil in the Subu wells (George et al., 2003). The "Family B" solid
bitumens were ascribed to having an origin from a calcareous source with a high
proportion of prokaryotic and a low proportion of terrestrial organic matter
input. The characteristics of the four Moose-1 and Moose-1 ST1 oil shows that
lead to this correlation are:
1. The high relative abundance of 2? - methylhopanes (Section 3.8.4),
2. The high relative abundance of 30-norhopanes (Section 3.8.5),
3. The high C(29) /C(30) ?? hopane ratios (Section 3.8.5),
4. The low content of rearranged hopanes and diasteranes, including low Ts/Tm,
C(29)Ts/C(29) ?? hopane, C(30)*/C(30) ?? hopane and diasterane /sterane ratios
(Sections 3.8.5 and 3.8.6), and
5. The lack of a significant terrestrial signature in the terpanes, diterpanes,
or aromatic hydrocarbons.
Note that some of these characteristics could be inherited from diesel
overprinting, for example some 30-norhopanes are present in the diesel. However,
some of these characteristics are certainly not inherited from the diesel, for
example the presence of 2?-methylhopanes in the oil shows but not in the
diesel.
Another pertinent features of these oil shows which is unlikely to be related to
the diesel is the presence of C(30) steranes, which indicates a marine
depositional environment. The C(26) sterane distribution provides some
age-specific information. The NDR ratios for the oil shows in Moose-1 vary
between 0.32-0.51, and the NCR ratios for the oil shows vary between 0.29-0.66.
These values therefore indicate that the oil shows contain C(26) steranes
derived principally from Cretaceous or younger strata (Section 3.9).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 78
The Pr/Ph ratios of 1.1-1.3 for three of these oil shows indicates an
oxygen-depleted depositional environment. The oil show sample 727 m has a higher
Pr/Ph ratio (1.9), which is likely influenced by the diesel (1.8). As the Pr/Ph
ratio of the diesel is higher than that of the oil shows, the true non-diesel
overprinted Pr/Ph ratios of these oils shows is likely to be even lower,
suggesting even more strongly an oxygen-depleted depositional environment. These
Pr/Ph values are lower than those of the non-altered "Family B" solid bitumens
from the Subu wells (predominantly 1.3 to 2.9).
Regarding thermal maturity of these oils shows, this is quite difficult to
establish accurately due to the effects of the diesel (and the Aus-Tex in other
oils shows). The alkylnaphthalene and alkylphenanthrene maturity parameters
indicate a lower maturity than the diesel, and a higher maturity than the
fine-grained rocks. The best estimate is peak oil window, about 0.8 to 0.9% VRE.
These biomarker and other data have to be interpreted very carefully, due to the
effects of overprinting. However, the accumulated data enable a confident
correlation to me made with Family B solid bitumens in the Subu wells.
Therefore, most of the natural portion of the Moose-1 oil shows are thought to
have been derived from the same source rock as the one from which the Family B
solid bitumens in the Subu wells were derived.
4.3.2 "Jurassic" source signature
Oil show sample 809.7 m has the least interference of any of the oil shows with
contaminants. No diesel, Aus-Tex or grease could be confidently discerned in
this sample, and it is only slightly biodegraded. Therefore, it is quite ironic
that its hydrocarbon composition indicates a mixture of oil signatures. The
dominant signature of this oil show sample is "Jurassic", in that it correlates
best with the Family A solid bitumens in the Subu wells, which are thought to
have been derived from a clay-rich, marine source rock low in sulphur, which had
significant input of terrestrial organic matter and was deposited in an oxic
depositional environment (George et al., 2003). In that report, this signature
was correlated with the Jurassic-sourced oils in the Foldbelt and at Puri-1. The
characteristics of the 809.7 m oil show that lead to this correlation are:
1. The high abundance of 4?(H)-19-isopimarane, ent-beyerane and isopimarane
(diterpanes indicative of a coniferous source; Section 3.8.2),
2. The high [C(24) tetracyclic terpane/(C(24) tetracyclic terpane + C(23)
tricyclic terpane) ratio, indicative of a strong terrestrial influence (Section
3.8.3),
3. The moderate to high content of rearranged hopanes and diasteranes (Sections
3.8.5 and 3.8.6).
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 79
However, a complication about the 809.7 m oil show sample is that it contains
moderate amounts of 2? -methylhopanes, 30-norhopanes, a high C(29)/C(30) ? ?
hopane ratio, a high sulphur content and a relatively low Pr/Ph ratio (1.4).
These characteristics are not typical of Jurassic-sourced oils in PNG, and
enable correlation of this oil also with the "Calcareous" source signature that
is apparent in the other oil shows (see Section 4.3.1). Therefore, the 809.7 m
oil show sample is interpreted to be a mixture of both oil signatures. The
mixture explains why some biomarker signatures for "Jurassic" are strong (e.g.
the diterpanes, which have not been significantly diluted), whilst others are
much less obvious than in the Family A solid bitumens in the Subu wells (e.g.
the terpane distribution and the relative abundance of rearranged hopanes).
Other oil shows are also likely to be mixtures to some extent. For example, oil
show sample 727 m has a high [C(24) tetracyclic terpane/(C(24) tetracyclic
terpane + C(23) tricyclic terpane) ratio, which is a terrestrial indicator and
may indicate a contribution of Jurassic-sourced oil at this interval too.
Regarding the thermal maturity of the 809.7 m oil show, this is easier to
establish as there are no interfering overprints. The alkylnaphthalene and
alkylphenanthrene maturity parameters indicate a lower maturity than the diesel,
and a higher maturity than the fine-grained rocks. Based on these data, and the
biomarker maturity parameters, the best estimate is peak oil window, about 0.8
to 0.9% VRE.
4.4 DISTRIBUTION OF OIL SHOWS AND CONTAMINANTS IN MOOSE-1 AND MOOSE-1 ST1
According to the drilling records, neat diesel was only put down the Moose-1
well once at 460m, when while air drilling with a hammer they became stuck and
needed lubrication. Subsequently diesel was only put in the Moose-1 well as a
minor component, used mainly to aid the solution of Aus-Tex and Cr650 mud
products. No diesel is recorded as having been used in Moose-1 ST1.
The geochemical detection of diesel in most of the oil show samples from Moose-1
ST1, and also the clear presence of Aus-Tex in some of the oil shows in Moose-1
ST1, thus needs explanation. There are two possibilities: Firstly, there was
only 1(degree) of separation between the parent Moose-1 well and the sidetrack
(Moose-1 ST1). This separation means that from 664 m (the depth at which the
sidetrack well was deviated) and the bottom oil show recorded that contained
diesel (840 m), there was only up to about 3 m of lateral separation between the
two wells. Thus it is possible that diesel and/or Aus-Tex passed between the two
wellbores along fractures or other permeable horizons. Secondly, there could
have been unofficial or unrecorded addition of diesel and/or Aus-Tex directly
into Moose-1 ST1.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 80
In Section 3.4 a preliminary assessment of the origin of the oil shows was
presented (Table 6), based on overall and gross distributions. Now, a final
summary (Table 12) is presented, showing a complete summary of the origin of oil
shows, based on all geochemical data.
Table 12: Summary of the origin of oil shows, based on all geochemical data.
CSIRO code Description Origin
- ------------ ----------------------------- -------------------------------------------------------
530 m brown slurry Diesel plus minor natural oil show, biodegraded, from
"Calcareous" source (Cretaceous or Tertiary)
675.1 m suspected oil show Diesel plus minor natural oil show, from "Calcareous"
source (Cretaceous or Tertiary)
686.2 m suspected oil show Diesel, Aus-Tex (minor) and minor natural oil show
727 m suspected oil mixed with Minor diesel and major biodegraded component. The
water biodegraded component could possibly be a grease (pipe
dope or grease gun??), but also possibly a natural oil
show, from "Calcareous" source (Cretaceous or
Tertiary)
759.5-759.6 m suspected oil show, oil/water Diesel, mix of Aus-Tex (minor) and minor natural oil
wet sample show
809.7 m suspected oil show Natural oil show, slightly biodegraded. No discernible
wellbore contaminants. Mixture of "Jurassic" oil from a
clay-rich, marine source rock with significant input of
terrestrial organic matter, and "Calcareous" source
(Cretaceous or Tertiary)
840 m water with oil Diesel plus natural oil show, from "Calcareous" source
(Cretaceous or Tertiary)
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 81
5 CONCLUSIONS
1. The Mendi Formation limestone section penetrated by Moose-1 and
Moose-1 ST1 contains several natural oil shows, but these were
variably overprinted by wellbore contaminants which have been
analysed in detail.
2. Oil shows from 530 m (Moose-1), 675.1 m, 686.2 m, 727 m, 759.5-759.6
m and 840 m (all Moose-1 ST1) were strongly overprinted by diesel.
Careful application of high resolution organic geochemistry has
enabled the indigenous signature of some of these oil shows to be
separated from that of the diesel. The diesel has a characteristic
n-alkane distribution maximising at n-C(16), and also a distinctive
pattern of branched and cyclic alkanes, but contains few biomarkers.
3. Oil shows from 686.2 m and 759.5-759.6 m (Moose-1 ST1) were also
strongly overprinted by a drilling additive called Aus-Tex, which is
characterised by unusually high abundances of some polycyclic
aromatic hydrocarbons, but which also contains abundant biomarkers
that strongly interfere with the natural geochemistry of these oil
shows. These oil shows were essentially unusable for obtaining
information on the natural component.
4. An oil show from 809.7 m contains no discernible wellbore
contaminants and indicated a mixture of oil signatures.
5. The main natural component of all the interpretable oil shows is an
oil with an origin from a calcareous source with a high proportion
of prokaryotic and a low proportion of terrestrial organic matter
input, which correlates well with the "Family B" solid bitumens in
the Subu wells and the fluid inclusion oil from Subu -1. Geochemical
features of this oil type are high amounts of 2?- methylhopanes and
30- norhopanes, high C(29)/C(30) ?? hopane ratios and lack of a
significant terrestrial signature.
6. The oil show from 809.7 m contains a mixture of the calcareous
sourced oil, and an oil derived from a clay-rich, marine source rock
low in sulphur, which had significant input of terrestrial organic
matter and was deposited in an oxic depositional environment. This
signature correlates with the Jurassic-sourced oils in the Foldbelt
and at Puri-1, and with the "Family A" solid bitumens in the rocks
intersected by the Subu wells. Geochemical features of this oil type
are high amounts of diterpanes and a high [C(24) tetracyclic
terpane/(C(24) tetracyclic terpane + C(23) tricyclic terpane) ratio,
indicative of a strong terrestrial influence, and a moderate to high
content of rearranged hopanes and diasteranes.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 82
7. The oil shows in Moose-1 and Moose-1 ST1 have a maturity in the peak
oil window (about 0.8 to 0.9% VRE), which is slightly higher than
that indicated by the geochemical signatures for the underlying
fine-grained samples. The difference in maturity, but more
importantly the major difference in source characteristics, means
that these fine-grained samples did not source the oil shows in the
Mendi Formation limestones.
8. The fine-grained samples in Moose-1ST1 were deposited in an oxic
marine depositional environment with major terrestrial organic
matter input, including a minor coniferous organic matter component
that could be derived from re-worked Jurassic rocks. They correlate
reasonably well with the fine-grained samples analysed from the
Subu wells. C(26) sterane distributions are consistent with
Cretaceous or younger ages for these strata.
9. The fine-grained samples in Moose-1ST1 have low TOC values (<1.2%)
and low hydrogen indices (mostly <155 mg/g), indicating type III
organic matter, with low liquid hydrocarbon generation potential. On
the basis of the maceral contents, in particular the liptinite
contents, the original oil generation potential ranges from poor to
very good. This is better than is apparent from the Rock-Eval
results, probably because of the diluting effect of inertinite on
hydrogen indices, and also the maturity level that this sequence has
reached.
10. The fine-grained samples in Moose-1ST1 have measured vitrinite
reflectance values (~0.65 to ~0.70%) that are `suppressed', by at
least 0.2%. The FAMM-derived equivalent vitrinite reflectance,
which is free from the effects of VR suppression, is about 0.9%,
indicating full maturity for oil generation.
11. The anomalously high maturity indicated for the uppermost sample
(vitrinite reflectance value of 1.25%) may be due to overthrusting,
localised thermal effects from igneous activity and associated
hydrothermal fluids, or the complicating effects of reworked
material.
12. On the basis of the geochemical data, the best estimate of the
thermal maturity of the fine-grained samples is about 0.7-0.8% (mid
oil window), which is consistent with the Rock Eval data but is
somewhat lower than the equivalent vitrinite reflectance data from
FAMM.
6 ACKNOWLEDGEMENTS
We thank Paul Marvig for sample preparation.
CSIRO Petroleum InterOil: Moose-1 and Moose-1ST1 geochemistry, Page 83
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