P11-06 Geochemistry Report (September 2008)
Geochemical Evaluation of MDT Oil, Gas and
Sidewall Core Samples from Well P11-06
Introduction and Objectives ........................................................................ 2
MDT Oil Sample ............................................................................................ 3
MDT Gas Sample .......................................................................................... 4
Sidewall Core Samples ................................................................................ 4
Gas Leg (SWC-27) ........................................................................................................... 5
Water Leg (SWC-37) ........................................................................................................ 6
Water Leg (SWC-36) ........................................................................................................ 7
Appendices
List of Figures
Figure 1, Chromatogram of the MDT oil and comparison of oil and extract alkane distributions. ........... 3
Figure 2, Carbon and deuterium isotope composition of the methane from the P11-06 MDT gas
sample compared with gases previously analysed from neighbouring wells. ........................ 4
Figure 3, SWC-27 viewed under low power microscopy and UV light. ................................................... 5
Figure 4, Chromatogram of the extract recovered from SWC-27. .......................................................... 5
Figure 5, SWC-37 viewed under low power microscopy, clearly reveals mild oil stain. .......................... 6
Figure 6, Chromatogram of the extract recovered from SWC-37. .......................................................... 6
Figure 7, SWC-36 viewed under low power microscopy. ........................................................................ 7
Figure 8, Chromatogram of the extract recovered from SWC-36. .......................................................... 7
Project No.: GC080053.
Page 1
P11-06 Geochemistry Report (September 2008)
Introduction and Objectives
The Petro-Canada P11-06 well encountered a gas leg at 1703m (GOC 1752m MDBRT), a thin oil leg
(OWC 1761m MDBRT) and a water leg below 1761m with oil shows reported in rotary sidewall
cores down to approximately 1800m. Evidence of suspected scattered oil shows is also apparent in
the gas leg (information provided by Corex Ltd.). Sidewall core samples were collected through all
three legs of the reservoir, whilst MDT gas and oil samples were collected at 1733.2m and an
unknown depth (cylinder 1331-06) respectively.
The objectives of this study were to characterise hydrocarbons recovered by solvent extraction from
two sidewall cores in the water leg and one sidewall core in the gas leg and to integrate the data
obtained with results acquired from analysis of the MDT oil and gas samples, allowing further
interpretation and correlation with the data from wells P10-05 and P11-05 (Project GC070016, 2007).
Solvent extraction was conducted using Soxtec extraction units and dichloromethane as the extraction
solvent. This process involves immersing the crushed core material in boiling solvent for one hour
followed by rinsing in clean solvent for one hour. Once the excess solvent is evaporated-off the
extract yield is determined gravimetrically.
Geochemical analyses conducted on the core extracts and MDT oil consisted of gas chromatography
(equipped with a 60m capillary column) to obtain a detailed fingerprint of the mobile hydrocarbons
(i.e. the saturated hydrocarbons and, to a lesser extent the aromatic hydrocarbons). Further analyses
conducted on the MDT oil and core extract at 1769.8m consisted of carbon isotope analysis of the
whole oil/extract and the saturated and aromatics fractions for the purposes of correlation, and gas
chromatography-mass spectrometry (GC-MS) analysis to obtain a detailed fingerprint of the
biomarker compounds (steranes and terpanes). The gas sample collected at 1733.2m was submitted
for compositional analysis (gas chromatography), plus carbon isotope analysis of the methane, ethane,
propane and butane components and deuterium isotope analysis of the methane component.
The core examination, extraction and gas chromatography analyses were undertaken at the
OceanGrove Geoscience laboratory in Aberdeen. Carbon isotope analysis of the whole/extract and
fractions was conducted by Iso-Analytical Ltd. (Cheshire), whilst GC-MS analyses were carried out
by LGC Ltd. (Middlesex) and the gas analyses by GHGeochem Ltd. (The Wirral). This report,
together with the appended data and core photographs are provided in digital format on CD.
Project No.: GC080053.
Page 2
P11-06 Geochemistry Report (September 2008)
MDT Oil Sample
The P11-06 oil sample (cylinder 1331-06) provided a carbon isotope composition (13Cwhole oil -28.2‰,
13Csaturate -28.6‰, 13Caromatics -29.0‰) almost identical to that of the extract recovered from 1769.8m
in the water leg. Further evidence of a positive correlation between the oil and extract is given by the
chromatogram of the MDT oil, which reveals a close resemblance in its smooth n-alkane distribution
from C15 out to beyond C30 and similar isoprenoid distribution pattern, including pristane and phytane
ratios (Pr/C17 0.58, Ph/C18 0.29). The oil also reveals a moderately strong component of volatile
hydrocarbons in the C3-C10 range, though the fact that the maximum peak heights of the
chromatogram are in the C10-C15 range rather than the C3-C10 range possibly suggests that partial
evaporative fractionation has occurred (cf. chromatograms for P11-A-01, -02, -03 oils).
MCH
Whole Oil Chromatogram, Well P11-06, Sample Cyl 1331-06 dead oil
CyC5 = cyclopentane
CyC6 = cyclohexane
MCP = methylcyclopentane
MCH = methylcyclohexane
ECP = ethylcyclopentane
ECH = ethylcyclohexane
Bz = benzene
Ebz = ethylbenzene
Tol = toluene
C15
C8
C18
Pristane (Pr)
1.2E+05
Phytane (Ph)
MCP
Bz
8.0E+04
C20
ECH
1.0E+05
C1-C5
6.0E+04
4.0E+04
C25
2.0E+04
C30
Peak Intensity
1.4E+05
C17
m+p xylenes
Tol
1.6E+05
C7
C6
CyC6
1.8E+05
C35
2.0E+05
C10
Solvent peak
2.2E+05
0.0E+00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Analysis Time (minutes)
Normalised Peak Heights Derived from Gas Chromatograms
P11-06 Well
18
Crude Oil Cyl 1331-06
16
Core Extract 1732.25m
Core Extract 1769.8m
14
Normalised Peak Height (%)
Core Extract 1782.5m
12
10
8
6
4
2
C35
C34
C33
C32
C31
C30
C29
C28
C27
C26
C25
C24
C23
C22
C21
C20
C19
C18
C17
C16
C15
C14
C13
0
Alkane Carbon Number
Figure 1, Chromatogram of the MDT oil and comparison of oil and extract alkane distributions.
Project No.: GC080053.
Page 3
P11-06 Geochemistry Report (September 2008)
MDT Gas Sample
The gas sample proved to be a wet gas mixture of C1-C5 gases with methane comprising 58% of the
sample. The results of carbon and deuterium isotope analysis of the methane component suggest that
the gas is derived possibly by association with oil or, from the cracking of oil, and in this respect plots
is a similar position to the gases analysed from the P10-05, P11-05 and P11-A wells.
-70
B
-60
o
-50
Ro%
TO
-40
TC
P11-A-02
P11-A-03
P11-A-01
P11-05 (RFT L11)
P10-05 (MDT A933)
P11-06
-30
(1733m)
B
M
To
Tc
Td
-20
-300
= bacterial dry gas
= mixed bacterial/thermogenic gas
= thermogenic gas (oil-associated)
= thermogenic gas (oil-cracking)
= thermogenic gas (dry gas)
-250
-200
-150
TD
0.5
0.7
1.0
1.3
2.0
3.0
4.0
Source rock maturity
(approximate)
Cmethane ( /oo)
M
-100
Dmethane ( /oo)
o
Figure 2, Carbon and deuterium isotope composition of the methane from the P11-06 MDT gas sample
compared with gases previously analysed from neighbouring wells.
(Diagram based on Schoell, 1984 and Peters et al, 2005)
Sidewall Core Samples
The sidewall core samples were examined at Corex Ltd. Those selected for geochemical analysis
were chosen on the basis of their position within the gas/water legs, their condition, lithotype
(particularly grain size), and reported oil stain and fluorescence characteristics (information provided
by Corex Ltd).
The samples were examined under low power microscopy at the OceanGrove
laboratory after scraping, cleaning and crushing the cores.
Project No.: GC080053.
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P11-06 Geochemistry Report (September 2008)
Gas Leg (SWC-27)
Sample SWC-27 (1732.25m) was selected from a position high in the gas leg on the basis of the
reported spotty residual oil stain and yellow fluorescence, plus the rationale that the fine grained
nature of the sandstone would be more likely to retain oil than coarser grained samples. Samples with
reportedly more extensive fluorescence near the base of the gas leg are suspected to contain the same
oil type as that in the oil leg. Further examination of the cleaned core material did not reveal
convincing evidence of visible oil stain or direct fluorescence. The very minor fluorescence observed
on the outer surface of the core prior to cleaning is attributed to contamination (mud additives?).
Figure 3, SWC-27 viewed under low power microscopy and UV light.
The crushed and homogenised core material provided a very lean solvent extract yield (0.3mgTSE/g
of rock) and a chromatogram signature characterised by a smooth distribution of n-alkanes out to C30
with maximum peak height at C17-C20, plus scattered contaminant peaks in the C14-C35 region, one of
which masks the pristane peak. The partial depletion of C17- peaks suggests that the oil at this horizon
has undergone evaporative fractionation within the reservoir. The alkane distribution pattern and, to a
lesser extent, the Ph/C18 and CPI values suggest a positive correlation with the MDT crude oil.
Whole Extract Chromatogram, Well P11-06, Core: 1732.25m
C20
C17
2.2E+04
C18
Solvent peak
2.4E+04
C15
2.0E+04
1.8E+04
1.4E+04
Pristane (Pr) ?
1.2E+04
1.0E+04
Phytane (Ph)
8.0E+03
6.0E+03
C25
Peak Intensity
1.6E+04
C10
2.0E+03
C35
C30
4.0E+03
0.0E+00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Analysis Time (minutes)
Figure 4, Chromatogram of the extract recovered from SWC-27.
Project No.: GC080053.
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P11-06 Geochemistry Report (September 2008)
Water Leg (SWC-37)
Sample SWC-37 (1769.8m) was selected on the basis of its fine-medium grained nature (sandstone)
and reported 5% patchy oil bleeding and patchy to even bright yellow fluorescence.
Further
examination of the crushed core material revealed mild light brown oil-wet/dry oil stain with strong
even light-medium golden yellow fluorescence and strong paraffinic hydrocarbon odour, which
suggests the presence of a mobile oil type rich in saturated and aromatic hydrocarbons. No evidence
of residual oil/asphaltic deposits was observed.
Figure 5, SWC-37 viewed under low power microscopy, clearly reveals mild oil stain.
The sample gave a rich extract yield (8.2mgTSE/g of rock) and a strong C13+ chromatogram signature
characterised by a smooth distribution of n-alkanes out to beyond C30 with maximum peak height at
C12-C17. The chromatogram shows the least influence of contaminants and thus, allows accurate
measurement of the pristane peak height. This extract shows a positive correlation and the closest
resemblance with the MDT oil on the basis of its alkane distribution pattern, Pr/C 17, Ph/C18 and CPI
values (0.55, 0.31 and 1.04, 1.07) and carbon isotope composition (13Cwhole oil -28.8‰, 13Csaturate 28.7‰, 13Caromatics -29.1‰).
Whole Extract Chromatogram, Well P11-06, Core: 1769.8m
C17
1.4E+05
C15
Solvent peak
1.6E+05
C18
1.2E+05
8.0E+04
C20
Pristane (Pr)
Peak Intensity
1.0E+05
C10
Phytane (Ph)
6.0E+04
C25
4.0E+04
C35
C30
2.0E+04
0.0E+00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Analysis Time (minutes)
Figure 6, Chromatogram of the extract recovered from SWC-37.
Project No.: GC080053.
Page 6
P11-06 Geochemistry Report (September 2008)
Water Leg (SWC-36)
Sample SWC-36 (1782.5m) consists of whitish grey fine-medium sandstone with reported 10%
medium brown oil patches and pale to moderate yellow fluorescence. Rare patches of orange-brown
stain observed on the ends of the core prior to scraping and cleaning gave a dull yellow-golden
fluorescence but no hydrocarbon odour and therefore are considered to be contaminants derived from
the drilling mud. Examination of the cleaned and crushed core material did not reveal any convincing
evidence of oil stain (hydrocarbon odour or fluorescence).
Figure 7, SWC-36 viewed under low power microscopy.
The core sample provided a lean solvent extract yield (0.2mgTSE/g of rock) similar to that at
1732.25m and a chromatogram signature characterised by a weak n-alkane distribution out to C30 with
maximum peak height at C17-C20, plus prominent contaminant peaks in the C11-C35 region that
effectively mask one or more of the n-alkane peaks and the pristane peak. The partial depletion of
C17- peaks suggests that the light-medium molecular weight mobile hydrocarbons have been depleted
within the reservoir. Nevertheless, the alkane distribution pattern, together with the Ph/C 18 and CPI
values suggest a positive correlation with the extract at 1769.8m and the MDT crude oil.
C15
3.0E+03
C18
3.5E+03
C17
Solvent peak
4.0E+03
C20
Whole Extract Chromatogram, Well P11-06, Core: 1782.5m
1.5E+03
C25
C35
2.0E+03
Phytane (Ph)
Pristane (Pr)
Peak Intensity
2.5E+03
C10
1.0E+03
C30
5.0E+02
0.0E+00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
Analysis Time (minutes)
Figure 8, Chromatogram of the extract recovered from SWC-36.
Project No.: GC080053.
Page 7
P11-06 Geochemistry Report (September 2008)
Appendices
P11-06 Geochemical Data
Rotary Sidewall Core Oil Stain (provided by Corex Ltd)
MDT Gas Sample Data (Composition and Isotope Data
Core Solvent Extract Yields
MDT Oil and Core Extract Carbon Isotope Data
MDT Oil and Core Extract Gas Chromatography Data and Traces
MDT Oil and Core Extract GC-MS Biomarker Data and Traces
GC-MS Biomarker Peak Identification Tables
Project No.: GC080053.
Appendix