Geoforensics for oil characterization WBPC2015

Making chemistry data meaningful
Geoforensic Chemical Analysis of Oil
Samples from the Madison Group
What Can It Tell Us?
Phil Richards and Court Sandau
© 2015
Chemistry Matters Inc.

2
© 2015
Geoforensic Chemical Analysis of Oil Samples from the Madison Group
Origin of Madison oil?
7 samples of oil from 2 areas in Canadian WB:
o  Area A – 2 Midale
o  Area B – 2 Midale
o  Area B – 3 Frobisher
From: USGS 2010. Geological Assessment of Undiscovered Oil and Gas Resources
in the Madison Group, Williston Basin, North Dakota and Montana

3
© 2015
Madison Group
(Lodgepole, Frobisher, Midale,
Ratcliffe, Poplar)
(Carbonate)
Bakken Formation
(Shale)
From: Obermajer et al. 2000, Org. Geochem. 31, 959.

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© 2015
o  Originally proposed that “Bakken
shale” was the source of overlying
oil reservoirs of the Madison Group.
o  Later established that the “Madison
carbonates” were the most probable
source for the Madison Group.
o  Variations within localized traps.
o  Potential for localized mixing-in of
Bakken oil.

5
GC-MS
© 2015
nC8
nC9
nC10
nC12
nC11
nC13
nC14
nC15
nC16
nC17
nC18
nC19
nC20
nC21
nC22
nC23
nC24
nC25
nC26
nC27
nC29
nC28
nC30
nC32
nC31
nC33
nC34
nC35
nC36
nC37
nC38
o  Alkanes
o  Isoprenoids
o  Alkylcyclohexanes
o  Sesquiterpanes
o  Adamantanes
o  Alkylbenzenes
o  PAHs
o  Alkyl-PAHs
o  Hetero-PAHs
o  Steranes and
Terpanes…

2DGC-TOFMS
6
© 2015
Alkanes
Bicyclic Alkanes
Naphthalenes BT DBT
PAHs
Steranes
Hopanes
MAS
TAS

Biomarkers
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© 2015
Originate from complex biological molecules
Membrane structural chemicals
o  Terpanes – prokaryotes (archea and bacteria)
o  Steranes – eukaryotes (plants and animals)
Relative concentrations of biomarkers can provide information
of the origin and history of the oil.

Biomarkers
8
© 2015
Typical
Bakken
Typical
Lodgepole
Example of Madison
oil product
Terpanes
1. Pattern of C21-C24 tricyclic terpanes
2. Ratio of Ts/Tm
3. Ratio of 17a21b-30-norhopane relative to 17a,21b-hopane
4. Enrichment of C35 homohopanes
1 2 31 2 31 2 3 4 4 4

Biomarkers
9
© 2015
Typical
Bakken
Typical
Lodgepole
Example of Madison
oil product
Steranes
f C27
oils,
C27
ce of
ining
and
pro-
ed to
Mol-
rther
mpo-
tion ratios) as the majority of oils from this family have
C21/C29 regular sterane ratio of less than 1.0.
The epimerization ratios of C29 regular steranes are
quite variable and inconclusive with respect to deter-
mining maturity of oils. The C29 abb/(aaa+abb) reg-
ular sterane isomerization ratio is the highest in oil
families B and C, often approaching equilibrium values.
Interestingly, this trend is not parallelled by the C29
S/(S+R) isomerization ratio which is the highest in oil
families A and D. These variable ratios are not always
consistent with maturity data derived from the gasoline
range parameters and the distribution of n-alkanes and
the saturate fraction showing the distribution of steranes in the Williston
H) 20S- C27 diasterane, C29±C29 regular sterane.
similar in all oil families, the proportion of C27
29 members is more variable. In the family B oils,
9 sterane occurs in same concentration as C27
e (Table 2). In contrast, the relative abundance of
erane are increasingly greater in the remaining
s, reaching more than 50% in oil families D and
erage of 51% and 58%, respectively). The pro-
n of C27:C28:C29 regular steranes is considered to
ighly speci®c correlation index (Peters and Mol-
, 1993, pp. 182±186), therefore providing further
t for classifying studied oil samples into compo-
ly distinct oil categories.
tion ratios) as the majority of oils from this family have
C21/C29 regular sterane ratio of less than 1.0.
The epimerization ratios of C29 regular steranes are
quite variable and inconclusive with respect to deter-
mining maturity of oils. The C29 abb/(aaa+abb) reg-
ular sterane isomerization ratio is the highest in oil
families B and C, often approaching equilibrium values.
Interestingly, this trend is not parallelled by the C29
S/(S+R) isomerization ratio which is the highest in oil
families A and D. These variable ratios are not always
consistent with maturity data derived from the gasoline
range parameters and the distribution of n-alkanes and
Representative m/z 217 mass fragmentograms of the saturate fraction showing the distribution of steranes in the Williston
ils. C21- pregnane, C27dia-17(H), 13

(H), 17(H) 20S- C27 diasterane, C29±C29 regular sterane.
C27
C28 C29
C27
C28
C29
Pattern of cholestanes (C27-C28-C29)

Isoprenoids
10
© 2015
Pristane (Pr) and Phytane (Ph) originate from the
decomposition of chlorophyll
oxidizing
reducing

0.0#
0.4#
0.8#
1.2#
1.6#
2.0#
Sample#
1#
Sample#
2#
Sample#
3#
Sample#
4#
Sample#
5#
Sample#
6#
Sample#
7#
Pr#/#Ph#Ra(o#
Isoprenoids
11
© 2015
Pristane / Phytane ratio 1, conditions generally in
line with Lodgepole (carbonate) source.
Some differences (Sample 3 and 4)
Bakken oils
Lodgepole oils
Pristane
Phytane
0.0#
1.0#
2.0#
3.0#
4.0#
5.0#
6.0#
7.0#
Midale#
A1#
Midale#
A2#
Midale#
B3#
Midale#
B4#
Frob#####
B5#
Frob####
B6#
Frob####
B7#
DBT$/$Phen$ra,o$

0.0#
1.0#
2.0#
3.0#
4.0#
5.0#
6.0#
7.0#
Midale#
A1#
Midale#
A2#
Midale#
B3#
Midale#
B4#
Frob#####
B5#
Frob####
B6#
Frob####
B7#
DBT$/$Phen$ra,o$
Other indicators (PAHs)
12
© 2015
Bakken oils
Lodgepole oils
DBT
Phen
High sulfur content of Lodgepole carbonates.

0
0.4
0.8
1.2
1.6
2
Midale
A1
Midale
A2
Midale
B3
Midale
B4
Frob
B5
Frob
B6
Frob
B7
Ts#/#Tm#ra(o#
Other indicators (Terpanes)
13
© 2015
Ts
Tm
Bakken oils
Lodgepole oils

More detailed analysis
All 7 samples conform with general
Lodgepole origin.
•  Bakken Contributions
•  Maturity
•  In situ degradation
14
© 2015

0.3$
0.4$
0.5$
0.6$
0.7$
0.8$
0.9$
1.0$
1.1$
1.2$
2.0$ 3.0$ 4.0$ 5.0$ 6.0$ 7.0$
Pr#/#Ph#
DBT#/#Phen#
Sample$1$
Sample$2$
Sample$3$
Sample$4$
Sample$5$
Sample$6$
Sample$7$
15
© 2015
Dibenzothiophene Phenanthrene
Pristane
Phytane
Potential For Bakken
Contributions
Bakken
0.15%
0.2%
0.25%
0.3%
0.35%
0.4%
0.6% 1.1% 1.6% 2.1%
Ts#/#(Ts+Tm)#
TAS#/#MAS#
Midale%A1%
Midale%A2%
Midale%B3%
Midale%B4%
Frob%B5%
Frob%B6%
Frob%B7%
M-B

0.15%
0.2%
0.25%
0.3%
0.35%
0.4%
0.6% 1.1% 1.6% 2.1%
Ts#/#(Ts+Tm)#
TAS#/#MAS#
Midale%A1%
Midale%A2%
Midale%B3%
Midale%B4%
Frob%B5%
Frob%B6%
Frob%B7%
16
Maturity Indicators
© 2015
Triaromatic Steranes Monoaromatic Steranes
Ts
Tm

0.0#
0.5#
1.0#
1.5#
2.0#
2.5#
0.4# 0.6# 0.8# 1.0#
n12$/$i13$
Pr$/$Ph$
Sample#1#
Sample#2#
Sample#3#
Sample#4#
Sample#5#
Sample#6#
Sample#7#
Mixing and in-situ degradation
17
© 2015
‘Weathering’
M-A
M-B
F-B
Frobisher samples present ‘in situ’ weathering
- loss of light end straight-chain hydrocarbons
Bakken
0.15%
0.2%
0.25%
0.3%
0.35%
0.4%
0.6% 1.1% 1.6% 2.1%
Ts#/#(Ts+Tm)#
TAS#/#MAS#
Midale%A1%
Midale%A2%
Midale%B3%
Midale%B4%
Frob%B5%
Frob%B6%
Frob%B7%

In-situ degradation
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© 2015
Midale
o  Normal profile of hydrocarbons
Frobisher
o  Altered profile
•  Biodegradation
•  Water / CO2 flood

Summary
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© 2015
•  Standard geoforensic analysis
Midale and Frobisher samples are of carbonate origin
•  Detailed geoforensic analysis
Midale samples demonstrate origin differences
o  2 samples may present minor Bakken contributions
o  1 sample presents distinctly higher maturity
Frobisher samples present alteration
o  ‘in situ’ biodegradation / washing

Geoforensics for oil characterization WBPC2015

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