How to Maximize the Use of TMAX,
Compositional Ratios and Stable
Carbon Isotopes to Accurately Infer
the Maturity of a Shale
Jean-Yves Chatellier
Tight Oil Canada 2013
August 21st
Maturity Indicators Talk Outline
•  Introduction
•  Tmax domain recognition
Method to map the overpressure domain
•  Transformation Ratio versus Tmax
•  Carbon isotopes
•  Pseudo-depth parameters for maturity profiles
•  Maturity estimate conflicts
•  Shale dehydration in overpressured Dry Gas Domain
•  Quartz cement modeling – the maturity time factor
•  Conclusions
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Rock-Eval versus Depth
DEPTH Alberta Data set -2500m
unreliable Tmax -3750m
Calibra.on problems -5000m
17,550 data points Tmax NYSE : TLM | TSX : TLM
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Vitrinite and Rock-Eval versus Depth
TVDss
0m
-1000m
Ro from Tmax (GSC)
Ro (GSC)
-2000m
Ro Calculated Ro calculated from Tmax using Jarvie’s equation: Ro = (Tmax*0.018) - 7.16
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Maturity Indicators in pre-Devonian Rocks
Courtesy R. Bertrand (2013)
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Tmax Depth Profile
1.1%Ro
Beef Calcite
possible generation
1.5%Ro = overpressure plane
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“Beef” Calcite (calcite expansion seams)
1999.5m
“beef” calcite vein
Shear plane filled with calcite
“beef”
calcite
Utica Shale
St Edouard
(Quebec)
Very fine
sedimentary
fracture fill
1999.9m
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3” diameter wireline core
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“Beef” Calcite (calcite expansion seams)
Utica Shale St Edouard (Quebec)
Oil cracking and beef calcite
precipitation is post thrusting in the
St Lawrence Lowlands.
The horizontal calcite layers crosscut a fold.
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Two Important Overpressure Planes
1.1%Ro
Beef Calcite
possible generation
1.5%Ro = overpressure plane
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Tmax versus Hydrogen Index
10-13-43-15W5
Max Tmax
HI
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Tmax versus Hydrogen Index
10-13-43-15W5
Max Tmax
HI
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Tmax versus Hydrogen Index
16-25-047-21W5
Max Tmax
HI
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3-D Projection of Overpressure Plane (in blue)
TVDss
SSE
NNW
Triangle Zone
Overpressure plane associated with secondary
gas cracking
100km
Blow-out
3-D Projection
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Rock-Eval vs Transformation Ratio (TR)
Alberta well 16-‐31-‐64-‐12W6 Ro calc (Tmax)
TR (Pelet, PI)
Tmax well profiles can
be extremely useful to
to build a reliable
understanding of the
maturity with depth
Transformation ratio is
totally meaningless
when comparing data
from various formations
or various lithologies.
Note the increase in
scatter in the middle
part of the profile
Its use is even
problematic within
some shale with
varying TOC content
(varying HI original –
see Quebec example)
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Rock Eval vs Transformation Ratio (TR)
Quebec Talisman cored wells Tmax
TR (Pelet PI)
Depth
Depth
Fm
Well
Lorraine
Leclercville
Upper
Utica
St David
Lower
Utica
Data from cores
in 3 different wells
No useful trends
Upper
Utica
St Edouard
Misleading trends
TR decrease too rapid in Upper Utica
in St David
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Rock Eval vs Transformation Ratio (TR)
Quebec Talisman cored wells Tmax
TR (Pelet)
Depth
Depth
Fm
Well
Lorraine
Leclercville
Upper
Utica
St David
Lower
Utica
Data from cores
in 3 different wells
No useful trends
Upper
Utica
St Edouard
Misleading trends
TR decrease too rapid in Upper Utica
in St David
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Total Gas Content from Canisters (Saint David 1 well)
Indian Castle
Highest total gas
Depth
Indian Castle
88.97
65.95
88.94
64.90
Lower Dolgeville
66.55
59.16
48.46
One
foot
long
canister
every
5 metres
Upper Dolgeville
55.18
Flat Creek
54.13
45.15
Total Gas Scf / Ton
57.92
43.17
52.15
48.86
Nice trends in Upper Utica
42.57
33.62
25.49
Total gas
Scf/Ton
25.80
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37.54
Lower Dolgeville
Best mechanical properties
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Transformation Ratio (PI) Influenced by TOC
TR (Pelet PI)
Total Gas Content
(TOC linked)
Depth
Upper Utica
Lower Utica
Lower Utica
Total Gas Scf / Ton
The TR rapid decrease is partially linked
Nice trends
in Upper
Utica
to the decrease
in gas
content
(and linked to TOC)
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Structural Control on Maturity (TR Pelet 750)
Transformation Ratios (Pelet 750) in a type II North American shale
unfiltered
filtered
A
20 miles
20 miles
TR is can be very useful to reveal structural elements.
In the present example a horst (Block A) at time of maximum
burial is characterized by much lower maturity levels
than surrounding rocks and rocks to the West
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Tmax unfiltered (Utica Shale - Ohio)
Ro calculated from Tmax
Map view
Geographic coloring based on
Rock-Eval depths trends (Tmax & TR)
Well behaved depth trend
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Transformation ratio (Utica Shale - Ohio)
TR (Pelet 750)
TR (Pelet PI)
At great depth there is a nice trend of TR (Pelet 750) with depth
At shallow depth the same parameter exhibits unacceptable scattering
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Isotopes and Compositional Ratios
•  Carbon Stable Isotopes
•  C1, C2 and C3
•  Compositional Ratios
•  iC4/nC4 or iC5/nC5
•  C3+/C1+ or C4+/C1+
•  Log (C3+/C1+)
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Other Maturity Indicators: Ratios and Carbon Isotopes
iC4/nC4
1.1% Ro
1.5% Ro
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Maturity Assessment with Carbon Isotopes
Examples from Saint Lawrence Lowlands in Quebec
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Carbon Isotope Reversal
Carbon isotopes from isojars
Ethane
Propane
approximation
1.1%Ro
Liquid
rich
gas
Rsquared
94.2%
Rsquared
88.7%
1.5%Ro
Rsquared
77.2%
Rsquared
65.3%
Very well defined trends in the liquid rich domain
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Carbon Isotope Reversal
Carbon isotopes from isojars
Ethane
Methane
approximation
1.1%Ro
Rsquared
25.1%
Rsquared
88.7%
Liquid
rich
gas
1.5%Ro
Rsquared
77.2%
Rsquared
16.9%
Alteration of Methane isotope
at and below reversal
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Carbon Isotope Reversal
Carbon isotopes from isojars
Ethane
Methane
approximation
1.1%Ro
Rsquared
85.8%
Rsquared
86.4%
Rsquared
98.1%
Rsquared
91.3%
Liquid
rich
gas
1.5%Ro
Well defined trends in the liquid rich domain
Major fault below the reversal predates the maximum burial
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Timing of burial versus tectonics
Ethane
approximation
1.1%Ro
Rsquared
85.8%
Rsquared
98.1%
Reactivated reverse fault
(post max burial)
Liquid
rich
gas
1.5%Ro
Major thrust
Pre maximum burial
(non-altered isotope trend)
Well defined trends in the liquid rich domain
Major fault below the reversal predates the maximum burial
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Carbon Isotope Reversal
Carbon isotopes from isojars
Ethane
Methane
approximation
1.1%Ro
Rsquared
81.5%
Rsquared
85.8%
Rsquared
98.1%
Rsquared
25.8%
Liquid
rich
gas
1.5%Ro
No obvious alteration of Methane
Isotope associated with reversal
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Carbon Isotope Reversal
Testing isojar data set from well 3 and 3Hz
Ethane
Propane
Rsquared
68.7%
approximation
1.2%Ro
Liquid
rich
gas
1.5%Ro
Rsquared
58.6%
Rsquared
71.4%
Rsquared
79.9%
Rsquared
93.3%
Rsquared
83.2%
Complementarity of data from two neighboring wells
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Effect of well Interference on isotope values
Methane isotopes
Saint Edouard #1
Saint Edouard Hz1
approximation
1.2%Ro
Liquid rich gas
1.5%Ro
Exceptional differences between two neighboring wells
(30 m from each other)
Fracking in St Edouard 1  Methane isotope fractionation in St Edouard Hz1
This is due to well interference not to a change in maturity (in a few meters)
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Pseudo depth references for maturity study
•  Compositional Ratios
•  C3+/C1+ or C4+/C1+
•  Log (C3+/C1+)
•  Methane Carbon Isotopes
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Other Maturity Indicators (gas ratio versus isotope)
C3+/C1+
Wetter
Produced gas data
Wet gas Isotope reversal
Overpressure
associated with
secondary cracking
Dryer
(C2 & C3 changed in C1)
C2 Carbone isotope
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Maturity Indicators Tool Dependency
Log (C3+/C1+)
Wetter
Production gas
as reference
isojars
isotubes
Dryer
C2 Carbone isotope
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Maturity Gas Ratios - Tool Comparison
Ratio from Chromat
C4+/C1+
Chromat vs Isotubes
R squared = 98.9%
Ratio from Isotubes
Comparison between two averages:
- C4+/C1+ from chromatography ( average from ~1300 data points)
- C4+/C1+ from isotubes (average from ~6 to 7 points data points)
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Compositional ratio alteration (not maturity)
897m
C3+/C1+
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C4+/C1+
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Compositional ratio alteration (not maturity)
Fault 1
897m
C3+/C1+
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C4+/C1+
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Wetness Increase associated with a fault
Fault 1
C3+/C1+
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Maturity Estimate Conflicts
•  Rock-Eval / Vitrinite vs Hydrocarbon Phase
matching maturity values and yield
hydrocarbon drier than expectation maturity (Bakken)
Hydrocarbon wetter than expectation (early migration)
•  Absolute values (isotopes or ratios) at reversal are
Formation specific
Area specific
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Maturity and Shale Dehydration
•  Flowback Water
•  Increased salinity with time
•  Large data collection
•  > 100 wells
•  > 800 water samples
•  Examples using Chloride content
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Dehydration in the Dry Gas Domain
No data filtering
TVD
Flow Back Water Chloride % (~500m3) Normal increase of choride content with depth as expected in a hybrid shale system Rock dehydra.on as a func.on of Burial depth. Hydrogen from water needed to create methane from ethane or propane The chloride content is a func.on of the available connate and movable water and relate to osmosis between the frac water and the in situ waters Chloride
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Dehydration in the Dry Gas Domain
No data filtering
TVD
Flow Back Water Chloride % (~1000m3) Chloride
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Dehydration in the Dry Gas Domain
No data filtering
TVD
Flow Back Water Chloride % (~3000m3) Chloride
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Dehydration in the Dry Gas Domain
TVD
Flow Back Water Chloride % through .me 1000m3 3000m3 500m3 Decrease in chloride
content with depth
below reversal :
Shale dehydration
Overpressure
Hydrogen extracted
from
the interstitial water to
generate methane:
Dehydration
C2H6+2H => 2CH4
Chloride
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Quartz Cement
a time dependent burial indicator
very useful for basin modelling
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Maturity indicator : one side of the story
Different Burial but same Tmax (Ro)
Depth
0
Time
More recent
Each of these cases has an identical maximum burial
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Quartz Cement : A Time Recorder
Effect of burial history on Lorraine Shale
Hybrid shale can be affected by quartz cementation
Schematic diagrams with percentages based on modelling
Depth
80ºC
Quartz
Cementation
Ordovician
Present
2% porosity left
5% Quartz cement
21% porosity left
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14% porosity left
28% Quartz cement
3% porosity left
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No porosity left
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Rock-Eval Useful in Liquid Rich Domain
What not to do:
Use averages for maturity assessments
Recommended steps:
1)  Look at the range of values obtained
2)  Filter for S2 > 0.5 and TOC > 1%
3)  Document and keep in mind the percentage of bad values
4)  Use the Max, or 90%ile value of Tmax as most representative
5)  Incorporate all Tmax values of shallower horizon
6)  On a map, incorporate all data and basement features
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Conclusions
•  Tmax can be used using ranges and maxima
•  Transformation Ratio for high maturity and single shale
•  Carbon isotopes
•  Production interference can alter the C1 isotope values
•  Gas composition ratios
•  Pseudo-depth parameters for maturity profiles can be used
•  C3+/C1+, C4+/C1+
•  Methane Carbon isotope
•  Liquid yield may not always match the maturity level
•  Shale dehydration in overpressured Dry Gas Domain
•  Quartz cement modeling – do not forget the maturity time factor
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Thanks
to
Talisman Energy inc.
for permission to present
this material
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