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Imagine the result Imagine the result
Isotopic Forensic Techniques for Methane Source Discrimination
Julie K. Sueker, Ph.D., P.H., P.E., ARCADIS, Lakewood, CO Boyce L. Clark, Ph.D., P.Hg., ARCADIS, Baton Rouge, LA
George H. Cramer, P.G., ARCADIS, Baton Rouge, LA
Stray Gas Incidence and Response Forum Cleveland, Ohio July 23 – 25, 2012
© 2010 ARCADIS 30 July 2012 2
Overview • Why use stable isotope forensics for stray gas
assessments? • Methane generation mechanisms • Stray gas forensic techniques
• Geochemistry • Isotopes • Geophysics • Well integrity
• Case study • Salt dome storage cavern
gas release
Methane bubbles in swamp
Imagine the result 3
Stray Gas Forensics • Methane derived from numerous sources (biogenic,
thermogenic) • Potential methane release site may have multiple
unrelated methane sources including thermogenic sources • Methane forensic techniques used in various settings to
differentiate methane sources
© 2010 ARCADIS 30 July 2012 4
Methane Generation Mechanisms
• Thermogenic • Coal bed and oil & gas formations
• Biogenic • Methanogenesis – “swamp or
landfill gas” and “drift gas” • Acetate fermentation – “landfill gas”
• Abiogenic • Mantel gas
USGS
© 2010 ARCADIS 30 July 2012 5
Geochemical Techniques • Light hydrocarbon gas composition
• Thermogenic versus biogenic
• Composition of other gases (CO2, O2, H2, Ar, He, etc.) • Gas source, migration pathway
• Groundwater geochemistry • Differentiate water “types”
• Trace CH4 generation pathway
• Identify formation/produced water
1
10
100
1000
10000
100000
0.001 0.01 0.1 1 10
Met
hane
/ Et
hane
Carbon Dioxide / Methane
Biogenic Gas Composition
Thermogenic Gas
Composition
Mixing
© 2010 ARCADIS 30 July 2012 6
Geochemical Techniques
0.001
0.01
0.1
1
10
100
1000
10000
Ba Sr Ca Mg Na + K Cl SO4 CO3 Br
Con
cent
ratio
n (m
eq/L
)
Rainwater Limestone Shale and Sandstone
Upper Devonian Shale Lower Devonian Shale Silurian Shale
Cations Anions
© 2010 ARCADIS 30 July 2012 7
Geochemical Techniques
0.001
0.01
0.1
1
10
100
1000
10000
Ba Sr Ca Mg Na + K Cl SO4 CO3 Br
Con
cent
ratio
n (m
eq/L
)
Well A Baseline Well A Post Incident Produced Water
Cations Anions
© 2010 ARCADIS 30 July 2012 8
Geochemical Techniques
0.001
0.01
0.1
1
10
100
1000
10000
Ba Sr Ca Mg Na + K Cl SO4 CO3 Br
Con
cent
ratio
n (m
eq/L
)
Well A Baseline Well A Post Incident Produced Water Mixed Water
Cations Anions
"Mixed Water" is a hypothetical mixture of 99.7% "Well A Baseline" and 0.3% "Produced Water"
Post Incident Water ≠ Baseline + Produced Water
Imagine the result 9
What are Isotopes? • Atoms of same element with differing masses
• same # of protons, different # of neutrons
p e-
Hydrogen 1H
n p
e-
Deuterium 2H, D
n p n
e-
Tritium 3H, T
Sum of protons and neutrons is the atomic mass Lighter Heavier
© 2010 ARCADIS 30 July 2012 10
Isotope Techniques • Stable carbon and hydrogen isotopes of methane • Carbon-14 (14C) and 3H of methane • Other isotopic tracers, e.g., 87Sr/86Sr, H and O of water
0 20 40 60 80 100 120 140 160
100,000
10,000
1,000
100
10
1
Not Detected
Not Detected
Landfill Gas
Sewer Gas Swamp Gas Glacial
Drift Gas
Thermogenic Gas
Radiocarbon, 14C (pMC)
Triti
um, 3
H (T
U)
Coleman et al., 1993
© 2010 ARCADIS 30 July 2012 11
Stable Isotope Signatures
-350
-300
-250
-200
-150
-100
-100 -80 -60 -40 -20 0
δ2H
CH
4 (‰
)
δ13C CH4 (‰)
Biogenic Gas (CO2 Reduction)
Biogenic Gas (Fermentation)
Thermogenic Gas ("Natural Gas",
Coal Bed Methane)
Schoell et al., 1993
© 2010 ARCADIS 30 July 2012 12
Molecular and Isotopic Data
-60 -55 -50 -45 -40 -35 -30 -25 -20
0.016
0.014
0.012
0.010
0.008
0.006
0.004
0.002
0
δ13C Methane (‰)
1 / [
Met
hane
/ (E
than
e+Pr
opan
e)] Gas Production Wells
Gas Shows
Water Supply Wells - Baseline
Water Supply Wells - Incident
Shallow “Background” Gas
Production Gas
Mixed Gas
13 © 2010 ARCADIS 30 July 2012
Case Study
Storage Cavern C
Storage Caverns A & B
14 © 2010 ARCADIS 30 July 2012
Typical Gulf Coast Salt Dome 0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
Salt
Cap Rock
Salt Mining Wells
Prepared at the request of counsel
Based on illustration from
www solutionmining org
Natural Gas Storage Cavern
15 © 2010 ARCADIS 30 July 2012
1 5 0
4 0 0
2 , 2 0 0
0
7 0 0
2 , 0 0 0
1 , 0 0 0
Casing Breaches
Identified on
Cavern A Well
1973΄
16˝ Casing / 20˝ Borehole
1195΄
20˝ Casing / 26˝ Borehole
495΄
24˝ Casing / 30˝ Borehole
Cavern Top 2,058΄
36˝ Casing
164΄
Release @ 1,575΄ Release @ 1,535΄ Release @ 1,450΄
Prepared at the request of counsel
Hypothetical Representation
Not to scale
16 © 2010 ARCADIS 30 July 2012 16
1 5 0
3 5 0
3 9 5
5 0 0
7 0 0
3 , 3 0 0
0
1 , 0 0 0
2 , 0 0 0
Theoretical Migration Pathways 500 ft
Cavern A Cavern B
Salt Dome
Cap Rock
Over- burden
17 © 2010 ARCADIS 30 July 2012
1 5 0
4 0 0
2 , 2 0 0
0
7 0 0
2 , 0 0 0
1 , 0 0 0
Plug on Cavern A Well
1973΄
16˝ Casing / 20˝ Borehole
1195΄
20˝ Casing / 26˝ Borehole
495΄
24˝ Casing / 30˝ Borehole
Cavern Top 2,058΄
36˝ Casing
164΄
Plug @ 1,716΄
Release @ 1,575΄ Release @ 1,535΄ Release @ 1,450΄
Prepared at the request of counsel
Hypothetical Representation
Not to scale
18 © 2010 ARCADIS 30 July 2012
Preparing Cavern A Well for Snubbing Operations
Prepared at the request of counsel
Photo as of 1-2-04
19 © 2010 ARCADIS 30 July 2012
Snubbing Operations on Cavern A Well
Prepared at the request of counsel
Photo as of 1-5-04
20 © 2010 ARCADIS 30 July 2012
1 5 0
3 5 0
3 9 5
5 0 0
7 0 0
0
1 , 0 0 0
1 , 5 0 0
Theoretical Relief Venting
Prepared at the request of counsel
Hypothetical Representation
Not to scale
21 © 2010 ARCADIS 30 July 2012
Installation of Vent Wells
Prepared at the request of counsel
Photo as of 1-11-04
22 © 2010 ARCADIS 30 July 2012
Example of a Vent Well
Prepared at the request of counsel
Photo as of 1-18-04
23 © 2010 ARCADIS 30 July 2012 23
Relief Vent
Bubbles
Legend Storage
Caverns A & B
Prepared at the request of counsel As of 1-28-04
Storage Cavern C
Abandoned Gas Wells Southern Vent
© 2010 ARCADIS 30 July 2012 24
Geochemical Data
1
10
100
1000
10000
100000
0.001 0.01 0.1 1 10
Met
hane
/ Et
hane
Carbon Dioxide / Methane
Biogenic Gas Composition
Thermogenic Gas Composition
Mixing
© 2010 ARCADIS 30 July 2012 25
-215
-200
-185
-170
-155
-140
-70 -65 -60 -55 -50 -45 -40 -35
δ2H
Met
hane
(per
mil)
δ13C Methane (per mil)
All Samples
Southern Vent
Cavern Gas
Biogenic Thermogenic
Cavern C
Caverns A&B
Isotope Data – All Samples (up to one year of sample collection with several repeat locations)
© 2010 ARCADIS 30 July 2012 26
-175
-170
-165
-160
-155
-150
-145
-50.6 -50.4 -50.2 -50 -49.8 -49.6 -49.4 -49.2 -49 -48.8
δ2H
Met
hane
(per
mil)
δ13C Methane (per mil)
90
174
98 77
125 114 153 159
Cavern B 132
118 139
145
70
63
47
41
Cavern C
385
202 218
189
84
244
105
Cavern A
Isotope Data – Southern Vent (one location, many samples)
27 © 2010 ARCADIS 30 July 2012 27
Relief Vent Vents -No Gas Bubbles-Match
Legend
Area of Surface Expression
of Gas (Bubbles)
Estimated Extent of Subsurface
Gas
Storage Caverns A & B
Prepared at the request of counsel As of 1-28-04
Storage Cavern C
Abandoned Gas Wells Southern Vent
Bubbles-No Match
Results
28 © 2010 ARCADIS 30 July 2012
New Event
© 2010 ARCADIS 30 July 2012 29
Recent Stray Gas Event
Pipelines
Bayou
Bubbles
Tubing through hole in bottom of pool
To hand pump and sample bag
Rope Rope
6’
1’
© 2010 ARCADIS 30 July 2012 30
Recent Stray Gas Event
1
10
100
1000
10000
100000
0.001 0.01 0.1 1 10
Met
hane
/ Et
hane
Carbon Dioxide / Methane
Biogenic Gas Composition
Thermogenic Gas Composition
Mixing
© 2010 ARCADIS 30 July 2012 31
Recent Stray Gas Event
-215
-200
-185
-170
-155
-140
-70 -65 -60 -55 -50 -45 -40 -35
δ2H
Met
hane
(per
mil)
δ13C Methane (per mil)
All Samples
Southern Vent
Cavern Gas
Biogenic Thermogenic
Cavern C
Caverns A&B
32 © 2010 ARCADIS 30 July 2012
Coming Soon?
© 2010 ARCADIS 30 July 2012 33
Former Bulk Fuel Terminal
SPH Plume
Sanitary Sewer Line
Former marshland, historic landfill
Sample for gas composition, δ13C and δ2H methane, δ13C CO2, 14C methane and CO2
Demonstrate SPH degradation for natural attenuation: Source of methane in soil gas??
200 feet
© 2010 ARCADIS 30 July 2012 34
Methane Forensic Techniques
• Cost effective and definitive investigation tool
• Highest standard of environmental forensics practice
• Establish baseline conditions • Evaluate extent of gas
migration
© 2010 ARCADIS 30 July 2012 35 35
Mother Goose and Grimm ©2001 Grimmy, Inc. Dist. By Tribune Media Services. All rights reserved.
Questions?
© 2010 ARCADIS 30 July 2012 36
Imagine the Result
Julie K. Sueker, PhD, PH, PE 303.231.9115 x112