Presentation at 2016 GeoConvention in Calgary, Alberta. Presentation covered best practices for the collection of samples then using advanced geochemistry and geoforensics to identify source zones of SCVFs.

1. © 2015
Chemistry Ma2ers Inc. 1 GeoConven)on 2016 – www.chemistry-ma:ers.com
Making chemistry data meaningful
Characterizing the source zones for surface
casing vent leaks
Court D. Sandau, PhD, P.Chem
March 8, 2016 – GeoConvenCon 2016, Calgary, AB

2. © 2015
Chemistry Ma2ers Inc.
Acknowledgements
2
• Sco: Mundle, PhD, C.Chem, P.Chem
GeoConven)on 2016 – www.chemistry-ma:ers.com
• Live tweets: #GeoCon2016 and #GeoForensics

3. © 2015
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Surface Casing Vent Flows and Geoforensics
3 GeoConven)on 2016 – www.chemistry-ma:ers.com

4. © 2015
Chemistry Ma2ers Inc.
Geoforensics
4 GeoConven)on 2016 – www.chemistry-ma:ers.com
Introducing a new term: Geoforensics
• Forensics is derived from latin “forens”, meaning of, belonging
to the forum, public
• Geoforensics is the application of scientific methods used to
identify source(s) of chemical constituents (natural or man
made) in fluids (gases, groundwater, oil), soil and/or rock from
the subsurface of the Earth for use in potential litigious issues or
for public debate or discussion.

5. © 2015
Chemistry Ma2ers Inc.
Surface Casing Vent Flows (SCVFs)
5 GeoConven)on 2016 – www.chemistry-ma:ers.com
SCVFs come in many shapes and sizes
- High pressure and intensity are generally easy to
identify (e.g. EOR fields)
- Low flows/pressures provide difficult sampling
opportunities (Houdini wells – “no you see them, now
you don’t”
- L.F. 2012 – “Flow’ers and Show’ers”

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What do SCVFs look like?
6 GeoConven)on 2016 – www.chemistry-ma:ers.com
Steam
Oily Bubbles Intermittent Flow Constant Fizz

7. © 2015
Chemistry Ma2ers Inc.
o Surface casing used to protect
shallow (potable) aquifers
o Fluids(gas and/or liquid)
migrate from deeper zones
through SCV
o Gas migration occurs outside
the SCV
o Irregular and low flow rates
(can be difficult to sample/
monitor)
o How can you determine the
source(s) of the leaks?
Surface casing vent flow and gas
migration
GeoConven)on 2016 – www.chemistry-ma:ers.com 7

8. © 2015
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o Geochemical characterization of sources to identify ‘fugitive’
gas migration in the oil/gas sector
Geochemical ‘fingerprinting’
GeoConven)on 2016 – www.chemistry-ma:ers.com 8

9. © 2015
Chemistry Ma2ers Inc.
Geochemical characterizaJons & forensics
o Gases/fluids for different
zones can be
‘fingerprinted’
o But why does this
approach sometimes fail?
GeoConven)on 2016 – www.chemistry-ma:ers.com 9

10. © 2015
Chemistry Ma2ers Inc.
The geochemistry is never wrong, but the
interpretaJon is oPen incorrect
o Common problems:
o Sample degraded prior to
analysis
o Either the wrong ‘end-
members’, or no ‘end-
members are used to
identify sources
o Misinterpretation of the
data (e.g. not noticing
altered fingerprints, or
using wrong data)
GeoConven)on 2016 – www.chemistry-ma:ers.com 10

11. © 2015
Chemistry Ma2ers Inc.
Don’t make assumpJons based on regional
geochemistry
o Where do the ‘fingerprints’
originate?
o Commercial isotope
“databases” often use
regional values rather than
local values that can
mislead interpretations
GeoConven)on 2016 – www.chemistry-ma:ers.com 11

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Sampling and Data AcquisiJon – Step 1
12 GeoConven)on 2016 – www.chemistry-ma:ers.com

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Need high quality SCV samples
o Can separate and collect gas, liquid and
steam
o AER is considering requirement for
monitoring SCV flow in SAGD wells, what
about steam?
o Need low atmospheric content in gas
samples for compositional and isotopic
characterization
Steam
GeoConven)on 2016 – www.chemistry-ma:ers.com 13

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Sample media can affect ‘fingerprints’
• Over time isotopic composition of methane and CO2 changes
• Methane artificially appears more ‘thermogenic’
• Shift in CO2 is not predictable
• Manufacturer recommendations = analyze in 48 hours
GeoConven)on 2016 – www.chemistry-ma:ers.com 14

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Goal for Gas Sampling
• Maximize gas concentra)on
– Least amount of air as possible
– Purge air from “system”, allow gas to
accumulate if necessary
• Eliminate moisture
– Break out water or steam
• Preserve sample to prevent
degrada)on
• Analyze sample within hold )me
– 48 hours for bags
15 GeoConven)on 2016 – www.chemistry-ma:ers.com

16. © 2015
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Liquids Sampling
• Slow/low volume liquid vent flows
problema)c sampling
• Requires passive sampling to preserve
chemistry of the liquid
16 GeoConven)on 2016 – www.chemistry-ma:ers.com
0.0001$
0.001$
0.01$
0.1$
1$
10$
100$
1000$
10000$
100000$
Lithium$
Sodium$
Potassium$
Rubidium$
Cesium$
Beryllium$
Magnesium$
Calcium$
Stron=um$
Barium$
Boron$
Aluminum$
Gallium$
Indium$
Thallium$
Silicon$
Germanium$
Tin$
Lead$
Phosphorus$
Arsenic$
An=mony$
Bismuth$
Sulphur$
Selenium$
Tellurium$
Chlorine$
Bromine$
Iodine$
Scandium$
YDrium$
Titanium$
Zirconium$
Vanadium$
Niobium$
Tantalum$
Chromium$
Molybdenum$
Tungsten$
Manganese$
Iron$
Cobalt$
Nickel$
Palladium$
Pla=num$
Copper$
Silver$
Gold$
Zinc$
Cadmium$
Mercury$
Lanthanum$
Cerium$
Praseodymium$
Neodymium$
Samarium$
Europium$
Gadolinium$
Terbium$
Dysprosium$
Holmium$
Erbium$
YDerbium$
Thorium$
Uranium$
BleedNbarrel$
FlowNthrough$Cell$
1 2 3 4 5 6 7 d-block f-block

17. © 2015
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Best PracJces Required for SCVF Sampling
• Ban the term “Grab a sample”
• Sampling gases is sampling the invisible
– Need good connec)ons/seals
– Leak tests (check connec)ons)
– Ensure sample integrity maintained
• Sampling liquids
– Easier to sample, some)mes harder to collect
– Passive collec)on systems, but protected from environmental
degrada)on
• Higher quality data = Higher chance for success!
17 GeoConven)on 2016 – www.chemistry-ma:ers.com

18. © 2015
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IdenJficaJon and CharacterizaJon of
Source Zones
18 GeoConven)on 2016 – www.chemistry-ma:ers.com

19. © 2015
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How can you get it right every Jme?
Mudgas Geochemical Profile
Characterized stratigraphy
Prod./Source Zones:
1.) Fluids
2.) Gases
Characterized end-members
Shallow Fluids
1.) Surface water
2.) Groundwater
Characterized inputs
SCVs:
Identify matrix
1.) Fluid
2.) Gas
GEOCHEMISTRY:
19 19 GeoConven)on 2016 – www.chemistry-ma:ers.com

20. © 2015
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Case Studies – Using End-Members to
IdenJfy SCVFs
20 GeoConven)on 2016 – www.chemistry-ma:ers.com

21. © 2015
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Case Study
• Collected four samples from each loca)on:
– SCV gas sample
– SCV liquid sample
– Produc)on casing gas sample
– Produc)on casing liquid sample
• Used local groundwater and deep aquifer wells in
region for comparison
• Targeted source zones (end-members) were sampled
and characterized
• Full MGIL for region
21 GeoConven)on 2016 – www.chemistry-ma:ers.com

22. © 2015
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Conservative Chemistry
o Characterization of SCV fluids focused on both routine and
‘conservative’ analytes:
• pH, alkalinity
• Concentrations of dissolved cations and anions
• Extended metals (65 in total)
• Stable isotopes (18O, 2H, 11B, 13C, 34S, 37Cl, 81Br, 87/86Sr)
• Conservative isotopes were required for the following
cases to elucidate fluid source due to pH alteration of all
susceptible analytes
22 GeoConven)on 2016 – www.chemistry-ma:ers.com

23. © 2015
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SCVF Analysis
o Specific conservative isotopes and their analyte
concentrations were discovered to be characteristic of
specific formations.
23 GeoConven)on 2016 – www.chemistry-ma:ers.com

24. © 2015
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SCVF – Example 1
Conclusion:
o SCV leak is from production zone
o Gas is entirely production formation
o Water is production zone mixed with
intermediate GW
C1 C2 C3 CO2
SCV -51.9 -45.4 -35.9 bdl
Casing gas -50.0 -43.1 -35.9 -2.5
Isotopevalue
Concentration value
Gas Results
Liquid Results
24 GeoConven)on 2016 – www.chemistry-ma:ers.com
Mississippian
Cretaceous
Mississippian
Cretaceous

25. © 2015
Chemistry Ma2ers Inc.
SCVF – Example 2
o Gas/liquid origin not from production zone
o Based on MGIL, 300-400 m origin
Conclusion:
o SCV leak is from shallow zone
C1 C2 C3 CO2
SCV -61.7 -48.0 bdl bdl
Casing gas -48.6 -39.9 -36.6 -18.8
Isotopevalue
Concentration value
Gas Results
Liquid Results
25 GeoConven)on 2016 – www.chemistry-ma:ers.com
Mississippian
Cretaceous
Mississippian
Cretaceous

26. © 2015
Chemistry Ma2ers Inc.
Best Practices for SCVF Sampling
• Collect high quality samples – protected from
degrada)on, purge gas prior to sampling, etc.
• Preserve samples in the field
• Collect poten)al source samples and from the
produc)on casing (if possible)
• Use basic chemistry but if not useful, may need
conserva)ve analytes
• Conserva)ve analytes can provide clarity for difficult SCV
fluid samples
26 GeoConven)on 2016 – www.chemistry-ma:ers.com

27. © 2015
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Best Practices for Identifying SCVF
• Proper sampling and characteriza)on of poten)al
source zones (gas and liquids)
• Solid MGIL for the area
• Good database for the area of successful
interven)ons
• Geochemistry data is always telling you
something, interpre)ng the message is key!
27 GeoConven)on 2016 – www.chemistry-ma:ers.com

28. © 2015
Chemistry Ma2ers Inc.
Thank you for your attention
Contact Info:
Chemistry Matters Inc.
Court Sandau
Cell: 403.669.8566
Email: csandau@chemistry-matters.com
URL: chemistry-matters.com
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