Geo-CSI in the oil patch presentation on how advanced geochemistry techniques can be used to solve common problems with surface casing vents, gas migration and stray gas investigations.

1. Making chemistry data meaningful
“Geo-CSI” in the oil patch – how
advanced geochemistry solves real
world problems
© 2015
Chemistry Matters Inc.
Scott Mundle* and Court Sandau
WBPC, Regina, SK, April 28-30, 2105
Presented at the Williston Basin Petroleum Conference, Regina, SK
April 28-30, 2015

2. o Geochemical characterization of sources to identify ‘fugitive’
gas migration in the oil/gas sector
“Geo-CSI”
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 2

3. o Surface casing used to protect
shallow (potable) aquifers
o Gas (and water) in SCVs migrate
from deeper zones (cement failure)
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
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 3

4. Geochemical characterizations & forensics
o Gases/fluids for different zones can
be ‘fingerprinted’
o But why do you keep getting
burned with this approach?
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 4

5. The geochemistry is never wrong, but the
interpretation is often 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 Numbers are reported that
are at or below the
detection limits of the
instrument
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 5

6. Don’t make assumptions 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
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 6

7. Need high quality SCV samples
o Can separate and collect gas and liquid
o Gas can be purged to remove “breathing”
gas from well
o Need low atmospheric content in gas
samples for compositional and isotopic
characterization
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 7

8. Sampling can affects water chemistry
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
Group 2 metals and f-block metals lower in bleed barrels
- suspended solids settle out in bleed barrel (low energy environment)
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 8

9. Sample integrity: The gas bag
• Over time isotopic composition of methane and CO2 changes
• Methane artificially appears more ‘thermogenic’
• Shift in CO2 is less predictable
• Manufacturer recommendations - analyze within 48 hours
© 2015
Chemistry Matters Inc.
*Arrows not to
scale
WBPC, Regina, SK, April 28-30, 2105 9

10. How can you get it right every time?
Mudgas Geochemical Profile
Characterized stratigraphy
Production and Potential Source
Zones:
1.) Fluids
2.) Gases
Characterized end-members
Shallow Fluids
1.) Surface water
2.) Groundwater
Characterized inputs
SCVs:
What are the Source(s)?
1.) Fluid
2.) Gas
GEOCHEMISTRY:
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 10

11. Complex case study: Fluid and gas flows
• Collected four samples from each location:
– SCV gas sample
– SCV liquid sample
– Production casing gas sample
– Production casing liquid sample
• Used local groundwater and deep aquifer wells in region for
comparison
• Used perforated wells with DST samples to acquire ‘end-
members’ for other potential source zones
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 11

12. No insight from water isotopes
o Water isotopes implicated groundwater sources that
conflicted with other indicators (chlorides, TDS, etc.)
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 12

13. A clearer picture with advanced analyses
o Different sources had characteristic ranges of concentrations
and isotope values
o Provided first line of evidence to indicate that different source
zones can be identified
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 13

14. Identifying source zones
o Fluids provide a line of evidence for potential sources, but
they do not provide a refined interpretation
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 14

15. Combined fluid and gas characterization
*Exact values property of client, shift in isotope values indicated
δ13C Values
GASES C1 C2 C3
SCV A - 1.9 B - 2.3 C
Casing A* B* C*
o Gases provide a second line of evidence for potential sources
and help confirm a production zone leak
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 15

16. Complete geochemistry = complete picture
δ13C Values
GASES C1 C2 C3
SCV A - 1.9 B - 2.3 C
Casing A* B* C*
*Exact values property of client, shift in isotope values indicated
δ13C Values
GASES C1 C2 C3
SCV A - 13.1 B - 8.1 bdl
Casing A* B* C*o Gases provide a second line of
evidence to confirm a cretaceous
zone leak
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 16

17. δ13C Values
GASES C1 C2 C3
SCV A - 13.1 B - 8.1 bdl
Casing A* B* C*
Identification of depth of source zone
o Mudgas log can refine cretaceous
leak to within 200-300m range
© 2015
Chemistry Matters Inc.
WBPC, Regina, SK, April 28-30, 2105 17

18. Where can it go wrong?
• Similar isotope
‘fingerprints can be
expected
• Need to account for
this complexity in the
interpretation
WBPC, Regina, SK, April 28-30, 2105 18

19. Best practices for ‘geoforensics’
• Collect high quality samples
• Collect samples for potential source(s) and from the
production casing (if possible)
• Ask the right questions and get it right !
– What source zone characterizations were used in the interpretation?
– Where were these source zones characterized (geographically)?
– What are the reliable detection limits for your instrumentation?
High quality samples, isotope analysis and accurate
interpretation of microbial effects provide more
conclusive source determination.
WBPC, Regina, SK, April 28-30, 2105 19

20. Thank You
csandau@chemistry-matters.com
www.chemistry-matters.com
403.669.8569