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© 2015
Chemistry Matters Inc.
Making chemistry data meaningful
Characterizing the source zones
for surface casing vent lea...
© 2015
Chemistry Matters Inc.
o  Geochemical characterization of sources to identify ‘fugitive’
gas/fluid migration in the...
© 2015
Chemistry Matters Inc.
o  Surface casing used to protect
shallow (potable) aquifers
o  Gas (and fluids) in SCVs mig...
© 2015
Chemistry Matters Inc.
Geochemical characterizations & forensics
o  Gases/fluids for different zones can
be ‘finger...
© 2015
Chemistry Matters Inc.
The geochemistry is never wrong, but the
interpretation is often incorrect
o  Common problem...
© 2015
Chemistry Matters Inc.
Don’t make assumptions based on regional
geochemistry
o  Where do the ‘fingerprints’
origina...
© 2015
Chemistry Matters Inc.
Need high quality SCV samples
o  Can separate and collect gas and liquid
o  Gas can be purge...
© 2015
Chemistry Matters Inc.
Sampling can affect water chemistry
0.0001$
0.001$
0.01$
0.1$
1$
10$
100$
1000$
10000$
10000...
© 2015
Chemistry Matters Inc.
How can you get it right every time?
Mudgas Geochemical Profile
Characterized stratigraphy
P...
© 2015
Chemistry Matters Inc.
Complex case study: Fluid and gas flows
•  Collected four samples from each location:
–  SCV...
© 2015
Chemistry Matters Inc.
No insight from water isotopes
o  Water isotopes implicated groundwater sources that
conflic...
© 2015
Chemistry Matters Inc.
A clearer picture with advanced analyses
o  Different sources had characteristic ranges of c...
© 2015
Chemistry Matters Inc.
Identifying source zones
o  Fluids provide a line of evidence for potential sources, but
the...
© 2015
Chemistry Matters Inc.
Combined fluid and gas characterization
*Exact values property of client, shift in isotope v...
© 2015
Chemistry Matters Inc.
Complete geochemistry = complete picture
δ13C Values
GASES C1 C2 C3
SCV A - 1.9 B - 2.3 C
Ca...
© 2015
Chemistry Matters Inc.
δ13C Values
GASES C1 C2 C3
SCV A - 13.1 B - 8.1 bdl
Casing A* B* C*
Resolving the depth of s...
© 2015
Chemistry Matters Inc.
Simpler case study: High gas flows
•  SCV had high gas flow
•  No fluids
•  Commercial isoto...
© 2015
Chemistry Matters Inc.
Bulk gas compositions gave little insight
o  Data equally implicates different zones and/or ...
© 2015
Chemistry Matters Inc.
Carbon isotopes suggest different zones
o  Data could implicate two different zones
19SPE Ga...
© 2015
Chemistry Matters Inc.
Advanced models implicate same zone
o  All leaks actually from similar zone!
20SPE Gas Migra...
© 2015
Chemistry Matters Inc.
Did it work?
•  Similar zone
implicated for all
SCV in area
•  Gas zone overlying
production...
© 2015
Chemistry Matters Inc.
Where can it all go wrong?
•  Similar altered
isotope ‘fingerprints
can be expected from
dif...
© 2015
Chemistry Matters Inc.
Best practices for SCV ‘geoforensics’
•  Collect high quality samples
•  Collect samples for...
© 2015
Chemistry Matters Inc.
Thank You
csandau@chemistry-matters.com
www.chemistry-matters.com
403.669.8569
24
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SPE-CSGM_Workshop_Mundle_May2015

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SPE-CSGM_Workshop_Mundle_May2015

  1. 1. © 2015 Chemistry Matters Inc. Making chemistry data meaningful Characterizing the source zones for surface casing vent leaks Scott Mundle* and Court Sandau Presented at: SPE/CSGM Gas Migration Challenges – Identification and Treatment Workshop May 13-14, 2015 SPE Gas Migration Workshop May 13-14, 2015
  2. 2. © 2015 Chemistry Matters Inc. o  Geochemical characterization of sources to identify ‘fugitive’ gas/fluid migration in the oil/gas sector Geochemical ‘fingerprinting 2SPE Gas Migration Workshop May 13-14, 2015
  3. 3. © 2015 Chemistry Matters Inc. o  Surface casing used to protect shallow (potable) aquifers o  Gas (and fluids) in SCVs migrate from deeper zones 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 SPE Gas Migration Workshop May 13-14, 2015 3
  4. 4. © 2015 Chemistry Matters Inc. Geochemical characterizations & forensics o  Gases/fluids for different zones can be ‘fingerprinted’ o  But why do you keep getting burned with this approach? SPE Gas Migration Workshop May 13-14, 2015 4
  5. 5. © 2015 Chemistry Matters Inc. 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 SPE Gas Migration Workshop May 13-14, 2015 5
  6. 6. © 2015 Chemistry Matters Inc. Don’t make assumptions based on regional geochemistry o  Where do the ‘fingerprints’ originate? o  Isotope “databases” often use regional values rather than local values that can mislead interpretations SPE Gas Migration Workshop May 13-14, 2015 6
  7. 7. © 2015 Chemistry Matters Inc. 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 SPE Gas Migration Workshop May 13-14, 2015 7
  8. 8. © 2015 Chemistry Matters Inc. Sampling can affect 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) SPE Gas Migration Workshop May 13-14, 2015 8
  9. 9. © 2015 Chemistry Matters Inc. How can you get it right every time? 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: What are the Source(s)? 1.) Fluid 2.) Gas GEOCHEMISTRY: SPE Gas Migration Workshop May 13-14, 2015 9
  10. 10. © 2015 Chemistry Matters Inc. 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 SPE Gas Migration Workshop May 13-14, 2015 10
  11. 11. © 2015 Chemistry Matters Inc. No insight from water isotopes o  Water isotopes implicated groundwater sources that conflicted with other indicators (chlorides, TDS, etc.) SPE Gas Migration Workshop May 13-14, 2015 11
  12. 12. © 2015 Chemistry Matters Inc. A clearer picture with advanced analyses o  Different sources had characteristic ranges of concentrations and isotope values. This provided first line of evidence to indicate that different source zones can be identified SPE Gas Migration Workshop May 13-14, 2015 12
  13. 13. © 2015 Chemistry Matters Inc. Identifying source zones o  Fluids provide a line of evidence for potential sources, but they do not provide a refined interpretation SPE Gas Migration Workshop May 13-14, 2015 13
  14. 14. © 2015 Chemistry Matters Inc. 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 SPE Gas Migration Workshop May 13-14, 2015 14
  15. 15. © 2015 Chemistry Matters Inc. 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 SPE Gas Migration Workshop May 13-14, 2015 15
  16. 16. © 2015 Chemistry Matters Inc. δ13C Values GASES C1 C2 C3 SCV A - 13.1 B - 8.1 bdl Casing A* B* C* Resolving the depth of source zone o  Mudgas log can refine cretaceous leak to within 200-300m range SPE Gas Migration Workshop May 13-14, 2015 16
  17. 17. © 2015 Chemistry Matters Inc. Simpler case study: High gas flows •  SCV had high gas flow •  No fluids •  Commercial isotope interpretations were consistently picking the wrong depth/zone SPE Gas Migration Workshop May 13-14, 2015 17
  18. 18. © 2015 Chemistry Matters Inc. Bulk gas compositions gave little insight o  Data equally implicates different zones and/or mixtures 18SPE Gas Migration Workshop May 13-14, 2015
  19. 19. © 2015 Chemistry Matters Inc. Carbon isotopes suggest different zones o  Data could implicate two different zones 19SPE Gas Migration Workshop May 13-14, 2015
  20. 20. © 2015 Chemistry Matters Inc. Advanced models implicate same zone o  All leaks actually from similar zone! 20SPE Gas Migration Workshop May 13-14, 2015
  21. 21. © 2015 Chemistry Matters Inc. Did it work? •  Similar zone implicated for all SCV in area •  Gas zone overlying production zone implicated •  Cement squeezes successful at predicted depth for all interventions undertaken in 2014 SPE Gas Migration Workshop May 13-14, 2015 21
  22. 22. © 2015 Chemistry Matters Inc. Where can it all go wrong? •  Similar altered isotope ‘fingerprints can be expected from different sources SPE Gas Migration Workshop May 13-14, 2015 22
  23. 23. © 2015 Chemistry Matters Inc. Best practices for SCV ‘geoforensics’ •  Collect high quality samples •  Collect samples for potential source(s) and from the production casing (if possible) •  Start with basic chemistry but may need more conservative analytes and advanced interpretations •  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. SPE Gas Migration Workshop May 13-14, 2015 23
  24. 24. © 2015 Chemistry Matters Inc. Thank You csandau@chemistry-matters.com www.chemistry-matters.com 403.669.8569 24

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