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GeoCSI solving gas migration problems WBPC 2015

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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.

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GeoCSI solving gas migration problems WBPC 2015

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

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