Más contenido relacionado La actualidad más candente (20) Similar a GeoConvention2016_Identifying Surface Casing Vent Flows (SCVF) Using Geoforensics (20) Más de Chemistry Matters Inc. (20) GeoConvention2016_Identifying Surface Casing Vent Flows (SCVF) Using Geoforensics7. © 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
13. © 2015
Chemistry Ma2ers Inc.
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
22. © 2015
Chemistry Ma2ers Inc.
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
24. © 2015
Chemistry Ma2ers Inc.
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
Chemistry Ma2ers Inc.
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
Visit my website and sign up for email for automatic
receipt of my blogs!
Twitter: @Chem_Matters
Slideshare: www.slideshare.net/csandau
28 GeoConven)on 2016 – www.chemistry-ma:ers.com