Identifying the Sources of Fugitive Methane …...Identifying the Sources of Fugitive Methane...
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Identifying the Sources of Fugitive Methane Associated with Shale Gas Development, updated with new data, Jan 2012 Karlis Muehlenbachs Department of Earth and Atmospheric Sciences University of Alberta Edmonton, Canada [email protected] Original presented on Nov. 14, 2011 at “Managing the risks of shale gas: Identifying a pathway toward responsible development” held at Resources For the Future, Washington, DC. http://www.rff.org/Events/Pages/Managing-the-Risks-of-Shale-Gas.aspx
Transcript of Identifying the Sources of Fugitive Methane …...Identifying the Sources of Fugitive Methane...
Identifying the Sources of Fugitive MethaneAssociated with Shale Gas Development,
updated with new data, Jan 2012
Karlis MuehlenbachsDepartment of Earth and Atmospheric Sciences
University of AlbertaEdmonton, Canada
Original presented on Nov. 14, 2011 at “Managing the risks of shalegas: Identifying a pathway toward responsible development” held atResources For the Future, Washington, DC.http://www.rff.org/Events/Pages/Managing-the-Risks-of-Shale-Gas.aspx
http://shakespearessister.blogspot.com/2011/09/holy-shit.htmlhttp://inafutureage.wordpress.com/2010/06/22/your-land-my-land-gasland/
http://www.treehugger.com/natural-sciences/alberta-oil-gas-collateral-damage-she-can-light-her-water-on-fire.html
Source of gas in burningwater:
Industry induced
Or natural background?
Natural gas seeps
Eternal flame,Chimaera Turkey
NW Alberta,Canada
Gas well, leaking 1914-2010,Turner Valley, Alberta
http://www.tcgasmap.org/media/Ingraffea%20Slides%207-25-11.pdf
Well Head, Dimock, PA
Anthropogenic gas seeps
M. Schoell
Incr
easi
ng d
epth
M. Schoell
Incr
easi
ng d
epth
Biogenic gas
M. Schoell
Incr
easi
ng d
epth
Biogenic gasTherm
ogenic gas
M. Schoell
Incr
easi
ng d
epth
Biogenic gasTherm
ogenic gas
Methane from shale gas
M. Schoell
Incr
easi
ng d
epth
Biogenic gasTherm
ogenic gas
Methane from shale gas, also has unique anddiagnostic ethane and propane values
Yes, but, what happens if the job isnot done right?
How frequently are instances of poorcementing and casing problemsencountered?
Tubing Leak
Microannulus
Poor muddisplacement
Cement not Gas tight
Poor cementing and tubingfailures lead to gas migratingto surface, causing:
Sustained casing pressure
Surface casing gas
From Schlumberger, Oilfield review
Tubing Leak
Microannulus
Poor muddisplacement
Cement not Gas tight
Poor cementing and tubingfailures lead to gas migratingto surface, causing:
Sustained casing pressure
Surface casing gas
From Schlumberger, Oilfield review
Note: gas can leak fromproduction tubing or fromanywhere up the well boreleading toSoil contamination
Aquifer contamination
Problems and poor cementing are common and leadto gas migration and sustained casing pressure
From Schlumberger, Oilfield review
A series of casings are placed to interceptfugitive gas migrating along well bores
Schematicstratigraphy
A series of casings are placed to interceptfugitive gas migrating along well bores
More than 70% of casing gasesdo not come from target zone,but from intermediate layers.
Schematicstratigraphy
A series of casings are placed to interceptfugitive gas migrating along well bores
More than 70% of casing gasesdo not come from target zone,but from intermediate layers.
But are casings effective in preventing gasmigration to surface?
Schematicstratigraphy
production gas surface casing gas gas bubbles wellcellar *
methane -37.17 -38.37 -36.61ethane -41.12 -37.54 -41.49
propane -39.54 -32.08 -36.23
Carbon isotope valuesExample from St Edouard Hz1a, Quebec
Schematicstratigraphy
Not relatedto QuebecStratigraphy
*Analysis are of gasfrom standing water inthe well cellar. No datarelated to ground waterat this well.
production gas surface casing gas gas bubbles wellcellar *
methane -37.17 -38.37 -36.61ethane -41.12 -37.54 -41.49
propane -39.54 -32.08 -36.23
Carbon isotope valuesExample from St Edouard Hz1a, Quebec
Schematicstratigraphy
Not relatedto QuebecStratigraphy
*Analysis are of gasfrom standing water inthe well cellar. No datarelated to ground waterat this well.
“roll over”or reversal,diagnosticof shale gas
production gas surface casing gas gas bubbles wellcellar*
methane -37.17 -38.37 -36.61ethane -41.12 -37.54 -41.49
propane -39.54 -32.08 -36.23
Carbon isotope valuesExample from St Edouard Hz1a, Quebec
Schematicstratigraphy
Not relatedto QuebecStratigraphy
*Analysis are of gasfrom standing water inthe well cellar. No datarelated to ground waterat this well.
“roll over”or reversal,diagnosticof shale gas
Gas in sump may come fromproduction zone
production gas surface casing gas gas bubbles wellcellar *
methane -37.17 -38.37 -36.61ethane -41.12 -37.54 -41.49
propane -39.54 -32.08 -36.23
Carbon isotope valuesExample from St Edouard Hz1a, Quebec
Schematicstratigraphy
Not relatedto QuebecStratigraphy
*Analysis are of gasfrom standing water inthe well cellar. No datarelated to ground waterat this well.
“roll over”or reversal,diagnosticof shale gas
NormalThermogenic,Source depth?
Carbon isotope variation of gases with depth from Quebec
Reversal
Utica
Lorraine
Profiles constructed from gas in cuttings
750
1000
1250
1500
1750
2000
TVD(m)
Carbon isotope (per mil)Profile courtesy of Talisman Energy (Chatellier et al., 2012 in prep)
▼Isotope fingerprintC1 -38.37C2 -37.54C3 -32.08
●■
The source depth of thesurface casing gas from StEdouard Hz1a may beabout 1500 m as revealedby comparing its isotopefingerprint with the profile:
production gas surface casing gas gas bubbles inwell cellar*
methane -35.79 -43.97 -41.42ethane -36.05 -34.55 -33.42
propane -28.26 -29.07 -27.39
Carbon isotope valuesExample from Gentilley 2, Quebec
Schematicstratigraphy
Not relatedto QuebecStratigraphy
*Analysis are of gasfrom standing water inthe well cellar. No datarelated to ground waterat this well.
Carbon isotope variation of gases with depth from Quebec
Reversal
Utica
Lorraine
Profiles constructed from gas in cuttings
750
1000
1250
1500
1750
2000
TVD(m)
Carbon isotope (per mil)Profile courtesy of Talisman Energy (Chatellier et al., 2012 in prep)
▼
Isotope fingerprintC1 -43.97C2 -34.55C3 -29.07
●■
The source depth of thesurface casing gas fromGentilley 2 may be about1000 m as revealed bycomparing its isotopefingerprint with the profile:
Carbon isotope variation of gases with depth from Quebec
Reversal
Utica
Lorraine
Profiles constructed from gas in cuttings
750
1000
1250
1500
1750
2000
TVD(m)
Carbon isotope (per mil)Profile courtesy of Talisman Energy (Chatellier et al., 2012 in prep)
▼
Isotope fingerprintC1 -41.42C2 -33.42C3 -27.39
●■
The source depth of gas inthe water in the well cellarfrom Gentilley 2 may beabout 1300 m as revealedby comparing its isotopefingerprint with the profile:
Quebec data summary
• Gas analysis are from surface casingvents and from standing water in cellarsnear the well head
Not from the Aquifer
• No data related to groundwater isavailable
• Isotopic profiling is very useful todetermine the source of gas.
An example from a shale gas well from PennsylvaniaCarbon isotope values
An example from a shale gas well from PennsylvaniaCarbon isotope values
“roll over”or reversal,diagnosticof shalegas
An example from a shale gas well from PennsylvaniaCarbon isotope values The gas isotope fingerprints
are the same. Gas from theproduction zone has reachedthe surface.
What is the source of methane in water wells?
Authors:
1) Gas released byhydraulic fracturing
2) Gas from faulty wellbores/cement failure.
Critics:
1) Gas not proven to befrom hydraulicfracturing
2) Gas may be naturalbackground methane
3) Gas leaked from old wells
4) Gas from faulty wellbores/cement failure.
More isotope data needed but whatwould conclusively ID problem gas?Need isotope fingerprints for:
• Pre-drilling baseline for water wells• Ethane (and propane) of water wells• Gas from legacy/abandoned wells• Gas in natural springs and seeps• Gases from well casings• Of production gases• Mud gas isotope profiles in area.
More isotope data needed but whatwould conclusively ID problem gas?Need isotope fingerprints for:
• Pre-drilling baseline for water wells• Ethane (and propane) of water wells• Gas from legacy/abandoned wells• Gas in natural springs and seeps• Gases from well casings• Of production gases• Mud gas isotope profiles in area.
To identify specific sources of gas contamination ingroundwater we need to mandate baseline isotopicfingerprinting of methane, ethane and propane for:
–Pre-development water wells–Production gases–Detailed gas isotope stratigraphy (mudgas isotope log)–Gases from:
– conductor, surface and intermediate casings– legacy wells if present– natural seeps, springs and soil.
Conclusions and suggestions to Industry and regulators:
To identify specific sources of gas contamination ingroundwater we need to mandate baseline isotopicfingerprinting of methane, ethane and propane for:
–Pre-development water wells–Production gases–Detailed gas isotope stratigraphy (mudgas isotope log)–Gases from:
– conductor, surface and intermediate casings– legacy wells if present– natural seeps, springs and soil.
Conclusions and suggestions to Industry and regulators:
*The above requirements are not onerous.
