Transcript The Abandoned Wells Project, SW Ontario: Finding a Solution to Determining Natural Gas and Aquifer Sources

The Abandoned Works Program, SW
Ontario: identifying the sources of
leaking formation waters and natural
gases
J. Potter, M. Skuce, F.J. Longstaffe, T.
Carter, L. Fortner
The University of Western Ontario
The Ministry of Natural Resources
The Problem:
Potentially >22,000 leaking wells in the
province that have not been fully recorded
 The Abandoned Works Program was set up by the Ministry
to confront this problem and establish a remediation program
 Plugging a well that has good records can cost ~$10,000
but “problematic” wells have been known to exceed the
$250,000 mark before successfully sealed
TYPICAL WELL CONSTRUCTION
TYPICAL WELL CONSTRUCTION
Abandoned Works
OIL/GAS
OIL/GAS
SURFACE CASING
SURFACE CASING
SURFACE SEDIMENTS
SURF
ACE SEDIMENT
FRESH
WATER S
FRESH WATER
SHALE
SHALE
SALTY WATER IN SANDSTONE
Which formation is source of the
sulfur water/oil/gas?
Where do plugs need to be set to
confine the aquifers?
Which formations are competent for
setting of plugs?
Where has casing corrosion likely
occurred?
SALTY WATER IN SANDSTONE
SHALE
SHALE
INTERMEDIATE CASING
INTERMEDIATE CASING
HO LE
HO LE
CEMENTSHEATH
CEMENTSHEATH
PRODUCTIO N CASING
PRODUCTIO N CASING
PRODUC TION TUBING
PRODUC TION TUBING
ANNULUS
ANNULUS
PACKER
PACKER
PERFORAT
RFORATIONS
IONS
PE
LIMESTONE
LIMESTONE
SANDSTONE
SANDSTONE
DOLOMITE
DOLOMITE
SHALE
SHALE
LIMESTONE
LIMESTONE
PR
PRO
O DUCT
DUCTION
ION FORMAT
FORMATION
ION
SHALE
SHALE
The Aim:
Identifying fluids from specific horizons
 Characterise the geochemical and isotopic compositions of
natural gases and waters from SW Ontario reservoirs and
aquifers, and use this knowledge to determine the source(s) of
gases/waters leaking from abandoned wells.
are there any differences between stratigraphic levels
 are any differences geographically related
 can we differentiate between these reservoirs and what
they may show with regard to origin
Analyses being done:
Geochemical analysis of waters
O and H-isotopes (water)
S and O-isotopes (sulphate)
C-isotopes (DIC)
Sr in water
C and H-isotopes (natural gas)
Water well records - MOE
(from Singer, Cheng, and Scafe 1997)
Petroleum Well Records - MNR
What can stable isotopes of natural gases
tell us?
Utilising methane isotope results can provide us with a
glimpse of how these gases were formed and subsequently
altered
now d2H
Whiticar (1999)
What can stable isotopes of natural gases
tell us?
 Methane and higher hydrocarbon isotopic compositions
can be modified by a number of processes (main processes
being):
 degree of thermogenic “cooking”
 mixing of reservoirs
 microbial methanogenesis
 microbial oxidation
 The d13C and d2H differences between methane (C1) and
higher hydrocarbons (C2+) can provide valuable information
including
 those diagnostic features that we are looking for and..
 how they were formed and subsequently altered due to
mixing, fluid infiltration and microbial interaction
Carbon- and hydrogen-isotope results of
methane – all results
A2 carb
-60.0
A1 carb
incr. microbial
influence
-55.0
Guelph
d13CCH4 ‰ (VPDB)
Thorold
-50.0
Grimsby
Whirlpool
-45.0
Trenton
-40.0
Black River
incr.
thermogenic
maturity
-35.0
Cambrian
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Hydrogen-isotope results of methane and ethane
A2
-260
A1
d2HC2H6 ‰ (VSMOW)
-240
Guelph
incr.
thermogenic
maturity
-220
Thorold
Grimsby
Whirlpool
-200
Trenton
-180
Black River
Cambrian
-160
-140
incr. microbial
influence?
-120
-100
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Cambrian
Cambrian - Oxford
-60.0
Cambrian - Kent
d13CCH4 ‰ (VPDB)
-55.0
Cambrian - Perth
-50.0
? T008045
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Lower Ordovician Black River
-60.0
Black River - Lambton
Black River - Essex
d13CCH4 ‰ (VPDB)
-55.0
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Middle Ordovician Trenton
-60.0
Trenton - Lambton
Trenton - Essex
-55.0
d13CCH4 ‰ (VPDB)
Trenton - Kent
Trenton - Elgin
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Lower Silurian Whirlpool
-60.0
Whirlpool - Haldimand
d13CCH4 ‰ (VPDB)
-55.0
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-280
-260
-240
-220
-200
-180
d2HCH4 ‰ (VSMOW)
-160
-140
-120
-100
d13CCH4 ‰ (VPDB)
Carbon- and hydrogen-isotope results of methane Lower
Silurian Grimsby
-60.0
Grimsby - Norfolk
-55.0
Grimsby - Elgin
-50.0
Grimsby - Thorold - Norfolk
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300.0
-250.0
-200.0
d2HCH4 ‰ (VSMOW)
-150.0
-100.0
Carbon- and hydrogen-isotope results of methane
Lower-Mid Silurian Thorold
-60.0
Thorold - SW Norfolk
d13CCH4 ‰ (VPDB)
-55.0
Thorold - NE Norfolk
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300.0
-250.0
-200.0
d2HCH4 ‰ (VSMOW)
-150.0
-100.0
d13CCH4 ‰ (VPDB)
Carbon- and hydrogen-isotope results of methane –
Middle Silurian Guelph
-60.0
Guelph - Lambton - Sombra
-55.0
Guelph - Lambton Enniskillen
-50.0
Guelph - Huron - Goderich
-45.0
Guelph - Huron - South Huron
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Upper Silurian A1 unit
-60.0
A1 - Lambton
-55.0
d13CCH4 ‰ (VPDB)
A1 - Kent
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Carbon- and hydrogen-isotope results of methane
Upper Silurian A2 unit
A2 -Lambton
-60.0
A2 - Kent
d13CCH4 ‰ (VPDB)
-55.0
-50.0
-45.0
-40.0
-35.0
-30.0
-25.0
-20.0
-300
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Our first unknown sample! The $250,000 question.
microbial CH4 fermentation –
terrestrial
-65
-60
microbial CH4 CO2
–reduction mainly marine
Unknown - Vienna
A2 carb
d13CCH4 ‰ (VPDB)
A1 carb
-55
Guelph
Thorold
-50
incr. maturity
-45
Grimsby
Whirlpool
-40
Trenton
-35
Black River
Cambrian
-30
-25
-20
-300
Lowest d13CCH4 observed so far.
Mix of near surface microbial CH4 + thermogenic?
d13CCO2 = -20‰
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Hydrogen-isotope results of methane and ethane
-260
d2H results for unknown
outside all fields
Unknown
A2
d2HC2H6 ‰ (VSMOW)
-240
A1
incr. maturity
-220
Guelph
-200
Thorold
-180
Grimsby
Whirlpool
-160
Trenton
Microbial
input?
-140
Black River
-120
-100
-300
Cambrian
-250
-200
d2HCH4 ‰ (VSMOW)
-150
-100
Hydrogen-isotope results for methane vs ethane in the Black
River and Trenton pools
Thorold
-220.0
Grimsby
Inverse trend
Trenton
-200.0
d2HC2H6 ‰ (VSMOW)
Black River
Cambrian
-180.0
-160.0
-140.0
Normal trend
-120.0
-100.0
-220.0
-200.0
-180.0
-160.0
-140.0
-120.0
-100.0
d2HCH4 ‰ (VSMOW)
In most thermogenic gas reservoirs d2HCH4 < d2HC2H6 but here we
observe a diagnostic feature where d2HCH4 ~ d2HC2H6
SUMMARY OF ISOTOPIC DATA FOR THE NATURAL GASES
A series of diagnostic features have so far been identified:
 The Cambrian gases are generally the most thermogenically mature
With decreasing age of reservoir, in general, a thermogenic trend to
less mature gases is observed
 The Ordovician Black River and Trenton natural gas samples
have distinct d2H values for CH4 and C2H6 that are easily
recognisable
- they are = or slightly inversed.
The Silurian Whirlpool and Thorold samples are immature with
respect to the Grimsby reservoir of the same age in the same area.
- they also sit slightly off the thermogenic trend
- more data required – geographically controlled?
SUMMARY OF ISOTOPIC DATA FOR THE NATURAL GASES
A series of diagnostic features have so far been identified:
 The large Silurian Guelph sample dataset clearly shows a microbial
input in samples from the Lambton area. Samples from Huron are
also distinguishable from other reservoirs but do not show quite a shift
to low d13CCH4 values
- distinctly high d13CC2H6 and d13CC3H8 values relative to other
reservoirs
 The Silurian A1 Salina Group samples in the Lambton area overlap
the Guelph samples from this region but can be distinguished by
lower d13CC2H6 values. Samples from the Kent area are very different,
sitting on the thermogenic trend
 The Silurian A2 Salina Group samples in the Lambton and Kent
areas do not show the “Lambton anomaly” – a possible time
constraint on fluid/microbial interaction in the reservoirs in the
Lambton area?
- caution, only 3 samples!
Water isotope data
0
Deep aquifers
(~500 - 1200m)
-20
δ2H‰ (VSMOW)
-40
Shallow aquifers
(<250m)
Dundee
Columbus
-60
Lucas (Detroit River Group)
Salina F unit (*subcrop)
Salina A2 carbonate
-80
Salina A1 carbonate
Guelph/Salina A1 carb
-100
Guelph
Rochester/Irondequoit
-120
Thorold/Grimsby
Trenton-Black River Group
Cambrian
-140
-20
-15
-10
-5
δ18O‰ (VSMOW)
0
5
FURTHER WORK
 Fill in the gaps:
- more samples from the Appalachian side of the Algonquin Arch
- stratigraphic horizons of interest with respect to geographic
locality – Lambton looks v. interesting for e.g.
 Critically analyse and interpret all these data to confirm
observed patterns and ascertain how these reservoirs have
been produced/modified and/or show migration/mixing
 Continue sampling of abandoned well fluids, as and when
required, will provide an ongoing test of this geochemical tool.
 create a user-friendly platform to input gas and water isotope
analyses and statistically analyse the results of unknowns vs
knowns to ultimately identify the unknown reservoir.
 SIARS seems to be a good statistical tool at present
Acknowledgments
As always: LSIS – Kim, Li and Lisa for help on the GC, Picarro,
Gasbench and TC/EA
Paul and Wendy at GGHatch, UofO for help with sulphur isotope
analyses
Scott Mundle at UofT for keeping us entertained in the field… even if it
is his fault that we have to stand out there for an hour at a time
freezing or melting!... Lee thanks for arranging the
coldest/hottest/post-tornado blowiest days for heading out into the
backwoods!