evolution of li-enriched oilfield brines in devonian...
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Evolution of Li-enriched oilfield brines
in Devonian carbonates of the south-
central Alberta Basin, Canada
G.F. Huff, Alberta Geological Survey
Purpose
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• Understand the origins of Li-enriched oilfield brines found
in Devonian carbonates of eastern-central Alberta.
• Definition:
Li-enriched > 50 mg/kg.
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Samples from Carbonates
Samples from Clastics
Evaporites
Dolomitized Carbonates
Non-Dolomitized Carbonates
Gas Pools
Oil Pools
Eccles and Berhane 2011, AGS OFR 2011-10
Current Thought
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• Brines present in east-central Alberta formed by
evaporation of ancient seawater past the point of halite
saturation followed by mixing with meteoric water
• Brines present in east-central Alberta formed by halite
dissolution
• Both
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0
100
200
300
400
0 50 100 150 200 250
Cl/B
r (m
ass)
Na/Br (mass)
Viking and Cardium Formations
Mannville Group
Wabamun Group and BanffFormation
Nisku Formation
Leduc Formation
Swan Hills Formation
Modern Seawater (Drever, 1982)
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Samples from Carbonates
Evaporites
Dolomitized Carbonates
Non-Dolomitized Carbonates
Gas Pools
Oil Pools
Eccles and Berhane 2011 AGS OFR 2011-10
Lithium ≥ 50 mg/kg
10
0
10
20
30
40
50
60
70
80
90
0.706 0.711 0.716 0.721 0.726
Li, m
g/K
g
87Sr/86Sr
Viking and Cardium Formations
Mannville Group
Wabamun Group and Banff Formation
Nisku Formation
Leduc Formation
Swan Hills Formation
Li enrichment from crustal fluids
(Eccles and Berhane, 2011) and
possibly formed through halite
dissolution
www.ags.gov.ab.ca
12 www.ags.gov.ab.ca
-140
-120
-100
-80
-60
-40
-20 -15 -10 -5 0 5 10
d2H
(o
/oo
)
d18O (o/oo)
Viking and Cardium Formations
Mannville Group
Wabamun Group and Banff Formation
Nisku Formation
Leduc Formation
Global Meteoric Water Line (Craig, 1961)
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0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40 50 60
Cl, m
mo
l/kg
H2O
Br, mmol/kg H2O
Viking/Cardium
Mannville Group
Wabamun/Banff/Nordegg
Nisku
Leduc
SET (McCaffrey et al., 1987)
15X 35X
Problem
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How do we explain Li-enrichment in a brine that shows
• No 87Sr/86Sr evidence of Li derived from silicates,
• Oxygen and hydrogen isotope ratios characteristic of evaporation, and
• Cl/Br ratios indicating a degree (but not enough) evapoconcentration?
Proposed Solution:
• Concentrate Br and Li,
• Mobilize them into evaporated seawater, and
• Get the brines from where they formed to where we found them.
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Wright et al., 1994
D D’ Step 1 – Concentrate Br and Li
D D’
Potash mineralization • Sylvite • Carnallite Remobilization/dissolution of potash minerals
Step 2 – Remobilize late-stage evaporites into
evaporated middle Devonian seawater
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• Remobilizing brine saturated with regard to halite but
undersaturated with regard to potash minerals?
– Storm events?
• Collect the Li and Br enriched brines in underlying
permeable carbonate (Winnipegosis/Contact Rapids)
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Step 3 – Tip the carbonates westward and allow the dense
Li-enriched brines to flow west
Wright et al., 1994
D D’
D D’
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Step 4 – Establish deep penetration of meteoric water due
to topography caused by Laramide Orogeny
Wright et al., 1994
D D’
D D’
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Samples from Carbonates
Evaporites
Dolomitized Carbonates
Non-Dolomitized Carbonates
Gas Pools
Oil Pools
Lithium ≥ 50 mg/kg in Leduc reefs and overlying
Nisku carbonates
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0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40 50 60
Cl, m
mo
l/kg
H2O
Br, mmol/kg H2O
Viking/Cardium
Mannville Group
Wabamun/Banff/Nordegg
Nisku
Leduc
SET (McCaffrey et al., 1987)
15X 35X
Br enrichment associated with
remobilization/dissolution of potash minerals?
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0
100
200
300
400
0 50 100 150 200 250
Cl/B
r (m
ass)
Na/Br (mass)
Viking and Cardium Formations
Mannville Group
Wabamun Group and Banff Formation
Nisku Formation
Leduc Formation
Swan Hills Formation
Modern Seawater (Drever, 1982)
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