Evolution of Li-enriched oilfield brines in Devonian...

Evolution of Li-enriched oilfield brines

in Devonian carbonates of the south-

central Alberta Basin, Canada

G.F. Huff, Alberta Geological Survey

Geologic Setting

2 www.ags.gov.ab.ca

D

D’

3 www.ags.gov.ab.ca

Wright et al., 1994

D D’

D

D’

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.

Sample locations

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6 www.ags.gov.ab.ca

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

7 www.ags.gov.ab.ca

• 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

8 www.ags.gov.ab.ca

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)

9 www.ags.gov.ab.ca


Evaporites



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


Mannville Group

Wabamun Group and Banff Formation

Nisku Formation

Leduc Formation


Li enrichment from crustal fluids

(Eccles and Berhane, 2011) and

possibly formed through halite

dissolution

www.ags.gov.ab.ca

11 www.ags.gov.ab.ca

Burke et al., 1982


-140

-120

-100

-80

-60

-40

-20 -15 -10 -5 0 5 10

d2H

(o

/oo

)

d18O (o/oo)


Mannville Group


Nisku Formation

Leduc Formation

Global Meteoric Water Line (Craig, 1961)


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


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.


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


• 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)


Step 3 – Tip the carbonates westward and allow the dense

Li-enriched brines to flow west

Wright et al., 1994

D D’

D D’


Step 4 – Establish deep penetration of meteoric water due

to topography caused by Laramide Orogeny

Wright et al., 1994

D D’

D D’



Evaporites



Gas Pools

Oil Pools

Lithium ≥ 50 mg/kg in Leduc reefs and overlying

Nisku carbonates


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?


0

100

200

300

400

0 50 100 150 200 250

Cl/B

r (m

ass)

Na/Br (mass)


Mannville Group


Nisku Formation

Leduc Formation


Modern Seawater (Drever, 1982)

Evolution of Li-enriched oilfield brines in Devonian...

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