a3 léa lévy electrical conduction of low-salinity hydrothermal systems: a quantitative measure of...

Léa Lévy - GEORG conference 1

ELECTRICAL CONDUCTION: A QUANTITATIVE MEASURE OF THE

SMECTITE AND CHLORITE CONTENT?STUDY BASED ON CORES FROM KRAFLA

24.11.2016

LÉA LÉVYIN COLLABORATION WITH:

ÓLAFUR G. FLÓVENZGYLFI PÁLL HERSIR

FREYSTEINN SIGMUNDSSONBENOIT GIBERT

AND MANY MORE


What is clay?

• CEC = Cation Exchange Capacity• Between T sheets „Internal exchange“

• Only in smectite• On the edges „External exchange“

• Minimal compared to internal• Unit = meq/100g or C/kg• Measured by chemical titration

24.11.2016

Chlorite

Illite

Smectite

• Phyllosilicates• T = tetrahedral sheet (Si)• O = octahedral sheet (Al or Mg)• Sequences T-O-T

• Substitutions Negative charge• Compensation between sheets

From multiple sources. Ex: Lyklema, 2001


Charge and mobility

24.11.2016

Internal CEC (meq/100g)

100

Smectites Illite Chlorite

# water layers

0

1

2

|Total charge|0 0.70.50.3 10.9 2

T-O No charge

T-O-T low charge

T-O-T high charge

higher charge stronger bondings structure more stableStability

Brucitic layer

Cation with 2 water shellsNothing Cations with 1 water shell Cations with 0 water shell

Weak Coulombian attraction Van der Waals bondings of increasing strength H bondings

Montmorillonite 2 water shells

From Meunier, 2000

Beidellite 1 water shell


The smectite chlorite transition

• Kinetic vs thermodynamics• Intermediary step

• Hydrothermal convection vs heat conduction

• Presence/absence of smectite

24.11.2016

„Smectite is a kinetic step in the formation of chlorite by hydrothermal convection.“

Electrical conduction

Chlorite

precipitation

Unstable smectite

Weak bondings

Hydrothermal convection

Low charge


Context of the study

24.11.2016

(b)

KH-5 (a) 288m – Epidote, quartz, wairakite. (b) 279 m – Epidote overprinted by laumontite.

(c) (d)

KH6. 594 m – Zeolite transforming into wairakite.

(b)

KH-3 – 273 m. Precipitation of MLC and chlorite in vesicles.

KH-1. 74 m – Stilbite and smectite.

Map by Þorbergsson and Víkingsson, 2016


Clay content and CEC

24.11.20160% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50CEC and clay fraction of whole rock samples

Based on XRD {d(001) + d(002)}

Clay fraction (XRD)

CEC

meq

/100

g



24.11.2016

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50

f(x) = 85.6732646863277 xR² = 0.998964852312329

f(x) = 109.554255319498 xR² = 0.992382803702646

CEC and clay fraction of whole rock samplesBased on XRD {d(001) + d(002)}100% smectite

Linear (100% smectite)75% smectite

Clay fraction (XRD)

CEC

meq

/100

g

𝐶𝐸𝐶0=110meq /100 g



24.11.20160% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50

f(x) = 67.3605198067388 xR² = 0.995675531585296

f(x) = 85.6732646863277 xR² = 0.998964852312329

f(x) = 109.554255319498 xR² = 0.992382803702646

CEC and clay fraction of whole rock samplesBased on XRD {d(001) + d(002)}100% smectite

Linear (100% smectite)75% smectiteLinear (75% smectite)

Clay fraction (XRD)

CEC

meq

/100

g

𝐶𝐸𝐶0=110meq /100 g



24.11.20160% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50

f(x) = 22.9271506126017 xR² = 0.991618970236235

f(x) = NaN xR² = 0f(x) = NaN xR² = 0f(x) = NaN xR² = 0f(x) = NaN xR² = 0 CEC and clay fraction of whole rock samples

Based on XRD {d(001) + d(002)}100% smectiteLinear (100% smectite)75% smectiteLinear (75% smectite)60% smectiteLinear (60% smectite)40% smectite

Clay fraction (XRD)

CEC

meq

/100

g

𝐶𝐸𝐶0=110meq /100 g



24.11.20160% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50

f(x) = 11.4645347289964 xR² = 0.906321037448669

f(x) = 22.9271506126017 xR² = 0.991618970236235

f(x) = NaN xR² = 0f(x) = NaN xR² = 0f(x) = NaN xR² = 0f(x) = NaN xR² = 0 CEC and clay fraction of whole rock samples

Based on XRD {d(001) + d(002)}100% smectiteLinear (100% smectite)75% smectiteLinear (75% smectite)60% smectiteLinear (60% smectite)40% smectite

Clay fraction (XRD)

CEC

meq

/100

g

𝐶𝐸𝐶0=110meq /100 g

Conductivity and CEC

24.11.2016 Léa Lévy - GEORG conference 11

𝜎 𝑏𝑢𝑙𝑘=𝜎𝑤

𝐹 +𝜎𝑠

1% 10% 100%10

100

1,000f(x) = 3.7495642436383 x^-1.88521828150962R² = 0.758377622899604

Formation factor and porosity

Porosity

Form

ation

fact

or

0.01 0.1 1 101E-03

1E-02

1E-01

1E+00Bulk conductivity vs fluid conductivity

Fluid conductivity (S/m)

Bulk

con

ducti

vity

(S/m

)

𝑚=1.89

1/F𝜎 𝑠

0 1 10 1001E-04

1E-03

1E-02

1E-01

1E+00

R² = 0.637033931540875

R² = 0.888254949986008

Interface conductivity vs CEC

Cs*F*PorPower (Cs*F*Por)

CEC (meq/100g)

Cond

uctiv

ity (S

/m)

m Rock type Published in

1.33 Seafloor MAR Pezard, 19901.74-2.43 Shaly sands Waxman & Smits, 1968

2.45 Hawaiian basalt Revil et al., 20162.75 Icelandic basalt Flóvenz et al., 2005

Fluid conductivity

Formation factor

Clay „Interface“ conductivity

𝜎 𝑠=f (CEC , F ,∅ )

𝐹=a∅−𝑚

Porosity

(Waxman & Smits, 1968)

(Archie, 1942)

Contribution of claySmall

Moderate High

12

Conductivity and smectite

24.11.2016 Léa Lévy - GEORG conference

𝜎 𝑠∗F ∗∅= f (CEC )=f (smec%)

1% 10% 100%1E-03

1E-02

1E-01

1E+00

Normalized interface conductivity vs clay%

Clay >50% smectiteClay 20-50% smectiteClay < 20% smectite

Clay fraction in the whole rock (XRD)

Whole rock < 2% smectiteBetween 7 and 20% of clay 5 to 18% chlorite in whole rock

0% 1% 10% 100%1E-03

1E-02

1E-01

1E+00

R² = 0.912397564063714

Normalized interface conductivity vs smectite%

Meaningful smectite content (> 1 %)Power (Meaningful smectite content (> 1 %))

Smectite fraction in the whole rock (CEC)

Cond

uctiv

ity (S

/m)

𝑤𝑡% (𝑠𝑚𝑒𝑐)=𝐶𝐸𝐶𝐶𝐸𝐶0

𝐶𝐸𝐶0=110meq /100 g


Conclusions• Electrical conductivity measures the smectite content

• At low-salinity• Normalized by F*φ• Independent of chlorite content

• Weak bondings in smectite are a key in geothermal exploration• Smectite content is a measure of hydrothermal activity (unstability)• Smectite content can be measured by electrical conduction (CEC)

Could we use the evolution of the smectite content to locate the transition between heat convection

and heat conduction?24.11.2016


Thank you !OTHER SCIENTISTS I WOULD LIKE TO ACKNOWLEDGE INCLUDE

PHILIPPE PEZARDPIERRE BRIOLE

SIGURÐUR SVEINN JÓNSSONÞRÁINN FRIÐRIKSSON

HELGA M. HELGADÓTTIRHJALTI FRANZSON

ANDRÉ REVILALAIN MEUNIER

PHILIPPE COSENZA

24.11.2016


Appendix

24.11.2016


Complex conductivity

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𝜎 𝑏𝑢𝑙𝑘∗ =𝜎 ′+𝑖𝜎 ′ ′

Carry an electrical current Stores electrical charges𝜎 ′= f (𝜎𝑤 ,CEC , F ,∅ )

(

1E+02 1E+03 1E+04 1E+051E-03

1E-02

1E-01

1E+00

f(x) = 0.00051061239042286 x^0.456852491142259R² = 0.544357484627649

Correlation of quadrature conductivity (using dif -ferent correction factors) and CEC

C''*F 10 Hz Cw=1,5 S/m

CEC (C/kg)

Qua

drat

ure

Cond

uctiv

ity (S

/m)


Comparison between borehole conductivity (from the 64'' resistivity log) and CEC from cuttings in borehole KJ-18

Conductivity and CEC in borehole KJ-18

CEC (cuttings) and conductivity (borehole log)

24.11.2016


Thermodynamics of cation exchange

0 100 200 300 400 500 600 700 8000

5

10

15

20

25

30

35

40

Variation of apparent CEC with rock massInitial concentration of Cu-trien varies between 1.52x10-3 and 1.73x10-3 mol/L

L81L82L96L40L31L22L16L14L11L09L06L99

mass of rock / initial concentration in mg/(mol/L)

CEC

appa

rent

(meq

/100

g)

24.11.2016


0 50 100 150 2000

5

10

15

20

25

30

L22 - CEC and K DeterminationK = 100

CEC = 24,2

(e)

0 20 40 60 80 100120140 1601802000

5

10

15

20

25

30

35

40


CEC = 38

Cu(t

rien)

cons

umed

by

the

reac

tion

in m

eq/1

00g

05

10152025303540


CEC = 37

0 20 40 60 80 100 120 140 160 180 2000

5

10

15

20

25

30

35


CEC = 32.8

2VCi/m = Initial Cu(trien) content in meq/100g

Cu(t

rien)

con

sum

ed b

y th

e re

actio

n in

m

eq/1

00g

0 40 80120

160200

05

10152025303540


CEC = 34


(a)

(c)

(d)

(b)

0 20 40 60 80 1001201401601802000

5

10

15

20

25

L11 - CEC and K DeterminationK = 50 or 25

CEC = 23,2 or 21,8


(f)

Analytical fit of experimental observations

24.11.2016


Normalization of interface conductivity

24.11.2016

0 1 10 1001E-04

1E-03

1E-02

1E-01

1E+00

1E+01

R² = 0.637033931540875

R² = 0.888254949986008

R² = 0.845168057471815

Interface conductivity vs CEC

Cs*FPower (Cs*F)

CEC (meq/100g)

Cond

uctiv

ity (S

/m)


References• Flóvenz, Ó. G., Spangenberg, E., Kulenkampff, J., Árnason, K., Karlsdóttir, R. and Huenges, E. (2005). The role of

electrical interface conduction in geothermal exploration. World Geothermal Congress, Ankara, Turkey, 2005.• Lyklema, J. (2001). Fundamentals of Interface and Colloid Science. Volume II Solid-Liquid Interfaces. Academic

Press.• Meier, L. and Kahr, G. (1999). Determination of the Cation Exchange Capacity (CEC) of Clay Minerals Using the

Complexes of Copper(II) Ion with Triethylenetetramine and Tetraethylenepentamine. Clays and Clay Minerals 47(3), 386–388.

• Meunier, A. (2013). Les argiles par la pratique. Vuibert• Pezard, P. A. (1990). Electrical properties of mid-ocean ridge basalt and implications for the structure of the

upper oceanic crust in Hole 504B. Journal of Geophysical Research 95(B6), 9237.• Vinegar, H. J. and Waxman, M.H. (1984). Induced polarization of shaly sands. Geophysics 49(8), 1267–1287.• Revil, A., Le Breton, M., Niu, Q., Wallin, E., Haskins, E. and Thomas, D.M. (2016). Induced polarization of

volcanic rocks. I. Surface versus quadrature conductivity. In press.• Waxman, M. H. and L. J. M. Smits (1968). Electrical conductivities in oil-bearing shaly sands. Soc. Pet. Eng. J. 8,

107–122.

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24.11.2016

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%0

5

10

15

20

25

30

35

40

45

50

f(x) = 9.20391697567538 xR² = 0.76237034371547

f(x) = 36.0222172472408 xR² = 0.944495433329317

f(x) = 67.8609886672848 xR² = 0.994174302124352

f(x) = 92.2302711736049 xR² = 0.982512087330206

CEC and clay fraction – based on the sum of d(001) and d(002) areas – of whole rock samples

Clay >90% SmectiteLinear (Clay >90% Smectite)MLC with 50-90% smectiteLinear (MLC with 50-90% smectite)MLC with 20-50% smectite

Clay fraction (assuming the highest has 50% of clay)

CEC

meq

/100

g

𝐶𝐸𝐶0=110meq /100 g

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