Yu mapping geothermal reservoir cover · 2009-08-23 · SEG Las Vegas 2008 Annual Meeting Mapping geothermal reservoir using broadband MT survey in Þeistareykir, Iceland. Yu, G.,

b

Y

KMS Technologies – KJT Enterprises Inc. An EMGS/RXT company

Mapping geothermal reservoir using roadband MT survey in Þeistareykir,

Iceland.

SEG Las Vegas 2008 Annual Meeting

u, G., Allegar, N., Gunnarsson, A., He, L. F., He, Z. H., Strack, K.-M., Tulinius, H.

© 2008 KMS Technologies An EMGS/RXT company 1

Mapping geothermal reservoir using broadband MT survey in

Þeistareykir, Iceland

Yu1, G., Allegar1, N., Gunnarsson2, Á., He4, L. F., He4, Z. X., Strack1, K.-M., & Tulinius3, H.

1KMS Technologies2Landsvirkjun

3Mannvit (former VGK-Hönnun)4BGP


Outline

• Introduction• Project objectives• Data acquisition• Data processing• Modeling & inversion• Interpretation• Conclusions


Introduction

• Much of Iceland’s energy supply is geothermal energy;

• Geothermal power station site selection to build new aluminum mills;

• Geothermal field E&D are key elements for sustaining development;

• Existing TEM has very limited depth penetration (<800 m);

• Using MT to explore deep geothermal reservoirs.


Introduction


Introduction

(Trønnes, 2002)Wolfe et al., (1997), Shen et al., (2002)& Ito (2002)

Armannsson 2000


Þeistareykir geothermal & geology maps


Geological section in NW-SE direction across Krafla hydrothermal system

Jonasson, 1994


Outline



Project objectives

• Confirm TEM survey findings of a high temperature reservoir under survey area;

• Outline better boundaries of the reservoir;

• Provide basis to map temperature & permeability variation.


Outline



Magnetotelluric (MT) methodMeasures natural variation of EM field

source: ionosphere & world wide thunderstorm activity;

Source field can be handled as vertical incident plane wave,influenced by ground conductivity.

Hy

ExHx

EyHz

y

x

z

Impedance: E / H

Resistivity of ground


N

AMT site0 1000 2000 3000 40000 1000 2000 3000 4000 m

SECT 01

SECT 02

SECT 03

SECT 04

SECT 05

SECT 06

SECT 07

SECT 08

SECT 09

Completed MT survey sites

Planned MT survey sites


Field MT data acquisition


Raw MT data display (I-104)


High level noise in I-103, I-102, & I-101


Outline



MT data processing flowchart

Verify, Editing Parameter

Copy calibrating filesto computer

Check calibrating files

Check the Parameter

Setup Robust Parameter

Process data

View files Check time

Copy data to PC

Edit Data


Cross power editing

Editing is done through deleting or restoring individualcross powers in the two graphs on the right.


Comparison of noise editing

Comparison of before (Left) & after (Right) auto editing

Comparison of before (Left) & after (Right) manual editing


Outline



Resistivity model for the survey area500 m, 500 ohm-m

200 m, 100 ohm-m

500 m, 10 ohm-m

10 ohm-m

1000 m, 80 ohm-m

1000 m, 80 ohm-m

4000 m, 80 ohm-m4000 m, 80 ohm-m 2000 m, 300 ohm-m

2000 m, 30 ohm-m

O

O

O

O

O

O

OO

OO


Continuous media & nonlinear conjugate gradients inversion result

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Distance ( km )

2D (MTIS) Inversion Result of Res-xy

-8

-7

-6

-5

-4

-3

-2

-1

Dep

th (k

m)

0102025304050606265707780110125140200300400500600

ohm-m

0 1000 2000 3000 4000 5000

Distance (m)

NLCG Inversion Result of Res-xy

-8000

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Dep

th (m

)

0102025304050606265708087.595110125140200300400500600

ohm-m


Comparison of NLCG (Emage-2D) & continuous media inversion (MTIS)

0 2 4 6 8 10 12

Distance (km)

Result of MTIS

0 2000 4000 6000 8000 10000 12000

Distance (m)

Result of Emage-2D

-12000

-10000

-8000

-6000

-4000

-2000

0

Dep

th (m

)

02357911131622283440557085100200300400500


N

AMT site0 1000 2000 3000 40000 1000 2000 3000 4000 m

SECT 01

SECT 02

SECT 03

SECT 04

SECT 05

SECT 06

SECT 07

SECT 08

SECT 09

Þeistareykir MT survey profile

layout


MT inversion result of Section 01

0 1 2 3 4 5 6 7 8 9 10 11 12

Distance ( km )

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km

)U

-508

U-5

07

U-5

06U

-505

U-5

04

I-11

9

I-11

8

I-11

7

I-11

6

I-11

5

I-12

3

I-11

0

U-5

33

U-5

34

U-5

35

U-5

36

U-5

37

U-5

38

U-5

39

N

N

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m



0 1 2 3 4 5 6 7 8 9 10 11 12 13

Distance ( km )

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km

)U

-502

U-5

00

I-10

0

I-10

1

I-10

2

I-10

3

I-11

3

I-10

4

I-10

5

I-10

8

U-5

25

U-5

26

U-5

27

U-5

28

U-5

29

U-5

30

U-5

31

U-5

32

N

N

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m



0 1 2 3 4 5 6 7 8 9 10 11

Distance ( km )

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km

)I-

120

I-12

1

I-12

2

I-11

5

I-11

4

I-10

4

I-10

5

I-10

6

I-10

7

U-5

11

U-5

12

U-5

13

U-5

14

U-5

15

U-5

16

U-5

17

U-5

18PG-03PG-02

PG-01PG-04PG-05

E

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m


Outline



TEM inversion result of profile 307

Data ModelForward modeling

Inversion

Subsurface

resistivity



0 1 2 3 4 5 6 7 8 9 10 11 12 13

Distance ( km )

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km

)

U-5

02

U-5

00

I-10

0

I-10

1

I-10

2

I-10

3

I-11

3

I-10

4

I-10

5

I-10

8

U-5

25

U-5

26

U-5

27

U-5

28

U-5

29

U-5

30

U-5

31

U-5

32

N

N

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m



0 1 2 3 4 5 6 7 8 9 10 11

Distance ( km )

y

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km

)

I-12

0

I-12

1

I-12

2

I-11

5

I-11

4

I-10

4

I-10

5

I-10

6

I-10

7

U-5

11

U-5

12

U-5

13

U-5

14

U-5

15

U-5

16

U-5

17

U-5

18PG-03PG-02PG-01PG-04PG-05

E

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m


Upper (sea level) geothermal reservoir

distribution range (~ 32 km2)

N

AMT site0 1000 2000 3000 40000 1000 2000 3000 4000 m

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m

Distribution Range of the Upper Geothermal Reservoir (0m in elevation)

Fovarable area


Lower (1,500 m below sea level)

geothermal reservoir

distribution range (~ 46 km2)

N

AMT site0 1000 2000 3000 40000 1000 2000 3000 4000 m

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m

Distribution Range of the lower Geothermal Reservoir (1500 meters below sea level)

Fovarable area


N

AMT site0 1000 2000 3000 40000 1000 2000 3000 4000 m

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m

Distribution Range of the deep conductive Geothermal Reservoir (-5000 m )Deep (5,000 m

below sea level) conductive geothermal

reservoir distribution range

(~ 54 km2)


MT inversion (cross well section)

2 3 4 5 6 7

Distance ( km )

-3

-2.5

-2

-1.5

-1

-0.5

0

Dep

th (

km )

I-115

I-114

I-104

I-105

I-106

I-107

0 400

0

500

1000

1500

2000

2500

0 400

0

400

800

1200

1600

2000

0 400

0

400

800

1200

1600

2000

PG-02PG-01

PG-03

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m


Comprehensive temperature preconception

0 1 2 3 4 5 6 7 8 9 10 11

Distance ( km )

Comprehensive temperature preconception

-7

-6

-5

-4

-3

-2

-1

0

Dep

th (

km )

-7

-6

-5

-4

-3

-2

-1

0

I-120

I-121

I-122

I-115

I-114

I-104

I-105

I-106

I-107

U-5

11

U-5

12

U-5

13

U-5

14

U-5

15

U-5

16

U-5

17

U-5

18PG-03PG-02PG-01PG-04PG-05

E

660

480

485

500

360

340

320

300280

260240220

200

540

660

420

420 PG-01PG-04PG-05

PG-03PG-02

CoTemperature of PG-03 ( )0 100 200 300 400

0

500

1000

1500

2000

2500

300007-11-2006

11-10-2006


0

500

1000

1500

200011-10-2006


0

500

1000

1500

2000

250027-08-2007

07-09-2007

11-10-2007

100 200 300 4000

400

800

1200

1600

200016-09-2002

13-10-2002

07-09-2004

CoTemperature of PG-01 ( ) CoTemperature of PG-05 ( )0 100 200 300

0

500

1000

1500

200012-10-2007


3-D resistivity inversion result (northwest)

588000

589000

590000

591000

592000

593000

594000

602000

601000

600000

599000

-3000

-5000

-7000

-9000

-11000

I-120 I-121

I-122

I-123 I-109I-108

I-124 I-125I-126

I-127I-110

U-525U-526

U-528U-529

I-133 I-131 I-112 I-129 U-533I-130

I-111 I-128U-534

U-544

U-540U-542

U-535U-541

U-543

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m


3-D resistivity slices in Z (depth),X (E-W) & Y (N-S) directions

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m588000

589000

590000

591000

592000

593000

594000

602000

601000

600000

599000

-3000

-5000

-7000

-9000

-11000

I-120 I-121

I-122

I-123 I-109I-108

I-124 I-125I-126

I-127I-110

U-525U-526

U-528U-529

I-133 I-131 I-112 I-129 U-533I-130

I-111 I-128U-534

U-544

U-540U-542

U-535U-541

U-543

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m

588000

589000

590000

591000

592000

593000

594000

602000

601000

600000

599000

-3000

-5000

-7000

-9000

-11000

I-120 I-121

I-122

I-123 I-109I-108

I-124 I-125I-126

I-127I-110

U-525U-526

U-528U-529

I-133 I-131 I-112 I-129 U-533I-130

I-111 I-128U-534

U-544

U-540U-542

U-535U-541

U-543


1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m588000

589000

590000

591000

592000

593000

594000

602000

601000

600000

599000

-3000

-5000

-7000

-9000

-11000

I-120 I-121

I-122

I-123 I-109I-108

I-124 I-125I-126

I-127I-110

U-525U-526

U-528U-529

I-133 I-131 I-112 I-129 U-533I-130

I-111 I-128U-534

U-544

U-540U-542

U-535U-541

U-543

3-D data volume shows contribution of moderate(6 ~ 15 Ωm, left, & 15 ~ 25 Ωm, right) resistivity volume

1

1.8

3.2

5.6

10

13.9

17.8

24.7

31.6

43.9

56.2

78.1

100

178

316

562

1000

3162

10000

Ohm-m

588000

589000

590000

591000

592000

593000

594000

602000

601000

600000

599000

-3000

-5000

-7000

-9000

-11000

I-120 I-121

I-122

I-123 I-109I-108

I-124 I-125I-126

I-127I-110

U-525U-526

U-528U-529

I-133 I-131 I-112 I-129 U-533I-130

I-111 I-128U-534

U-544

U-540U-542

U-535U-541

U-543


Model for resistivity data interpretation • Fracture zone defined by lower resistivity within high resistivity host rock; • Clay cap occurs above hydrothermal system & heat source below;• Resistivity contrasts below clay cap causes polarization & splitting in MT data.

(Malin, Onacha, and Shalev, 2004).


Comparison of geologic cross-section in SW Iceland with observed resistivity

5 6 7Distance (km)

-3

-2.5

-2

-1.5

-1

-0.5

0

Dep

th (

km )

I-105

I-106

I-107

PG-03

11.83.25.61013.917.824.731.643.956.278.11001783165621000316210000

Ohm-m

Resistivity(ohm-m)

0

500

1000

1500

2000

2500


Outline



Conclusions

MT is an effective method for hydrothermal exploration;

Geoelectric structure in NW corner is a 4-layer model up to 7,000 m;

Hydrothermal reservoir consists of two parts:Upper part reservoir to 1,000 m is water saturated with a mean T ~205 oC;

Main aquifers in lower part link to fissures & intrusives with T from 300 oCto 350 oC or more;

Bottom of upper thermal part is 900 m ~ 1,200 m with coverage ~32 km2;

High potential hydrothermal zone is from 3,200 m to 3,400 m & covers ~ 46 km2;

A deep conductive geothermal reservoir with coverage of more than 54 km2 from 4,000 m to 7,000 m, & T may be more than 500 °C.


Acknowledgements

Thanks to Landsvirkjun, Husavik Energy, & Mannvitin Iceland.

Support of Þeistareykir Ltd. management in facilitating project is specifically acknowledged.

Special thanks also to Hreinn Hjartarson, Ragnar Heiðar Þrastarson, Hilmar Sigvaldason, & RanXuefeng for their contributions to this project.

KMS Technologies – KJT Enterprises Inc. An EMGS/RXT company 6420 Richmond Ave., Suite 610 Houston, Texas 77057, USA Tel: +1.713.532.8144 Fax: +1.832.204.8418 www.KMSTechnologies.com

Documents

Yu mapping geothermal reservoir cover · 2009-08-23 · SEG Las Vegas 2008 Annual Meeting Mapping geothermal reservoir using broadband MT survey in Þeistareykir, Iceland. Yu, G.,