04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 1

Geothermal Resource Mapping of Northern

Switzerland

Geothermal Resource Mapping of Northern

Switzerland

Thomas Kohl, Nathalie Andenmatten-Bertoud,S. Signorelli,L. Rybach

Geowatt AG, Zurich, Switzerland

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 2

BackgroundBackground

Project goal:– Interpretation of Swiss Resource

potential in main populated area

– 3D geological modeling

– Numerical analysis

– GIS interpretation

Conventional resource mapping:– Total Energy = f(T,V)

– Utilizable Energy = total Energy x recovery factor

Here:– 3D subsurface structures

– Evaluation of transmissivity

– Assumption of utilization scenario

– Utilization energy = f(Tr, T, ….)

– Combination with GIS toolsVTcE Ptot dtTQcE

fPut

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 3

3D determination of subsurface structures

3D determination of subsurface structures

Northern Switzerland

Well investigated for research of nuclear waste deposit– Borehole, seismic profiles, geophysical & geological interpretation

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 4

Geological 3D mappingGeological 3D mapping

• Geological surface interpolation with GOCAD software from data basis

• Example top Malm & Muschelkalk layers with borehole marker

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 5

Development of local numerical model

Development of local numerical model

– Triangulation of surfaces– Tetrahedrization of geological model– Construction of Finite Element Mesh

LeuggernBöttstein

BenkenWeiach

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 6

Numerical patch testNumerical patch test

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 7

Petrophysical DataPetrophysical Data

Measured and averaged parameters from Weiach

[W / m K]

Dep

th

0 1 2 3 4 5 6

0

500

1000

1500

2000

2500

Therm. Conductivity

Dep

th

0

500

1000

1500

2000

2500

Basement

Carbon

Perm

O. Muschelkalk

Perm

KeuperLiasDogger

Malm

U/M. Muschelkalk

Tertiary

Lithology

A[mW/m3]

Dep

th

10-1 100 101

0

500

1000

1500

2000

2500

Heat Production

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 8

Local temperature calculationLocal temperature calculation

• Calculation of thermal and hydraulic field:Example Weiach

-5000

-2500

0

670000672500

675000677500

680000682500

685000

260000

265000

270000

275000

XY

Z

TEMP: 9 10 11 12 25 50 75 100 125 150 175 200 225 250

Temperature [C]

Dep

th[m

]

0 50 100

0

500

1000

1500

2000

2500

Grad T [K/m]

Dep

th[m

]

0 0.02 0.04 0.06 0.08

0

500

1000

1500

2000

2500

WEIACH Data topWEIACH Data bottomModelled

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 9

Temperature DataTemperature Data

Weiach Benken

T red, 35K/km [K]

Dep

th[m

]

-5 0 5

0

500

1000

1500

BENKEN Data ABENKEN Data BModelled

Temperature [C]

Dep

th[m

]

0 20 40 60 80

0

500

1000

1500

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 10

Transmissivity evaluationTransmissivity evaluation

• Evaluation from existing data

• Thermal evaluation:– heat flow variation: background vs. local value – Peclet Analysis from regional borehole distribution:

relating heat flow variation to vD

– With assumption on head gradient =>Transmissivity estimation

zc

jj

zc

jj

fP

fP

2

1

D

D

2

1

ln

ln:AnalysisPeclet

v

v

Lc

j

jPe fP

D

kond

konvv

hKhK DD:Darcy vv

j2

j1

T

z

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 11

Utilization ScenarioUtilization Scenario

Doublet System:Calculation over time span t

Transient Gringarten (1978) solution:

– Necessary surface area– Sustainable flow rate– Reservoir geometry

=> Utilizable heat energy

= f(t, Tr, T, V, …)

in individual reservoir zoneDistance x

Transmissivity

21 /3ln

4

wi

bi rztcQ

PTrQ

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 12

Example: Resource PotentialExample: Resource Potential

Northern Switzerland:

Resource of altered crystalline basement for 30 yr production

Surface area <1km2

Borehole j [mW m-2 ]

Tr [m2/s] P[W] Recovery Factor

Weiach 25 5 x 10-6 3 x 107 5%

Böttstein 20 4 x 10-6 2 x 107 4%

Leuggern 20 4 x 10-6 2 x 107 4%

Benken 0 0 0 0%

Similar evaluation for sedimentary aquifers

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 13

Benken

Basserdorf

Lindau Local Model

Benken Local Model

Kloten

Nordschweiz Regional Model

Boettstein Local Model 100 – 110mW/m2.

WeiachBoettstein - Leuggern

110mW/m2.90mW/m2.

80mW/m2.

Beznau Birmenstorf

Riniken Local Model110mW/m2.

Weiach Local Model

Kaisten Local Model 110mW/m2.

Eglisau

Ruchfelden

Riniken

Zurzach

Kaisten

From Local to Regional ModelsFrom Local to Regional Models

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 14

Permocarbon Trog Rand

Temperatur:

Legend: N

Prel. Temperature Distribution in 2000m b.s.l

Prel. Temperature Distribution in 2000m b.s.l

04 October 2004 New and Classical Uses of Heat Flow Studies, Aachen 15

ConclusionConclusion

• Evaluation of 3D geology and regional temperature field

• Individual assessment of recovery factor and production time

• Cost analysis possible (borehole depth, geological structures, …)

• Future combination with GIS tools