GEORG Geothermal Workshop 2016 SESSION A1, Upstream

1. Modeling of tracer transport in
Reykjanes
Jean-Claude Berthet, Hilmar Már Einarsson, Andri Arnaldsson

2. 2016-11-24www.vatnaskil.is - Reykjanes tracer modeling
• Four tracers injected in Reykjanes, in:
RN-20B, RN-33, RN-34 and RN-29
• Tracers reveal flow paths and fractures
• Does the injected water flow straight
into the production zone?
‒ Important to be able to predict thermal
breakthrough
• Naphthalenesulfonates
‒ Relatively stable at 300 °C
‒ Low detection limit
‒ Measured by High Performance Liquid
Chromatography
Tracer test in Reykjanes
2
• RN-33
‒ 150 kg of 2-NS on 2014-01-10
‒ 55 kg/s of cold water for 6 months
‒ Strongest response in RN-18, RN-21 and
RN-24
• 2-naphthalenesulfonic acid

3. www.vatnaskil.is - Reykjanes tracer modeling
• Model includes all three geothermal areas:
o Reykjanes
o Eldvörp
o Svartsengi
• 1102 km²
• 15 layers: +0 to -3400 m A.S.L.
• 33345 elements, 2223 per layer.
• 7000 m² around Reykjanes, hexagonal mesh,
88 m between adjacent nodes.
Reykjanes–Svartsengi model
2016-11-24 3

4. www.vatnaskil.is - Reykjanes tracer modeling
• ITOUGH2 equation of state 1 (EOS1)
‒ Water and water with tracer
• Mesh refined along fracture
‒ 88 m to 35 m between nodes
• Calibration performed using a submesh
‒ 2.5×4.5 km²
• The fracture is simulated by a line of
elements.
• The elements inside the fracture have
higher permeabilities and lower porosity
than in the surrounding rock.
‒ Permeability inside the fracture ~ 10-12 m²
(outside 10-15 m² to 10-12 m²)
‒ Porosity inside the fracture ~ 2% (outside
10% to 15%)
Hexagonal mesh
2016-11-24 4

5. Permeability and fracture
www.vatnaskil.is - Reykjanes tracer modeling 2016-11-24 5

6. Permeability and fracture
www.vatnaskil.is - Reykjanes tracer modeling 2016-11-24 6

7. 2016-11-24www.vatnaskil.is - Reykjanes tracer modeling
Measured Analytical ITOUGH2
Breakthrough
time, [days]
64 57 60
Peak time, [days] 218 203 198
Peak
concentration,
[µg/L]
14.0 14.0 15.0
Mass recovery,
[Mm/Mi]
6.5% 6.7% 6.5%
2-NS in RN-18
7

8. 2016-11-24www.vatnaskil.is - Reykjanes tracer modeling
Measured Analytical ITOUGH2
Breakthrough
time, [days]
77 71 75
Peak time, [days] 293 225 235
Peak
concentration,
[µg/L]
6.2 5.3 6.4
Mass recovery,
[Mm/Mi]
2.6% 3.1% 2.2%
2-NS in RN-21
8

9. 2016-11-24www.vatnaskil.is - Reykjanes tracer modeling
Measured Analytical ITOUGH2
Breakthrough
time, [days]
84 78 78
Peak time, [days] 279 280 235
Peak
concentration,
[µg/L]
6.1 5.4 6.0
Mass recovery,
[Mm/Mi]
4.5% 2.8% 4.1%
2-NS in RN-24
9

10. 2016-11-24www.vatnaskil.is - Reykjanes tracer modeling
• Calibration of the tracer injected in
RN-20B
‒ 2,7-NDS
• Injection scenarios to predict the long
term effect of injection:
‒ Pressure
‒ Temperature
‒ Flow rate
‒ Steam.
Future work and work in progress
10
2,7-NDS in RN-19