Modeling of tracer transport in Reykjanes

Jean-Claude Berthet, Hilmar Már Einarsson, Andri Arnaldsson

www.vatnaskil.is - Reykjanes tracer modeling 22016-11-24

• 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

• 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

3www.vatnaskil.is - Reykjanes tracer modeling

• Model includes all three geothermal areas:o Reykjaneso Eldvörpo 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

www.vatnaskil.is - Reykjanes tracer modeling 4

• 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

www.vatnaskil.is - Reykjanes tracer modeling 5

Permeability and fracture

2016-11-24

www.vatnaskil.is - Reykjanes tracer modeling 6

Permeability and fracture

2016-11-24

www.vatnaskil.is - Reykjanes tracer modeling 72016-11-24

  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

www.vatnaskil.is - Reykjanes tracer modeling 82016-11-24

  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

www.vatnaskil.is - Reykjanes tracer modeling 92016-11-24

  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

www.vatnaskil.is - Reykjanes tracer modeling 102016-11-24

• 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 progress2,7-NDS in RN-19