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Permeability and Thermal Conductivity Measurements of Near Surface Units at the Wairakei Geothermal Field, New Zealand

Mielke, P. and Bignall, G. and Sass, I. (2010):
Permeability and Thermal Conductivity Measurements of Near Surface Units at the Wairakei Geothermal Field, New Zealand.
In: World Geothermal Congress 2010, Bali, 25.-29.04.2010, [Conference or Workshop Item]

Abstract

Thirty one outcrop and drill core samples (to about -500 mRL) from geothermal wells from Te Mihi, western Wairakei Geothermal Field (New Zealand), have been analysed for their mineral assemblage and hydrothermal alteration, thermal conductivity, permeability, bulk rock porosity and density, as part of a study on the affect of the geological parameters on the thermal conductivity. At Wairakei, cores of Huka Falls Formation (soft, lacustrinedeposited tuff and sediments), Waiora Formation (variably consolidated, medium hard, hydrothermally altered volcanic tuff) and Karapiti Rhyolite (hard, altered rhyolite lava and breccias) were analysed from wells WK223, WK224 and WK227 (unaltered/least altered field margin); WK206, WK207, WK212, WK219 and WK247 (Te Mihi upflow zone); and WKM14, WK205, WK210, WK213 and WK221 (infield, south and east of Te Mihi). The effect of hydrothermal alteration (rank and intensity) on thermal conductivity was tested by analysing samples from the same stratigraphic units from different wells, albeit with a range of styles of hydrothermal alteration (e.g. claydominated argillic, characterised by a progression from smectite to illite-dominated clay assemblages, to propylitic). Results demonstrate a good correlation between porosity and thermal conductivity, but no clear relationship between permeability and thermal conductivity. We also compared permeability and thermal conductivity from the Wairakei Field samples with data from rocks in central Europe.

Item Type: Conference or Workshop Item
Erschienen: 2010
Creators: Mielke, P. and Bignall, G. and Sass, I.
Title: Permeability and Thermal Conductivity Measurements of Near Surface Units at the Wairakei Geothermal Field, New Zealand
Language: English
Abstract:

Thirty one outcrop and drill core samples (to about -500 mRL) from geothermal wells from Te Mihi, western Wairakei Geothermal Field (New Zealand), have been analysed for their mineral assemblage and hydrothermal alteration, thermal conductivity, permeability, bulk rock porosity and density, as part of a study on the affect of the geological parameters on the thermal conductivity. At Wairakei, cores of Huka Falls Formation (soft, lacustrinedeposited tuff and sediments), Waiora Formation (variably consolidated, medium hard, hydrothermally altered volcanic tuff) and Karapiti Rhyolite (hard, altered rhyolite lava and breccias) were analysed from wells WK223, WK224 and WK227 (unaltered/least altered field margin); WK206, WK207, WK212, WK219 and WK247 (Te Mihi upflow zone); and WKM14, WK205, WK210, WK213 and WK221 (infield, south and east of Te Mihi). The effect of hydrothermal alteration (rank and intensity) on thermal conductivity was tested by analysing samples from the same stratigraphic units from different wells, albeit with a range of styles of hydrothermal alteration (e.g. claydominated argillic, characterised by a progression from smectite to illite-dominated clay assemblages, to propylitic). Results demonstrate a good correlation between porosity and thermal conductivity, but no clear relationship between permeability and thermal conductivity. We also compared permeability and thermal conductivity from the Wairakei Field samples with data from rocks in central Europe.

Uncontrolled Keywords: Permeability;thermal conductivity;rock properties;hydrothermale Alteration;Huka Falls Formation;Waiora Formation;Wairakei Geothermal Field
Divisions: 11 Department of Materials and Earth Sciences > Earth Science > Geothermal Science and Technology
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences
Event Title: World Geothermal Congress 2010
Event Location: Bali
Event Dates: 25.-29.04.2010
Date Deposited: 06 Nov 2014 15:04
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