3D conceptual and TOUGH2 modelling of the Waiotapu geothermal field, New Zealand
The Waiotapu geothermal system is a liquid dominated, high-temperature system located in the Taupo Volcanic Zone (TVZ) in the North Island of New Zealand. Seven exploration wells were drilled in Waiotapu in the late 1950s, which are drilled to around 500 m - 1100 m depth. Although Waiotapu has seven deep exploration wells that reached a high temperature reservoir, these wells are considered non-production because they are protected by the Waikato Regional Council, the environmental regulator of most of the Taupo Volcanic Zone. Two main fault structures affect the geothermal system of the area which are the Paeroa and Ngapouri faults that extend from northeast to southwest of the thesis project area. This thesis aims to analyse and study the characteristic reservoir of the Waiotapu geothermal system and its surroundings through 3D conceptual modelling and numerical modelling. The conceptual model is created using existing data obtained from surface and subsurface exploration. Leapfrog Geothermal software was used to build the model. This 3D conceptual model was used as the basis of a numerical TOUGH2 model. The numerical model was calibrated to measured well temperature and the result of this calibration shows the temperature, permeability, and fluid flow distribution of the system. Modelled results indicate that the Waikite area can possibly have a deep outflow from the Waiotapu geothermal system although there also needs to be some heat input below the Waikite area. The meteoric recharge comes mostly from north-east of Maungakakaramea, and the main geothermal upflow zone is located at the Waiotapu, and in the vicinity of Wt-5.
Orkuverkfræði, Meistaraprófsritgerðir, Jarðhitasvæði, Líkanagerð, Hugbúnaður, Sustainable energy engineering, Geothermal field, Modeling, Computer software
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