NUMERICAL MODELLING OF THE INFLUENCE OF GEOLOGY AND GROUNDWATER RECHARGE ON GEOTHERMAL SYSTEMS IN THE CENTRAL TVZ

Abstract

Geothermal activity in the Taupo Volcanic Zone (TVZ) is focused into 23 high-temperature geothermal systems that have varying geological, geographical and physical properties. We have created numerical models of a central part of the TVZ to assess the roles that geology and groundwater recharge play in determining the locations and characteristics of geothermal systems.
Our model grid extends from Ngatamariki in the southwest to Waiotapu in the northeast. The grid blocks are 500 m by 500 m horizontally, and 250 m vertically. We began by creating a model with homogeneous permeability and uniform heat input into the base. We then explored the effects of different rock properties and recharge conditions.
In this way, we can determine the influences of geology and recharge on hydrothermal fluid flow in the central TVZ, and determine the levels of detail useful to simulate the location, temperature and mass/heat flow of geothermal systems in our study area. Ultimately, these models will provide the basis for answering broad questions about the geothermal systems in the TVZ, for example why geothermal systems are located where they are, and whether they are interconnected at depth.