Factors Controlling Large-Scale Convective Geothermal System in the Taupo Volcanic Zone (TVZ), New Zealand

Abstract

A review of Taupo Volcanic Zone (TVZ) geothermal fields’ settings shows that most systems share the same general characteristics, some of which include: low topographical terrain, river/lake systems proximity, a capping structure and a highly fractured zone. In a number of cases, the presence of surface water seems to be associated with the separation of the plume into two entities on either side of the body of water. This paper aims to model typical TVZ-like geothermal systems to natural state using a single large-scale model to explore the impact of the system’s internal (e.g. caprock permeability, faults) and external (e.g. cold surface water, topography) features on the geometry and location of the heat plume. 2D models developed include the total extent of the hydrological system (from the surface down to the ductile impermeable crust) and key internal and external features to evaluate if a large-scale, self-contained 2D model can account for heat patterns observed in TVZ geothermal fields. Numerous simulations were conducted using Super Critical- AUTOUGH2 to assess the qualitative impact of each parameter on the convective model of heat distribution.