An integrated Python-based workflow for geological and geothermal fluid flow modelling to investigate lateral fluid movement in the Taupo Volcanic Zone

Abstract

Lateral fluid flow within geothermal systems significantly affects reservoir sustainability, resource targeting, and surface expressions, but remains challenging to predict in structurally complex volcanic settings like the Taup? Volcanic Zone (TVZ). This study introduces a python-based workflow that couples 3D geological models with supercritical heat and fluid flow simulations to investigate geological conditions that promote lateral geothermal fluid movement.
We are developing a methodology to couple structural and stratigraphic modelling with multiphase fluid and heat flow simulations using open-source tools where possible. Geological models are constructed in GemPy, with custom Python scripts employed to extract rock types and fault geometries. Geological units are then parameterised for fluid flow modelling, building on the University of Auckland’s modelling framework. Finally, we use the supercritical AUTOUGH simulator to model the high-temperature, high-pressure environments characteristic of the deep roots of geothermal systems. This approach enables dynamic, repeatable population of reservoir models, supporting flexible natural state simulations and quantification of geological uncertainty.
Modelling the deep roots of the Ohaaki geothermal system provides a case study for this work. Unusually, magnetotelluric imaging suggests that fluids beneath Ohaaki move ~5 km laterally between 8 and 3 km depth. Geological structures inferred from gravity and magnetics provide possible fluid pathways or permeability contrasts that redirect fluid flow. Our preliminary models are exploring variations in lithological properties, fault permeability, intrusive heat sources, and anisotropy, allowing systematic analysis of how different geologies influence lateral flow.