The application of geologically-constrained 3D heat conduction models to geothermal exploration

Abstract

Renewed interest in the thermal structure of the upper crust has led to the development of a new generation of tools capable of modelling the 3D heat conduction problem, incorporating the complex geology and physical properties of the crust. The numerical and resolution requirements of such models has necessitated a high performance performance computing approach, utilising massively parallel machine architecture to obtain ~10m resolution of models over a basin-scale. Here we demonstrate the application of the StGermain/Underworld geodynamic modelling framework to basin-scale geodynamic problems. The default code has been modified to incorporate importing of geometrically complex geological units, each with its own conductivity and heat production, and temperaturedependent thermal conductivity. Thermal models demonstrate the importance of incorporating 2 & 3D geometries, with large lateral variations in the subsurface temperature field and heat flow as a result of the heterogenous basin architecture. We explore the effect of lithological resolution, and identify a critical level of detail required to adequately represent basin-scale temperature variations. The regional temperature field play a dominant role in determining tenement-level subsurface temperatures, and highlight the importance of understanding regional temperature variations in geothermal exploration.