Shallow geothermal subsurface temperature contour mapping aided by numerical reservoir modelling; Taupō, New Zealand

Abstract

Geothermal resources in Taupō town, New Zealand, are integral to the region’s sustainable energy use, yet understanding shallow subsurface temperature distribution remains challenging due to scattered data. This study addresses this gap by collecting and analysing data to create refined temperature contour maps for geothermal resource management and utilisation strategies.

Data from 279 domestic bores (wells) were collected for this study and supplemented with older data from publicly available sources. These data were used to develop initial contour maps, which were subsequently improved through kriging interpolation and the integration of artificial temperature-depth profiles to address gaps in data coverage. A numerical reservoir model simulated shallow subsurface thermal conditions, allowing contour maps adjustments in areas with limited data.

Results indicate distinct temperature patterns between the cooler Northern Tauhara aquifer and the Southern Tauhara aquifer, where hot water is abundant for direct-use applications. Findings were validated using mock-up bores and comparing their temperature profiles to residents' observations from their domestic bores. A strong correlation was observed between the artificially generated temperature profiles and those observations, confirming the map’s qualitative reliability.

Despite data sparsity and interpolation limitations in some regions necessitating cautious interpretation of the contour maps, this study provides insights that can inform decision-making process for the sustainable utilisation of Taupō’s shallow geothermal resources, including temperature profile predictions within the study area.