This study demonstrates how a multidisciplinary approach can optimize reservoir characterization and thereby reduce the risk of failure for a potential geothermal development. A geological model of three Lower Triassic low-enthalpy geothermal reservoirs is presented based on available existing data, where 2D and 3D seismic surveys and five deep wells provide data for structural, petrophysical, petrographical, provenance and pore water analysis. Reservoir properties and continuity are controlled by depositional environment and are further affected by the highly saline formation brine, nitrogen gas and cementation by carbonate, anhydrite and halite. The lower Bunter sandstone forms a continuous reservoir of excellent quality, the middle Bunter sandstone constitutes a potential upside reservoir and the upper Bunter sandstone displays variable reservoir properties due to spatial variations in reservoir continuity.