To assess the geothermal potential of an aquifer estimates of the following six aquifer properties are required:
- Top depth - the depth beneath the surface to the top of the aquifer
- Thickness – the thickness of the aquifer
- Net-to-gross – the ratio of sand to shale in the aquifer
- Porosity – the fraction of pore space in the aquifer
- Permeability – the ability of water to flow through the aquifer
- Temperature – the temperature of the aquifer
Together the top depth and thickness describe the geometry of an aquifer. They are modelled using borehole and seismic data.
The aquifer properties net-to-gross, porosity and permeability are modelled using borehole measurements of these properties, combined with maps of the maximum depth an aquifer has been buried to. They are the properties which have the greatest uncertainty and also the greatest influence on the geothermal potential of an aquifer. Together these are called the 'property maps'.
The temperature is modelled using a combination of various borehole temperature observations and a physics based approach.
ThermoGIS v2.3 shows the geothermal potential of 29 water-bearing layers or aquifers (reservoirs), five aggregate layers that consist of two or more aquifers ('period') and an overview layer covering all aquifers (see table below). The Nomenclature of the Deep Subsurface on the DinoLoket website provides more geological background on the aquifers.