Title: Interpretation of the temperature data of the Ellidaár geothermal field, SW-Iceland

Abstract

A study of temperature data in the Ellidaar geothermal field is discussed in this report It is one
of the geothermal fields that supplies the city of Reykjavik with hot water. The cooling process
taking place in this field is of particular interest. Estimates of the magnitude of the cooling at
different depths have been done using a constructed average temperature graph of the initial
(undisturbed) temperature, and measured or reconstructed temperature graphs of the present state.
Cold water inflow to the aquifers at 600-1200 m depth was established on the basis of temperature
distribution maps at different levels and cross-sections. It has a SE-NW direction with the strongest
cooling effect at 800 m depth. This conclusion was confirmed by temperature data measured at
the wellhead of the production horeholes, provided by Hitaveita ReykjaVl1rur (ReykjaVIK District
Heating Service).