Interpretation of the temperature data of the Ellidaár geothermal Field, SW-Iceland

Abstract

A study of temperature data in the Ellidaár geothermal field is discussed in this report. It is one of the geothermal fields that supplies the city of Reykjavík 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 boreholes, provided by Hitaveita Reykjavíkur (Reykjavík District Heating Service).