The geochemistry of thermal fluid in the geothermal field near Alia airport in Jodan and Selfoss geothermal field, S-Iceland

Abstract

Chemical analysis from 26 wells from the area near Alia airport in Jordan were reviewed and the chemical characteristics of the thermal fluid studied. An Icelandic low-temperature geothermal field at Selfoss, was chosen for comparison. All the data were interpreted by the use of the WATCH program for speciation and the construction of mineral equilibrium diagrams and other graphical presentation and classification. The maximum reservoir temperature for the Jordanian wells predicted by calculation of various geothermometers exceeds 100°C, whereas for the Selfoss geothermal field, its range is from 130 to 150°C. There is evidence of mixing with cold water in both fields. The thermal fluid in Jordan is of bicarbonate type water with the reservoir rocks being mainly marly and cherty limestone. In the Selfoss geothermal area, which has been used for district heating for fifty years, there has been observed inflow of cold water into the thermal waters during the past years. This is clearly demonstrated by the geochemical study of the waters.