Chemical and Isotopic Survey of Geothermal Reservoirs in Western Anatolia, Turkey

Abstract

The main high enthalpy geothermal fields of Western Anatolia and their reservoir temperatures are as follows; Denizli-Kizildere (242oC), Aydin-Germencik (232oC) and low enthalpy areas in Soke region. The Kizildere field is situated in the eastern part of the Buyuk Menderes Graben. The power plant with 20 MWe capacity was installed in 1984. Also, a factory started production of CO2 in 1986 with a capacity of 40,000 ton/year. Besides 20 exploration and production wells, the reinjection well (R1) was drilled to a depth of 2261 m in 1998. The highest reservoir temperature determined for this area is 242oC. The chemical analysis shows the water type is NaHCO3. Germencik geothermal field is located 100 km west of Kizildere. The temperatures of the first and second reservoirs are found to be 203-217 and 216-232oC. According to the chemical studies the water types in wells are NaCl and the springs are NaCl and NaCl-NaHCO3. The geothermal waters are of meteoric origin in the region. Kizildere and Germencik waters are partially equilibrated and deep reservoir temperatures estimated by using different geothermometers are 250-260oC and 230-260oC, respectively. There are clear ɬ 18O shifts from the Mediterranean Meteoric Water Line (MMWL) in Kizildere and Germencik fields. Also, a good relationship is observed between the high temperature and the ɬ 18O shift, which shows deep circulation and water rock interactions. In Soke region, low temperature, small isotope shift, shallow circulation and mixing with shallow cold water and seawater are documented.