| Abstract |
The Karahayit geothermal field is located at intersection of the Buyuk Menderes and Gediz grabens in the Denizli Province, Western Turkey. The reservoir rocks in the field are Paleozoic marble, various schist and quartzite which have high secondary permeability. The impermeable sediments of Neogene have good caprock characteristics. The temperatures of thermal waters in the field range from 33 to 61.5°C. The thermal waters are in the type of Ca-SO4-HCO3 and of meteoric origin. The Karahayit village is a natural beauty and thermal tourism place and visited by more than 1,000,000 tourists annually. The thermal fluid from the wells is used for swimming pool, bath and spa. Each hotel and pension in the Karahayit village has one or more wells producing hot water. At the present, there are about 200 wells in a part of 1.0 km2 of the Karahayit geothermal field. The depths of wells vary between 5 m and 140 m. All wells work in summer season, especially. The uncontrolled over exploited of the thermal water has led to lowering of piezometric level of the reservoir. Consequently, while there were many thermal springs, which have a temperature of 50-56°C, deposited red travertine in Karahayit area before 1981, almost all of them have disappeared in 1981-1994 period. Also, shallow wells have been dried up and the piezometric level lowered in the deep wells. To provide sustainable utilization of the geothermal system, Denizli governorship is made a decision to drill three deep thermal water production wells and one re-injection well, to distribute to the hotels and pension to be produced the thermal water and then to close all private thermal well in the Karahayit village. After geological, hydrogeological and geophysical studies, the three production wells in the depths of 452 m, 468 m and 570 m were drilled in 2007. The temperatures and total discharge of the thermal waters from these wells are 58°C to 61.5°C and 92 l/sec, respectively. According to physico-chemical and bacteriological analyses, the thermal waters are applicable to therapeutic use. The drilling of the re-injection well and construction of distribution piping system to the hotels of thermal waters will be completed in 2009. It is hoped that utilization-protection balance of the thermal waters in the Karahayit geothermal field would be established in the near future. |