Göynük (Bolu) Çatak Hamamı-Ilıca-Karacalar Fields, Geothermal Geology Investigation in Turkey

Abstract

The Göynük province is located approximately 250 km NW of Ankara which is the capital of Turkey. There are three different low enthalpy geothermal fields around Göynük named Çatak Hamamı (38.5oC), Ilıca (32.4oC) and Karacalar (27.3oC). Each of these fields have several natural hot water springs. The aim of the investigation is researching the geothermal energy possibilities and determining the drilling locations for effective geothermal fields.
Two different sedimentary deposits of Jura-Tertiary age were observed in the investigation area. The most suitable unit for the reservoir rock is Cretaceous limestone. The Yenipazar formation’s marl, shale, Üzümlü formation’s tuff and agglomerate, Taraklı and Himmetoğlu formation’s clay levels have cap rock features. Although volcanic activity is observed, the level of the temperature is not high enough for geothermal energy possibilities.
The investigation area located in West Pontides tectonic units was affected by Alpine orogenic movement and because of approximately N-W direction compression forces, E-W direction structural shapes were formed.
Detailed geological mapping revision was realized and hydrologic, hydrogeological and hydrogeochemical conditions were determined to evaluate geothermal possibilities of the fields. Radon and CO2 gas measurements were also realized at different points on the surface to research probable crack and fracture systems. The chemical results of the hot waters also show low temperature. Poor mineral content of the water (except Karacalar field), Na/K ratio and SiO2 quantity show low reservoir temperature.
The Ilıca spring and especially Karacalar area should be determined with research drillings study in order to examine geothermal possibilities.