Hydrogeochemical investigation of the Eskişehir-Türkmentokat geothermal field

This thesis focuses on the geological, geophysical and geochemical studies to reveal the geothermal potential of the area around Türkmentokat and Harmandalı villages (Eskişehir-Odunpazarı). In the study area, Triassic metamorphic and ophiolitic rocks form the basement rocks and are cut by Upper Cretaceous granodiorite. Neogene units are unconformably over all of these basement rocks. Quaternary aged alluvium deposits cover all these units with unconformity. Within the scope of geophysical surveys, vertical electric drilling and self potential studies were carried out. As a result of geological and geophysical investigations, EMT-2016/2 exploration well was drilled to a depth of 2200 m in an area presenting geothermal anomaly. The surface waters in the region fall into Ca + Mg-HCO3 type hydrochemical facies formed as a result of the dissolution of magnesium-rich minerals in carbonates and ophiolitic rocks. The chemical composition of EMT-2016/2 drilling well water differs from other water points in the region. EMT-2016/2 well water, which is rich in ionic concentration, fall into the Na-Cl hydrochemical facies. The formation of Na-Cl facies at this point is thought to be caused by the contribution of paleo sea water. The reservoir temperature for the EMT-2016/2 well was calculated by using geothermometric methods in the range of 65 ° C to 71 ° C. The EMT-2016/2 geothermal well has been opened and the 3.3 Mwt heat energy potential has become visible and this is the first research result for this region. It is possible to reveal the geothermal potential of the region in more detail with additional drilling in the study area. Keywords: Eskisehir, hydrogeochemistry, environmental isotopes, geothermal.