Investigation of the lithology and tectonically controlled change of the geothermal gradient from east to west (between Tekkehamam-Germencik) and the affecting factors on the northern border of the Menderes Graben

The increase in permeability due to the opening tectonics of the northern boundary fault in the Büyük Menderes Graben and the resulting synthetic step faults and jump faults at the jump point of the segments reaching the deep geothermal reservoir and providing fluid flow are considered as important tectonic elements in terms of geothermal potential. When the productive drillings in the geothermal areas in the Büyük Menderes Graben are examined, it is seen that most of the drillings cut the northern boundary detachment main fault in the graben. However, geothermal drillings that can capture the fractured media permeability in the reservoir are also potentially productive. Although there are much deeper drillings in the graben, the depth of the drillings using temperature, pressure, lithology and productivity index data in this study; It varies between 400 m and 3800 m. While the attainable fluid temperature varies between 175 ºC and 95 ºC, the fluid flow rate that can be produced in the wells is; It has been observed that it varies between 50 tons/hour and 600 tons/hour. It is thought that ongoing rock melting with the effect of many developed fault systems and magmatic intrusion in the Kızıldere and Ömerbeyli geothermal fields, which have the highest geothermal gradient, further increases the fluid temperature. It has been determined that the geothermal gradient increases from Denizli to the West, and especially according to the well bottom temperatures measured from East to West in the Kızıldere, Kuyucak and Ömerbeyli fields, the geothermal gradient has reached the highest values in the region. It has been evaluated as approaching magmatic intrusion or further crustal thinning in these regions. Afterwards, it was observed that the geothermal gradient decreased from East to West, from Germencik to Gümüşköy.