| Title | Assessment of the Early Development Work for Kuyucak Geothermal Field, Turkey |
|---|---|
| Authors | Gözde YAL, Arif Mert EKER, Selim CAMBAZOGLU, Osman SEN, Haluk AKGUN |
| Year | 2017 |
| Conference | Stanford Geothermal Workshop |
| Keywords | magnetotelluric, geothermal exploration, deep drilling, power generation, Büyük Menderes Graben, Kuyucak, Aydın, Turkey. |
| Abstract | There are a number of geothermal fields that are developed or currently under development for power generation in the Buyuk Menderes Graben and recent exploration field works and drilling operations indicate that this number is bound to increase in the near future. An example for a newly discovered region is located at the northern flank of the Buyuk Menderes Graben, within a small-scale graben structure perpendicular to the main graben. The study area covers the geothermal operation license owned by SDS Enerji. This area is mainly characterized by EW- trending high-angle normal faults of the Buyuk Menderes Graben. This study entails the correlation of the exploration work including geological and geophysical field studies and the deep drilling works conducted in the study area. Menderes Massif is unconformably overlain by the Neogene sediments which are further overlain by the Quaternary deposits in the study area. The Menderes Massif mainly consists of highly jointed, thick bedded-massive marble, quartzite and intensely folded various schists and gneisses. This unit is highly deformed and fractured due to metamorphism and the tectonic activity in the region. The reservoir formation generally consists of the marble units of this massif as it is the case for the entire Buyuk Menderes geothermal system. According to the geological field works, the Menderes Massif acting as the bedrock formation for the entire Buyuk Menderes Graben could be encountered at shallow depths towards the north of the study area in line with the topography. A magnetotelluric (MT) survey was conducted at 83 points within the study area. MT (~10 km penetration depth) data were employed to identify the deep seated geothermal system of the study area located at depths below 2500 m. At these depths, a low resistivity zone was observed in the MT sections. The observed decrease in resistivity accompanied with a slight increase in the geothermal gradient was mainly tied to the permeable fracture zones filled with saline hydrothermal fluids. The results of the MT analysis (Schlumberger, 2015) were consistent with the geological studies and further allowed the determination of the geometry of the reservoir. Two wells, KS-1 and KS-2 were drilled by considering the results of the geological and geophysical studies and the accessibility of the drilling sites at the study area. The correlation of the lithological logs, the depth of loss of circulation, and the temperature measurements of the two wells with the 3D MT results indicated that the MT measurements were able to identify the approximate depth of the reservoir. However, the well logs indicated the presence of two reservoir sections, which was not visible on the MT cross-sections due to the low resolution of MT at great depths. Further, the results of the PT and flow rate measurements taken from the wells showed that the area was suitable for geothermal power generation. Thus, results of this study indicate that for the further development of the field, starting with the currently proven areas around the KS-1 and KS-2 wells, new wells could be drilled towards the northern part of the license area where the reservoir could be encountered even at shallower depths. |