抄録
The geothermal energy exploration, which began in 1960, has been implemented by the MTA General Directorate until now. In 30 geothermal fields, 242 gradient, 74 shallow and 35 deep wells have been drilled. The explored geothermal fields are water-dominated and hot water type. Turkey is located on an active tectonic belt. The geothermal areas are found along many grabens, main faults and fracture zones. In geothermal areas, although reservoir developments depend on secondary porosity and permiability due to intense tectonism, they also show different characteris-tics according to lithology type. In surveyed geothermal fields, the main reservoir rock type is marble-limestone (Paleozoic-Mesozoic). However, rocks which are magmatic-metamorphic in origin like granite, diabase, spilite, (Paleozoic-Mesozoic), ignimbrite and andesite (Neogene) type rocks also form reservoirs. The com-mon cap rocks consist of claystone, sandstone, conglomerate, and clayey limestone type sedimentary rocks (Cenozoic). The sandstone, conglomerate, clayey limestone levels in those units form subor-dinate reservoirs. During exploitation some problems due to reservoir lithology were encountered. The major problem was scaling, particularly in carbonate (limestone-marble) type reservoirs. Another problem is sandstone erosion caused by loosely cemented sandstone and conglomerate. Elsewhere, expansion of clay in the cap rock created another problem during drilling. In this paper, reservoir lithology and problems based on lithology type will be presented. Also some areas like Denizli-Kizildere, Aydin-Germencik, Canakkale-Tuzla, Kestanbol, Izmir-Balcova, Ankara-Kizilcahamam, etc. will be given as examples.
