Structure and Geothermal Potential of the Bourgas Hydrothermal Basin, Bulgaria

Abstract

Six hydrothermal fields and nine hydrothermal occurrences are available in the Bourgas hydrothermal basin. The area does not contain many surface expressions of hydrothermal activity, such as hot springs and altered rock. The temperature of the waters is within the range of 20?C to 49?C. Because of its special geological structure, the total dynamic resources of the thermal and sub-thermal waters were estimated at about 110 l/s. Exploitation is still on a very limited scale, 47% of the geothermal potential of the basin, and the basic application is related to baths and spas and for bottling potable waters. The work carried out in the Bourgas hydrothermal basin consisted of geological and hydrogeological mapping, geophysical investigations and water sampling of thermal springs and wells for geochemical analysis. Silica and cation geothermometers were applied to predict possible subsurface temperatures. The equilibrium state of thermal waters was studied by means of log Q/K diagrams and the Na-K-Mg triangular diagram. It was found that water with temperature 80-100oC could be obtained by drilling.