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Geothermal research

Geothermal research in the CGS has a long tradition and has been conducted since it's founding until nowadays. Skilful as he was a geologist Dragutin Gorjanović Kramberger, PhD, had performed investigations in the field of geothermics even before the Geological Committee for Kingdom of Croatia and Slavonia (the precursor of the CGS) was founded. His most renowned work from that period is about (later often cited) geothermal lines in the Croatian northwest, published in 1894. While he was at the head of the Geological Committee, Kramberger visited and described almost all significant geothermal springs in Croatia. During one hundred years of existence of the CGS after his death, about twenty of his successors were involved in the research of geothermal water and energy as well as in other specialized fields of geology.

D. Gorjanović-Kramberger
Rad JAZU, Zagreb, 1894.

Recently, geothermal research is performed within framework of the scientific research project "Geothermal map of the Republic of Croatia", including various commercial projects. The latter include studies of geothermal potential, optimization of the use of the geothermal resources, suggestions concerning formation of the protection zones around geothermal springs, environmental studies concerning protection of geothermal springs, planning geothermal wells and offering expert opinions and consulting on the projects that include acquisition of geothermal water and heat. Besides, monitoring works concerning the exploitation of geothermal water and heat is also carried out together with measurements of the thermal properties of rocks, all based on the geothermal research.

Studies on geothermal potential

Izvorište geotermalne vode u Tuheljskim toplicama

Studies on geothermal potential are based on the data on geothermal properties of the research area as well as from various investigations which carried out in order to assess the geothermal potential of the particular area. These studies include data on the known existing objects containing geothermal water, average geothermal gradient and possible deviations from the average, average thermal conductivity coefficients and volume heat capacities of individual lithostratigraphic units, average surface heat flow density values and possible deviations, possibility of the existence of geothermal aquifers, smaller areas with better perspective for further geothermal exploration, and, finally, recommendations of appropriate technologies for geothermal energy exploitation on a given locality. Geothermal potentiality studies are undertaken for broader regions as well as for counties, cities and municipalities. Expertise is also made for smaller territorial units.

Optimization of the geothermal resource utilization process

Mjerenje razine geotermalne vode u bušotini prilikom pokusnog crpljenja

During the process of geothermal water exploitation lower quantities of water or lower temperatures than expected can be found. In such cases it is possible to perform research in order to determine the water quantities available and the procedures which will enable extraction of water of desired temperature. Investigations of that kind can differ in methods and extent, including geologic mapping, tectonic structure modeling, geothermal water experimental extraction, flow and groundwater level measurements, calculations of thermal conductivity and volume heat capacity values for lithostratigraphic units, calculations of the geothermal gradient and surface heat flow density, geoelectric sounding, quantitative hydrogeochemic and isotope analyses, etc.

Geothermal water protection studies

Lociranje pojave geotermalne vode

Extensive construction work near the geothermal water springs, excessive extraction, vicinity of the polluting industries and traffic infrastructure, etc., can have adverse impact on geothermal waters and their source areas. Anthropogenic activities that could adversely affect groundwater can be identified and measures for spring protection suggested. For example, on some locations the quantity of water decreases with continuous exploitation or water has to be extracted in places of natural outflow. It is worth noting that one of these locations suffered a forty meters water level drop. Studies are needed to determine the causes of the level drop and to recommend appropriate actions to protect the springs from further decrease.

Geologic projects of the geothermal boreholes

Bušenje geotermalne bušotine

Geologic projects of the geothermal boreholes are made based on the previous research. The project contains geothermal water borehole forecast, possible geothermal aquifers and expected geothermal parameters: formation thermal conductivity coefficient, geothermal gradient, formation temperature and heat flow density.


Mjerenje fizičko-kemijskih parametara geotermalne vode

The results of geothermal exploration, just like other geologic research, are usually not exact or unambiguous, which means that investments into research and exploitation carry a high degree of risk. Performing an expertise the investors minimize the risks as much as possible. That is why consulting an expert can help the investor make a top-quality tender as well as give advice in assessing tenders, i.e. projects concerning exploration and exploitation of geothermal water and energy. Besides, expert opinions are made on geothermal potentiality of smaller areas. 


Geological supervision and consulting

Toplice u Topuskom

We offer the services of geological supervision of activities aiming at geothermal water and energy exploitation. We help the investor evaluate our work out, advise how to proceed and whether additional works are necessary.

Thermal properties measurement

Mjerenje termičkih svojstava materijala

Contemporary geothermal research would be inconceivable without understanding of the thermal properties of rocks which conduct the heat from the interior to the Earth's surface. Therefore, the geothermal research includes measurements of rock properties performed on the rock samples from research areas. Our laboratory is equipped for measuring of the thermal properties which include both rocks and construction materials. Measurements of thermal conductivity are possible in the range 0.3 – 6.0 W/mK, while the range for volume heat capacity is 1.5 x 106 – 4.0 x 106 Jm2/K.