Moznosti vyuziti hlubinne geotermalni energie v oblasti Vseboric (Usti nad Labem) a vztahy k oblasti Litomeric

Available geological and geothermal information was analyzed and evaluated to assess the potential of exploiting the deep geothermal energy in the broader area of Všebořice (NW suburbs of the city of Ústí nad Labem). The Tertiary Eger Rift is the major geothermal structure in the area concerned (Fig. 1). Another important structure, from the geothermal point of view, is the Teplice-Altenberg Caldera of Variscan orogeny age in the eastern Krušné hory/Erzgebirge Mts.
A total of 51 boreholes deeper than 500 m with available thermometry records were used for evaluation of the Eger Rift and its surroundings regarding the geothermal energy potential.
The temperature records were subjected to mathematical processing and extrapolated to a depth of 5 km. The results are shown in Tables 1 and 2. The extrapolation has been done to 5.5 times greater depths than the actual temperature measurements so that the results should be considered as very approximate. Subsequently, the results of mathematical processing were interpreted from the geothermal point of view with taking into account the geology and structure of the broader area.
Nevertheless, some general assumptions or conclusions can be drawn from the evaluation of temperature measurements with regard to the geothermal potential of the Všebořice area, and even the Czech Republic as a whole:

The reliability of extrapolation of temperature measurements in deeper boreholes is at least acceptable when the boreholes are more than 1 km deep.
Boreholes with temperature field evidently affected by the groundwater flow are to be excluded from extrapolations.
The course of temperature curve of the borehole is influenced by geological structure, but the dependence of temperature on tectonics and geology can be substantial to depths of 1.5 to 2 km, and may camouflage the general geothermal gradient.
One of the two determining geological elements, indicating favourable conditions for utilization of geothermal energy, is the occurrence of deep-seated faults in the area of Eger Rift.
The second critical factor is the occurrence of granitic dykes related to the Variscan orogeny with increased radioactivity (heat source) combined with heat-insulating capping bed (supporting the heat accumulation).
Nevertheless, a mere occurrence of Tertiary volcanic rocks should not be considered a sole favourable indicator of suitability of a certain area for utilization of deep geothermal energy.

Based on the analysis and interpretation of temperatures in boreholes and with regard to the local geological structure, three areas promising for exploitation of geothermal energy can be depicted in the Všebořice area (Fig. 2):

Krupka – Libouchec (on the lineament of the Krušné hory Fault N of Všebořice).
Krušné hory Mountains (area N to NW of the Krušné hory Fault).
Ústí nad Labem (area SE of the Krušné hory Fault).

Since both Všebořice and Litoměřice are located in the area of Eger Rift, the results obtained at Všebořice can be applied and extended to the Litoměřice area, which may represent a district promising for exploitation of the deep geothermal energy.

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