Although geothermal structure of the Ďurkov depression is by many considered the most prospective for a large-scale direct geothermal energy production, no project has been launched yet at the site. Revision of hydrogeothermal evaluation took part to introduce a concept of probability-based assessment and sustainable production into a topic. Both, a conservative t = 40 years and t = 100 years balance period has been quantified, the latter corresponding to a minimum production period meeting sustainability concept as defined by Axelsson et al. in 2001. Combination of specified recovery factor based on a production-efficiency method, volumetric (heat-in-place) USGS method and reserve capacity ratio approach has been applied to both, Monte Carlo based quantification and Turning-bands derived spatial distribution of energy base. According to 10,000 iterations, the median for HT = 5.8 EJ. At calculated R0 = 0.053, the mean value of H0 = 305 PJ. Following the booking concept, P90(H0) = Rpv = 37 MWt for tprod = 100 years and P90(H0) = Rpv = 92 MWt when balanced for 30 years only. This leaves Rpb = 60 MWt or Rpb = 150 MWt to prove under a probabilistic concept (50 % probability). However, the modified reserve capacity ratio yields a critical limit of Pth = 49 MWt and Pth = 121 MWt respectively, if turning to a sustainable geothermal production. With a reference to a pioneering hydrogeothermal evaluation, 42 MWt were proven through free-flow and 92 MWt modeled for pumping. To quantify the first, it appears that as long as a model is valid, there is 88 % probability of a long-term production at a given rate even balanced for 100 years. For both periods, the resultant reserve capacity ratio for such an installed capacity would count rcap = 0.58 and rcap = 0.83 respectively, implying a sustainable character of the production.

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