Probabilistic Models of Booking the Geothermal Reserves (McKelvey Scheme) in Construction of Geothermal Potential Catalog for Slovakia – Case Studies for the Levoča Basin, S and W Part

Abstract

With already proven geothermal reserves Rpv = 35 MWt, the Levoča Basin – southern and western part is among most explored geothermal water bodies in Slovakia. Actual installed thermal output of all online wells, i.e. Pth,inst = 25 MWt gives it highest ranks in the country too. In addition, new geothermal well in town of Kežmarok is under testing aimed for geothermal district heating system, plus another two wells apply for new geothermal water withdrawals, recalling actions to assess total and sustainable geothermal capacity to avoid reservoir depletion. Construction of probabilistic (sustainable) model of McKelvey scheme is based on Monte Carlo simulation of the USGS volume method later combined with modified reserve capacity ratio approach. The recovery factor is assessed through simulation of perspective reservoir volume method. Both, the guided (background models for setting PDFs) and conceptual (geothermal water regimes) approaches control the simulation. Thus, PDFs for western part are constructed from cumulative histograms of background data, while for the southern, reservoir units in different tectonic units are considered a single reservoir as they spatially alternate; then both parts are simulated individually, with products aggregated through arithmetical summation. The recovery factor is likely to vary R0 ϵ less than 0.048 ; 0.19 greater than for its western and R0 ϵ less than 0.042 ; 0.115 greater than for the southern part. The western part is more perspective in terms of thermal potential, i.e. 141 / 57 MWt for tprod = 40 / 100 years, so that with sustainable capacity of Pth(S) = 72 / 28 MWt, there is still a potential for development even on a sustainable (long-term) scale, i.e. Pth(D) or Pth(D*) = 21 MWt to 3 MWt respectively, whereas sustainable capacity for the southern part, Pth(S) = 8 MWt is all available for development as this is not produced.