In this paper we present the results of 3D conductive thermal modeling of the Alpine-Pannonian transition zone. The study area comprises the Vienna, Danube, Styrian and Mura-Zala basins, surrounded by the Eastern Alps, the Western Carpathians and Transdanubian Range. The model consists of three layers: Tertiary sediments, the underlying crust and lithospheric mantle. The crust and mantle were homogenous with constant thermal properties. Heat production in the sediments and crust was 1 lW/m 3. The thermal conductivity of sediments varied horizontally and vertically and based on laboratory measurements. We tested two scenarios: a steady-state and a time-dependent case. The conductive heat transport equation was solved by finite element method using Comsol Multiphysics. The results of the steady-state model fit to the observation in the northern part of the study area, but this model predicts lower heat flow density and temperatures than observed in the southern part of the study area including the Styrian basin. The area underwent lithospheric stretching during the Early-Middle Miocene time, therefore the temperature field in the lithosphere is not steady-state. We calculated the initial temperature distribution in the lithosphere at the end of rifting using non-homogeneous stretching factors, and we modeled the present day thermal field. The results of the time-dependent model fit to the observed heat flow density and temperatures, except in those areas where intensive groundwater flow occurs in the carbonatic basement of the Transdanubian Range and Northern Calcareous Alps, and the metamorphic basement high between the Mura trough and Styrian basin. We conclude that time-dependent model is able to predict the temperature field in the upper 6-8 km of the crust, and is a valuable tool in EGS exploration.
The Pannonian basin in Central Europe is well known for its rich geothermal resources. Although geothermal energy has been utilised, mainly for direct use purposes, for a long time, there are still a lot of untapped resources. This paper presents novel methods for outlining and assessing the theoretical and technical potential of partly still unknown geothermal reservoirs, based on a case study from the Dráva basin, one of the sub-basins of the Pannonian basin along the Hungarian–Croatian border. The presented methods include reservoir delineation based on combining geological bounding surfaces of the Upper Pannonian basin-fill units with a set of isotherms deriving from a conductive geothermal model. The geothermal potential of each identified reservoir was calculated by a Monte Carlo method, which was considered as being represented by the heat content of the fluids stored in the effective pore space (‘moveable fluid’). The results underline the great untapped geothermal potential of the Dráva basin, especially that of the reservoir storing thermal water of 50–75°C, which has the largest volume and the greatest stored heat content.
Data on thermal water sources with outflow temperature of 30 °C and above were analyzed from the N-ern parts of Bosnia and Herzegovina, Serbia and Croatia, S-ern parts of Hungary, W-ern parts of Romania, and NE-ern parts of Slovenia, altogether from an area of 99,347 km 2. The overview identified 771 geothermal sources; only 7 were thermal springs. The average well depth is about 1.2 km. About 13% of wells are younger than 10 years, additional 17% below 30 years; while 26% are older than 50 years. Average thermal water outflow temperature is 54 °C being the highest, 170 °C, in Croatia. Most thermal water is produced from basin fill sediments-Lower and Upper Pannonian (Mio-Pliocene) loose sandstones which are tapped by 86% of wells. The rest appertains to basement rocks-fissured, fractured and karstified Paleozoic, Mesozoic and Middle Miocene metamorphic, carbonate and siliciclastic rocks. In total, 72% sources hold water rights, 6% mining rights, 2% geothermal rights and 1% has no rights. The permits allow much higher water abstraction as currently listed. Usage for bathing and balneology encompasses 24% of all active sources (155), some of these also with heating (23). 104 objects (16%) are used for heating, also district heating (13) and individual space heating (3). An additional 10% (70) are used in agriculture, mainly greenhouse heating. There are 41 reinjection wells (5%). It is primarily in Hungary that drinking water (17%), industrial usage (5%) and monitoring wells (2%) are also common.
<p>Society is increasingly looking to the subsurface for our energy needs, be that for extracting geothermal energy, shale gas, or buffering heat, gas, or storing by-products of energy production. An increasingly crowded subsurface presents risks to groundwater relied on for water supply, since subsurface activities can introduce or release contaminants and alter subsurface properties. The VoGERA project is investigating the vulnerability of shallow groundwater from a range of subsurface energy technologies across different hydrogeological and geological settings within Europe. A suite of conceptual models compares the intrinsic vulnerability for different geological (crystalline, poorly consolidated and well consolidated sedimentary basins) and hydrogeological (basin centre and margins) conditions. They also consider the impacts of different subsurface activity types broadly categorised as those processes including injection, abstraction and a neutral fluid balance. Potential contamination pathways are being investigated at four case study sites; the Rauw Fault in Belgium, Panonian Basin in Hungary, The Peel Boundary Fault in the Netherlands and the Vale of Pickering in the UK. Geophysical, hydrological and hydrochemical data from these sites will be assessed in order to improve contamination pathway process understanding in a European setting. Findings from the case study sites will be used to evaluate the conceptual models and to develop a tool for decision makers and the public to assess the vulnerability to shallow groundwater from subsurface energy activities depending on the activity, and geological and hydrogeological conditions at a specific location. The VoGERA project is funded as part of the European Union&#8217;s Horizon 2020 GeoERA network of projects under the Groundwater theme (Grant agreement number 731166).</p>
In spite of its considerable size and the presence of mature oil source rocks, the Neogene Danube Basin is characterized by the absence of commercial oil accumulations. However, important [Formula: see text] fields have been discovered in the basin, which have been possibly explained recently by displacement of oil by later migration of [Formula: see text] into the reservoirs. Previous studies performed independently in the southern, Hungarian part of the basin (known as the Little Hungarian Plain) have attempted to model petroleum generation/migration history, to identify sources of the [Formula: see text], and to understand the tectonic evolution of the basin and its deep-water flow regime. We were attempting to combine the results of these studies to interpret the fluid-migration history and reveal the influencing processes. This work supports the hypothesis that [Formula: see text] could have played a key role in preventing the formation of oil accumulations. During the latest Miocene, early mature oil and saline water, the latter formed by dissolution of up to now unidentified halites, moved together toward the Mihályi High, a regional uplifted structure in the central part of the basin. Modest amounts of oil could have been trapped there while saline water mixed with the low-salinity water of the reservoirs, with the [Formula: see text] arriving later and displacing the oil.
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