Basin-Scale Hydraulic Evaluation of Groundwater Flow Controlled Biogenic Gas Migration and Accumulation in the Central Pannonian Basin
Brigitta Czauner,
Zsóka Szabó,
Béla Márton
et al.
Abstract:Biogenic or microbial methane has an increasing share in the global gas resource base, though its exploration still faces challenges and welcomes innovations. Critical elements of its migration and accumulation models are the groundwater flows which gather and transport the gas in aqueous solution, and the seal rocks or aquifers which lead groundwater flows horizontally over great distances. This paper intends to introduce the hydraulic trap concept into these models, which is able to drive fluids horizontally… Show more
“…The areas are located on the southern border of the regional recharge area in the Nyírség region, where, at shallow depths (>500 m), flow-through starts to occur and become more dominant towards SW, followed by discharge conditions more to the south. This finding is consistent with the results of Szabó [39] and Czauner et al [58], who showed recharge-flow-through conditions at a shallow depth (>500 m) in the South-Nyírség region and discharge conditions to the south of the study area. Szanyi [45] also obtained similar results, showing that original flow-through existed in the South-Nyírség region, but the large water exploitation around Debrecen (a town near the study area, Figure 1b) changed the conditions to mainly recharge-dominated.…”
Section: Regional Groundwater Flow Conditions Around the Wetlandssupporting
confidence: 93%
“…It appears as a transient zone first, represented by the near-hydrostatic upwelling water of the dissipated overpressure regime on the p(z) plot, as well as on the cross-section. This transient zone was identified in other parts of the Great Hungarian Plain, too [58,59]. Real overpressure values occur only at ~−2000 mBf, representing the upward-directed overpressured flow regime.…”
Section: Regional Groundwater Flow Conditions Around the Wetlandsmentioning
Climate change and increasing human impacts are more emphasised in recharge regions, where the main flow direction is downward, resulting in negative water balance. Two wetlands located in the recharge position of regional groundwater flow systems were investigated in the Nyírség region, Hungary, as pilot areas for representing wetlands in similar hydraulic positions. Hydraulic data processes, chemical data evaluations, and numerical simulations revealed that the wetlands are fed via local flow systems, superimposing regional-scale recharge conditions in the area. The wetlands are discharge and flow-through types in connection with local flow systems. Nevertheless, in the case of significant regional water table decline—due to the high vulnerability of recharge areas to climate change—local flows are degraded, so they are not able to sustain the wetlands. To preserve the groundwater-dependent ecosystems in the areas, water retention at the local recharge areas of the wetlands may help in the mitigation of water level decline under present-day conditions. If the regional water table continues to decline, comprehensive water retention solutions are needed in the whole region. The results highlight that understanding the natural wetland–groundwater interactions at different scales is crucial for the preservation of wetlands and for successful water retention planning.
“…The areas are located on the southern border of the regional recharge area in the Nyírség region, where, at shallow depths (>500 m), flow-through starts to occur and become more dominant towards SW, followed by discharge conditions more to the south. This finding is consistent with the results of Szabó [39] and Czauner et al [58], who showed recharge-flow-through conditions at a shallow depth (>500 m) in the South-Nyírség region and discharge conditions to the south of the study area. Szanyi [45] also obtained similar results, showing that original flow-through existed in the South-Nyírség region, but the large water exploitation around Debrecen (a town near the study area, Figure 1b) changed the conditions to mainly recharge-dominated.…”
Section: Regional Groundwater Flow Conditions Around the Wetlandssupporting
confidence: 93%
“…It appears as a transient zone first, represented by the near-hydrostatic upwelling water of the dissipated overpressure regime on the p(z) plot, as well as on the cross-section. This transient zone was identified in other parts of the Great Hungarian Plain, too [58,59]. Real overpressure values occur only at ~−2000 mBf, representing the upward-directed overpressured flow regime.…”
Section: Regional Groundwater Flow Conditions Around the Wetlandsmentioning
Climate change and increasing human impacts are more emphasised in recharge regions, where the main flow direction is downward, resulting in negative water balance. Two wetlands located in the recharge position of regional groundwater flow systems were investigated in the Nyírség region, Hungary, as pilot areas for representing wetlands in similar hydraulic positions. Hydraulic data processes, chemical data evaluations, and numerical simulations revealed that the wetlands are fed via local flow systems, superimposing regional-scale recharge conditions in the area. The wetlands are discharge and flow-through types in connection with local flow systems. Nevertheless, in the case of significant regional water table decline—due to the high vulnerability of recharge areas to climate change—local flows are degraded, so they are not able to sustain the wetlands. To preserve the groundwater-dependent ecosystems in the areas, water retention at the local recharge areas of the wetlands may help in the mitigation of water level decline under present-day conditions. If the regional water table continues to decline, comprehensive water retention solutions are needed in the whole region. The results highlight that understanding the natural wetland–groundwater interactions at different scales is crucial for the preservation of wetlands and for successful water retention planning.
“…) mellett a közel hidrosztatikus nyomásviszonyok. A megújulás mértékének és pontos tartományának hidraulikai megértése azonban további kutatásokat igényel (Czauner et al 2023). Ezzel szemben a mélyebb túlnyomásos tározókba a csapadékvíz semmiképpen nem tud természetes úton bejutni, így azokról feltételezhetjük, hogy nem megújuló vizet tartalmaznak (Mádl-Szőnyi-Simon 2016; Mádlné Szőnyi,…”
Összefoglalás.
Magyarországon az energiaválság kapcsán előtérbe került a kedvező geotermikus
adottságok kihasználásának szükségessége. A cikkben az európai geotermikus
viszonyokból kiindulva mutatjuk be a hazai adottságokat, alkalmazható
technológiákat. Az adottságok villamosáram-termelésre csak sporadikusan, magas
kockázatok és technológiai fejlesztések mellett alkalmazhatók. Ugyanakkor az
ország szinte teljes területén van lehetőség sekély geotermikus és hidrotermás
készletek, valamint a hulladékhő további hasznosítására. A jövőben a termálvizek
települési szintű, kaszkád rendszerű teljes körű hasznosítása lenne kívánatos. A
fenntarthatóság kulcsa a lefűtött termálvizek nagyarányú visszasajtolása. A
felszín alatti térrész, a különböző fluidumok és a bennük rejlő nyersanyagok
hasznosítása kutatást és új, komplex szemléletet igényel.
Summary.
The need to exploit the favourable geothermal potential has emerged in Hungary
due to the war-induced energy crisis. In this paper, we present the geothermal
conditions of Hungary with a European comparison. The elevated heat flux of the
Pannonian Basin, thanks to the thinned lithosphere, provides beneficial
conditions along with the thermal-bearing aquifers primarily for medium enthalpy
resources. We detail the potential technologies applicable to exploit the
various types of resources and the risks related to their utilisation. Although
not all of the technologies can be applied everywhere in the country, our
results show that shallow geothermal or hydrothermal utilisation is possible in
the entire country, as well as the utilisation of waste heat from used water or
natural springs. Assessing geological risks is a decision criterion in the
project preparation phase: supporting the investment with lower geological risk
leads to more successful projects and, simultaneously, helps to gain more
knowledge about the geological formation. With high risks, Hungarian geothermal
resources can only be used sporadically for electricity generation. Experience
of ongoing international projects in enhanced geothermal systems should be
gathered for the future use of deep basement resources. The main unconsidered
potential in Hungary lies in the cascaded use of thermal water at the municipal
level, which can be a key in constructing low-carbon district and space heating
systems combined with agricultural use. The unsolved research-intensive issue of
sustainable exploitation is the extensive reinjection of cooled thermal waters,
which prevents the overuse of slowly renewable resources. Developing this sector
in Hungary regarding conventional and combined innovative exploitation of the
subsurface space requires research and new complex approaches.
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