Présentations Colloques

Oral Presentation
8.06
Session 8.06: Verification of conceptual patterns and expected natural effects of regional groundwater flow by interpretation of relevant field observations
Madl-Szonyi Judit
Comparison of 2D simulated flow pattern and measured hydraulic data for a confined aquifer to reveal the influence of gravity and heat on flow pattern
The gravity-driven flow concept was originally developed for unconfined sedimentary basins. However, the aquifers are often confined in different rate. This issue is especially important for confined carbonates, where the fluids are sources for geothermal utilization and hydrocarbon exploration. The basic issue of the paper is the hydrodynamic behaviour of confined aquifers, i.e. what is the role of different driving forces, heat and gravity. **For the first step the effect of the water table undulation was examined on the flow pattern, afterwards the influence of the heat was investigated on the flow pattern and vice versa. It was found that with real water table differences and basin conditions and parameters, the gravity is the main driving force in the area. The temperature distribution however, is determined primarily by the advective heat transport due to gravity-driven flow and influenced by the insulation effect of low permeability confining layer. **These results were compared with the results of hydrodynamic data analyses based on preproduction hydraulic data of water and hydrocarbon wells for the Hungarian Paleogene Basin. The study revealed the existence of dynamic fluid flow systems including gravity-driven flow in carbonate aquifer. Not only the horizontal connections with unconfined carbonates but also the vertical interaction were revealed between confining strata and aquifer sequences. **Finally, numerical simulation was again executed by the involvement of findings of data evaluation. Therefore it could be revealed that this iteratively used approach can be used in regional groundwater-flow system evaluation. The significance of gravitational driving force in confined aquifers could be established. The research was supported by OTKA NK 101356.**
Hungary