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The paper introduces the method of regional hydrodynamic analysis based on pore pressure evaluation into the preliminary geothermal evaluation, in sedimentary basins influenced by overpressured and superimposed gravity-driven flow. This novel approach complements the usual reservoir and temperature analysis. Understanding of subsurface pore pressure distribution is also beneficial during planning of thermal water reinjection. The approach is demonstrated for the Duna-Tisza Interfluve of the Pannonian basin and the results are compared with operational experiences. The results can give basis for numerical modeling and provide background for aligned utilization of drinking water, thermal water and hydrocarbons in sedimentary basins.

In addition to geological conditions, hydrocarbon migration and entrapment is highly influenced by regional groundwater flow based on hydraulic theory of hydrocarbon migration. As a consequence, hydrogeological flow analysis contributes to petroleum exploration. The case study is represented from the Pannonian Basin, characterized by a complex groundwater flow situation, with an overpressured flow regime overlain by a gravity-driven flow system. In this situation the hydrocarbon migration is controlled by the way of overpressure dissipation, while hydrodynamic constraints influence the entrapment. The hydrocarbon migration can hydrodynamically occur up to the boundary of downward gravity-driven flow and upward flow of the overpressured system. Based on the study, these are contolled by the hydraulic function of fault zones and low-permeability formations. These findings were verified on three study areas with hydrochemical and temperature data as well.

The exploitation of geothemal energy in sedimentary basins requires detailed investigation of the geothermal and fluid flow field and the reservoirs of an area. Usually, geothermal evaluations are constrained to reservior scale. Investigations are carried out regarding the available heat and fluid, and the reservoir properties. However, in hydraulically continuous sedimentary basins the reservoir can not be handled as an individual entity. To resolve this problem, the term „reservoir” has to be extended to „basin scale” to understand processes and fluid-based geothermal possibilities in a sedimentary basin. The regional hydrodynamic evaluation give a framework and complements the traditional reservoir scale analysis. The findings are demonstrated for the Pannonian Basin, Hungary.