Complex Scientific Analysis in Geothermal Exploration in the Pannonian Basin

Abstract

The deep sedimentary Pannonian Basin has unique geology and hydrogeology. Below its unconfined gravitational flow system, there are some aquifers with outstanding geothermal potential. This paper will give the details of a complex investigation into one of the most promising geothermal reservoirs in Hungary. In addition to revealing its geological and hydrogeological features, the paper discusses the detailed technical investigations and calculations that were carried out to determine the viability of geothermal energy utilization from the investigated aquifer. Although there is a considerable risk given the high salt content of the groundwater and the extreme over-pressure, the results obtained are very promising and convincing for further investments in the near future.
Between two wells in a fractured limestone geothermal reservoir, the flow was investigated using two different methods in order to characterize tracer transport phenomena. The knowledge of reliable tracer transport simulation is key to the determination of the petrophysical properties of geothermal reservoirs. In the first simulation, the flow was considered in an equivalent plane fracture using the Hele-Show flow approach. The second method replaced the fractured system with an equivalent porous layer in which a Darcy flow develops. The Hele-Show flow is described by analytic complex variable functions, while the Darcy flow is determined applying the finite difference simulation method. The obtained results exhibit adequate correlation. The agreement is especially strong between the injection and production wells.