MAGYAR ÁLLAMI EÖTVÖS LORÁND EÖTVÖS LORÁND GEOPHYSICAL INSTITUTE GEOFIZIKAI INTÉZET OF HUNGARY GEOFIZIKAI KÖZLEMÉNYEK CONTENTS Geothermal conditions of Hungary P. Dövényi. F. Horváth, P. Liebe. J. Gá/fi, /. Erki 1. Introduction .......................................................................... 3 2. Historical overview .............................................................. 5 3 . Temperature data in Hungary........................................ 7 ВЕНГЕРСКИЙ 3.1. Compilation of temperature data catalogue ............ 12 ГЕОФИЗИЧЕСКИЙ 3.2. Map construction and data analysis......................... 14 4. Heat flow determinations in the Pannonian basin ......... 19 ИНСТИТУТ 4.1. Measurements of thermal conductivity .................... 1 9 4.2. Heat flow determinations in Hungary ...................... 24 ИМ Л. ЭТВЕША 4.3. Heat flow map of the Pannonian basin ................... 30 5. Interpretation of geothermal data ..................................... 31 5.1. Geothermics and subsurface water circulation ....... 35 5.2. Geothermics and basin form ation............................ 40 ГЕОФИЗИЧЕСКИЙ 6. Results and conclusions ..................................................... 41 БЮЛЛЕТЕНЬ Bibliography ............................................................................. 42 Tables (I— XVI) ........................................................................ 49 Appendix: Catalogue of temperature data............................ 89 VOL. 29. N0.1. APRIL 1983. (ISSN 0016— 7177) BUDAPEST TARTALOM Magyarország geotermikus viszonyai Dövényi Péter, Horváth Ferenc, Liebe Pál, Gálfi János, Erki Imre 1. Bevezetés ....................................................................................................................................... 59 2. Történeti áttekintés........................................................................................................................ 61 3. Hőmérsékleti adatok Magyarországon ..................................................................................... 62 3.1. Hőmérsékleti adatrendszer összeállítása............................................................................ 65 3.2. Térképszerkesztés és adatfeldolgozás ................................................................................. 67 4. Hőáram-meghatározások a Pannon-medencében .................................................................... 69 4.1. Hővezetőképesség-mérések .................................................................................................. 70 4.2. Hazai hőáram-meghatározások........................................................................................... 73 4.3. A Pannon-medence hőáramtérképe ................................................................................... 77 5. A geotermikus adatok értelmezése............................................................................................. 78 5.1. A geotermika és a felszín alatti vizek áramlásának kapcsolata..................................... 81 5.2. Geotermika és medencefejlődés........................................................................................... 84 6. Eredmények és következtetések ................................................................................................. 85 Bibliográfia........................................................................................................................................ 42 Táblázatok (I—XVI) ....................................................................................................................... 49 Függelék: Hőmérsékleti adatgyűjtemény ...................................................................................... 89 СОДЕРЖАНИЕ Геотермические условия Венгрии П. Девени. Ф. Хорват, 88 (резюме) П. Либе. Й. Галфи, И. Эрки GEOPHYSICAL TRANSACTIONS 1983 Vol. 29. No. 1. pp. 3— 114 GEOTHERMAL CONDITIONS OF HUNGARY Péter DÖVÉNYI*, Ferenc HORVÁTH*, Pál LIEBE**, János GÁLFI**, Imre ERKI* A brief review is given of the history of geothermal investigations in Hungary followed by a summary of the methods of temperature measurement, their reliability and applicability. All available and valuable temperature data are qualified on the basis of conditions and probable accuracy of measurements and are listed in a temperature catalogue. A map of geoisotherms at 1 km depth on a scale of 1 : 1,000,000 and another at 2 km depth (scale 1 : 2,500,000) are constructed for Hungary and adjoining territories. In addition, average temperature vs. depth profiles are presented for different sub-units of the Pannonian basin. All Hungarian measurements are used to obtain the average thermal conductivities of Neo­ gene sedimentary rocks and of basement rocks. Hungarian heat flow determinations are reviewed and three new heat flow data are also presented. A method is proposed for estimating the heat flow value for boreholes where no actual thermal conductivity measurements were performed but the temperature conditions and the lithology are well known. The heat flow map of the Pannonian basin has been prepared by the use of measured and estimated heat flow data. The Pannonian basin is characterized by high temperature and heat flow values with signifi­ cant spatial variations. An estimate is made of the temperature disturbance caused by regional water circulation systems. The conclusion is reached that if the influence of water convection is corrected, high undisturbed (purely conductive) temperature and heat flow values are obtained for the Mesozoic carbonate complex of the Transdanubian Central Range. In other parts of the country —apart from local anomalies—water circulation does not influence significantly the conductive temperature field. Finally a review is given on the geodynamic interpretation of the Pannonian basin thermal anomaly and attention is called to the importance of knowledge of the paleogeothermal conditions. d: geothermics, heat flow, geothermal gradient, thermal conductivity, thermal waters, Hungary, Pannonian basin 1. Introduction It might well be useful to avoid any confusion by defining here what we mean by Pannonian basin. It is a fairly big Neogene intramontane depression surrounded by the Alps, Carpathians and Dinarides. It is however not a uniform depression because locally pre-Neogene basement rocks crop out (e.g. Trans­ danubian Central Range) which separate the Pannonian basin into sub-units. The largest part of the Pannonian basin belongs to Hungary and the peripheral parts lie in the surrounding countries (Austria, Czechoslovakia, USSR, Roma­ nia and Yugoslavia). Geothermal research in the Pannonian basin and the utilization of geother­ mal energy have been well in the forefront of scientific interest for more than * Eötvös Loránd University, Department of Geophysics, H-1083 Budapest, Kun В. tér 2. ** water Resources Research Centre, H-1095 Budapest, Kvassay J. u. 1. Manuscript received: 20 October 1982 4 P. Dövényi— F. Horváth— P. Liebe— J. Gálfi— I. Erki a century. Since the beginning of drilling activities it has become clear that thermal waters are available in vast amounts in the Mesozoic carbonates of the Hungarian mountain chain (Transdanubian Central Range, Mátra, Bükk, see Enclosure 2) and in the Neogene sediments of the basins; these thermal waters can be utilized for balneology and also as an energy source. After initial investigations, major development work started in the 1950s. Thermal conduc­ tivity measurements started at the same time, and they showed that not only the thermal gradient but also the terrestrial heat flow is markedly higher than the world average in most parts of country (Figure 1). This suggests that thermal highs in the Pannonian basin are not local features related to upward migration of thermal waters but are parts of a regional phenomenon which reflect elevated temperatures of the whole lithosphere. Nevertheless, tem­ peratures vary considerably from place to place and the mapping and under­ standing of this variation are important tasks. Construction of reliable tem­ perature maps is however a difficult job because most of the temperature data measured during routine geophysical surveys do not fulfil strict physical require­ ments. In view of this, temperature data should somehow be corrected and, if necessary, some of them should be dropped. Fig. 1. Frequency diagram of continental 300 ! heat flow data [Jessop et al. 1976] and the average for Hungary 200 I 1. ábra. A kontinentális hőáramsürűség adatok hisztogramja [Jessop et al. 1976] ! A,p.-c, -ijrujary a magyarországi átlagérték feltüntetésével 100 Фи.\ /. Частотная диаграмма данных о континентальном тепловом потоке 0 : ^ - — n________ ^ [Д жесоп и др. 1976] с указанием средних 0 50 100 150 200 250 значений для Венгрии. q (mw/rrí) The recent energy crisis has upgraded the value of geothermal energy. Intensive research has been initiated to seek low or high enthalpy geothermal reservoirs and to use them as an alternative energy source. There is, however, further value to be obtained from knowledge of geothermal conditions. For example, they are important parameters which constrain geodynamic models of basin formation. Furthermore, it is widely accepted that the generation of liquid hydrocarbons and their migration through permeable rocks are basically thermally controlled processes. The prime goal of this paper is to present all reliable temperature data for Hungary in the form of a data catalogue, maps of geoisotherms and temperature depth diagrams. A new heat flow map of the