The Geothermal Well Ilz Thermal 1
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THE GEOTHERMAL WELL ILZ THERMAL 1 Detailed lithological, hydrogeological and geothermal investigations for potential utilization as an alternative source of energy. WOLFGANG HASENBURGER MASTER THESIS Applied Geosciences – Economic and Environmental Geology W. Hasenburger – The Geothermal Well ILZ Thermal 1 Submitted at the Chair of Applied Geophysics of the Montanuniverstaet Leoben. Supervision: Ass. Prof. Dipl.-Ing. Dr. mont. Nina Gegenhuber, Chair of Applied Geophysics, Montanuniversitaet Leoben Hon. Prof. Dr. rer. Nat. habil. Jürgen Schön, Chair of Applied Geophysics, Montanuniversitaet Leoben Univ.-Prof. Dr. Johann Goldbrunner, Geoteam Ges.m.b.H., Graz Eidesstattliche Erklärung Ich erkläre an Eides statt, dass ich diese Arbeit selbständig verfasst, andere als die angegebenen Quellen und Hilfsmittel nicht benutzt und mich auch sonst keiner unerlaubten Hilfsmittel bedient habe. Affidavit I declare in lieu of oath, that I wrote this thesis and performed the associated research myself, using only literature cited in this volume. ________________ __________________________________ Date Signature 1 W. Hasenburger – The Geothermal Well ILZ Thermal 1 Acknowledgements First of all, I would like to thank my supervisor Ass. Prof. Dipl.-Ing. Dr. mont. Nina Gegenhuber for making possible this thesis, for discussions and advices and especially for all the correction work. Special thanks also to Univ.-Prof. Dr. Johann Goldbrunner from Geoteam Ges.m.b.H., Graz also for making possible this thesis, for providing log data and hydrogeological data, for discussions, advices and corrections. Furthermore, I would like to thank him for the possibility of doing an internship at his company during the time of completion of this work. I would also like to thank em. O. Univ.-Prof. Mag. Et Dr. rer. nat. Walter Vortisch, Dipl.-Ing. Dr. mont. Eva Wegerer and Mister Franz Seidl from the Chair of Petroleum Geology, University of Leoben for the assistance with the XRD analyses, for discussions and utilization of the software. Further thanks to the Chair of Resource Mineralogy under Univ.-Prof. Dr. phil. Johann Raith, University of Leoben for utilization of a microscope and the RAMAN and to Mr. Maik Zimmermann for assistance with preparation of thin sections. Thanks also to the “Wirtschaftskammer Österreich” (WKO) – Steiermark for the awarding of a scholarship for this thesis and subsequent financial support. Greatest thanks deserves my family, especially my parents, for supporting me financially and personally during all times of studies. It would not have been possible without this support. Last but not least and most important, I would like to thank my girlfriend Theresa for all your support, for always finding the right words in stressful times, for always being on my side and just for everything. I LOVE YOU. 2 W. Hasenburger – The Geothermal Well ILZ Thermal 1 Abstract The well ILZ Thermal 1 was drilled in the year 1998 to a final depth of 1,906.0 m. Located about 15 km west of the town of Fürstenfeld in the Eastern Styrian Neogene Basin, it perforated Miocene sediments until 1,466.0 m comprising Lower Pannonian to Karpatian sequences. Those are underlain by dolomites of the Graz Paleozoic until 1,906.0 m comprising the basement Formations were investigated regarding their reservoir characteristics including lithological, hydrogeological and geothermal parameters to define the geothermal system in the area of the well. A focus thereby lies on the Paleozoic basement not only because of highest data density from well logs and cuttings but also because of highest expectable temperatures for geothermal energy utilization. Lower Pannonian and Sarmatian sediments consist of an interlayering of gravels and sands to fine- grained deposits. The Lower Pannonian can be correlated regionally with the “Feldbach-Formation”, whereas the Upper Sarmatian corresponds to the “Gleisdorf-Formation”. Lower to Middle Sarmatian sediments might be correlated with the “Rollsdorf-“ or “Grafendorf-Formation”. Major potential aquifers for drinking water supply are formed by several coarse developed horizons, making up a total aquifer net thickness of 153.8 m with an average resistivity-derived porosity of around 20%. The Badenian series starts with the much finer developed “Bulimina-Bolivina/Rotalia-Cibicides Zone” (BB/RC-Zone). Below, the “Sandschaler Zone” is dominated by coarse sandstones with few shaly to marly intercalations and hence presents major potential for geothermal utilization with temperatures of up to 46.5°C, calculated from a geothermal gradient of 45.5°C/km. Porosities range between 22- 25% and transmissivity was calculated to 3.15*10-6 m²/s. The water of the Sandschaler Zone is a sodium-bicarbonate type with a content of total dissolved solids (TDS) of 5.01 g/l. The Sandschaler Zone is underlain by the Lower Badenian Lageniden Zone, consisting of the upper fine and impermeable “Tonmergel Series” and the lower much coarser developed Base Conglomerate, which forms, together with the Karpatian Conglomerate-rich Group, the second important geothermal aquifer. Those are characterized by a more or less very homogeneous very coarse conglomeratic development with minor thin shaly and marly intercalations. However, porosities range between 11- 15% and transmissivity was determined to 6.61*10-5 m²/s. The water is typed as a sodium-chloride- bicarbonate water with very high mineralization of 17.9 g/l. This, together with very high CO2- and 226Ra-content might cause problems when extracted and for utilization, especially in balneology, unless treated requiring additional costs. Temperatures reach 76.5°C at 1,466.0 m. Finally, the basement is formed by dolomites of the Graz Paleozoic and can be subdivided into three major zones. The upper light to dark gray dolomites and marls (1) are assigned to the “Flösserkogel” Formation of the “Rannach” Facies (Lower to Middle Devonian) and are developed very heterogeneously. Major geothermal potential lies in the uppermost part and around 1,600 m with permeabilities of > 100 mD and 60 mD, respectively. Temperatures gain 76-83°C, but again a very high 226 water mineralization (TDS = 17.6 g/l) and high CO2- and Ra-content might lead to problems. The Paleozoic water itself was classified as sodium-bicarbonate type. The lower dark gray dolomites (3) show a very homogeneous development with abundance of breccias increasing towards depth and therefore can be assigned to the Schöckl Facies through correlation with the lower dolomites of the well Arnwiesen 1. Although temperatures reach 96.5°C at the final depth, those dolomites are not regarded as potential aquifers due to permeabilities of < 50 mD. The upper and the lower zone are separated by a fault zone (2), which represents the major structure for convective heat transport in the geothermal system with a permeability of > 260 mD. All in all, geothermal resources can be classified as low enthalpy resources and total heat in place was calculated to nearly 1010 MJ or 2.8*109 kWh. The temperature range would allow application in agriculture (e.g. green houses), domestic hot water supply, balneology, radiators, for example. 3 W. Hasenburger – The Geothermal Well ILZ Thermal 1 Zusammenfassung Die Tiefbohrung ILZ Thermal 1 wurde im Jahr 1998 bis auf eine Endtiefe von 1,906.0 m niedergebracht. Sie befindet sich in der Marktgemeinde Ilz, ca. 15 km westlich der Stadt Fürstenfeld im Oststeirischen Neogenbecken. Dabei wurden miozäne Sedimente von Unterpannon bis Karpat durchbohrt, welche von Dolomiten des Grazer Paläozoikums unterlagert werden. Alle Formationen wurden hinsichtlich ihrer Reservoireigenschaften untersucht. Dabei wurden detaillierte lithologische, hydrogeologische und geothermische Analysen durchgeführt um Aussagen über die Nutzbarkeit der Thermalwässer als alternative Energiequelle treffen zu können. Die unterpannonischen und sarmatischen Ablagerungen werden von einer Wechsellagerung von Sanden und Kiesen und feinkörnigen Ablagerungen aufgebaut. Das Unterpannon kann aus regional- geologischen Überlegungen der „Feldbach-Formation“, das Obersarmat der „Gleisdorf-Formation“ zugeordnet werden. Das Unter- bis Mittelsarmat entspricht eventuell der „Rollsdorf-“ oder „Grafendorf-Formation“. Sand- und Kieshorizonte mit einer gesamten Nettomächtigkeit von 153.8 m und einer durchschnittlichen Widerstandsporosität von 20% bilden die vielversprechendsten Horizonte für eine potenzielle Trinkwassererschließung. Das Baden beginnt mit der sehr feinkörnig entwickelten Bulimina-Bolivina/Rotalia-Cibicides Zone. Die darunterliegende Sandschalerzone wird von Grobsandsteinen mit wenigen feinkörnigen Ein- schaltungen dominiert und bildet deshalb eine Zone geothermischen Potenzials. Die Temperaturen erreichen 46.5°C, resultierend aus einem berechneten geothermischen Gradienten von 45.5°C/km. Die Porosität liegt bei 22-25% mit einer Transmissivität von 3.15*10-6 m²/s. Das Thermalwasser wurde als Natrium-Hydrogenkarbonat-Typ mit einer Summe an gelösten Stoffen von 5.01 g/l klassifiziert. Die Sandschalerzone wird von der unterbadenischen Lagenidenzone unterlagert, bestehend aus der feinkörnigen Tonmergelserie und dem grobkörnien Basiskonglomerat, welches zusammen mit der darunterliegenden karpatischen konglomeratreichen Serie einen zweiten geothermischen Aquifer bildet. Die Porosität variiert zwischen 11-15% mit einer Transmissivität von 6.61*10-5 m²/s. Temperaturen erreichen max. 76.5°C. Das Thermalwasser wurde als Natrium-Chlorid-Hydrogen- karbonat-Typ klassifiziert mit einer Summe an gelösten Stoffen