Nina Gegenhuber

Improved petrographic-coded model and its evaluation to determine a thermal conductivity log

Thermal conductivity is one of the crucial properties for thermal modelling as well as tunnelling or geological modelling. Available data are mainly from laboratory measurements. Therefore, additional ways, such as correlations with other properties to derive the petrophysical parameter, will be an advantage. The research presented here continues and improves the petrographic-coded model concept with an increased set of data, including a variety of lithologies, and, furthermore, the correlations, including the electrical resistivity. Input parameters are no longer taken from the literature, but are derived directly from measurements. In addition, the results are compared with other published approaches. Results show good correlations with measured data. The comparison with the multi-linear regression method shows acceptable outcome, in contrast to a geometric-mean method, where data scatter. In summary, it can be said that the improved model delivers for both correlation (compressional wave velocity and electrical resistivity with thermal conductivity) positive results.

Axiale Prüfkörperdurchschallung während einaxialer Druckversuche

ZusammenfassungIm Erkundungsprogramm von Tunnelbauwerken erfolgt die Durchschallung zur Qualitätskontrolle der Prüfkörper vor der eigentlichen Verwendung im einaxialen oder triaxialen Druckversuch. Für die Projektentwicklung Kraftwerk Tauernmoos wurden sowohl im Labor als auch in Bohrlöchern die Kompressions- und Scherwellengeschwindigkeiten ermittelt. Die Prüfkörper zeigten jedoch nur halb so hohe Wellengeschwindigkeiten. Dies begründete, zusammen mit der Beurteilung der entsprechenden Druckversuche anhand der Spannungs-Dehnungsdiagramme, den Bau der Versuchseinrichtung zur Durchschallung der Prüfkörper während einaxialer Druckversuche. Kraftwerksprojekt, Laufzeitmessung, Versuchsaufbau und spannungsabhängige Wellengeschwindigkeiten von Weißschiefer und Granit werden hier vorgestellt und diskutiert.AbstractUltrasonic wave propagation is carried out in the exploration programme of tunnels for the quality control of the specimens before the actual use in the uniaxial or triaxial compression test. For the project development of Power Station Tauernmoos the compressional and the shear wave velocity were determined both in the laboratory and in drill holes. The specimens showed, however, only half as high wave velocities. This fact together with the evaluation of the corresponding compression tests on the basis of the stress-strain diagrams reasoned the construction of the test setup for the ultrasonic wave propagation of the specimens during uniaxial compression tests. The power station project development, travel-time measurement, test setup and strain-dependent wave velocities of white schist and granite are introduced and discussed here.

Elastic rock properties influencing factors - mineralogy, porosity and microstructure

Summary We present data from laboratory measurements of elastic properties of different lithologies. Measurements were carried out on plugs with 25 mm diameter and 22 mm length in dry and brine saturated conditions with an ultrasonic device. Thin sections had been used to obtain mineralogy and microstructures of the samples. For model calculations ( Schon, 2015 ) the host materials compressional- and shear modulus were calculated from mineral composition (from thin sections) but also derived from the empirical data by extrapolation for zero porosity. Bound models of Voigt (1910) and Reuss (1929) were used to calculate upper and lower boundary respectively. Further also the generalization of Lichtenecker and Rother (1931) with the exponent α was applied and used to subgroup the data. Analogous we applied exponential approximation curves (using another exponent β) which helped to automatically divide the data into the subgroups similar to the α-values. The α- and the corresponding β-values describe data groups with similar microstructural parameters and changing porosity. Overall we found out that the empirically derived host material parameters worked better for our approach.

Well-log based rock physics template of the Vienna Basin and the underlying Calcereous Alps

Abstract In this study, the ratio of compressional and shear wave velocity versus acoustic impedance as rock physics template for northern part of the Vienna Basin has been derived for siliciclastic rocks based on formation evaluation of well-log data. The results have been verified through wells in different areas drilled in various depths. Additionally, depositional sequences like prograding deltas and braided rivers have been plotted onto the rock physics template to illustrate the effect of changing shale volume. Carbonates below the basin have been included into the study and results from previous projects, based on laboratory data and petrophysical models on certain lithologies in the Vienna Basin, have been used to compare the outcome. The result is a rock physics template which includes important properties such as porosity, true vertical depth and fluid type from log data and which is considered useable throughout different areas and various lithologies of the Vienna Basin.

Testing of Clustering Algorithms on Different 3D Seismic Models

Summary In seismic interpretation, a big amount of data has to be handled to segment the data cube in zones and faults. In the conventional method, inlines, crosslines and seismic sections are interpreted to divide the geological zones on seismic reflectors and on seismic discontinuities. This segmentation is often guided by seismic attributes, wells and further geological information. The other approach of seismic interpretation is dividing seismic data by algorithms. One popular method to achieve an automatic segmentation is clustering of seismic attributes. There are several clustering algorithms available in all different kinds of scientific disciplines. Some are also already used in seismic interpretation. To get an overview of clustering algorithms and to understand the different kinds of algorithms a research study was done. Therefore, multiple algorithms were classified in a matrix and a workflow was created to test various algorithms on different synthetic 3D seismic data models and subsequently a test environment was founded to understand algorithms to use them for automatic or semiautomatic interpretation of seismic data.

Introduction to special section: Geothermal energy

Geothermal energy is heat generated and stored in the earth, a combination of residual heat from earth’s formation and heat generated by radioactive decay. Ninety-nine percent of earth’s mass has a temperature in excess of 1000°C, a source of low-pollution energy that potentially is available