Investigation of Water-permeability and Ultrasonic Wave Velocities of German Malm Aquifer Rocks for Hydro-Geothermal Energy

In Germany geothermal energy production plays an important role in the area of renewable energies. The Upper Jurassic (Malm) aquifer beneath the Molasse Basin is predestinated for hydro-geothermal energy. As part of the research program PrognosPermae several laboratory tests were performed on Malm limestones and dolomites. The rock samples were characterized by uniaxial compressive strength (UCS), tensile strength, Young's Modulus, Poisson's ratio, bulk density, porosity and ultrasonic p- and s-wave velocities. Additionally water-permeability was measured in a triaxial cell under varying stress conditions. Ultrasonic wave velocities were investigated on dry and saturated samples, free to leak. The aim of this study is to ascertain a correlation between the lithology of the target horizon, permeability and the ultrasonic wave velocities. Furthermore, the influence of different stress levels on water-permeability of the specimens is investigated.