Upper Cretaceous sandstones from the subsoil of the Vienna Basin are of utmost importance as potential reservoir rocks. Therefore detailed petrographical studies were carried out on a selection of 14 wells drilled by OMV (methods: polarizing microscopy combined with cathodoluminescence microscopy, x-ray diffraction analysis, scanning electron microscopy, resistivity measurements). The focus of analysis was the so-called base-sandstone of the Ameis complex.