Using High Resolution Seismic Reflection for Imaging of a Shallow Gas Horizon within Urban Vienna, Austria

The current subway network of Vienna should be expanded to the south. For the planning it was necessary to drill several exploratory wells along possible corridors. In one of these exploratory wells gas was encountered in a 20 cm thick sand layer at a depth of 38 m below ground elevation. The gas bearing layer consists mainly of sand and gravel and might be part of braided stream deposits of Pannon D. In the course of this research project the lateral extension of this gas bearing layer should be mapped. Considering the resolution potential of seismic reflection at these depths and the strong velocity/density contrast the gas bearing sand would provide we decided to use this geophysical method for delineating the lateral extension of the gas bearing horizon.