Detection and Evaluation of Gas Leakages Simulated in Near Surface Aquifer of Ellerbek Paleo-channel

Renewable energy resources are intermittent and need buffer storage to bridge the time-gap between production and demand peaks. The North German Basin has a very large capacity for compressed air/gas energy storage (CAES) in porous saltwater reservoirs and salt cavities. Even though these geological storage systems are constructed with caution, gas leakages can occur, and stored gases can migrate upwards into shallow potable aquifers. Using a realistic virtual CAES leakage scenario into a shallow aquifer in North Germany, we demonstrate the resolution of an integrated geophysical monitoring method, consisting of acoustic joint waveform inversion of surface and VSP borehole data, ERT and gravity. This combined approach is able to map successfully the shape and to determine physical properties of the simulated gas phase body at a very early stage after the leakage begun.