Detailed Geological Site Characterisation of Jemgum Salt Cavern Gas Storage Facility (Lower Saxony Basin, Germany)

A detailed geological site characterisation has been conducted at the new Jemgum Salt Cavern Gas Storage Facility in Northern Germany. Specific geomechanical requirements as well as complex Zechstein internal stratification had to be taken into account. 3D seismic processing including data regularisation and anisotropic controlled beam prestack depth migration provided an accurate image in depth. In order to accelerate modeling of the complex salt structure consisting of two salt canopies a new seismic interpretation workflow based on fault segments instead of horizons has been applied. This approach overcomes severe multi-z-value limitations inherent to grid based seismic interpretation software. Key advantages are an improved visibility, an increased picking efficiency and a higher degree of freedom while shaping the salt model. At all stages of modeling appropriate seismic attributes have been successfully incorporated. The 3D structural model provided a key element for all subsequent subsurface planning as well as drilling operations. Finally a blind well at the steep flank of the salt dome indicates a small lateral uncertainty of the salt edge.