Seismic velocities

During preparations of the deep Digital Geological Model (DGM), seismic travel time data have to be converted to depth data. The VELMOD regional velocity model has been developed for this purpose, using velocity data recorded in wells (sonic logs and time-depth relationships). The ‘layer cake’ approach has been applied for all lithostratigraphic units, with the exception of the Zechstein Group. 

Each new version of VELMOD includes various changes, such as a switch from analogue to digital, increased data density and more detail in the lithostratigraphic units. The published VELMOD-versions are arranged in order of realisation date, with the most recent version listed at the top.

Recently (March 2024), version 3.2 was released, as the successor to VELMOD 3.1. The improvements in VELMOD-3.2 include among others improved data selection with respect to both VELMOD-3.1 and VELMOD-4. This way, only high-quality data is used to construct the velocity model. However, VELMOD-4 is additionally based on stacking velocities of 2D and 3D seismic data in between well locations. Therefore, it is based on more detailed data than VELMOD-3.2 which is only based on well data. Considering the above mentioned, VELMOD 3.2 and VELMOD 4 will continue to co-exist. Guidance on the use of both versions and detailed explanation of the improvements of VELMOD-3.2 compared to VELMOD 3.1 and VELMOD-4 is available on the VELMOD-3.2 page.