Velmod-3.1 is the successor of Velmod-2, a seismic velocity model that was built in the context of a Joint Industry Project (van Dalfsen et al, 2007). This model, as well as the previous models, are based on velocity data from sonic logs and checkshot data to which depth markers of lithostratigraphic layer boundaries had been assigned. With this data a layer-cake velocity model is constructed based on V0-k parameterization.

The primary application of the Velmod-3.1 model is time-depth conversion for large scale (regional) seismic interpretation and mapping.

In comparison with its predecessor, Velmod-3.1 had more digital sonic data of much more boreholes at its disposal (1642 compared to 1383). Enlargement of the digital sonics database was effected by data release of E&P companies in the context of the mining law.

On November 13th, 2018 an erratum has been added to the Velmod-3.1 report. This erratum contains a correction of the V0 and k value of the CK layer (Table 1 on page 8).

Velmod-3.1, rapport TNO 2017 R11014

Apendix A Velocity borehole data files
Apendix B Velocity model well results
Apendix C Vint, V0 & kriging standard deviation grids
Apendix D T/Z pairs

Maps (V0, Vint and standard deviations)
ZMAP grid
ARC grid