The Jurassic Petroleum System in the Danish Central Graben (PETSYS). Technical notes

The following note gives a brief description of the regional structural interpretation of the Jurassic in the Danish Central Graben carried out in the PETSYS project with the aim to facilitate the use of the horizon files of selected seismic markers uploaded to the Website system. The note summarises information on the 3D seismic database, interpretation methodology, selection and definition of regionally mapable markers. In addition the methodology to construct synthetic seismograms, key seismic structural profiles, time-structure and time-isochore maps are described. Separate chapters deal with analyses of well derived acoustic velocities and used velocity functions to depth-convert selected horizons critical for maturity modelling.

A series of socalled spatio-temporal activity maps have been produced from time-isochore maps to describe the structural styles and tectonostratigraphic evolution through Jurassic times in DCG. They are supplemented by Jurassic subcrop and supercrop maps. The nomenclature of structural units we use in the text follows Japsen et al. (2003).

Finally rock physics templates showing Vp/Vs ratios versus acoustic impedance (AI) plots for different lithostratigraphic units and depth ranges are described for wells with both P- and S- sonic logs.