Seismic stratigraphy of the Chalk Group in the Norwegian Central Graben, North Sea

Abstract

The Late Cretaceous to Early Palaeogene Chalk Group in the Norwegian Central Graben contains prolific hydrocarbon reservoirs that have been producing at high rate for more than forty years. Based on integration of regionally extensive 3D seismic data and numerous wells, this paper describes the seismic development of the Chalk Group with particular focus to the syndepositional geomorphological features produced by the activity of bottom currents and large-scale gravity flows. Using standard seismic stratigraphic interpretation techniques, eight seismic sequence boundaries are identified, which in turn define seven seismic stratigraphic sequences characterized by different seismic facies and well log signatures. The seismic sequences can be grouped into three sequence groups that reflect the general tectono-stratigraphic evolution of the chalk depositional system in the Norwegian Central Graben. During the Late Cretaceous, uplift of the Lindesnes Ridge and the Albuskjell Anticline due to inversion tectonic and halokinesis modified the physiography of the Norwegian Central Graben basin and affected the style of chalk sedimentation by influencing the location and importance of gravity flows. In addition, bottom currents, sea-level fluctuations and environment changes significantly influenced the chalk depositional system creating regional unconformities and influencing the input of terrigenous material in the chalk epeiric sea.