Abstract: Sequence Stratigraphy of the Cretaceous of the Norwegian Sea

CECCHI, MARCELLO

The Cretaceous of the Norwegian Sea (63-68 N, 6-12 E) comprises a siliciclastic succession up to 6 km thick, with deep marine sandstone reservoirs and potential source rocks occurring at different stratigraphic horizons.

To provide stratigraphic and geographic locations for source and reservoir distribution, biostratigraphy, core sedimentology, log-motif and subsidence analyses have been combined to seismic stratigraphic analysis.

The Cretaceous succession may be subdivided into five major, unconformity-bounded and tectonically controlled, T-R cycles, 1) Berriasian - Early Hauterivian; 2) Late Hauterivian - Middle Albian, 3) Late Albian - Early Turonian, 4) Late Turonian - Coniacian and 5) Santonian - Maastrichtian. The transgressive portions of each T-R cycle correspond to periods of dramatic increases of subsidence rates (synrift phase), whereas regressive portions correspond to periods of more uniform subsidence (postrift phase).

Reservoirs mostly occur within the regressive portion of the T-R cycles, and mostly occur within the I) Middle Albian, II) Late Turonian - Coniacian and III) Campanian stratigraphic intervals. Reservoir distribution also depended upon changes in the provenance areas and drainage pattern, likely caused by changes in regional stress orientation, which alternatively and selectively reactivated older lineaments. Source rocks are mostly found within the Barremian to Aptian and Albian intervals.

Correspondingly, the Cretaceous seismic package consists of five major seismic units, composed of nine, regionally correlative, seismic mappable units. Within these units, seismic facies indicate potential locations for reservoirs and source rocks.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria