Prediction of Sand Content in the Paleogene of the West Barents Sea Through Application of Stratigraphic Forward Modelling

Carlos Fonseca

The western Barents Sea in northern NO represents a frontier exploration area with potential prospectivity in shelfal and deepwater turbidite deposits within the Paleocene and Eocene sequences. The separation of Greenland from NO during Early Eocene renewed uplift of pre-existing structural highs in north and central Barents promoting a corresponding acceleration in subsidence rates and increase in sedimentation on the western margin of the Barents Sea. Seismic transects across the Bjørnøyrenna Fault Complex, the Stappen High, the Bjørnøya Sør Basin, the Veslemøy High and Sørvestsnaget Basin show the existence of clinoforms at Eocene and Paleocene levels of the Torsk Formation with predominant westward transport directions. In the Bjørnøya Sør Basin the clinoforms prograded westwards where the Paleocene shelf edge became anchored at the western margin of the Veslemøy High that acted as a pivot whilst subsidence continued in the Sørvestsnaget Basin. This migration of the Paleocene shelf edge covered a distance of 80 km along which the character of the clinoforms evolved due to 3rd and higher order eustatic cycles, fault reactivation and imprint of the underlying faulted Cretaceous and Jurassic sequences. In the proximity of the western flank of Loppa High the geometry of Paleocene clinoforms indicates that the shelf in the Paleogene was narrow, no more than 16-20 km in width with relatively steep slopes. Slope gradients of shelf clinoforms and extent of topsets varied in relation to their position with respect to active faults and major paleotopographic features such as the Loppa and Veslemøy highs. Slumping at the toe of the slope and shelf margin collapse along active highs were common processes during the Late Paleocene-Early Eocene and were mechanisms for slope accretion that allowed the shelf margin to prograde. Seismic transects from the southern flank of the Stappen High into Bjørnøya Basin display only remnants of the Paleogene shelf as it has been eroded by Oligocene and younger sections however there is evidence of local clinoforms prograding southwards into the Sørvestsnaget Basin. Data from exploration wells that encountered the Paleogene in the Sørvestsnaget, Tromsø and Bjørnøya Sør basins indicate that the occurrence of sands in the Paleocene is low whilst in the Eocene sands are restricted to deepwater turbidites of Mid Eocene age, highlighting the risk of encountering reservoirs of this age in the western Barents Sea. In order to investigate the mechanisms that could have controlled the deposition and distribution of sands, the results from a series of three dimensional forward stratigraphic models built with the intention of de-risking leads, will be discussed. These models enable better framing of the uncertainty space and consequently enhance prediction of sand content and location.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013