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Cenozoic Evolution of Siliciclastic Sediments and Implications for Hydrocarbon Prospectivity in Southwestern Barents Sea


Sediment infill during the Cenozoic remains a mystery in the Southwestern Barents Sea due to the general lack of good quality data and the complex interplay of tectonic, uplift, erosion, and glaciation. The distribution of the Eocene sands is a continuing subject of debate for exploration and production companies active in the area. In this work, we have used seismic interpretation, seismic attributes and facies analysis, and seismic geomorphologic methods to understand the evolution of Cenozoic siliciclastic sediments in the Sørvestsnaget Basin and the adjoining areas. The interpreted horizons are Jurassic, Cretaceous, Cenozoic, and seven Neogene sequences. Our work revealed the presence of several canyons and channels signifying subaerial erosion during Miocene to Pliocene in the Sørvestsnaget Basin. An indication that clastic wedges in the basin were not entirely related to Neogene glaciation. The seven Neogene sequence (S1-S7) varies from low to high amplitude reflections with internal geometries such as toplap, onlap, parallel to sub-parallel, divergent fill, sigmoid to chaotic recognizable stratal pattern, onlap fill and internal convergence reflectors. The Neogene package is composed of prograding sequences from S1 to S5 and those back stepping towards the shelf-edge from S6 to S7. Submarine channels and sand lobes above the Eocene interval have NNE-SSW direction with provenance possibly from the Stappen High. On seismic sections, the top Eocene sand is a high amplitude reflection that is severely faulted, trending in more or less N-S direction from the Stappen High and beyond the Sørvestsnaget Basin. We document important control on sedimentation of the sands to include a number of intrabasinal highs, which were active barriers deforming the area since the Late Cretaceous. A supporting evidence for the absence of Eocene sands in exploration wells drilled on the Veslemøy High. Based on the seismic character and well tie, we have interpreted three basin-scale sand bodies in the Veslemøy High. These are N-S (a) Eocene sands below the clastic wedges (b) Miocene sands at the base of the clastic wedges and (c) Pliocene sands included in the clastic wedges. Compartmentalization within the sands is due to the presence of several rotated fault blocks to the western flank of the Veslemøy High. Our work presents new ideas on the distribution of Cenozoic reservoir rocks and their importance for ongoing exploration activities in the area.