Quantification of Magnitude of Net Erosion in the SW Barents Sea using Sonic Velocities and Compaction Trends in Shales and Sandstones

On the Norwegian Continental Shelf (NCS), the western Barents Sea Margin is generally ice-free and more accessible than any other Arctic region, and is also a frontier area for hydrocarbon exploration. During the Mesozoic and Cenozoic, most of the areas of the Barents Sea were subjected to several uplift and erosion episodes. This study seeks to estimate net erosion based on shale compaction. In this context the estimation is carried out using sandstone trends (Triassic) in areas heavily eroded, as measured by well-log velocities and the integration of geophysical data. Initially, Normal Compaction Trend (NCT) models from the published literature were investigated in order to have a better understanding of the velocity constraints of a new NCT model from available well-log data. Based on velocity trends and interpretation of seismic data along the NCS, a new NCT model including the Triassic section was applied at great depths and to areas that have been deeply-eroded. This new NCT model that is suggested based on our data, gives a good estimation of net apparent erosion of each of the selected wells, consistent with geological observations. As a result of the study of 40 wells, a new net erosion map was constructed for the SW Barents Sea. The amount of erosion is getting less towards the South and especially to the SW. The highest erosion values are observed towards Svalbard with the highest values reaching 2600 m. Likewise the smallest values are observed in the western part of the Barents Sea reaching as low as 300m. Two different trends of net erosion are observed: an increase along a NS direction and a decrease along a SE NW. In the NW part of the study area the rate of change of net erosion is much faster due to the close configuration of the isopachs. Although the general trends can be established, a certain degree of uncertainty in the net erosion values remains in areas with total absence of well information.