Overpressure in the Barents Sea and Other Atlantic Margin Basins - Implications for Exploration
Stephen O'Connor, Richard Swarbrick, Sam Green, Alexander Edwards, and Jakob Heller
GeoPressure Technology, Durham, United Kingdom.
Since the first well was drilled in the Barents Sea in 1980, discoveries have been made proving a viable petroleum system exists. Subsequently, one producing field (Snohvit) and oil accumulations such as Goliat, Nucula and Obesum further demonstrate the potential of this emerging petroleum province. However, the system is not fully understood: there are dry holes, some with shows, and from our experience there is a strong possibility of seal breach in the past. These results are a consequence of the complicated geological and pressure history of the Barents Sea that includes several periods of uplift and erosion, causing re-distribution of hydrocarbons within the basin.
Overpressure is a key control in understanding fluid movement within a basin and can therefore be utilised to predict the likely location of hydrocarbons. Where the overpressures are high, as observed in some areas of the basin, traps are at risk due to tensile or shear failure, causing leakage of hydrocarbons to shallower levels. Where overpressures are anomalously low, lateral drainage of pressures and fluids is suggested, setting up the possibility of hydrodynamic flow and non-structural controls on fields and up-dip migration of hydrocarbons.
This paper will review the distribution of overpressures at the present data, and using Apatite Fission Track, Vitrinite Reflectance and Thermal Reconstruction data, comment on the relationship between pressure history and seal breach of gas-prone reservoirs and implications for undrilled prospects. Case study material will also be shown from the Scotian Shelf and Mi-Norway regions.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.��������������������������������������������������������������������������������������������������������������������