Migration of petroleum into Brent Group reservoirs: some observations from the Gullfaks field, Tampen Spur area North Sea

Abstract

Abstract Whereas the processes of petroleum generation and primary migration are beginning to be understood from a quantitative viewpoint, the process of secondary migration is still incompletely quantitatively understood. We estimate that typically the carrier systems feeding Brent Group reservoirs contain an average of around 3% residual oil saturation, the petroleum flowing in high saturation petroleum rivers through the most permeable carrier bed zones. Most of the carrier porosity contains no petroleum. The filling of the Brent Group reservoir in the Gullfaks field (Tampen Spur) is elucidated by petroleum geochemistry and this study indicates that the field has filled from more than one source basin and has been biodegraded post oil-emplacement. The complex filling and degradation history suggests that geochemical study of reservoir petroleum columns is a useful exercise providing information on the fillpoints of these complex reservoir systems and potentially information on the palacohydrogeology of the area.