Molecular migration tracers and basin modeling reconstruct the initial filling of the Ivar Aasen, Edvard Grieg, Solveig, and Johan Sverdrup fields of the Haugaland High, Norwegian North Sea

Abstract

An integration of geological, geochemical, and geophysical disciplines into a classical basin model is the key for a profound understanding of the migration and filling history of reservoirs in the Haugaland High, North Sea, as it delineates the generation, expulsion, and migration of hydrocarbons. The numerical basin model for migration assessment was tuned and calibrated with molecular geochemical data, especially by the application of benzocarbazole ratios as migration tracers and geochemical fingerprinting of oil families. Benzocarbazole distributions resolved the complex filling history and the initial filling directions of different migration sectors for the Haugaland High via their decreasing [a]/([a]+[c]) isomer ratios. These decline with increasing migration distance for different migration sectors extracted by a numerical basin model. The filling history was reconstructed as a complex multicharge system in a context of variable stages of paleobiodegradation. Hereby, benzocarbazole ratios obtained from oils and reservoir core extracts remained unaffected by biodegradation. They indicate an oil migration trend from the Viking Graben in the west of the Haugaland High towards the southeast, filling the present-day fields, e.g., Johan Sverdrup, Edvard Grieg, and Ivar Aasen. Benzocarbazole distributions represent the initial filling and do not show overprint effects by later and mature charges of oil lean in polar constituents. They thus exhibit a migration scenario in agreement with migration reconstruction via numerical basin modelling and previously proposed non-polar biomarker distributions.