Oluwatobi Olobayo, Mads Huuse, Christopher Aiden-Lee Jackson 

The Northern North Sea (NNS) is an archetype Giant Injected Sand Province (GISP). Previous studies have documented individual stratigraphically-bound injectite complexes in the North Sea and beyond. Despite two decades of continuous studies, there are still speculations in terms of parent sand identification, visible pathways, fluid source, overpressure generation mechanisms and triggers. This study is based on a 29,000 km2, 3D seismic volume calibrated to boreholes, and documents for the first time, the stratigraphy of the NNS Basin GISP, spanning five (5) injection episodes over 80 m.y. Sizes range from 500 m to 8 km wide and from 50 to 250 m in height, for individual intrusions. Well data confirms sandstones lithology emplaced within polygonally-faulted mudstones. Fluid budget has been attributed to a combination of several sources, which includes hydrocarbons and diagenetically-released water from opal A to opal CT transformation, smectite to illite transformation and physical compaction of sediments. Basin modelling in the North Viking Graben shows that hydrocarbon generation started during Late Cretaceous for oil and Late Neogene for gas. Presence of sandstone injectites suggests breach in the sealing host rocks, therefore needs to be incorporated into existing stratigraphic framework for accurate reservoir models in basins where they have been encountered.