New insights on subsurface energy resources in the Southern North Sea Basin area

The Southern North Sea Basin area, stretching from the UK to the Netherlands, has a rich hydrocarbon exploration and production history. The past, present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals, ranging from the Lower Carboniferous to Cenozoic. In the period between 2007 and 2017, a total of 95 new hydrocarbon fields were discovered, particularly in Upper Carboniferous, Rotliegend and Triassic reservoirs. Nineteen geothermal systems were discovered in the Netherlands onshore, mainly targeting aquifers in the Rotliegend and Upper Jurassic/Lower Cretaceous formations. Although the Southern North Sea Basin area is mature in terms of hydrocarbon exploration, it is shown that with existing and new geological insights, additional energy resources are still being proven in new plays such as the basal Upper Rotliegend (Ruby discovery) for natural gas and a new Chalk play for oil. It is predicted that hydrocarbon exploration in the Southern North Sea Basin area will probably experience a slight growth in the coming decade before slowing down, as the energy transition further matures. Geothermal exploration is expected to continue growing in the Netherlands onshore as well as gain more momentum in the UK

Pre‐breakup extension in the northern North Sea defined by complex strain partitioning and heterogeneous extension rates

The early stages of continental rifting are accommodated by the growth of upper‐crustal normal fault systems that are distributed relatively evenly across the rift width. Numerous fault systems define fault arrays , the kinematics of which are poorly understood due to a lack of regional studies drawing on high‐quality subsurface data. Here we investigate the long‐term (~150 Myr) growth of a rift‐related fault array in the East Shetland Basin, northern North Sea, using a regionally extensive subsurface dataset comprising 2D and 3D seismic reflection surveys and 107 boreholes. We show that rift‐related strain during the pre‐Triassic‐to‐Middle Triassic was originally distributed across several sub‐basins. The Middle‐to‐Late Triassic saw a decrease in extension rate (~14 m/Myr) as strain localized in the western part of the basin. Early Jurassic strain initially migrated eastwards, before becoming more diffuse during the main, Middle‐to‐Late Jurassic rift phase. The highest extension rates (~89 m/Myr) corresponded with the main rift event in the East Shetland Basin, before focusing of strain within the rift axis and ultimate abandonment of the East Shetland Basin in the Early Cretaceous. We also demonstrate marked spatial variations in timing and magnitude of slip along‐strike of major fault systems during this protracted rift event. Our results imply that strain migration patterns and extension rates during the initial, pre‐breakup phase of continental rifting may be more complex than previously thought; this reflects temporal and spatial changes in both thermal and mechanical properties of the lithosphere, in addition to varying extension rates