North Sea

North Sea

The use of the North Sea is increasing: besides shipping and fishing, the area has become home to an increasing number of large wind farms and their associated cable routes. Parts are being used as military exercise areas or nature reserves, as well as for oil, gas, and sand production. In view of all this activity, knowledge of the North Sea seabed is growing in importance. To find out as much as we can about the subsurface of the North Sea, the Geological Survey of the Netherlands (GDN) is using new techniques that are able to acquire more information from existing data.

Digitalisation of seismic profiles

The Dutch part of the North Sea is roughly one-third larger than mainland Netherlands and geological research at sea is often more expensive than on land. That is why the amount of available data for the sea’s subsurface is only a fraction of what we have available for the subsurface of the mainland.  Deep drillings in particular are scarce. There is, however, a lot of 2D seismic data: long profiles show the reflection of sound on and in the seabed, revealing the structure of the subsurface. To make our paper seismic archive available online, we scanned thousands of roles of paper. Noise and artefacts were filtered from the scans as much as possible. By adding positioning data, every profile can be directly uploaded into modern interpretation software.

Three-dimensional seismic data is empowering the energy transition

A lot of time has been spent searching for oil and gas in the North Sea using 3D seismic data. Unlike drilling points and 2D seismic, 3D seismic generates area-covering data and images that are easier to interpret than point or line data. This form of seismic data especially targets kilometres-deep oil and gas fields. Using advanced geophysical software, we are increasingly able to generate clear images of the top 100 metres. This is making the mapping of tunnel valleys from the Ice Age and old riverbeds increasingly easy. Knowing their locations helps to position wind farms and artificial energy islands. Locations that pose the greatest geological risks can be avoided. Due to our statutory task of managing subsurface data, the location-specific information that developers gather automatically flows back to GDN, after which it becomes publicly accessible and we can use it for our mapping.

Sediment composition for nature, infrastructure, and coastal reinforcement

Some organisms thrive on sand while others prefer silt-rich environments. For good nature conservation, it is therefore important to know which materials are present on the seabed. Engineers tasked with installing energy cables or pipelines, for example, use that spatial information. To map the seabed more efficiently than when using paper maps, we are using artificial intelligence. Artificial intelligence can compose and update seabed maps automatedly using a database of drilling descriptions and grain-size analyses. We interpolate this point data using water-depth maps, current-speed models, and other guiding information. Through our research into the composition of the seabed, we can ensure the optimal usability of the North Sea’s resources for their desired application, with as little negative impact on marine life as possible.

Geomorphological map of the underwater world

The relief of the seabed is also important. Using increasingly better depth data, collected by Rijkswaterstaat (the Netherlands’ Directorate-General of Public Works and Water Management) and the Royal Netherlands Navy, accurate terrain models of the North Sea seabed are being made. GDN interprets these models by comparing the depth, scale, steepness, and orientation of the underwater relief to data from drillings and seismic research. The new geomorphological map reveals that the seabed in the southern part of the Netherlands Continental Shelf is primarily made up of sandbanks and northerly-migrating sand waves. In the northern part, the seabed is partly made up of extensive mud plains at greater water depth. On the other hand, the shallower, relief-rich Dogger Bank and Cleaver Bank, both formed during the last Ice Age, are characterised by sand and stones. The Cleaver Bank in particular is so rich in stones that remarkable flora and fauna, including cold-water corals, have been preserved. Geological knowledge helps define and protect these unique areas.

International collaboration

Seven countries each manage part of the North Sea seabed. To do so optimally, we work together in a European context. Within the Marine Geology Expert Group of  EuroGeoSurveys, the various geological surveys strengthen each other with their knowledge and expertise. The European marine observation network,  EMODnet, is used by many marine knowledge institutes to make scientific data freely available. In the future, these international partnerships will make it possible to connect geological models to each other and to link them to biology and land use, for example. This will generate more detailed and applicable knowledge of the North Sea, leading to better decision-making, less damaging laws and regulations, and more support for the Green Deal.

More about our geological research on the North Sea

Would you like to find out more about our geological research on the North Sea, or would you like to discover how our techniques and products can help you? Contact Jelte Stam or Sytze van Heteren via the blue ‘mail directly’ button below.