UK OFFSHORE GEOLOGY

The geology of the UK is extremely diverse and documents almost all periods of geological time. While the UK's complex geological history has not only shaped the landscape, it has also created a wide range of resources, from coal, to oil and gas, to geothermal energy. While not all of the stratigraphic intervals represent mature hydrocarbon production, those that do have proven to be rich and fueled much geological exploration, which has been largely offshore. Exploration for oil and gas along the UK Continental Shelf began in the late 1960's and is still ongoing.

THE NORTH SEA BASIN

The North Sea hydrocarbon province is located on the UK Continental Shelf, between the East coast of the UK and the West coasts of Norway, Denmark and the Netherlands. The North Sea Basin was dominated by a significant rifted basin system, which formed during the Triassic and Jurassic, and was later infilled by siliciclastic and carbonate deposition.

At the height of its success, the combined exports of the UK, Norway, Denmark and the Netherlands made the North Sea the world's fourth largest oil producer and third largest gas producer. While a significant number of fields in the North Sea are now in decline and the basin as a whole is in a mature stage, it has been estimated that the proven reserves could sustain production for another 20 years.

Distribution of hydrocarbon fields on the UK Continental Shelf. For more information, zoom in and click on a field. Map created with ArcGIS Online and field distribution layer from the Oil and Gas Authority Open Data resource.

Generalised stratigraphy of the UK Continental Shelf. Drafted by K. Wright, after the Millennium Atlas: Petroleum Geology of the Central and Northern North Sea (2003).

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PRECAMBRIAN - ORDOVICIAN

Precambrian to Ordovician rocks form the crystalline 'basement' on which the younger sediments were deposited. They are rarely documented in the North Sea, but where they have been sampled they are known to include low to high grade metamorphic rocks, igneous rocks and metasedimentary rocks. These basement rocks can be highly fractured due to having undergone multiple phases of deformation. The rocks underlying the North Sea are thought to be remnants of the Baltica, Laurentia and Eastern Avalonia crustal blocks which were once part of the supercontinent Pangea.