United Kingdom Continental Shelf

The UK Continental Shelf (UKCS) is the region of waters surrounding the United Kingdom, in which the country claims mineral rights. This principally refers to the North Sea, where there are large resources of hydrocarbons. The North Sea is also bordered by Norway, Denmark, Germany and The Netherlands. A median line, setting out the domains of each of these nations was established by mutual agreement between them.

Responsibility for the UKCS rests with the Department of Energy and Climate Change (DECC), which awards licences to oil companies to produce hydrocarbons from specific areas and regulates how much they can produce over what period.

The UKCS is divided into rectangular blocks, numbered from the North-West going East, then South. These blocks are then further subdivided. This then forms the block number for a particular development. For example, the Harding oilfield, which resides in a fairly northern position, is in block 9, subdivision 23, denoted "9/23" (9/23b specifically to differentiate it from the Gryphon oilfield).