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	Onshore licence co-ordinates

Onshore licence co-ordinates are defined using the National Grid referencing system, which is a metric grid on a Transverse Mercator projection. National Grid coordinates are expressed as distances measured in metres east and north from the grid origin, which is located west of the Isles of Scilly. The National Grid defines a series of 100km squares, each of which is further subdivided into 10km squares. The 100km squares are identified by two letters e.g. SE or TL. The 10km squares are identified by the letters of the 100km square that they lie in, plus a number from 00 to 99 as follows:

Example: If this diagram showed the SE Block, then square 46 would be referred to as SE46.

For DTI’s Oil & Gas licensing purposes each 10km square is called a block. A licence may cover a whole block, part of a block, or several blocks or part-blocks.

For more information on the National Grid, visit the Ordnance Survey website (www.ordnancesurvey.co.uk/products/natgrid/nghelp1.html).

The system of quadrants and blocks used in offshore licensing does extend onshore, but we only use it for well numbering (see Petroleum Operations Notice 12 for details: http://www.og.dti.gov.uk/regulation/pons/pon_12.htm). A map showing the relationship between the National Grid and quadrants and blocks is available here.

For further information about onshore coordinates or well numbering, contact

Geoff Swann
email: geoff.swann@dti.gsi.gov.uk
phone: +44 (0) 20 7215 5062
fax: +44 (0) 20 7215 5070