Which has had the most spills? North Sea oil rig

Oil spills by North Sea rigs: which is the worst?

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See which North Sea oil rig has had the most leaks
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North Sea oil rigs operating in UK waters suffered major or significant leaks at a rate of almost one every week throughout 2009 and 2010.

The revelations of spills off the UK's shores come as part of a Guardian investigation showing shortcomings in safety and oversight in UK operations.

The data, obtained through the Freedom of Information Act, shows more than 25,000kg of oil and gas leaked from UK oil platforms between January 2009 and December 2010, in 110 separate incidents.

A further 6,000kg of oil and gas leaked in incidents classed as "minor".

The register includes all leaks voluntarily declared by operators to the Health and Safety Executive, as part of security measures set up in response to the Piper Alpha disaster in 1988, which killed 167 workers.

The worst-performing rig on the register was "Brent Charlie", owned by Shell, which leaked a a total of 4,900kg of material in seven separate incidents rated at significant or higher.

The chart below details the total quantity of oil and gas leaked by rig. To concentrate on a particular rig operator, click its name on the left-hand menu. To see how many incidents occurred at a given rig, hover over its bubble in the chart.

There was at least one significant or major leak in every single month in 2009 and 2010. August 2010 was the quietest month, with just one leak, while January 2009 had the most incidents, at 11.

The full data can be viewed, searched, sorted and downloaded below. The operator information reflects the situation recorded in the data as it was received by the Guardian: ownership may have subsequently changed hands, or switched from one contractor to another.

Seen something in the data that we've missed? Let us know in the comments below, on twitter, or by email.