Oil company Shell intends to start a 10-year process to dismantle and remove one of Britain's oldest and biggest oil platforms, Brent Delta, the company said on Tuesday.

Britain's North Sea basin is one of the most mature oil and gas production areas in the world and many of its oldest fields are approaching the end of their operational life.

Decommissioning about 500 offshore installations and 10,000 kilometres of pipelines is expected to cost GBP10.4 billion ($15.7 billion) by 2022, according to industry estimates.

Shell has submitted plans to the government to start the decommissioning process of its old Brent platforms, starting with the removal of the above-water topside at Brent Delta, the company said on Tuesday.

Brent Delta stopped producing oil in November 2011 and after several years of assessing alternative uses for the platform Shell decided decommissioning was the best way forward.

The remainder of the Brent field, whose platforms Alpha and Bravo stopped producing oil last November, is expected to be decomissioned in a second phase. – Reuters