Decommissioning plan for Shell’s Kingfisher field under assessment

UK authorities are assessing the plan for the decommissioning of Shell’s Kingfisher installations and fifteen associated infield pipelines off the UK.

The Kingfisher field lies in Block 16/8 of the UK Sector of the North Sea and comprises three reservoirs. Brae I is a gas and condensate one, Brae II holds volatile oil, while Heather is another gas and condensate reservoir.

The field
lies some 280 kilometres northeast of Aberdeen and was developed as a subsea
tie-back to the RockRose Brae Bravo platform.

It started
producing in October 1997 and had a design life of 15 years. Produced oil was exported
via Brae Bravo to the Forties pipeline system.

The
decommissioning plan submitted to the UK authorities consists of two decommissioning
programmes for the Kingfisher installations and fifteen Kingfisher infield
pipelines.

The RockRose
Brae Bravo platform has reached the end of economic life and the Oil and Gas
Authority (OGA) gave a formal cessation of production (CoP) approval for Brae
Bravo’s Brae field production in 2016 and production ceased in July 2018.

For Kingfisher,
OGA and the partners – Shell, Esso, and RockRose –  agreed with the cessation of production
assessment made by Shell.

Kingfisher
production was not economically viable on a standalone basis and, following a
period of production on a best endeavours basis, the field ceased production on
the 5 July 2018, aligning with Brae Bravo’s decommissioning timeline.

Shell’s
decommissioning plan is spread out into five distinct phases. The first phase involves
flushing of available chemicals cores in the Kingfisher manifold umbilical,
flushing of hydrocarbons from 10” production pipelines – completed in July 2018
– and physical isolation of the pipelines from the manifold – a task completed in
September 2018.

The second
one entails subsea wells plugging and lubrication, flushing of hydrocarbons
from production jumpers, and flushing of Kingfisher manifold umbilical
hydraulic cores. Flushing tasks are also done, completed between January and
April 2019.

The
remaining three phases have no completed tasks. Phase three includes removal
and remediation of Kingfisher subsea infrastructure outside the Brae Bravo 500-metre
safety zone while phase four is the removal and remediation of subsea
infrastructure inside that zone. Phase four must be in with a separate approved
DP which will be submitted at a later date.

The last
remaining part – phase five – is focused around the well plug and abandonment
completion.

It is worth
stating that all installations will be recovered to shore for re-use or
recycling. Surface laid sections of pipelines and umbilicals will either recycled
or disposed of.

Trenched and
buried pipeline sections will be decommissioned in situ. The end of the
pipelines will be cut, and additional rock cover will be added to cut ends to
reduce snagging risk.