Marathon Oil files Brae decommissioning plans to UK authorities

U.S.-based oil company Marathon Oil has submitted a draft decommissioning program for its Brae Area facilities in the UK sector of the North Sea to the authorities. 

The Brae Area lies approximately 170 miles (274 km) north-east of Aberdeen in a water depth of approximately 110m.

The area consists of three fixed jacket platforms, three Marathon Oil operated subsea tie-backs and numerous pipelines and subsea components. Third parties also use the Brae Area facilities.

In the draft submitted to the UK’s Department for Business, Energy and Industrial Strategy (BSEI), the oil company as the operator outlined four decommissioning programs for 14 installations and 64 pipelines.

The document contains combined decommissioning programs for Brae Alpha and Brae Bravo platforms including jacket/sub-structure and Brae Bravo flare jacket/sub-structure and bridge. It also includes, Central Brae subsea template, associated pipelines, flowlines umbilicals and power cables. Furthermore, it includes West Brae subsea wells, manifold and extension manifold, Sedgwick wells and associated pipelines, flowlines and umbilicals.

The East Brae platform topsides, jacket/sub-structure and Braemar subsea facilities are covered by a separate decommissioning program.

Before decommissioning work can proceed, the programs must be approved by the regulatory bodies, following engagement with all stakeholders.

Brae Alpha started production in 1983, Brae Bravo in 1988 and East Brae in 1993. The Central and West Brae/Sedgwick subsea tie-backs to Brae Alpha started production in 1989 and 1997, respectively. The Braemar subsea tie-back to East Brae started in 2003.

Marathon Oil has already extended the life of the Brae field beyond initial projections. According to the company, production will become sub-economical in the short term and other hydrocarbon opportunities have been evaluated and considered unviable, therefore the decision to cease production has been made.

Brae Bravo to cease in 2018

A COP (Cessation of Production) application for Brae Bravo was submitted in 2015 and approved by OGA in 2016. COP of Brae Bravo is currently expected in 2018. COP of Brae Alpha, Central Brae, West Brae and Sedgwick will take place after Brae Bravo COP, and COP applications will be submitted for these facilities at the appropriate time.

The Brae Alpha and Brae Bravo platform topsides will be returned to shore for reuse, recycling or disposal.

When it comes to jackets/sub-structures for the Brae Alpha and Brae Bravo, these will be removed to the top of the footings, which is approximately 28m above seabed for Brae Alpha and 34m above seabed for Brae Bravo. Recovered material will be returned to shore for recycling or disposal.

Marathon Oil has proposed to put in place post-decommissioning safety zones around the Brae Alpha and Brae Bravo footings to assist in preventing fishing vessels inadvertently snagging their nets on the jackets/sub-structure footings or trawling through drill cuttings piles. The post-decommissioning safety zones will be recorded on the FishSAFE system and Admiralty charts to warn mariners of the presence of subsea obstructions.

600 projects up for decom

According to a late-2016 report by IHS Markit,  the decommissioning of aging offshore oil and gas platforms, subsea wells and related assets is increasing dramatically, with more than 600 projects expected to be disposed of during the next five years alone.

IHS Markit expects spending on decommissioning projects to increase from approximately $2.4 billion in 2015, to $13 billion-per-year by 2040, or an increase of 540 percent.

Offshore Energy Today Staff