Don Field Decommissioning Programme (pdf, 7.8MB) null - BP

DON-BP-001Don Field Decommissioning ProgrammeThe primary role of these protection features is to act as a safety feature to protect usersof the sea from snagging/interacting with the pipelines. The secondary role is to preventthe pipeline from being damaged by anchors/dropped objects etc. The recommendeddecommissioning option for these features is to: Remove all features at the Don manifold area and the pipeline spools to themanifold area Remove all features from the umbilicals (umbilicals cut back and buried) Remove all flexiweight mattresses and small grout bags Cut out and recover sections of pipe that emerge out of the seabed back to stableburied pipe, so that there is no possibility of a snagging hazard Grout formwork to remain in situ and will be made safe for other users of the sea asdemonstrated by over-trawlability trialsIf, due to the condition of the flexible mattresses, risk to diving personnel is such thatrecovery to surface is not practicable, BP will apply for necessary consents to leavethese in situ.Refer to Section 6 Paragraph 3 for further details.Flexiweight MattressesThe majority of the flexiweightmattresses are located within the Donmanifold area and comprise of blocks ofconcrete cast on to polypropylene rope asshown in Figure 10.14. The mattressesare typically 5m x 2m and weighapproximately 3 tonnes.Figure 10.14 Flexiweight MattressGrout FormworkThe majority of grout formwork liesbetween the NLGP crossing and the Donmanifold area, and each formworkcomprises a canvas sack filled with groutas shown in Figure 10.15.Figure 10.15 Grout FormworkPipelines10-14 May 2011