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

DON-BP-001Don Field Decommissioning ProgrammeEach xmas tree incorporates the following main elements: Xmas tree block and valve assembly Retrievable valve package Completion equipment Associated flowlines and fittings Subsea choke Debris capThe Subsea Control Module (SCM) is supplied separately, but forms part of theretrievable valve package that is cantilevered off the main xmas tree frame.Xmas tree physical data is as follows: Weight – 34.5 tonnes Height above seabed – 5029mm Footprint – 2565mm x 2565mm Construction – Carbon steel2.2.2 Don ManifoldThe Don manifold (refer to Figure 4.6) was designed in 1988 by John Brown Engineers &Constructors Ltd and built by Peterhead Engineering Company Ltd. The manifold wasdesigned as a compact structure, capable of being installed and retrieved from either aMobile Offshore Drilling Unit (MODU) (via the moonpool) or by crane on a conventionalDiving Support Vessel (DSV).The Don manifold, which is secured to the seabed by two 20in steel piles to a depth ofapproximately 10m, was the connecting point between the Don Field and Thistle for: Collecting oil from the wells into the 8in production pipeline Distributing water from the 8in water injection pipeline to the water injection wells Distributing chemicals to the production wells Receiving and distributing control signals from Thistle to the wells Receiving and distributing data signals from the wells to ThistleInfield flowline and umbilical jumpers connected the manifold to individual wells. AnSCM was mounted on each xmas tree to control its valves (some SCMs have sincebeen removed). Manifold valves were controlled from an SCM mounted on the wellPN01 xmas tree.The manifold structure provides protection for the following items: Control umbilical termination box Chemical injection umbilical termination box Valves and associated pipework InstrumentationDescriptions of Items to be Decommissioned4-8 May 2011