Decommissioning and abandonment

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Decommissioning and abandonment

The bundle and towheads are prepared and raised clear of the seabed for towing to an onshore bundle fabrication area in the on or off-bottom mode. Outline procedure: Remove flowline spools and fit pig launchers and receivers Fit carrier pipe clamps with fill and drain valves at suitable points Check integrity of ballast chains and replace as necessary Purge carrier with air to displace inhibited water Purge flowlines to raise bundle clear of seabed (fit any supplementary buoyancy) Connect tow and trail tugs Shorten rigging to raise towheads clear of seabed Tow to fabrication area along pre-surveyed route with protected pipeline crossing points Recover on fabrication area for disposal/recycling or re-use after refurbishment Advantages No offshore cutting of pipeline Less dependency on specialist vessels Disadvantages Extent of preparatory work before tow can commence Probable use of divers Dependent upon structural integrity of bundle Need to protect third party crossings

RECOVERYSUMMARY

RECOVERY – SUMMARY

ƒ Recover the following ƒ Small diameter rigid and flexible pipes ƒ Downhole and flowline tubing

ƒ Bundles and contaminated pipelines ƒ Landfalls if required by local authority ƒ Methods of recovery ƒ Reeling or lay-barge recovery (pipe lay in reverse)

ƒ Cut and lift or refloat and tow ƒ Off-bottom tow for bundles

Any questions?

Recovery of pipelines is a viable options for the above listed pipeline types. The methods of recovery are detailed above and are specific to the type of pipeline being recovered. The method available will be dependent on the type of pipeline and we have examined the appropriate methods for different pipeline types.