Decommissioning and abandonment

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Decommissioning and abandonment

RECOVERY

RECOVERY

RECOVERY

ƒ Recovery preferred option in UK for: ƒ Small diameter rigid and flexible lines that are not trenched or buried ƒ Up to 323.8 mm or even 406.4 mm (12¾ in or 16 in) ƒ Short flowlines rather than long, large diameter trunklines ƒ Bundles with integral towhead manifolds ƒ Recovery presumed in US for all lines ƒ BOEM / BSEE may permit derogation based on safety case ƒ In all cases certain lines must be removed: ƒ Contaminated pipelines (mercury or cadmium) ƒ Landfalls and inshore lines, subject to local authority control Smaller unburied lines are easiest to remove. Even 406.4 mm (16 in) lines (larger than required by legislation) may be disposed of in this way. It is becoming the policy to remove all the small diameter and short flowlines within fields, leaving the main length of large diameter, long trunk (export) lines in place. Bundles are large diameter structures that sit on the seabed. These are unburied and may be towed away on-bottom. However, the East Frigg bundle in Norway only had the manifold ends removed. Contaminated lines and the landfall section of other lines may require removal by the appropriate regulatory authorities. For example, the Dutch P15 lines recover oil with significant amounts of mercury. The developers were given permission on the understanding that all these lines – some 60 km (37 miles) of both flow and trunk lines – must be removed as the fields become depleted. At landfalls, there is often a local authority requirement for the beach section (only) to be removed. This prevents concerns regarding far-future (50 years plus) erosion of the shoreline and any protective cliffs or sand dunes.

RECOVERY