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Wintershall Platform Removal


Wintershall Platform Removal
K-10 C and K-13 B

From 1 July to 10 August 1997, we worked together with Seaway Heavy Lifting, based in Zoetermeer, Holland, to remove two decommissioned oil platforms in the Dutch sector of the North Sea.

The client was Wintershall AG.

The supervising authority was the Dutch Staatstoezicht op de Mijnen (chief mining office). The equipment was classified by Lloyd's Register.

The supply ship “Neftegaz-66” was converted into a dive ship, and fitted with an A-frame, a diving bell, two decompression chambers, etc.

The personnel comprised:

  • 12-man crew
  • 12 divers
  • 2 supervisors
  • 2 representatives of the oil company

To prepare for removal the following tasks were carried out within the space of 38 days:

  • 121 dives
  • 79 pipe measurements
  • 263 plant growth measurements,
  • 15.5 metric tonnes of material hoisted on deck
  • 26 underwater thermal cuts,
  • 2690 m² supports and beams,
  • and 975 m² rock dump examined.

On 1 July 1997, the "Neftegaz-66", which had been converted into a dive supply ship, left the harbour of Rotterdam on its way to the platforms K-10 C and K-13 B in the North Sea.

After the general inspection, during which all loose parts were removed from the platforms, we started to inspect the platform supports and beams for water inleakage and plant growth.

The seabed underneath and around the platforms was then cleared of any debris. While this was being done, we discovered a 1.5 metre thick layer of iron-ore slag lying on the 10” and 2” pipelines. A hydraulic hammer was used to break up this deposit.

Once all pipes and lines had been severed, the first sections and the valve station (see photo below) were lifted with the aid of the vessel’s powerful winch (tractive force: 150 metric tonnes).

A pipeline pulling head, purpose-built for the pipeline, was used to lift 2 x 17.5 m pipeline, pull the sections out of the rock dump, separate them under water and lift them on deck.

Once the location had been cleared and the platforms cut loose, the platforms were hoisted by the “Stanislav Udin”, a floating crane, and towed ashore.

Frank Mettbach and Andreas Stutz were on board as operation managers for Nordseetaucher GmbH.