Re-float operation Persian Gulf

In September 2009, Vuyk was approached by Dulam International, a provider of sub sea services to the oil and gas industries in the Middle East, for assistance with a re-float operation of a “laid-up” rig in the Persian Gulf. The rig SHAHED had been abandoned for the 12 years and was only in use as a storage unit for a production platform offshore Iran. The rig is of a triangular shape with a distance of about 98 metres between the legs.

Vuyk provided the de-ballasting procedure for the re-float operation and on-site assistance during the final preparations and execution of this procedure. Special attention was paid to the trim and list of the platform during the re-float operation, as there was only 10 meters free distance between the SHAHED and the production platform.

The SHAHED is a caisson stabilized, semi-submersible barge which was formerly named the SEDCO 135G. With a triangular shape and stabilized by three vertical caissons, the barge was ballasted down to the sea bottom. Only the upper compartment in each caisson was accessible, all the other compartments were used as storage tanks.

During the preparations it became clear that not all the required information was available. Vuyk was able to make an estimate of the light ship weight based on data available before 1989 and pictures taken on board during a recent survey of Dulam.

Several re-float scenarios were calculated. In order to incorporate all the uncertainties regarding center of gravity position and weight, a bandwidth was used for all the scenarios. In June 2010, two experienced naval architects of Vuyk went to the Persian Gulf to render assistance for the actual operation.

During the de-ballasting sequence, the barge came afloat within the expected bandwidth. The barge was successfully towed away from the production site and ballasted aground at a safe distance. After the successful move of the barge, it was handed over to its owners.