August 8 - Coscol's semi-submersible vessel Xiang Yun Kou has transported a 10,000-tonne subsea oil storage tank, destined for the Solan oilfield in the North Sea, from Dubai to Scotland's Lerwick Harbour.

With more than 9 m water depth, the quay at Holmsgarth met the requirements for berthing the 216.7 m x 43.1 m Coscol vessel, explained Lerwick Port Authority. The vessel was turned port side in order to allow shore-based cranes to complete the removal of seafastenings.

Xiang Yun Kou then moved to the Breiwick area of the harbour to ballast down overnight - an operation that required 30 m of water depth to partially submerge the vessel.



The subsequent float-off operation involved a number of tugboats, including Lerwick Port Authority's vessels Knab and Kebister.

Once afloat, the tank was returned to Holmsgarth quay and transferred to ocean-going tugs for transport offshore, while Xiang Yun Kou deballasted and departed the port for Suez.



The tank was towed to the Premier Oil-operated Solan field in just two days, where it was installed in 130 m of water.

With a displacement of 47,285 tonnes, Lerwick Port Authority claims that the Xiang Yun Kou is the largest displacement tonnage ship to berth alongside at the harbour.

The port was also used by Heerema's semi-submersible crane vessel Thialf, which spent one and a half days mobilising before heading for the Solan field to await the tank for installation.

Lerwick Port Authority's harbour master, Captain Calum Grains, said that to accommodate two vessels the size of Xiang Yun Kou and Thialf, while servicing other oil and gas projects, is a clear demonstration of Lerwick's scope.

"Our investment in facilities, including a major dredging project a few years ago, is paying off for the oil industry, the port and Shetland. We continue to develop resources, with plans including further deepwater facilities," said Grains.

Bibby Offshore will also use the port of Lerwick during the installation of subsea equipment for the Solan project.



Watch a timelapse video of the project here: