Caspian Drilling to a Greater Depth

After a mere 32 months, the construction of the Maersk Contractors Semi- Submersible Drilling Rig LIDER (Maersk Explorer) is reaching completion.

The Caspian Shipyard now appears somewhat empty, after the rig departed from the yard on the 17th August 2003 to finalise commissioning and load out at a deeper water location.

The conception of the LIDER (Maersk Explorer) commenced with the signing of a drilling contract between Exxon Azerbaijan Operating Company (EAOC), Chevron Overseas Operating Company and Maersk Contractors. The contract called for a drilling rig, which could safely and efficiently drill, in the deeper structures of the Caspian sea, while maintaining maximum protection to the environment.

Maersk Contractors in turn approached Keppel Fels and the Caspian Shipyard Company, who had already experienced construction of a Jack Up Drilling Rig in the region.

The Semi-submersible drilling rig DSS-20 designed by Keppel Fels and Marine Structure Consultants of Holland was selected, as it provided optimal operating capacity and salient safety features for drilling in water depths of up to 1,000 meters. The DSS-20 is a four column semi submersible designed and equipped with drilling equipment suitable for exploration drilling, development drilling and well work-over.

The contract between Keppel Fels, Caspian Shipyard Company and Maersk Contractors was signed on 1st February 2001. The task was then to engineer a cost-effective construction.

The modular construction arrangement of the rig allowed for "two center" building. The pontoons, upper columns and rig floor substructure were fabricated in Singapore, while the topside modules were fabricated in Baku. Sailing from Singapore to Baku in Azerbaijan sounds like an insuperable voyage. Nevertheless the pontoons, columns and substructure sections, covered the approximate 7,000 nautical miles in 45 days. The voyage was successful and the first shipment arrived in Baku two weeks ahead of schedule.

The long sea voyage from Singapore to Baku started on 8 April 2002 when the two pontoons left Singapore on the heavylift vessel TERN, followed by the four columns and the substructure sections on a separate heavylift vessel, the WILMA. The course was mapped for the Black Sea.

After crossing the Indian Ocean, the Red Sea and finally the Mediterranean, the two heavylift vesels reached the Black Sea.

Passing the locks of the Don and Volga

The next step of the voyage was the navigation through the rivers Don and Volga. However, before entering the river system of the Don, the modules had to be offloaded from the heavylift vessel, as these vessels fully loaded were much too large to pass through the river, canal and lock system.

On 1 May 2002 the pontoons were offloaded at Kerch in the Ukraine, outside the Sea of Azov. The pontoons, fabricated as sealed units and able to float, were towed by two tugs.

A few days later the columns and the substructure sections were reloaded on to two barges in Mariupol also in Ukraine.

The barges and the pontoons were towed to Rostov where they were cleared for Russian waters. In Rostov two additional towing tugs joined to assist with the challenging handling through the locks of the Don and Volga to Astrakhan, situated at the northern shores of the Caspian Sea.

The barges and the pontoons passed through a total of 19 locks in the Don and Volga. And in some places the river system narrowed to approximately

Distance from Singapore to Baku

- approximately 7,000 nautical miles

Duration of voyage from Singapore to Baku - 45 days

Number of locks passed in the Don and Volga - 19

Most narrow passage in the Don and Volga - approximately 17 m wide, 3 m deep and 14 m in air draft

17 m, which required very precise manoeuvring of the barges and the pontoons.

The passage through the Don and Volga took one week.

The river system of the Don and Volga is frozen and generally not passable from 1 November to May every year, which of course had to be taken into account when scheduling the fabrication of the modules in Singapore.

After leaving the Volga, the barges and the pontoons were finally towed to their final destination, Baku Azerbaijan on the south western shore of the Caspian Sea.

Assembly in Baku

With the arrival of the pontoons, columns and substructure sections in Baku on 22nd May 2002, assembly of all components commenced at the Caspian Shipyard Company .

A reduced construction period

Despite the long sea voyage from Singapore to Baku, parallel fabrication of the components in Singapore was a very sensible solution. The construction of a rig of this nature requires a large amount of man-hours and expertise, and by fabricating at "two centres" simultaneously, limitations in the yard capacities and facilities were avoided and the total construction period reduced.