In the next 18 months, deepwater drilling in the Caspian Sea will take on new meaning when a new semisubmersible makes its debut.

ExxonMobil and ChevronTexaco plan to cash in on the benefits from the latest drilling platform technology when a new unit designed in the Netherlands and built in both Asia and Baku begins operations in the Caspian Sea.

Until the past few years, drilling capacity in the Caspian Sea region has been restricted due to a lack of modern, well-equipped rigs. Come 2004, Maersk Contractors will see its DSS 20 CAS unit launched and operating in the region.

Contracts

Firm contracts for at least 3 years have been inked for Maersk's new four-column semisubmersible. ExxonMobil will use the unit to drill two wells on its Zafar Mashal block, where it has a 30% interest through Exxon Azerbaijan Operating Company. The DSS 20 also will drill two wells on the Nakhchivan contract area, in which ExxonMobil has a 50% stake. And Chevron Overseas Petroleum Azerbaijan Ltd. has booked the rig to drill one well in the ChevronTexaco-operated Absheron region.

Jens J. Madsen, commercial director for Maersk, points out that although the rig has been committed to these blocks, it will be up to the operators to decide on the actual drilling sequence.

ExxonMobil agreed with the State Oil Company of the Azerbaijan Republic (Socar) in the late 1990s to explore Zafar Mashal, in water depths between 1,800 ft and 2,900 ft (550 m to 900 m) and nearly due east of Baku. The block covers a total of 250 sq miles (640 sq km) and previously was designated by Azerbaijan officials as the D9 (Zafar) and D38 (Mashal) structures in the Azeri sector of the Caspian Sea.
ExxonMobil signed for the Nakhchivan contract area - east of Zafar Mashal and approximately 75 miles (110 km) south east of Baku - a few years later.

Construction

Earlier this year, Keppel's Far East Levington (FELS) shipyard in Singapore completed 50% of the construction work on the new semisub for Maersk. Parts of the drilling unit were delivered to Baku by Keppel FELS and comprised two pontoons, the four columns for the semisub and the substructure for the rig's drill floor. These components left Singapore in April for the 45-day voyage to Baku via the Indian Ocean covering 7,300 nautical miles.

The parts were delivered at the end of August - two weeks ahead of the original schedule - but this was no easy feat. The FELS-fabricated elements, including the pontoons, had to negotiate 19 locks along the Don and Volga river and canal systems to reach the Caspian Sea. "In some places, the passage between the two banks was only around 55 ft (17 m) and 10 ft (3 m) deep," Keppel noted.

Getting the components to Baku during summer weather has been critical to the construction schedule. Failure to make the deadline would have delayed construction by 5 months, the length of time the Don and Volga rivers are closed by ice during Russian winters.

"The transhipment of huge and heavy structures across the locks is very difficult, but our earlier experience with the Gurtulush, Caspian Sea's first western class jackup rig, stands us in good stead," said Tong Chong Heong, managing director and chief operating officer of Keppel Offshore and Marine.
Keppel had just completed the Gurtulush - dubbed the Trident 20 - jackup for TransoceanSedcoForex when it won the US$167 million deal to build the new DSS 20 semisubmersible for Maersk in February 2001.

Now the Caspian Shipyard Company (CSC), also owned by Keppel, is responsible for completing the new unit. Completion will involve integrating the topsides - including installing a 130-man accommodation module - to the hull. Up to 1,000 technicians are expected to complete the rig in Baku by the third quarter of 2003 so that it can be tested, finished with sea trials and ready for drilling in 2004.
"CSC, which has already completed about 50% of the overall work, is now entering into the next phase of the construction to join the lower hull sections together and fully consolidate the upper hull onto it," said Keppel.

Until now, BP has largely monopolized modern drilling capacity in the Caspian region, utilizing the Dada Gorgud and the Istigal semisubs on the Shah Deniz and Azeri-Chirag-Guneshli (ACG) developments. Any other operators in the region have been denied the opportunity to operate with the maximum efficiency and uptime that a modern semisub can offer.

Maersk claims its new unit, designed jointly by Keppel FELS and Marine Structure Consultants of Holland, will be the most technologically advanced unit operating in the region.

Specifications

Technical specifications on the DSS 20 will allow it to operate in water depths

up to 3,280 ft (1,000 m) - sufficient for the deepest regions of the Caspian Sea - and will allow drilling to a depth of 30,000 ft (9,140 m).

Apart from being the largest and most powerful drilling unit in the Caspian Sea, Maersk asserts that the design features a high level of environmental protection equipment, which is regarded as critical for the Caspian because of the sensitivity of the sturgeon fish population to pollution. "Only cooling water will be dumped over the side of the rig once it becomes operational," says the drilling operator. "Even the rainwater will be contained in tanks for cleaning before it is discharged."

High automation of the drill floor is part of the design, too, and the DSS 20 features vertical riser storage, automatic pipe-feeding, stabbing and pipe-handling, eliminating much of the risk of rig crew injury by removing personnel from the drill floor. Despite this, manual controls are being provided as a back up for drilling systems.

Mooring the rig will be via an eight-point system, capable of operating to a water depth of 1,640 ft (500 m), but using pre-set anchoring, the rig will be able to operate to its maximum water depth of 3,280 ft (1,000 m).

Specifications of the DSS 20 allow a load up to 4,000 tons over a deck, which will measure 208 ft (63.5 m) long, 211 ft (64.5 m) wide, with a depth of 114 ft (35 m), while the maximum operational displacement will be 30,000 tons.

Maersk's design allows the derrick, crown-mounted heave compensator and traveling block to be rated up to an industry standard 2 million lbs. Drawworks are equipped with a 4,000-hp drive. Three mud pumps feature working pressures of 7,500 psi each, and a reserve mud system with a capacity of 21,187 ft (600 cu m) is also part of the drilling equipment specification.

More exploration

Meanwhile, Iran plans to launch another semisubmersible in the same region by 2004.
Iran intends to develop another new semisubmersible to operate in the Caspian Sea using a heavy duty rig design from Sweden's GVA.

After a cabinet meeting in May, the country' Soil Minister, Bijan Namdar Zangeneh, backed up the signal for more exploration by Iran of the Caspian Sea. "We have invested $300 million on infrastructure and equipment to prospect and exploit the oil in the Caspian Sea," said Zangeneh.
If Iran is serious about another new rig, it is likely to be built and deployed in the southern Caspian Sea, where maritime borders between the five littoral states are still to be settled. If Iran can drill and prove up estimated reserves for structures in the southern Caspian, it is likely to intensify efforts to resolve the demarcation lines for those disputed territorial waters.

Two of Socar's Shelf-class rigs are undergoing upgrades for further operation in the region, which will help alleviate the rig famine.

And in May, Friede and Goldman Ltd., the naval architecture and marine engineering unit of Friede and Goldman, was sold for $15 million to United Heavy Machinery of Russia, which has rig construction expertise and the avowed intention to build new drilling units for the Caspian.

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