The successful 'mating' of the installation's Topsides to the four legs of the concrete gravity base placed on the seabed last summer, follows the 11 day tow of the Topsides from its fabrication yard in South Korea. The Topsides arrived on location on Sunday, June 18th.
The operation began early on Friday morning, June 23d when the installation barge carrying the Topsides was carefully towed between the legs of the concrete gravity base structure (CGBS), and then positioned using the so-called 'float-over' technique. This involves lowering the massive Topsides, weighing 21,800 tons, slowly and carefully onto the CGBS by ballasting down the purpose built barge. Leg mating units, weighing 130 tons each, were pre-installed in each of the CGBS legs to centralise the topsides during the lowering process and to act as shock absorbers during the initial contact. Given the total weight of the Topsides, this installation has broken the world record for installation operations of this type.
The Topsides settled comfortably onto its final resting place on top of the CGBS at 09:30 a.m., in a process that took several days to prepare since its arrival off the Sakhalin coast. The preparation included the mooring of the installation barge and Topsides in front of the CGBS, the testing of the barge ballasting equipment and the cutting of the sea fastenings.
The installation process was a carefully prepared and well executed operation that took over 9 hours, involving the coordination of the Topsides on its transport barge, the Saipem Castoro-8 installation support vessel and a fleet of five tugs and anchor handling vessels.
Sakhalin Energy Phase II Project Director David Greer said: "This operation is a great example of professional engineering and marine mastery. The marine team not only safely towed the giant Topsides all the way from Korea to Lunskoye, they then successfully placed them atop their concrete legs. This was truly a thoroughly professional operation, involving the excellent co-operation of all parties involved and was completed efficiently without incident. The 'silent elegance' of the docking and mating of these two structures was a wonderful piece of engineering and a new world record. The top of the Lunskoye-A platform, which will become Russia's first offshore gas production platform, now stands proudly some 110 m above the Sea of Okhotsk.
This operation highlights the beginning of a new era in Russia's oil and gas production history. It is a great day for Russia, for Sakhalin and for Sakhalin Energy."
This is a major event in the Sakhalin ll Phase 2 Project, as the platform will be the main source of gas for Russia's first LNG plant at Prigorodnoye. The platform will now undergo hook up and commissioning work before commencing drilling of gas production wells. LNG production is expected to start in 2008.
The Lunskoye offshore platform (Lun-A) is located 15 kilometers off the north-eastern coast of Sakhalin Island in a water depth of 48 meters on the Lunskoye gas field. The Lunskoye platform consists of the Topsides and the concrete gravity base structure (CGBS).
The Lun-A Topsides facilities were fabricated by Samsung Heavy Industries at their shipyard in Korea on Geoje Island and completed in May 2006. The transportation and installation of the Lun-A Topsides were subcontracted to SAIPEM.
The Topsides comprise a fully integrated deck that incorporates all necessary drilling and production equipment, hydrocarbon liquids separation facilities and living quarters for personnel. The structure includes 27 well slots for directional drilling, which will enable full development of the Lunskoye field. The platform's production capacity will be over 50 million cubic meters of gas per day (1,800 million standard cubic feet per day), approximately 50,000 barrels of condensate per day (8,000 cubic meters per day) and will supply the majority of the gas for Russia's first LNG plant that is being built in the south of Sakhalin Island. Separation, including treatment and separation of the Lunskoye gas and condensate, will be undertaken onshore at the Onshore Processing Facility (OPF), which will also supply power to the platform via submarine cable. The Lun-A Topsides have been designed and constructed to support the commercial development of the Lunskoye gas field in the extreme and demanding environment, offshore Sakhalin Island in eastern Russia.
Prior to this offshore operation, the enormous LUN-A Topsides were successfully raised to a height of 29 meters to allow the loadout support frame to be slid underneath, a world record for land lift. A purpose built 190 meters long by 95 meters wide T-shape barge was used to transport these Topsides over a distance of 1,500 nm (2831 km). This barge with the topside was towed by three large towing tugs from Korea to Sakhalin, which took 11 days.
The LUN-A platform will also have special sliding connections (called friction pendulum bearings) installed between the CGBS structure and the Topsides. These bearings allow the Topsides to move independently of the base, which helps to protect the topside against damage during a severe earthquake. This is the first time these bearings have been used in the oil and gas industry anywhere in the world.
The Lunskoye CGBS was the first such facility built in the port of Vostochnoye in the Primorsky Krai, Russian Far East. It consists of a base caisson and four shafts topped by cylindrical steel deck connector legs that support the topsides of the new offshore platform. It has a total dry weight of 103,000 tons. The base is 105 meters by 88 meters and 13.5 meters high. The diameter of each shaft measures more than 20 meters and they are some 56 meters high. Total height of the entire structure is 69.5 meters. The thickness of the concrete for the structure ranges between half and three quarters of a meter, and is reinforced with steel bars throughout the structure.
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