Shtokman Gas Condensate Deposit Barents Sea, Russia

The Shtokman gas condensate deposit lies in the Barents Sea, in the north of Russia. The timing of the project is intended to coincide with an increase in demand for LNG, principally from the US market and the search for operational partners focuses on the need for external expertise in LNG transport and deep water / long distance gas production.

The development cost has been estimated at $10 billion to $25 billion. The field will be commercial for 50 years, with stable production accounting for half of the time.

The Shtokman field was discovered in 1988 to the east of Murmansk. It lies 555km from land, in 350m of water. The field covers an area of 1,400m² and lies inside the arctic. It is subject to icebergs of up to 1 million tons drifting at up to 0.25m/s, and 1.2m drift ice moving at up to 1m/s.

APPRAISAL DRILLING AND RESERVES

An appraisal drilling programme was carried out between 1990 and 1995, and following this, a production sharing system was signed in 2000 by the Russian government. The licensee is Sevmorneftegaz, which is owned by the companies Rosneft (state) and Gazprom (state/private). In late 2004 and early 2005, preliminary agreements were signed with ChevronTexaco, ConocoPhillips, ExxonMobil, Statoil and Norsk Hydro.

Reserves of gas have been put at 3.2 trillion m³, with another 31 million t of condensate. The deposits lie in four main layers. The reservoir depth is between 1,900m and 2,300m.

FIELD DEVELOPMENT

It is anticipated that the Shtokman field will require three or four phases for full field development. The development will include up to four platforms. Sevmorneftegas have estimated that the total number of wells required to develop the Shtokman will be around 156, which breaks down to 144 production wells, three monitor wells and nine reserve wells. There are likely to be around 40 wells completed subsea.

Early estimates predict that TLP and spar-type platforms are likely to be the most preferable choices of platform construction. The key feature of the design is the strengthened angled ice wall in the zone of ice impact. The platforms could have reception facilities for around 36 surface completed wells, including 24 wells drilled directly from the platform. In addition, the platform will load the gas from 12 to 16 subsea wells.

The floating platforms are tentatively planned with a typical topside mass of 50,000t and a deadweight of 184,000t. Model testing of various aspects including the base and tethers of TLP type systems is being carried out at the Krylov Institute at St Petersburg.

Its design output has been configured to satisfy an annual production of 100 billion m³ of gas. It will process around 30 billion from the very start, of which 22 to 24 billion m³ will be liquefied to produce up to 15 million t of LNG for America.

GAS TRANSPORT

It has been estimated that the development will require four 42in pipelines to be laid between the offshore platforms and the receiving facilities at Teriberka, 565km away. The seabed is very uneven. The pressure at the platform will be around 19MP, however this will reduce to only6MP by the time the gas reaches the coast.

The gas will be forwarded by two onshore, 1,100 to 1,400mm lines, in the 1,400km route between Teriberka via Medvezhegorsk - to Vyborg. There will be ten compressor stations which will raise the gas to a working pressure on 9.8MP.

Gazprom hopes to put Shtokman on stream as early as 2010.

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