Schiehallion oilfield

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Schiehallion oil field
Schiehallion oil field
Schiehallion Vessel 2004
Location of Schiehallion oil field
Country United Kingdom
Region North Sea
Offshore/onshore offshore
Coordinates

60°20′N 4°20′W / 60.333°N 4.333°W / 60.333; -4.333Coordinates: 60°20′N 4°20′W / 60.333°N 4.333°W / 60.333; -4.333{{#coordinates:60|20|N|4|20|W|type:landmark_region:GB|| |primary |name=

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Operator(s) BP
Partners BP, Shell, Amerada Hess, Murphy Oil, Statoil, OMV
Field history
Discovery 1993
Start of production 1998

The Schiehallion oilfield is a deepwater offshore oilfield approximately 175 kilometres (110 mi) west of the Shetland Islands in the North Atlantic Ocean. The Schiehallion and adjacent Loyal field were jointly developed by BP on behalf of the Schiehallion field partners; BP, Shell, Amerada Hess, Murphy Oil, Statoil and OMV, and the Loyal field partners; BP and Shell.

The Schiehallion field together with Foinaven and Clair fields, form the frontier area generally termed as the West of Shetland.

Field development

Schiehallion field was discovered in 1993 by the semi-submersible drilling vessel Ocean Alliance drilling the third exploration well in block 204 (well 204-3). The field is located in blocks 204/20 and 204/25 of the United Kingdom Continental Shelf in a water depth of 350 to 450 metres (1,150 to 1,480 ft). Recoverable oil reserves of Schiehallion are estimated to be between 450 and 600 million barrels (72×10^6 and 95×10^6 m3).[1][2]

During 1994 and 1995 an appraisal of Schiehallion and Loyal was carried out, culminating in a successful extended well test, which demonstrated well rates of up to 20,000 barrels per day (3,200 m3/d). The combined development of the Schiehallion and Loyal fields was sanctioned in April 1996 and the oil production started on 29 July 1998.[1]

The design and construction of the Schiehallion FPSO vessel was contracted to the Atlantic Frontier Alliance–a new group that consisted of Harland and Wolff, Single Buoy Moorings, and Brown and Root.[3] The vessel was designed as a simple barge form, with a 245-metre (804 ft) length similar to a Suezmax tanker. The contract was placed in June 1995, and the vessel was constructed at the Harland and Wolff shipyard in Belfast, and handed over to operator BP on 31 December 1997. The vessel has a dead-weight of 154,000 tonnes (152,000 long tons; 170,000 short tons), a processing capacity of 200,000 barrels per day (32,000 m3/d), and a storage capacity of 900,000 barrels (140,000 m3).[2]

Oil and gas is produced from subsea wells via a manifold and rigid flowlines to the base of the vessel where flexible risers carry it into the Schiehallion FPSO vessel. There are 42 subsea wells in total in five clusters with peak production rates of around 190,000 barrels per day (30,000 m3/d).[1]

Oil is exported primarily to the Sullom Voe Terminal by the dynamically positioned shuttle tanker Loch Rannoch delivered in August 1998, and operated by BP Shipping.[4]

Produced natural gas is used to power the vessel. Rest of gas is exported through the West of Shetland pipeline to the Sullom Voe Terminal. Some of the exported gas is used as fuel in the Fortum operated Sullom Voe power station. The remainder is enriched with liquefied petroleum gas and exported to the Magnus platform for enhanced oil recovery in Magnus field.[1]

The Schiehallion FPSO is in a poor condition after a decade working in the harsh North Atlantic, and requires significant maintenance and repairs, which can only be performed in the summer season due to the hostile weather in the region. The composition of the production fluids is changing due to increased water production, and the present FPSO processing system is becoming very constrained. It is expected that the current FPSO will be returned to dry dock for refurbishment or a new FPSO will be built to replace the current FPSO within the next 5 to 6 years in order to continue production from the field. The upgrade project, known as Quad 204 has formally requested tenders from far East shipyards to build a new hull.[citation needed]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 "The Schiehallion Field" (PDF). BP. http://www.bp.com/liveassets/bp_internet/globalbp/STAGING/global_assets/downloads/U/uk_asset_schiehallion.pdf. Retrieved 2009-12-19.
  2. ↑ 2.0 2.1 "Schiehallion Oil Field, United Kingdom". Hydrocarbons Technology. Net Resources International. http://www.offshore-technology.com/projects/schiehallion/. Retrieved 2008-02-16.
  3. ↑ Script error
  4. ↑ "Loch Rannoch Shuttle Tanker". BP. http://www.bp.com/sectiongenericarticle.do?categoryId=9019903&contentId=7036765. Retrieved 2009-12-19.

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