Schiehallion oilfield
Encyclopedia
The Schiehallion oilfield is a deepwater offshore oilfield approximately 175 kilometres (108.7 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.
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 m (1,148.3 to 1,476.4 ft). Recoverable oil reserves of Schiehallion are estimated to be between 450 Moilbbl.
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 20000 oilbbl/d. The combined development of the Schiehallion and Loyal fields was sanctioned in April 1996 and the oil production started on 29 July 1998.
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
. The vessel was designed as a simple barge form, with a 245 metres (803.8 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 154000 tonnes (151,567.3 LT), a processing capacity of 200000 oilbbl/d, and a storage capacity of 900000 barrels (143,088,565.5 l).
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 190000 oilbbl/d.
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.
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
.
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.
Shetland Islands
Shetland is a subarctic archipelago of Scotland that lies north and east of mainland Great Britain. The islands lie some to the northeast of Orkney and southeast of the Faroe Islands and form part of the division between the Atlantic Ocean to the west and the North Sea to the east. The total...
in the North Atlantic Ocean. The Schiehallion and adjacent Loyal field were jointly developed by BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
on behalf of the Schiehallion field partners; BP, Shell
Royal Dutch Shell
Royal Dutch Shell plc , commonly known as Shell, is a global oil and gas company headquartered in The Hague, Netherlands and with its registered office in London, United Kingdom. It is the fifth-largest company in the world according to a composite measure by Forbes magazine and one of the six...
, Amerada Hess
Hess Corporation
The Hess Corporation is an integrated oil company based in New York City. The company explores, produces, transports, and refines crude oil and natural gas. Vertically completing the logistical chain, about 1,360 Hess branded filling stations market gasoline to consumers in 16 states along the...
, Murphy Oil
Murphy Oil
Murphy Oil Corporation is an international oil and gas company, founded in 1944 as C.H. Murphy & Co by Charle H Murphy Sr., that conducts business through various operating subsidiaries. Murphy produces oil and/or natural gas in the United States, Canada, Malaysia, the United Kingdom and Republic...
, Statoil
Statoil
Statoil ASA is a Norwegian petroleum company established in 1972. It merged with Norsk Hydro in 2007 and was known as StatoilHydro until 2009, when the name was changed back to Statoil ASA. The brand Statoil was retained as a chain of fuel stations owned by StatoilHydro...
and OMV
OMV
OMV is Austria's largest oil-producing, refining and gas station operating company with important activities in other Central European countries...
, and the Loyal field partners; BP and Shell.
The Schiehallion field together with Foinaven
Foinaven oilfield
Foinaven oil field is deepwater oil development approximately west of the Shetland Islands. Together with Schiehallion, Loyal and Clair fields it forms the area generally termed as the West of Shetland.-Field description:...
and Clair
Clair oilfield
The Clair oilfield is an oil field on the United Kingdom Continental Shelf located west of Shetland in water depths of up to . It extends over an area of some , covering five licence blocks.-History:...
fields, form the frontier area generally termed as the West of Shetland.
Field development
Schiehallion field was discovered in 1993 by the semi-submersibleSemi-submersible
A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...
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 m (1,148.3 to 1,476.4 ft). Recoverable oil reserves of Schiehallion are estimated to be between 450 Moilbbl.
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 20000 oilbbl/d. The combined development of the Schiehallion and Loyal fields was sanctioned in April 1996 and the oil production started on 29 July 1998.
The design and construction of the Schiehallion FPSO
Floating Production Storage and Offloading
A floating production, storage and offloading unit is a floating vessel used by the offshore industry for the processing of hydrocarbons and for storage of oil. A FPSO vessel is designed to receive hydrocarbons produced from nearby platforms or subsea template, process them, and store oil until it...
vessel was contracted to the Atlantic Frontier Alliance–a new group that consisted of Harland and Wolff
Harland and Wolff
Harland and Wolff Heavy Industries is a Northern Irish heavy industrial company, specialising in shipbuilding and offshore construction, located in Belfast, Northern Ireland....
, Single Buoy Moorings
SBM
SBM may stand for:* School business manager* Screaming Bloody Murder, a 2011 album by rock band Sum 41* Super Bit Mapping* SBM Offshore, a Dutch-based oil services company* Sheboygan County Memorial Airport's IATA code...
, and Brown and Root
KBR
KBR can stand for:* KBR - American engineering and construction company* Key-based routing* Royal Library of Belgium* The ISO 639 linguistic identifier code for the Ethiopian language Kaffa ....
. The vessel was designed as a simple barge form, with a 245 metres (803.8 ft) length similar to a Suezmax
Suezmax
Suezmax is a naval architecture term for the largest ship measurements capable of transiting the Suez Canal, and is almost exclusively used in reference to tankers. Since the canal has no locks, the only serious limiting factors are draft , and height due to the Suez Canal Bridge...
tanker. The contract was placed in June 1995, and the vessel was constructed at the Harland and Wolff
Harland and Wolff
Harland and Wolff Heavy Industries is a Northern Irish heavy industrial company, specialising in shipbuilding and offshore construction, located in Belfast, Northern Ireland....
shipyard in Belfast
Belfast
Belfast is the capital of and largest city in Northern Ireland. By population, it is the 14th biggest city in the United Kingdom and second biggest on the island of Ireland . It is the seat of the devolved government and legislative Northern Ireland Assembly...
, and handed over to operator BP on 31 December 1997. The vessel has a dead-weight of 154000 tonnes (151,567.3 LT), a processing capacity of 200000 oilbbl/d, and a storage capacity of 900000 barrels (143,088,565.5 l).
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
Subsea
Subsea is a general term frequently used to refer to equipment, technology, and methods employed in marine biology, undersea geology, offshore oil and gas developments, underwater mining, and offshore wind power industries.- Oil and gas :...
wells in total in five clusters with peak production rates of around 190000 oilbbl/d.
Oil is exported primarily to the Sullom Voe Terminal
Sullom Voe Terminal
The Sullom Voe Terminal is an oil and liquefied gas terminal at Sullom Voe in the Shetland Islands of Scotland. It handles production from oilfields in the North Sea and East Shetland Basin...
by the dynamically positioned
Dynamic positioning
Dynamic positioning is a computer controlled system to automatically maintain a vessel's position and heading by using its own propellers and thrusters...
shuttle tanker Loch Rannoch delivered in August 1998, and operated by BP Shipping.
Produced natural gas is used to power the vessel. Rest of gas is exported through the West of Shetland pipeline
West of Shetland pipeline
The West of Shetland Pipeline is a pipeline system which transports natural gas from three offshore fields in the West of Shetland area to Sullom Voe Terminal on the Shetland Isles of Scotland.-West of Shetland area:...
to the Sullom Voe Terminal
Sullom Voe Terminal
The Sullom Voe Terminal is an oil and liquefied gas terminal at Sullom Voe in the Shetland Islands of Scotland. It handles production from oilfields in the North Sea and East Shetland Basin...
. Some of the exported gas is used as fuel in the Fortum
Fortum
Fortum Oyj is a Finnish publicly listed energy company, which focuses on the Nordic and Baltic countries, Poland and the north-west of Russia. After acquisition of Russian energy company TGC-10 in year 2008, Western Siberia has become an important operating area for Fortum. The head of the company...
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
Magnus oilfield
The Magnus oilfield is a large oilfield in the United Kingdom's zone of North Sea. It is located north-east of the Shetland Islands. The field is located mainly in Block 211/12a. Resources are estimated to total of oil, of which are recoverable reserves....
.
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.