Clair oilfield
Encyclopedia
The Clair oilfield is an oil field
on the United Kingdom Continental Shelf located 75 kilometres (46.6 mi) west of Shetland in water depths of up to 140 metres (459.3 ft). It extends over an area of some 220 square kilometres (84.9 sq mi), covering five licence blocks.
to Carboniferous
continental sandstone
. In the 1980s ten appraisal wells were drilled. This activity demonstrated that the structure extended to an area of some 400 square kilometres (154.4 sq mi) with static oil-in-place, although it failed to confirm the presence of economically recoverable reserves. Two further wells were drilled in 1991, two in 1992 and one in 1995. Two of these wells (206/8-8 and 206/8-9z) demonstrated the potential for commercial flow rates but were not produced for long enough to give confidence in long term reservoir deliverability.
In 1996 there was a breakthrough in the drilling and extended well testing (EWT) of well #206/8-10z. The EWT was followed by the side-tracking of an offset well into the pressure sink created by the EWT. The 1996 well test results set the scope for the 1997 drilling programme and triggered interest in a first phase of development. Two further wells were drilled in 1997 to appraise the 'Graben' and '3A' segments to reduce uncertainty in these areas adjacent to the core area.
In May 1997 it was agreed by the Clair partners to jointly develop the field. BP
was appointed as the operator and programme coordinator. Development of was approved in 2001. The production facilities were installed in 2004. The first stage of the development was inaugurated on 23 February 2005.
and one drill cuttings re-injection well. Plateau production is expected to be 60000 oilbbl/d of oil and 20 Mcuft/d of gas.
Noble Drilling and Wood subsidiary Mustang Engineering, part of the Wood Group
, won the contract for Front-End Engineering Design (FEED). They proposed a single steel jacket with an integrated topsides deck with processing facilities, accommodation and a separate modular drilling rig. The steel jacket for Clair is located over the existing 206/8-10z well. The jacket is a four legged single steel structure with a height of approximately 165 metres (541 ft). At its base, the jacket measures 45 by, has a height of 169 metres (554.5 ft), and a total weight of 8,800 tons. Both jacket and topsides are designed for fabrication, transportation and installation as single fully integrated lifts (maximum 10,500t) that require access to the heaviest lift capability vessels on the installation market. BP awarded the contract for the fabrication of the platform jacket to Aker Verdal.
The contract for the construction of the platform topsides was awarded to AMEC
. There are additional processing facilities for offshore power generation, water injection, produced water and cuttings re-injection, surplus gas disposal (export or re-injection) and flare gas
recovery. Artificial lift is provided for all producing wells with the option of Electric Submersible Pumps (ESPs) for future well intervention. The operations will feature simultaneous drilling and coil tubing well intervention operations (SIMOPS). The topsides deck (including the flare boom) weighs 10,700 tonnes.
The contract to build the accommodation modules was awarded to Leirvik Module Technology. The accommodation contract involves the fabrication of the living quarters and utility building which have a weight of 1000 tonnes. The contract for the drill rig fabrication contract was awarded to Heerema Hartlepool. The scope of the fabrication work incorporates fabrication of a Derrick Equipment Set (DES) module, with substructure and skid base and a Drilling Support Module (DSM). The work includes equipment installation and extended commissioning and the modules weigh approximately 2000t and 2400t respectively. The entire structure has a design life of 25 years.
A further development phase is being planned called 'Clair Ridge' which aims to develop other areas of the field with further fixed platforms.
Oil field
An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...
on the United Kingdom Continental Shelf located 75 kilometres (46.6 mi) west of Shetland in water depths of up to 140 metres (459.3 ft). It extends over an area of some 220 square kilometres (84.9 sq mi), covering five licence blocks.
History
The Clair reservoir was discovered in 1977, with exploration well #206/8-1a penetrating a 568 metres (1,863.5 ft) oil column in a thick sequence of DevonianDevonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
to Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
continental sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
. In the 1980s ten appraisal wells were drilled. This activity demonstrated that the structure extended to an area of some 400 square kilometres (154.4 sq mi) with static oil-in-place, although it failed to confirm the presence of economically recoverable reserves. Two further wells were drilled in 1991, two in 1992 and one in 1995. Two of these wells (206/8-8 and 206/8-9z) demonstrated the potential for commercial flow rates but were not produced for long enough to give confidence in long term reservoir deliverability.
In 1996 there was a breakthrough in the drilling and extended well testing (EWT) of well #206/8-10z. The EWT was followed by the side-tracking of an offset well into the pressure sink created by the EWT. The 1996 well test results set the scope for the 1997 drilling programme and triggered interest in a first phase of development. Two further wells were drilled in 1997 to appraise the 'Graben' and '3A' segments to reduce uncertainty in these areas adjacent to the core area.
In May 1997 it was agreed by the Clair partners to jointly develop the field. 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"...
was appointed as the operator and programme coordinator. Development of was approved in 2001. The production facilities were installed in 2004. The first stage of the development was inaugurated on 23 February 2005.
Development
The first phase of development targets the 'Core', 'Graben' and 'Horst' segments of the southern area of the reservoir, which have 1.75 Goilbbl, of which 250 Moilbbl can be recovered. The development plan includes drilling of 15 producing wells, eight water injectorsWater injection (oil production)
Water injection refers to the method in oil industry where water is injected back into the reservoir, usually to increase pressure and thereby stimulate production. Water injection wells can be found both on- and offshore, to increase oil recovery from an existing reservoir...
and one drill cuttings re-injection well. Plateau production is expected to be 60000 oilbbl/d of oil and 20 Mcuft/d of gas.
Noble Drilling and Wood subsidiary Mustang Engineering, part of the Wood Group
Wood Group
John Wood Group PLC is a multinational oil and gas services company headquartered in Aberdeen, Scotland, United Kingdom. It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index.-History:...
, won the contract for Front-End Engineering Design (FEED). They proposed a single steel jacket with an integrated topsides deck with processing facilities, accommodation and a separate modular drilling rig. The steel jacket for Clair is located over the existing 206/8-10z well. The jacket is a four legged single steel structure with a height of approximately 165 metres (541 ft). At its base, the jacket measures 45 by, has a height of 169 metres (554.5 ft), and a total weight of 8,800 tons. Both jacket and topsides are designed for fabrication, transportation and installation as single fully integrated lifts (maximum 10,500t) that require access to the heaviest lift capability vessels on the installation market. BP awarded the contract for the fabrication of the platform jacket to Aker Verdal.
The contract for the construction of the platform topsides was awarded to AMEC
AMEC
AMEC plc is a global consultancy, engineering and project management company headquartered in London, United Kingdom. It is focused on the oil and gas, minerals and metals, renewable energy, environment and infrastructure sectors and has offices in 40 countries worldwide...
. There are additional processing facilities for offshore power generation, water injection, produced water and cuttings re-injection, surplus gas disposal (export or re-injection) and flare gas
Gas flare
A gas flare, alternatively known as a flare stack, is an elevated vertical conveyance found accompanying the presence of oil wells, gas wells, rigs, refineries, chemical plants, natural gas plants, and landfills....
recovery. Artificial lift is provided for all producing wells with the option of Electric Submersible Pumps (ESPs) for future well intervention. The operations will feature simultaneous drilling and coil tubing well intervention operations (SIMOPS). The topsides deck (including the flare boom) weighs 10,700 tonnes.
The contract to build the accommodation modules was awarded to Leirvik Module Technology. The accommodation contract involves the fabrication of the living quarters and utility building which have a weight of 1000 tonnes. The contract for the drill rig fabrication contract was awarded to Heerema Hartlepool. The scope of the fabrication work incorporates fabrication of a Derrick Equipment Set (DES) module, with substructure and skid base and a Drilling Support Module (DSM). The work includes equipment installation and extended commissioning and the modules weigh approximately 2000t and 2400t respectively. The entire structure has a design life of 25 years.
A further development phase is being planned called 'Clair Ridge' which aims to develop other areas of the field with further fixed platforms.
Partners
The Clair Partnership comprises five partners with the following fixed equity interests:- BPBPBP 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"...
- 28.6% - ConocoPhillipsConocoPhillipsConocoPhillips Company is an American multinational energy corporation with its headquarters located in the Energy Corridor district of Houston, Texas in the United States...
- 24.0% - Chevron CorporationChevron CorporationChevron Corporation is an American multinational energy corporation headquartered in San Ramon, California, United States and active in more than 180 countries. It is engaged in every aspect of the oil, gas, and geothermal energy industries, including exploration and production; refining,...
- 19.4% - Royal Dutch ShellRoyal Dutch ShellRoyal 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...
- 18.7% - Amerada HessHess CorporationThe 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...
- 9.3%