Clair oilfield
The Clair oilfield is an offshore oil field in Scottish territorial waters west of Shetland in water depths of up to . The field is the largest oilfield on the UK Continental Shelf with an estimated 8 billion barrels of oil-in-place, according to the BP Plc’s website. It extends over an area of some , covering five licence blocks. History The Clair reservoir was discovered in 1977, with exploration well #206/8-1a penetrating a oil column in a thick sequence of Devonian to Carboniferous continental sandstone. In the 1980s ten appraisal wells were drilled. This activity demonstrated that the structure extended to an area of some 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. A development plan was approved in 2001, representing an investment of £650m by BP and its four partners in the project – ConocoPhilips, Chevron, Enterprise, and Amerada Hess. 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 , of which can be recovered. The development plan includes drilling of 15 producing wells, eight water injectors and one drill cuttings re-injection well. Plateau production is expected to be of oil and of gas. Noble Corporation and Wood subsidiary Mustang Engineering, part of the Wood Group, won the contract for Front-end loading. 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 . At its base, the jacket measures , has a height of , 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