Brent oilfield
From Wikipedia, the free encyclopedia
The Brent oilfield is one of the most productive parts of Scotland's offshore oil assets. The name Brent refers to the Brent Goose (Shell named all their oil fields after birds), although it is also an acronym for the members of the Jurassic Brent formation that make up the field: Broom, Rannoch, Etive, Ness and Tarbert (in turn named after features in the Scottish Highlands).[1]
Situated in the East Shetland Basin, the Brent is the archetype for many of the fields in the area, consisting of a tilted fault block exposing the eponymous Brent formation next to bounding faults which allowed migration from deeper adjacent "kitchen" areas where the Kimmeridge Clay Formation becomes fully mature and releases hydrocarbons. Unusually on a world-wide scale (but common in this basin), the seal or cap rock for the reservoir (which stops the hydrocarbons from migrating further towards the surface) is also the Kimmeridge Clay. The field supplies oil via the Brent System pipeline to the terminal at Sullom Voe, while gas is piped through the FLAGS pipeline ashore at St. Fergus on the north east coast of Scotland.
The Brent field is exploited by 4 oil platforms in an irregular SSW-NNE line. The first in place was the concrete legged "Condeep" Brent Bravo in 1975, followed by the concrete legged Brent Delta, Brent Charlie and steel-jacket Brent-A (as of 2004, the platform still produces oil through a manifold all Brent Alpha fluids are produced across to Brent Bravo). A fifth installation, the floating Brent Spar served as a storage and tanker loading buoy and was installed early in the field's construction. The "spar" design of this installation lead to the name by which it became the best known of the Brent installations (outside the oil industry) - as the infamous "Brent Spar". The field also included a remote flare, the "Brent Flare", which was used to flare off excess gas before gas handling and export facilities were installed in the field. This unit was decommissioned and finally removed using a heavy lifting barge in 2005.
The field went through an upgrade in the mid 90s which unlocked significant quantities of gas from the reservoir.
Brent Field
- Position - 186km (116 miles) north-east of Lerwick, Scotland
- Block number - 211/29
- Operator - Shell
- Licensees - Shell/Esso
- Discovery date - July 1971
- Water depth - 140m (460ft)
- Production start-up - Brent B - 11 November 1976 into storage, 13 December 1975 first tanker loaded
- Reservoir depth - 2651m (8700ft) Brent, 2865m (9400ft) Statfjord (9000ft)
- Production - Oil: Initially via Spar loading facility but from November 1979 via the Brent System to Sullom Voe.
- Gas: Produced via FLAGS line to St Fergus.
