The Central Brae Field, Block 16/7a, UK North Sea

Central Brae Oilfield is the smallest of three Upper Jurassic fields being developed in UK Block 16/7a. The field was discovered in 1976 and commenced production in September 1989 through a subsea template tied back to the Brae 'A' platform in the South Brae Oilfield. Recoverable reserves are estimated as 65 MMBBL of oil and 6 MMBBL of NGL. The Central Brae reservoir is a proximal submarine fan sequence, comprising dominantly sand-matrix conglomerate and sandstone with minor mudstone units. The sediments were shed eastwards off the Fladen Ground Spur and were deposited as a relatively small and steep sedimentary cone at the margin of the South Viking Graben. Mudstone facies border the submarine fan deposits to the north and south, forming stratigraphic seals. The structure is a faulted anticline developed during the latest Jurassic and early Cretaceous possibly in response to large-scale rotational slump movement within the easterly-dipping graben margin sequence. The western boundary of the field is formed by a sealing fault, whilst to the east, there is an oil-water contact at 13 426 ft TVSS. The overlying seal is the Kimmeridge Clay Formation, which also interdigitates with the coarser facies basinwards, and provides the source of the hydrocarbons.