The Tartan Field, Block 15/16, UK North Sea

Abstract

Abstract Tartan Field lies 118 miles northeast of Aberdeen in UK Block 15/16 on the southern flank of the Witch Ground Graben. The Field consists of two major southerly-dipping rotated fault blocks, the 'Upthrown Block' to the south and the 'Downthrown Block' to the north. The primary reservoir comprises Oxfordian-Kimmeridgian shallow marine sandstone of the Piper Formation deposited during a regional marine transgression. The secondary reservoir consists of Volgian turbidites (the 'Hot Lenses') within the Kimmeridge Clay Formation. The accumulations have been sourced from maturation of the Kimmeridge Clay Formation below approximately 10000 ft in adjacent basins. The Piper Formation exhibits markedly different petrophysical properties within each block. A relatively homogeneous intergranular porosity system is present throughout the oil zone of the 'Upthrown Block'. Porosities are lower and more variable in the 'Downthrown Block' as a result of cementation and the presence of an intense compaction fabric. The trapping mechanism is a combination of structural and stratigraphic elements. The Field was discovered in December 1974 by the 15/16-1 well which penetrated 263 ft of Piper Formation sandstone full to base with oil. A further ten straight holes and three sidetracked holes delineated the structure. Tartan Field came onstream in January 1981 and is currently producing 30000 BOPD through eight platform producers, assisted by six subsea water injection wells. Ultimate recoverable reserves are currently estimated at 116 MMBBL of crude oil.