The Fife and Fergus Fields, Block 31/26a, UK North Sea
M. Shepherd, A. MacGregor, K. Bush, J. Wakefield, 2003. "The Fife and Fergus Fields, Block 31/26a, UK North Sea", United Kingdom Oil and Gas Fields Commemorative Millennium Volume, J. G. Gluyas, H. M. Hichens
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The Fife Field and its smaller satellite the Fergus Field are the southernmost of the cluster of oil fields within the UK Central North Sea. The Fife Field lies at the intersection of four blocks, 31/26a, 31/27a, 39/1a and 39/2a. It is a small to moderate size offshore field with reserves of 48. 3 MMSTB and is produced by five sub-sea wells through a Floating, Production, Storage, Offloading (FPSO) vessel. The field was discovered in 1991 and the first oil was produced in 1995. The Fergus Field, located in Block 39/2a, is a satellite located 5 km SE of the Fife Field. It is produced by a single well tied-back by a sub-sea flowline to the Fife Field infrastructure. The Fergus Field was discovered in 1994 and first oil was produced in 1996. Reserves are estimated as 11. 3 MMSTB.
The main reservoir interval in both fields comprises fine-grained, heavily bioturbated, shallow marine shelf sandstones of Upper Jurassic age. Significant volumes of chert and carbonate cements, both banded and nodular, occlude porosity and impart reservoir layering within an otherwise thick sandy, mud deficient reservoir interval. Sandstone porosity is in the range 19-31%. Permeabilities are low in the Fife Field reservoir sandstones, typically less than 100mD. By contrast, better permeabilities (average 500 mD) are seen in the Fergus Field, where a more proximal shelf sandstone facies is present within the oil leg. Two thin intervals of pebbly, very coarse-grained sandstone are intercalated with the shelf sandstones in the crest of the Fife Field. These may represent submarine toes of fan deltas sourced from an active fault system located to the north of the field. The pebbly sandstones show permeabilities in excess of a Darcy and have caused early water breakthrough problems in production wells.
A subsidiary reservoir is present within the Tor Formation of the Chalk Group in the Fife Field, but is not oil bearing within the Fergus Field. This comprises white to grey, intensely bioturbated, stylolitized chalk with an average porosity of 24. 5% and an average air permeability of slightly less than a millidarcy. Both the Fife and Fergus Fields are defined by simple four-way dip closure at top Jurassic. An episode of structural inversion at the end of the Jurassic created both structures. The overlying Chalk oil pool in the Fife Field has a trap defined by dip closure on three sides and a probable diagenetic trapping element to the south.
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Memoir 20 is the most comprehensive reference work on the UK’s oil and gas fields available. It updates and substantially extends Memoir 14 (1991), United Kingdom 0il and Gas Fields, one of the Geological Society’s best-selling books. This new edition contains updates on many of the ageing giant fields, as well as entries for fields either undiscovered or undeveloped when Memoir 14 was published.
The book is divided into nine parts covering the major petroleum provinces both offshore and onshore United Kingdom, from the Gas Basin in the southern North Sea to the Viking Graben in the northern North Sea, from the Atlantic Frontier to the Irish Sea and from the Wessex Basin to the East Midlands. Each part contains a reference map showing field locations. The introductory chapters reveal the stories behind the major plays and discoveries therein, and their tectonic and stratigraphic framework. There are two appendices: tabulated field data and a comprehensive list for all of the UK's 300+ oil and gas fields.