The A-Fields (Audrey, Ann, Alison and Annabel) are
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
reservoirs and gas production facilities in the southern
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
; about 123 km east of
Spurn Head, Yorkshire. The fields produced natural gas from 1988 to 2016.
The A-fields
The Ann gas field was discovered as early as May 1966 and Audrey in March 1976 but there was limited local infrastructure to transport gas to shore.
The
Lincolnshire Offshore Gas Gathering System (LOGGS) was commissioned in 1988 and designed to act as a hub and central gas processing, compression and transport facility for the area. Gas from LOGGS was routed to the
Theddlethorpe gas terminal.
The Audrey field is located in the UK Offshore Blocks 49/11a and 49/15a. The field was initially developed and operated by
Phillips Petroleum Co
Phillips Petroleum Company was an American oil company incorporated in 1917 that expanded into petroleum refining, marketing and transportation, natural gas gathering and the chemicals sectors. It was Phillips Petroleum that first found oil in the ...
. Ltd., later
ConocoPhillips
ConocoPhillips Company is an American multinational corporation engaged in hydrocarbon exploration and production. It is based in the Energy Corridor district of Houston, Texas.
The company has operations in 15 countries and has production in ...
, then by Spirit Energy.
The Ann field is in Block 49/06 and 48/10a and was developed by Phillips, later ConocoPhillips, then by Spirit Energy. Alison in Block 49/11a was originally licensed to Phillips. Annabel was in Block 48/10a and was also originally licensed to Phillips, it was designed to produce gas from the Saturn gas field.
The gas reservoirs in the A-Fields are Upper Leman
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
Formation of the Lower Permian
Rotliegend Group.
[Asset Data Sheets for Audrey, Ann, Alison, Saturn (Annabel) Centrica]
Phillips had assigned the letter ‘A’ to the license; all the prospects were given female names starting with ‘A’.
Development
The A-Fields were developed by a number of platforms, subsea structures and pipelines.
The design parameters of the Audrey and Ann production facilities are summarised in the table.
The design parameters of the Alison, Annabel and Ensign production facilities are summarised in the table.
In addition to the gas production pipelines there were also 3-inch methanol pipelines from LOGGS to Audrey A and B and to Ensign. There were also control umbilicals to the subsea wellheads.
Gas production
A summary of the key gas production data for the A-Fields is shown in the table.
The gas production profile, in mcm/y, for Audrey is as shown.
Decommissioning
The Alison and Ann fields had reached the end of their economic lives in 2010 and 2012 and were closed-in. Audrey was shut down in 2016. Ensign was still operating but the closure of LOGGS and Theddlethorpe gas terminal in August 2018 closed the gas export route; when no alternative export route was found the Ensign installation was decommissioned.
See also
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List of oil and gas fields of the North Sea
*
Theddlethorpe Gas Terminal
*
Lincolnshire Offshore Gas Gathering System
*
Easington Catchment Area The Easington Catchment Area (known as ECA) is a group of natural gas producing fields in the Southern North Sea. They lie in UK Blocks 42 and 47 between east of the Yorkshire and Lincolnshire coast. The fields are operated by Perenco.
Developm ...
*
Planets gas fields
References
{{reflist
Natural gas fields in the United Kingdom
North Sea energy