The Amethyst gas field was discovered in 1972 in acreage awarded in the first and fourth UK licensing rounds. Gas was found 2,700 metres below the seabed in a water depth of 30 metres in Permian sandstone some 280 million years old, capped by a layer of Zechstein salt which trapped the gas escaping from coal measures lying underneath.

Between 1972 and 1985 a number of appraisal wells were drilled, culminating in a decision to develop the field in 1988. The initial Amethyst Development involved the use of two unmanned steel satellite wellhead platforms A1D and A2D on Amethyst East. The jackets weighing around 900 tonnes each and topsides also around 900 tonnes were built by UIE in Glasgow and were installed in July 1989.

Two additional satellite platforms, B1D to develop further Amethyst East and C1D to develop Amethyst West, were ordered, again from UIE, in 1990 and installed in April 1991. C1D is connected to the A1D platform via a 12-inch infield line whilst B1D is connected to to the A2D platform via a 10-inch infield line.

On each platform, well fluids are collected from individual fields and routed to a two-phase production separator via 6-inch flowlines fitted with adjustable choke valves.

The Amethyst development was unique when commissioned in that the operation of the field is entirety controlled from shore. Control of the Amethyst platforms is carried out by BP from the Dimlington control room at Easington. No processing is carried out offshore.

Amethyst production is exported via a dedicated 30-inch diameter line from the A2D platform 40 kilometers to the Easington terminal operated by Centrica Storage Limited. This is paralleled by a 3-inch methanol supply line and power cable from onshore. Amethyst East came on stream in October 1990 followed by Amethyst West in October 1991.