Alma / Ardmore Field Development, North Sea, United Kingdom

Key Data

Scotland-based company EnQuest is planning to redevelop the Ardmore field (known earlier as the Argyll field) located in the central North Sea. The field covers UK continental shelf blocks 30/24 and 30/25 and lies in a water depth of 80m. It will be renamed Alma under the redevelopment project.

First oil from the project is expected in August 2013. The life of field is estimated to be ten years. EnQuest is planning to invest $850m into the project.

Discovery and geology of the North Sea field

Alma was discovered as Argyll in 1971 by the Hamilton Brothers (now BHP) with the drilling of the 30/24-2 discovery well.

The Alma field contains three main productive reservoirs - Zechstein carbonates, Rotliegend sandstone and Devonian sandstone. It lies in a large Palaeozoic tilted fault block, which measures 2.5km wide and 6km long.

Expected oil reserves at the Alma projet

Alma is estimated to contain 20.7 million barrels of oil and a high recovery case of 32.5 million barrels of oil. The field is expected to achieve a peak production of 4.5 million barrels during the first year and 7.8 million barrels in a high recovery case.

Field development history

"The life of field is estimated to be ten years. EnQuest is planning to invest $850m into the project."

The Argyll field was the first field to produce oil in the UK in 1975. It produced 72.6 million barrels of light sweet crude oil with 37° API over a 17-year period.

Three platforms, including the Trans-world 58 and Deepsea Pioneer, were used to produce the field. From 1991, production from the field started declining. Due to lack of sufficient gas lift facilities and other constraints, the field was decommissioned in 1992.

In January 2002, Tuscan Energy and Acorn Oil and Gas acquired the licence to redevelop the field. The field was renamed Ardmore and two wells were drilled in 2003. It was estimated to contain 21 million barrels of oil which Tucson and Acorn planned to recover.

The field was produced using Rowan's Gorilla VII jackup rig modified to include both drilling and production facilities. Between 2003 and 2005, the field produced 5.2 million barrels of oil through high angle wells. In 2008, the field was decommissioned again as it became economically unfeasible.

Plans for redevelopment by EnQuest

The Alma field development is in line with the UK Government's policy to stimulate indigenous production of oil and gas and increase security of energy supply. Although Alma is a marginal field, development is feasible due to the current oil prices.

"The field covers UK continental shelf blocks 30/24 and 30/25 and in water depths of 80m. It will be renamed Alma under the project."

The redevelopment project consists of drilling six production wells and two water injection wells. Water injection is required due to low reservoir pressures at the field. The wells will be drilled from two drill centres located to the north and south.

The production wells will be drilled from the northern drill centre and water injection wells from the southern drill centre. Production wells will be fitted with electrical submersible pumps to regulate flow rates.

The two drill centres will be connected to the Uisge Gorm floating production, offloading and storage facility (FPSO) through 10in flowlines. Since the life of the field is relatively short, EnQuest decided to use an FPSO instead of a platform. Two control umbilicals and one power cable form part of the subsea infrastructure.

A semi-submersible drilling rig will be used to drill the production and injection wells. Drilling activities are expected to commence in January 2012.

The field will be decommissioned and abandoned at the end of its life. All wells will be plugged and abandoned and all subsea infrastructure and the FPSO will be removed.

Uisge Gorm FPSO

The Uisge Gorm FPSO began operations in 1995 at the Fife field for Amerada Hess. It is capable of operating in water depths of more than 1,500m. The vessel will be modified to accommodate production from the Alma field.

The turret, control systems and accommodation facilities will be upgraded. A new chemical injection skid, a first stage separator and new subsea control system equipment will be installed on the FPSO.

Exporting the oil produced

Oil produced will be offloaded onto a shuttle tanker through a loading hose and tanker mooring system. The tanker will visit the field once every two weeks. Produced gas will be used to power the FPSO.

The Alma field is located in the UK continental shelf in blocks 30/24 and 30/25.

Alma will be redeveloped using the Uisge Gorm FPSO.

Uisge Gorm first began operations in 1995 and is undergoing modifications.