South Cormorant

Location

The South Cormorant oil field is situated 161 kilometres (100 miles) northeast of Lerwick, Shetland, Scotland, in block number 211/26a.

Discovery and Development

The South Cormorant field was discovered in September 1972. The discovery well, 211/26-1, was drilled by the semi-submersible rig Staflo at a water depth of 150 metres (490 feet). However, the oil reservoir itself is located at a much greater depth of 2,895 metres (9,498 feet).

Platforms and Infrastructure

The primary platform for the South Cormorant field is the Cormorant Alpha platform, which is a concrete gravity platform of the Sea Tank Co type. This platform was installed in May 1978 at Ardyne Point and began production in December 1979. Here are some key details about the Cormorant Alpha platform:

• Design and Construction: The platform has four legs and a storage capacity for 1 million barrels (160,000 m³) of oil. The total sub-structure weight is 294,655 tonnes, and it is designed to carry a topsides weight of 32,350 tonnes.
• Facilities: The platform includes facilities for drilling, producing, metering, and pumping oil. It also has the capability to re-inject water to maintain reservoir pressure. Initially, there were facilities for 17 oil production wells, 18 water injection wells, and one gas injection well.
• Production Capacity: The production capacity was 60,000 barrels of oil per day and 900,000 standard cubic metres of gas per day. The platform has a single production train with three stages of separation.

Operations

• Production Start: Production from the Cormorant Alpha platform began in December 1979, with peak production reaching 24,000 barrels per day in 1979.
• Pipeline Connections: The platform is the starting point for the Brent System pipeline and is connected to the Vesterled gas pipeline, which links into the FLAGS pipeline at Brent Alpha to the St Fergus Gas Terminal.
• Additional Infrastructure: Besides the Cormorant Alpha platform, the field also includes an Underwater Manifold Centre (UMC) that started operations in mid-1983. The UMC has a design capacity for 50,000 barrels per day and is controlled from the Cormorant platform. Additionally, there is a single satellite well (P1) linked to the platform with a design capacity of 10,000 barrels per day.

Ownership and Operation

Originally, the South Cormorant field was operated by Shell and licensed to Shell/Esso. On 7 July 2008, the field was purchased by the Abu Dhabi National Energy Company (TAQA).

Geology and Reserves

The oil reservoir in the South Cormorant field is located within the Jurassic Brent Group sandstones. The estimated recoverable reserves for the entire Cormorant field (including North and South Cormorant) are over 600 million barrels of oil and more than 180 billion cubic feet of gas.

Current Status

The field continues to be operated by TAQA, which has invested in various projects to enhance production and extend the life of the field. This includes reinstating dormant drilling rigs and drilling infill wells to increase production.

In summary, the South Cormorant oil field, operated primarily through the Cormorant Alpha platform, is a significant contributor to the UK's North Sea oil production, with a long history of operation and ongoing efforts to optimize and extend its production life.