West Don

West Don Oil Field Profile

Discovery and History

• The West Don oil field was discovered in 1975 by Burmah Oil while drilling well 211/18-9, which encountered oil in Middle Jurassic Brent Group sandstones at rates of 5,000 barrels of oil per day (bopd).
• Further appraisals were conducted in 1976 for well 211/13-4, and in 1990, the third well 211/13b-11 tested oil at rates of up to 7,600 bopd.

Location

• The West Don oil field is located in the northern part of the North Sea, specifically in blocks 211/13b to 211/18a. It is situated approximately 150 km north-east of the Shetland Islands and 12 km north of the Thistle field, in water depths of about 170 meters.

Geology

• The West Don reservoir consists of a 470ft-thick Brent sandstone sequence, similar to the nearby Thistle, Penguin, and South Magnus oil fields. The oil gravity of the West Don field is 34° API.

Development and Production

• The field development plan was submitted by Petrofac in 2007, which included a three-well development: two producing wells and one injector. The development was conducted concurrently with the nearby Don Southwest field.
• Production from the West Don field commenced on April 28, 2009, with initial peak production rates of 25,000 bopd. The field was developed using the Northern Producer as a floating production vessel, which has a capacity of 55,000 barrels of oil per day.
• The oil is exported through a single anchor leg (SAL) to an offshore tanker and later through pipelines tied to the Thistle platform and the Brent oil export infrastructure, ultimately delivered at the Sullom Voe terminal.

Wells and Infrastructure

• The development involved drilling two up-dip high-angle producers and one down-dip water injector well from a central cluster. The drilling commenced in 2008 and was completed by 2009.
• The field is tied back to the Northern Producer floating production facility. Subsea flow lines connect each field to the Northern Producer, and oil is transported via 8-inch production lines to a sub-sea riser base.

Ownership and Partners

• The ownership structure includes Petrofac with a 27.7% stake, First Oil with 19.3%, Nippon Oil with 18.5%, Valiant Petroleum with 17.275%, and Stratic with 17.3% through a fixed field unitisation agreement.

Contractors and Services

• Technip was involved in pipeline stabilization, crossings, and T-cover protection. KWSubsea handled the detailed design of the infield pipelines, export pipelines, and tie-in spools. Bibby Offshore managed the tie-in phases.

Reserves and Production Rates

• Estimates by Stratic indicate probable reserves for the West Don field at 21.5 million barrels from a stock tank oil initially in place (STOIIP) of 53 million barrels. Proved reserves were increased from 7.5 million barrels to 11.6 million barrels.
• Peak production from the West Don and Don Southwest fields could exceed 40,000 bopd.

Development Timeline

• 2007: Petrofac submitted the field development programme (FDP) for the West Don field.
• 2008: Development approval was granted by the UK Government’s Department for Business, Enterprise and Regulatory Reform (BERR), and refurbishment works on the Northern Producer were completed.
• 2009: Production commenced on April 28, with initial peak production rates of 25,000 bopd.
• 2010: Connection to the Thistle platform and the Brent oil export infrastructure was completed, and oil exports began through the Sullom Voe terminal.

Current Status

• The field is currently operated by EnQuest, following changes in ownership and operational responsibilities over the years.