Elgin

Location and Geology

The Elgin-Franklin fields are located in the UK North Sea’s Central Graben, approximately 240 kilometers east of Aberdeen. The fields are situated at a water depth of about 93 meters. Elgin is spread across blocks 22/30b, 22/30c, and 29/5b, while Franklin is located within block 29/5b, approximately six kilometers south-east of Elgin.

Discovery and Development

• Elgin was discovered by Elf in 1991 with the well 22/30c-8.
• Franklin was discovered by Ultramar Corp. in 1986 with the well 29/5b-4 and was further appraised by wells 29/5b-6 and 29/5b-8.

Joint Development

The decision to develop Elgin and Franklin jointly was driven by economic benefits and the complementary nature of the fields. The Elgin field has a richer condensate-gas mix compared to Franklin, allowing for early sales of liquids and maintaining a gas plateau over a longer period. This joint development enabled the optimization of production, with preferential production from Elgin to maximize early liquids output and later compensating with gas production from Franklin.

Infrastructure and Platforms

• The development includes a large processing, utilities, and quarters (PUQ) platform located on Elgin, which is connected to a bridge-linked wellhead platform on Elgin and a wellhead platform on Franklin.
• The Elgin wellhead platform has a 1,743-ton topsides and a 2,715-ton, four-leg steel jacket with 12 platform slots.
• The Franklin platform has a 2,800-ton jacket supporting 2,093-ton topsides with nine platform slots.
• The PUQ platform is of a jack-up-style TPG 500 design, chosen for its ability to be built onshore as a complete unit, reducing offshore heavy lifts.

Production and Capacity

• Production began in 2001, with Elgin coming online in April and Franklin in October of the same year.
• The fields achieved peak production by March 2002, producing 140,000 barrels of condensate and 485 million cubic feet of gas per day.
• The PUQ platform has the capacity to process 525 million cubic feet of gas and 175,000 barrels of condensate per day.
• The development's value is derived two-thirds from condensate and one-third from gas, despite the main design constraints being related to gas production.

High-Pressure/High-Temperature (HP/HT) Challenges

• The Elgin-Franklin fields are the world’s largest HP/HT development, with initial pressures of approximately 1,100 bar and temperatures of 190°C.
• The HP/HT nature of the reservoir required early drilling of wells to avoid depletion issues and maintain well productivity. Most drilling had to be completed within 3-6 months after the start of production.

Investment and Costs

• The total investment in the Elgin-Franklin development was approximately £1.6 billion ($2.6 billion), with an overall budget for Elf-operated activities initially set at £1.85 billion ($2.96 billion) but ultimately completed for £1.7 billion ($2.72 billion).
• Significant preparatory research and development costs were incurred, with £21 million ($34 million) spent between 1993-96 to master the necessary technologies.

Production History and Incidents

• By 2012, the fields had exceeded initial production expectations, producing over 220,000 barrels of oil equivalent per day, which was approximately 7% of total UK production.
• In 2012, a significant gas leak occurred at the Elgin G4 well, leading to the evacuation of over 200 people and a temporary shutdown of production. Production was restarted in March 2013 after safety measures were implemented.

Life Extension and Future Plans

• Total and its partners have been considering a life extension for the Elgin-Franklin fields, which included facilities and integrity work to prolong production.
• By 2020, the fields had produced over one billion barrels of oil equivalent, exceeding initial estimates.
• Plans for drilling new infill wells and the West Franklin Phase II development were underway to restore and maintain production levels.

Export and Pipeline Infrastructure

• Hydrocarbons are exported via a new 24-inch diameter spur line, the Southern Spur, connected to the Forties System. Liquids from the nearby Shell-operated Shearwater platform are also transported through this spur line.
• The liquids export line and the SEAL line were laid and connected with spool pieces and subsea intervention valves. The modification of the Shell terminal at Bacton was part of the development.

Current Status and Ownership

• Total (now TotalEnergies) operates the Elgin-Franklin fields with a 46.17% stake. Other partners include Chrysaor (now part of Harbour Energy), Eni, ExxonMobil, Ithaca, One Dyas, Premier Oil, and Summit.

The Elgin-Franklin project is a complex and significant development in the North Sea, marked by its HP/HT challenges, innovative infrastructure, and ongoing efforts to extend its productive life.