Oseberg

Location and Discovery

The Oseberg field is located in the northern part of the North Sea, within the Norwegian continental shelf, specifically in blocks 30/6 and 30/9. The field was discovered in 1979 by Norsk Hydro AS.

Development and Production

• The plan for development and operation (PDO) was approved in 1984, and production started in December 1988 from the Oseberg Field Centre, which initially consisted of Platforms A and B.
• The field has been developed in multiple phases:
  • Oseberg A and B: These are the original platforms, with Oseberg A being a concrete platform with process equipment and living quarters, and Oseberg B a steel jacket platform with drilling, production, and injection equipment.
  • Oseberg C: This platform, located 14 km north of the field center, is an integrated production, drilling, and quarters facility (PDQ) that started production in December 1991. It has a productive capacity of 110,000 barrels per day (b/d) and was part of a $1.5 billion project that included the North Gamma development.
  • Oseberg D: Approved in 1996, this platform is dedicated to gas processing and export and was connected to the field center with a bridge in 1999.
  • Oseberg South: This platform, located 13 km south of the Oseberg Field Centre, started production in February 2000 and includes several subsea installations.
  • Oseberg East: The smallest platform, located 25 km northeast of the Oseberg Field Centre, started production in May 1999 and is equipped for first-stage processing.
  • Oseberg H: An unmanned wellhead platform (UWP) located 8 km northwest of the field center, part of the Oseberg Vestflanken II development approved in 2016.

Reservoir and Geology

• The Oseberg field produces oil and gas from sandstone of Middle Jurassic age in the Brent Group, primarily from the Oseberg and Tarbert Formations, but also from the Etive and Ness Formations. The reservoirs are at depths of 2300-2700 meters and have generally good quality.

Recovery Strategy

• The field is produced using pressure depletion as well as pressure maintenance through gas and water injection. Massive upflank gas injection has provided excellent oil displacement, and a large gas cap has developed. Gas injection was previously imported from Troll Øst.

Transport and Infrastructure

• Oil is transported through the Oseberg Transport System (OTS) to the Sture terminal on Norway's west coast. Gas is transported via the Oseberg Gas Transport (OGT) pipeline and the new Heimdal bypass to the Statpipe system and further to continental Europe and the UK via the Vesterled pipeline.

Current Status and Future Plans

• As of 2021, Equinor (formerly Statoil) has planned a significant overhaul of the Oseberg field, converting it from primarily an oil production complex to a gas producer. This involves adding two new compressors, partially electrifying the field center and Oseberg South platform to reduce emissions, and installing new modules. The project aims to reduce annual emissions by 320,000 metric tons and is expected to be completed by 2026.
• The field is expected to produce more than 100 billion cubic meters (bcm) of gas towards 2040. Despite oil production being in its tail-end phase, 60% of the gas is yet to be recovered.

Partners and Operators

• The Oseberg field is operated by Equinor, with a significant interest held by the state-owned Den norske stats oljeselskap AS (now Equinor). Other partners include Petoro, TotalEnergies EP Norge, and ConocoPhillips Skandinavia.

Investments and Economic Impact

• The development of the Oseberg field has involved substantial investments, with the initial development costing around $5.5 billion. The Platform C project, including North Gamma development, added another $1.5 billion. Recent electrification and upgrade projects are valued at over NOK 4 billion ($443 million).

Environmental Considerations

• Equinor has introduced measures to reduce emissions from the field, aiming for a 50-70% reduction by 2030. The partial electrification of the field center and Oseberg South platform is a key part of this strategy.

Production Capacity and Reserves

• The Oseberg field has reserves of about 1.5 billion barrels of oil and 92 billion cubic meters of gas, making it one of the largest fields in the North Sea. The field's production capacity was significantly boosted with the addition of Platform C, reaching a total capacity of about 450,000 b/d.

In summary, the Oseberg oil and gas project is a complex and multi-phase development that has been a cornerstone of Norway's offshore petroleum industry, with ongoing efforts to optimize production, reduce emissions, and transition towards increased gas production.