Oseberg Sør

Field Overview

Location and Discovery: The Oseberg Sør field is situated in the northern part of the North Sea, approximately 115 km from the shore and 13 km south of the main Oseberg field. It was discovered in 1984 by Norsk Hydro through the drilling of well 30/9-3.

Water Depth and Geology: The field is located in a water depth of about 100-101 meters. The reservoirs are primarily in sandstone formations of Jurassic age, specifically the Tarbert and Heather Formations, which are part of the Brent Group and Upper Jurassic sections.

Development and Operation

Plan for Development and Operation (PDO): The PDO for Oseberg Sør was approved in 1997. The field has been developed with an integrated steel facility that includes living quarters, a drilling module, and first-stage oil and gas separation. Additional developments include subsea templates tied back to the Oseberg Sør facility, such as the PDO for Oseberg Sør J approved in 2003, a PDO exemption for the G-Central structure granted in 2008, and the PDO for the Stjerne deposit approved in 2011.

Production Start and Facilities: Production at Oseberg Sør began in 2000. The field is supported by a lattice steel-jacket substructure with a platform deck built as an integrated structure. The facility has design production capacities of 4,900 m³ per day of oil, 13,000 m³ per day of water, and 3.8 million cubic meters per day of gas. It also accommodates water injection at 41,500 m³ per day and gas injection at 38 million cubic meters per day.

Reservoir and Recovery Strategy: The reservoirs are at depths of 2200-2800 meters and have moderate quality. The field is mainly produced using water and gas injection, with water alternating gas (WAG) injection in some parts. Water for injection is produced from the Utsira Formation. Some structures are produced by pressure depletion.

Transport and Processing

Oil and Gas Transport: The oil is transported from the Oseberg Sør facility by pipeline to the Oseberg Field Centre for further processing. It is then transported through the Oseberg Transport System (OTS) to the Sture terminal. The gas is transported via the Omega Nord deposit to the Oseberg Field Centre for processing and then to the market through the Oseberg Gas Transport (OGT) system, either to Statpipe or Vesterled.

Current Status and Future Plans

Maturation and Challenges: Further maturation of drilling targets is a focus area, but the lack of available well slots is a challenge. Several projects are under evaluation to increase recovery from Oseberg Sør.

Electrification and Emissions Reduction: As part of a broader strategy to reduce emissions, the Oseberg field, including Oseberg Sør, is undergoing partial electrification. This involves converting the field from primarily an oil production complex to a gas producer, with the addition of two new compressors and the electrification of the field center and the Oseberg South platform. This project aims to cut annual emissions by 320,000 metric tons and is expected to be completed by 2026.

Operators and Partners

Original Operators: The field was originally operated by Norsk Hydro, with a 32.02% interest, on behalf of Statoil, Conoco, and Mobil. Following the merger between Norsk Hydro and Statoil in 2006, the operations are now managed by Equinor (formerly Statoil).

Current Partners: Other partners in the license include Petoro, TotalEnergies EP Norge, and ConocoPhillips Skandinavia.

Production and Reserves

Production Capacities: The Oseberg Sør facility has significant production capacities, including oil, water, and gas. The field's production has been enhanced through various projects, including the installation of new separators and the upgrade of gas compressors.

Reserves and Recovery: The field's estimated resources have increased over time, with a notable increase of almost 50 million barrels of oil in place, including 15 million barrels of recoverable oil. The field is expected to produce more than 100 billion cubic meters of gas towards 2040, with 60% of the gas yet to be recovered.

In summary, the Oseberg Sør field is a significant oil and gas project in the North Sea, characterized by its integrated development, advanced recovery strategies, and ongoing efforts to reduce emissions and increase efficiency.