The Oseberg oil and gas field is located in the northern part of the North Sea, offshore Norway. Operational since December 1988, it is the third biggest oil producer ever on the Norwegian Continental Shelf (NCS), behind the Statfjord and Ekofisk fields.
The Oseberg field was developed in multiple phases based on an original plan for development and operation (PDO) approved in 1984. Norwegian energy company Equinor operates the field with 49.3% interest, while the other partners are Petoro (33.6%), TotalEnergies EP Norge (14.7%), and ConocoPhillips Skandinavia (2.4%).
Although initially expected to produce about one billion barrels of oil over its lifetime, the offshore field had produced 2.9 billion barrels of oil by 2018. Oseberg is currently in the tail-end oil production phase, with the field’s overall oil production expected to reach 3.2 billion barrels.
The Oseberg licence partners submitted an amended PDO to the Norwegian authorities in November 2021 to shift production focus towards gas and reduce emissions through electrification of the field infrastructure.
Location and reservoir details
The Oseberg field is located at a water depth of 100m in blocks 30/6 and 30/9 of the Norwegian North Sea, approximately 130km north-west of Bergen, Norway.
The field contains oil and gas resources in the Oseberg, Tarbert, Etive, and Ness Middle Jurassic sandstone formations of the Brent Group. While Oseberg and Tarbert are the main reservoirs, additional production also comes from the Statfjord and Cook Formations through the satellite structures.
Oseberg field infrastructure
Located in the southern part of the Oseberg field, the Oseberg field centre consists of three bridge-linked platforms, namely Oseberg A, B and D.
Oseberg A is a concrete base platform housing process equipment and accommodation facility and Oseberg B is a drilling, production, and water injection facility, whereas Oseberg D is a steel platform equipped with gas processing and export equipment.
Oseberg C, which is also part of the Oseberg field centre, features an integrated production, drilling, and quarters facility (PDQ) mounted on a steel jacket. It is located 10km north of the Oseberg field centre.
Gas export from the Oseberg field centre commenced in October 2000. The Oseberg project also includes the development of Oseberg Delta, Oseberg Delta II, and Oseberg Vestflanken 2 fields to enhance production from the area.
Tiebacks to Oseberg field centre
The fields tied back to the Oseberg field centre include Oseberg South, Oseberg East, Oseberg Delta, Oseberg Delta 2, Oseberg Vestflanken (Oseberg West Flank), and Oseberg Vestflanken 2.
The Oseberg East and South fields were commissioned in 1999 and 2000 respectively, whereas the Oseberg Delta 2 field commenced production in February 2015.
The Oseberg Vestflanken 2 field development came on stream with an unmanned wellhead platform named Oseberg H in October 2018. Operated remotely from the Oseberg field centre, Oseberg H is the first unmanned platform on the NCS.
Oil and gas export from Oseberg field centre
The 115km-long and 28in-diameter Oseberg Transport System (OTS) pipeline exports crude oil from the Oseberg field to the Sture terminal located in the municipality of Øygarden in Vestland, near Bergen. Operated by Equinor Energy, the OTS pipeline has been operational since 1988.
The Oseberg field centre also receives oil from the Brage and Tune fields for transport via the OTS pipeline to the Sture terminal.
The 109km-long and 36in-diameter Oseberg Gas Transport (OGT) pipeline, operated by Norwegian state-owned gas transportation company Gassco, exports gas from the Oseberg field to the Heimdal Riser platform in the North Sea.
Furthermore, the Heimdal gas field is connected to Statpipe and Vesterled pipeline systems for export. The OGT pipeline has been operational since 2000.
Gas production potential of the Oseberg field
With 60% of the gas resources of the field still in the ground, the Oseberg field is considered to hold the third biggest remaining gas resources on the NCS, after the Troll and Snøhvit fields.
The field development partners are planning to transform Oseberg into a major gas producer on the NCS with a target of achieving more than 100 billion cubic metres (bcm) of gas output from the field by 2040.
They are also planning to reduce the carbon footprint of the field significantly by using electrically-powered gas compressors.
The total investment in the further development of the Oseberg field is estimated to be Nkr10bn ($1.11bn). The new gas compressors and electrical facilities at the field are expected to start operations in 2026.
Electrification of Oseberg field infrastructure
The Oseberg field electrification project will involve the installation of electrical equipment to receive power supply from the shore and power the new gas compressors at the field.
The Norwegian Ministry of Petroleum and Energy awarded a licence to Equinor to construct and operate electrical facilities at the Oseberg field centre and the Oseberg South platform in March 2021.
The project is expected to cut emissions from the Oseberg field centre and the Oseberg South platform by 50% by removing 320,000t of carbon dioxide (CO2) emissions from the field operations a year.
Aibel was awarded an engineering, procurement, construction and installation (EPCI) contract worth more than Nkr4bn ($441.7m) for the partial electrification of the Oseberg field centre and Oseberg South in November 2021. The company will also upgrade the gas processing capacity of the Oseberg field centre.
The contractual scope includes the fabrication of three modules weighing 3,400t in total for the Oseberg field centre and electrical installations for a new substation at Kollsnes, Norway.
The EPCI contract followed the completion of a front-end engineering design (FEED) study to maximise gas exports from the Oseberg field and identify a solution for the electrification of the gas compressors.
Heerema Marine Contractors received a contract worth approximately Nkr60m ($6.7m) to transport and install the three new electrical modules for the Oseberg project in November 2021. Heerema will use its semi-submersible crane vessel Sleipnir to transport the modules from Aibel’s yard in Haugesund and install the same at the Oseberg field centre in 2024.
French cable manufacturer Nexans will deliver subsea power cables for the project under a framework contract with Equinor. The first order under the contract requires the company to provide a 132km-long power cable, which will be installed using its new cable-laying vessel Nexans Aurora in 2023.
Skanska Norge, a project development and construction company based in Norway, was contracted to construct the substation, cable trenches and the landfall facility at Kollsnes.