Dvalin

Location and Geology

The Dvalin gas field is situated in the central part of the Norwegian Sea, specifically within blocks 6507/7/9 and 6507/8 of production licence 435, in the Haltenbanken area. It is located approximately 15 kilometres northwest of the Heidrun field and 35 kilometres south of the Skarv fields. The water depth in this area ranges between 340 and 400 metres.

Reservoir Details

The gas reservoirs at Dvalin are found in the Middle Jurassic sandstone of the Ile and Garn Formations, approximately 4,500 metres underneath the seabed.

Field Structure

The Dvalin field consists of three separate structures:

• Dvalin East: Discovered in 2010.
• Dvalin West: Discovered in 2012.
• Dvalin North: Discovered in 2021 and is the largest discovery on the Norwegian shelf that year.

Development and Production Plan

Dvalin East and West

• The development plan for Dvalin East and West was approved in March 2017.
• The field is developed as a subsea tieback to the Equinor-operated Heidrun platform.
• The development includes a subsea template with four high-pressure, high-temperature (HPHT) production wells connected to the Heidrun platform via flowlines and umbilicals.
• A new gas processing and compression module, weighing approximately 3,500 tonnes, was installed on the Heidrun platform to handle the well stream from Dvalin.
• Production started in the fourth quarter of 2020 but was temporarily halted in January 2021 due to high levels of mercury in the gas flow. Mitigation measures are underway, and production is expected to resume.

Dvalin North

• The plan for development and production (PDO) for Dvalin North was approved in June 2023.
• Dvalin North will also be developed as a subsea field tied back to the Heidrun platform via the Dvalin field.
• A subsea template with three gas production wells and one spare slot for future development has been installed. This template was installed six months ahead of schedule in the first half of 2024.

Production and Export

• The processed gas from Dvalin is transported to the Heidrun platform via a 14.9 km pipeline.
• From the Heidrun platform, the gas is further transported through a 7.5 km pipeline to the Polarled trunk line, and then to the Nyhamna onshore gas terminal for final processing.
• The gas is eventually shipped to the European market via the Gassled system.

Reserves and Production Volume

• The Dvalin field (East and West) is estimated to hold approximately 113 million barrels of oil equivalent (boe).
• Dvalin North is estimated to hold around 84 million barrels of oil equivalent.
• The total expected production volume from the Dvalin field is about 18.2 billion cubic metres (bcm) of natural gas.

Operators and Partners

• Wintershall Dea operates the field with a 55% working interest.
• Petoro holds a 20% interest in Dvalin East and West, and 35% in Dvalin North.
• Sval Energi holds a 10% interest in Dvalin East and West, and 10% in Dvalin North.

Contractors and Suppliers

• Aibel provided engineering, procurement, construction, and installation (EPCI) services for the modules on the Heidrun platform.
• Aker Solutions supplied the subsea production system and provided maintenance services.
• Transocean Norway Operations drilled the production wells using the Transocean Arctic drilling rig.
• TechnipFMC's heavy subsea construction vessel North Sea Atlantic was involved in the installation of the subsea template for Dvalin North.
• OneSubsea and its partner Aker Solutions supplied the subsea production system for Dvalin North.

Challenges

• The field faced a significant challenge due to the detection of high levels of mercury in the gas flow in January 2021, which led to the temporary halt of commercial production. Mitigation measures for mercury removal are ongoing.

Future Outlook

• Production from Dvalin East and West is expected to resume once the mercury mitigation measures are completed.
• Dvalin North is expected to come on stream in late 2026.