Tyrihans

Location and Geology

• The Tyrihans oil and gas field is located in the Norwegian Sea, specifically in the Halten Bank area, approximately 25-35 kilometers southeast of the Åsgard field and 35 kilometers southeast of the Kristin field.
• The field is situated in water depths of about 270-285 meters.

Discovery and History

• The Tyrihans field was discovered in 1983, with the discovery well drilled by the Dyvi Delta rig. However, commercial production was only feasible after the development of nearby fields like Åsgard and Kristin in the late 1990s and early 2000s.
• An appraisal well drilled in 2002 increased the reserves estimate by 25%, making the field more commercially viable.

Reservoirs and Production

• The Tyrihans field consists of two main structures: Tyrihans South and Tyrihans North.
  • Tyrihans South is an oil field with a condensate-rich gas cap.
  • Tyrihans North is a gas and condensate field with a thin underlying oil zone.
• The main reservoirs are in the Middle Jurassic Garn Formation, at a depth of approximately 3,500 meters. Additional oil production comes from the Middle Jurassic Ile Formation.

Development and Infrastructure

• The field was developed with a total of 12 wells, including nine production wells, two gas injection wells, and one seawater injection well. Some of these wells are multilateral and utilize smart well technology.
• The wells are connected to five subsea templates, which are tied back to the Kristin platform. Gas for injection and gas lift is supplied from the Åsgard B platform.
• The wellstream is transported to the Kristin platform through a 43 km, 16-18 inch diameter multi-phase pipeline. Gas is exported via the Åsgard Transport System (ÅTS) to the Kårstø terminal, while oil and condensate are transported to the Åsgard C storage ship for export by shuttle tankers.

Production and Recovery Strategy

• Production at the Tyrihans field started in July 2009 and is expected to continue until around 2029.
• The initial recovery strategy involved pressure support through water and gas injection. Currently, the main strategy is pressure depletion and gas cap expansion.
• Plateau production rates are approximately 55,000 barrels of oil per day and 13 million cubic meters of gas per day (459 million cubic feet per day).

Recent Developments

• In 2021, Equinor and its partners made a new oil and gas discovery at the Tyrihans North field, which is expected to extend the life of the producing fields. This discovery holds between 19 million and 26 million barrels of oil equivalent (boe) of recoverable resources.

Operators and Partners

• The operator of the Tyrihans field is Equinor (previously Statoil). Partners include Total, Exxon, and Eni.

Contracts and Contractors

• Key contractors involved in the development include Stolt Offshore (now Acergy) for pipeline installation, FMC Technologies for subsea equipment, and Butting of Germany for steel pipe delivery. Ramboell Denmark conducted the engineering for the pipelines.

Technological Innovations

• The Tyrihans project has incorporated several advanced technologies, including multilateral wells, downhole integrated fiber-optic systems, remote operation of subsea wells, subsea injection of raw seawater, and direct electrical heating of the production pipeline. Smart completions and real-time monitoring systems are also used to optimize production.