Troll

Location and Geology

The Troll oil and gas field is situated in the northern part of the North Sea, approximately 65 kilometers west of Kollsnes, near Bergen, Norway. The field spans across blocks 31/2, 31/3, 31/5, and 31/6, in water depths of 315-345 meters.

Discovery and Development

• The Troll field was discovered in 1979 by the well 31/2-1, which encountered significant quantities of oil and gas. Following this, 20 appraisal wells were drilled between 1980 and 1993 to further assess the reserves.
• The field was declared commercial in 1983, and the licences were unitised in 1985 to allow for the development of the field as a single unit.

Reserves and Production

• The Troll field is one of the largest gas fields in the North Sea, holding approximately 40% of Norway's total gas reserves and about 60% of Norway’s gas reserves. It also contains significant oil reserves, with an estimated 1.8 trillion cubic meters of natural gas and two billion barrels of oil.
• The field is divided into three main areas: Troll East, which contains two-thirds of the gas reserves; the Troll Oil Gas Province, which has one-third of the gas reserves and a thin oil layer; and the Troll Oil Province, which is primarily oil-bearing.

Platforms and Infrastructure

• Troll A Platform: This is the tallest structure ever moved by mankind, standing at 472 meters tall. It is a concrete deepwater structure (Condeep) and is the first platform on the Norwegian Continental Shelf (NCS) to receive power from shore. Troll A is primarily focused on gas production from Troll East.
• Troll B Platform: A floating processing and accommodation platform with a concrete hull, located east of the oil province. It began production in September 1995 and has produced over one billion barrels of oil. Troll B is connected to the Mongstad oil terminal via the 86 km long Troll Oil Pipeline.
• Troll C Platform: A floating processing and accommodation platform with a steel jacket, which started production in late 1999. It produces from the thin oil-bearing layers in the Troll West reservoir and is connected to the Mongstad terminal via the Troll Pipeline II.

Production History and Volumes

• Oil Production: Regular oil production from the Troll West oil province began in late 1995. By 2002, the field was producing over 400,000 barrels per day (bpd). As of 2016, Troll B had produced one billion barrels of oil, with an average daily production of 20,600 cubic meters during its operational life.
• Gas Production: Gas production from Troll East started in June 1996. The field produces roughly 120 million metric standard cubic meters per day (Mmscm/d) of gas. The gas is processed at the Kollsnes Gas Processing Plant and delivered to continental Europe via the Zeepipe Gas Pipeline.

Operators and Partners

• The field is operated by Equinor (formerly StatoilHydro), which holds a 30.58% interest. Other partners include Petoro (56%), Norske Shell (8.1%), Total (3.69%), and ConocoPhillips (1.62%).

Technological Innovations

• The recovery of oil from the thin oil layers in the Troll field has required advanced drilling and production technologies. The field features extensive use of subsea wells, with Troll B having 24 subsea satellite oil producers tied back to it. In 2015, a record was set with 145,000 meters drilled in the reservoir.
• The Troll A platform is notable for being the first on the NCS to receive power from shore, and it is designed for a producing life of 70 years.

Economic Impact

• The production from Troll B has generated significant revenue, with one billion barrels of oil producing NOK 268 billion, of which around NOK 200 billion has been channelled back to the Norwegian state through direct ownership and taxes.
• The combined oil and gas production from the Troll field has represented values worth NOK 1300 billion as of 2016.

Future Prospects

• The field is expected to continue producing gas until around 2060, with oil production forecasted to continue for another 8-10 years from the platforms. In 2021, the Troll West gas cap was put on stream through eight subsea wells, increasing the Troll gas production significantly.

The Troll oil and gas field is a cornerstone of Norwegian energy production, showcasing advanced technological solutions and significant economic contributions to the country.