Ormen Lange

Location and Geology

• The Ormen Lange gas field is situated approximately 120-140 kilometers northwest of Kristiansund, Norway, in the Norwegian Sea.
• The field lies in water depths ranging from 800 to 1,100 meters, making it one of the first deepwater projects on the Norwegian continental shelf.

History and Discovery

• The discovery well 6305/5-1 was drilled in 1997 by Norsk Hydro (now part of Equinor).
• Gas production from the field began in September 2007, with the official opening ceremony attended by the King and Queen of Norway on October 6, 2007.

Reserves and Production

• Ormen Lange is the second- or third-largest gas discovery on the Norwegian shelf, depending on the source, with estimated recoverable gas reserves of around 300-375 billion cubic meters.
• The field produces approximately 70 million cubic meters of natural gas per day and is expected to continue production for up to 40 years.

Field Development

• The field development involves subsea production facilities tied back directly to an onshore gas processing plant at Nyhamna, rather than using conventional offshore platforms. This includes 24 subsea wellheads in four seabed templates connected by two 30-inch pipelines to the onshore terminal.
• The development plan was submitted to Norwegian authorities in December 2003 and approved in April 2004. The initial phase included the installation of two subsea templates, with additional templates planned as needed.

Infrastructure and Technology

• Gas from the field is processed at the Nyhamna terminal and then exported via the Langeled pipeline, which is the world's second-longest subsea gas pipeline, stretching approximately 1,200 kilometers to the Easington Gas Terminal near the Humber estuary in the UK. The pipeline has varying diameters, with the northern section being 42 inches and the section from Sleipner to Easington being 44 inches.
• The project required innovative solutions due to extreme natural conditions, including subzero temperatures, stormy seas, strong underwater currents, and uneven seabed. The area is also near the Storegga slide, a significant submarine landslide that occurred around 8,000 years ago, but the risk of recurrence is considered negligible.

Ownership and Operators

• The ownership of Ormen Lange is shared among several companies:
  • Petoro AS: 36.4850%
  • Statoil (now Equinor): 25.3452%
  • Norske Shell: 17.8134%
  • DONG Energy: 14.0208%
  • ExxonMobil: 6.3356%.
• During the development phase, the project was operated by StatoilHydro (now Equinor). Norske Shell took over as the operator in the operating phase starting November 2007.

Technical Challenges and Innovations

• The project faced significant technical challenges, including the need for rock supports to stabilize the pipelines due to the uneven and steep seabed conditions. A detailed procedure was developed to assess the immediate settlements of these rock supports.
• The development of Ormen Lange has been a showcase for technological advancements in subsea production systems. It includes the evaluation of subsea gas compression systems, which would be a major technological step forward if implemented.

Economic and Environmental Considerations

• The total cost of the project is estimated to be around 66 billion Norwegian kroner (approximately US$12 billion).
• The project's economic viability is influenced by factors such as capital expenditures, operating expenditures, production rates, and component failure rates. Efficient production and minimal downtime are crucial for the field's economic performance.

Environmental and Safety Aspects

• The project had to address the risks associated with the Storegga slide and ensure that the pipelines and other infrastructure were designed to withstand the extreme natural conditions of the area.
• High-resolution seismic surveys, seabed mapping, shallow coring, and deep geotechnical drilling were conducted to understand and mitigate these risks.

In summary, the Ormen Lange gas field is a significant and technologically challenging project that has pushed the boundaries of subsea gas production and transportation, providing a substantial portion of the UK's natural gas needs.