Ormen Lange gas field located in the Norwegian Sea is one of the biggest gas fields in Norway. The giant offshore gas field is operated by Norske Shell, a subsidiary of Royal Dutch Shell, which holds a 17.81% participating interest.
The other development partners of the Ormen Lange gas project are Petoro (36.48%), Equinor (25.34%), INEOS E&P Norge (14.02%), and Var Energi (6.33%).
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Vår Energi, a joint venture of Eni (69.6%) and HitecVision (30.4%), acquired ExxonMobil’s 6.33% stake in the Ormen Lange field in 2019.
The Ormen Lange field was brought on stream in 2007. The annual gas output of the field dropped from 22.2 billion cubic metres (bcm) in 2012 to 12.6bcm in 2019.
The field developers are implementing innovative measures including the installation of a subsea gas compression system to improve gas recovery at the field.
Location and reservoir
The Ormen Lange gas field is located in the southern part of the Norwegian continental shelf approximately 120km north-west of the Nyhamna gas processing plant in Gossa Island, Norway. The water depth in the field area ranges from 800m to 1,100m.
The field’s reservoir comprises the Egga sandstone formation and is spread over an area of approximately 350km2 with the depth extending up to 2,900m below sea-level.
Ormen Lange gas field development
The Ormen Lange gas field was discovered in 1997. The field development and operation plan was approved in 2004, while the first gas was produced in 2007.
Currently, the field consists of four eight-slot subsea templates, out of which two templates were installed in the central part of the field as part of the initial development that commenced operations in 2007. The third template was installed in the southern part of the field in 2009, while the fourth template was installed in the northern part of the field in 2011.
The field currently produces from a total of 24 wells. The gas is transported through two 30in-diameter and 120km-long subsea pipelines to the Nyhamna gas processing plant.
The 1,166km Langeled pipeline, one of the longest subsea pipelines in the world, exports the processed gas from Nyhamna to the Easington gas terminal in the United Kingdom. The condensate is stored in underground caverns and offloaded to oil vessels.
Nyhamna gas processing plant
The gas processing plant located at Nyhamna in Gossa Island, Norway has been operational since 2007. It was expanded to increase its daily processing capacity from 70 million cubic metres (mcm) to 84mcm in 2017.
The plant’s capacity was increased to process gas from the Equinor-operated Aastha Hansteen offshore field. It receives gas supply from the Aastha Hansteen field through a Gassco-operated 482km-long Polarled subsea pipeline.
Enhanced recovery methods at Ormen Lange
As part of the Nyhamna processing plant expansion project, two onshore compressors were installed in 2017 to improve gas recovery from the Ormen Lange field.
After conducting a pilot project for testing subsea gas compression systems, Norsk Shell is planning to install a subsea multiphase compression system for the Ormen Lange field.
The compression system will comprise two 16-MW subsea compression stations to be installed at a water depth of 850m. The existing manifolds and pipelines will be tied into compressor stations, while the Nyhamna processing plant will supply power to compressor stations through subsea umbilicals.
Contracts awarded
OneSubsea, a subsidiary of Schlumberger, entered into a frame agreement with Norske Shell for an engineering, procurement, construction and installation (EPCI) contract to supply a subsea multiphase compression system for the Ormen Lange field in October 2019.
Subsea 7 received a sub-contract from OneSubsea for a front-end engineering design (FEED) study for the subsea umbilicals and flowlines system for the subsea compressor project at the Ormen Lange field in the same month.
Nexans was sub-contracted by OneSubsea for the design, manufacturing, and supply of two 120-km long power umbilicals for the subsea compression system. The power umbilicals will comprise a 52kV electric cable, a hydraulic cable, and a fibre optic cable. The umbilicals will be installed in 2023 with the use of Nexan’s cable-laying vessel Aurora.
Kongsberg Digital received a contract worth £8.9m ($11m) for a real-time dynamic visual representation of the Nyhamna gas processing plant in October 2019.
Kvaerner provided the engineering, procurement, construction, and management (EPCM) services for the Nyhamna gas processing plant expansion project.
Seismic survey and seafloor monitoring
Shearwater GeoServices was contracted to conduct a 4D marine seismic survey on the Ormen Lange field in April 2019. The survey was conducted over a large area of 1000km2 by Shearwater’s survey vessel Polar Empress.
Sonardyne received a 10-year contract from Norsk Shell to monitor seafloor movement at the Ormen Lange field in September 2019. Fetch pressure monitoring transponders (PMTs) were deployed in the field, as part of the contract.
Fetch PMTs collect and store data on pressure, temperature, and inclination at the seafloor, and the PMTs are fitted with an acoustic modem to transmit this data through the water. XOCEAN’s unmanned surface vessel XO-450 was used in a data-gathering mission in April 2020. The data gathered during the on-going survey are intended to be used for better reservoir management of the Ormen Lange gas field.
