The mighty Johan Sverdrup

A new and exciting chapter has opened in the history of the Norwegian Continental Shelf. Meg Chesshyre reports.

Fig. 1: Johan Sverdrup phase 1, comprised of four bridge-linked platforms. Image from Statoil.

Statoil has a tight development program for Johan Sverdrup, targeting first production from the giant oilfield by the end of 2019, with a pre-drilling phase starting in 2018.

The field, sitting on the Utsira High in a mature part of the Norwegian North Sea, is the largest offshore oil find in Norway for 30 years. With estimated reserves of 1.8-2.9 billion boe, it has a production horizon beyond 2050. It is expected to produce 550,000 - 650,000 boe/d when fully developed,

The impact of this massive project on Norwegian industry and society “cannot be exaggerated,” says Statoil’s senior vice president for the Sverdrup development Oivind Reinertsen. “It represents a new and exciting chapter in the history of the NCS.” Total investment will range between NOK100 billion and NOK200 billion, and operational costs for phase 1 will be from NOK3 to NOK5 billion per year. The investment in phase one is put at NOK100 – 120 billion alone.

The Johan Sverdrup field extends over about 200sq km, an area about half the size of Greater Oslo. “We have an ambition for this field to produce up to 70% of the oil in place,” says Reinertsen.

The Johan Sverdrup discovery was made in 2010, (originally named Avaldsnes) and 2011, (Aldous Major) by Lundin and Statoil, respectively, in an area where oil activities on the Norwegian Continental Shelf started. The fields are situated in the two old production licenses 1 and 7, first awarded in 1966 and 1972. The first exploration well drilled on it back in 1967 was the second exploration well ever drilled on the NCS.

The water depth, at only 120m, means that the field can be developed using cost-efficient jacket solutions. Water injection will be the primary drive mechanism, with gas lift as artificial lift.

Fig. 2: Core sample at Johan Sverdrup.  Photos from Annette Westgard, Statoil.

Aker Solutions received a framework contract from Statoil in December 2013, to provide engineering services, procurement and management assistance (EPMa) for as many as 10 years at Johan Sverdrup. The contract includes front end engineering and design (FEED) work building on concept studies Aker Solutions carried out last year. Aker Solutions has assembled one of its biggest engineering teams ever, involving 400 employees in Oslo and London, to deliver the initial plans for the engineering and design phase.

The final FEED report is slated for delivery before the end of the year [2014] and will be used by the field partners to make a final investment decision for the first phase development. A plan for development is then expected to be submitted in February 2015 to Norwegian authorities for approval. The next stage, after approval, will be detailed design and procurement services. Aker Solutions’ contract with Statoil has an EPma option for the development’s first phase and additional options for work in later phases.

Multiple phase development

Johan Sverdrup will be developed in multiple phases. This first will consist of a field center with four bridge-linked processing, drilling, riser and accommodation platforms (Figure 1). These will be designed to allow for future expansion. The reservoir is at a depth of 1800-1900m.

Fig. 3: Core samples at Johan Sverdrup.

The oil handling design capacity of the process platform will be 315,000 boe/d divided into two trains and gas capacity 6Mcu m/d. The processing system includes three stage separators, gas dehydration and gas recompression equipment, gas export compressor, gas-fired heaters, produced water processing equipment etc. The topsides will measure 100m x 25m and will have a dry weight of 23,000 tonnes.

• The riser platform will be a combined riser/utility platform, providing water and chemical injection, oil and gas export, and field power, which can be used for future tie-ins. The platform will be designed for a total of 45 risers and J-tubes as well as 10 caissons. The topsides will be supported on an eight-legged jacket structure. The topsides will be 125m x 30m, and the dry weight will be 19,000 tonnes.
• The drilling platform will also provide well bay, production and injection manifolding functionality. The topside will include a module support frame, drilling support module and drilling equipment set. Ancillary equipment includes two platform cranes and supports for bridges to the riser and process platforms. The platform is based on a 4 x 12 well slot configuration, giving 48 well slots in total. The topside dimensions will be 40m x 83m with a dry weight of 15,000 tonnes.
• The living quarters platform (LQ) will provide 450 cabins and serve as the field center (control room) for operations and telecommunications. It will contain workshops/stores and provide emergency power and other utilities for the field. The main mustering stations, equipped with nine lifeboats, will be located on the LQ. A permanently stationed search and rescue helicopter will be based here. The topside dimensions will be 85m x 28m and the dry weight 16,500 tonnes. There will be three trussed-structure bridges of various lengths (80-120m).

Fig 4. Core sample at Johan Sverdrup.

In June this year, under a newly-signed five-year agreement, Kvaerner was given a letter of intent to engineer and build the jackets and piles for the riser and drilling platforms, with delivery in summer 2017 and spring 2018, respectively. The engineering is being performed at Statoil’s offices in Oslo and the structures will be built at Kvaerner’s Verdal yard. The field will be operated by electrical power generated onshore. ABB has the FEED study for the power plant and National Oilwell Varco for the drilling equipment. Kongsberg is performing FEED for safety and automation systems and IKM Ocean Design for the infield pipelines.

Oil will be exported to the Mongstad terminal by a 275km, 36in pipeline and gas to Kårstø via a 165km pipeline which will tie into Statpipe. Pipelay is scheduled for 2018.

Johan Sverdrup is in blocks 16/2, 16/3 (PL501, PL 265) and 16/5 (PL 502). The partners in three production licenses are: Statoil, Lundin Norway, Petoro, Maersk Oil and Det norske oljeselskap. It is the result of discoveries by Lundin on the Avaldnes prospect and Statoil on Aldous Major in 2010 and 2011.