Facilities of many different types, sizes and materials have been installed on the NCS over 50 years of Norwegian oil and gas production. They have all been constructed to handle demanding drilling, production and processing jobs – and to ensure these activities cause no harm to people, the environment and material assets.

Their designs result from an interaction between industry responses to technological challenges and government requirements for managing risk and shaping offshore workplaces.

The Brage field
Brage in the North Sea is one of many Norwegian fields developed with a platform supported on a steel jacket. Photo: Wintershall Dea

Jackets

The technology for offshore facilities resting on steel jackets was first developed in the Gulf of Mexico after 1945. Since water depths at the southern end of Norway’s North Sea sector were fairly similar, such structures were a natural choice there.

Oil and gas operations on the NCS were initially characterised by the award of production licences to large foreign companies and by drilling and service companies hailing largely from the USA. They already had long experience from American waters, and had developed technical standards and work operations for offshore operations. These were also applied to the NCS. But they had little to say about working conditions, for example.

With the passage of the Working Environment Act in 1977, the Norwegian government got to grips with such problems as noise, ergonomics and chemical exposure. That eventually had consequences for designing NCS facilities.

Rough Norway’s offshore industry was characterized for its first couple of decades by rough working conditions and much manual labour with heavy and dangerous equipment.

The American approach to personal safety was often to send people who made mistakes home on the first helicopter. That could also happen if they reported dangerous or unhealthy working conditions. The result was a relatively large number of injuries.

A widespread view within risk research at the time was that cutting the number of personal injuries would also reduce the risk of major accidents.

As the personal injuries declined, however, no corresponding decrease was observed in the number of incidents with a major accident potential.

The government and the scientists therefore had to accept that no necessary relationship existed between these two kinds of risk.

The concrete GBSs for Statfjord A and Brent B under construction in Jåttåvågen outside Stavanger in the 1970s. Photo: Aker/Norsk oljemuseum

Deeper

Several big discoveries were made during the 1970s in the northern North Sea, where water depths were greater than the roughly 70 metres found on Ekofisk. These included Statfjord and Troll, in 150 and 300 metres respectively.

Norway’s Condeep platform technology was a response to the challenges presented by depth and storage requirements.

The concrete GBSs supporting these structures offered particular benefits of robustness in relation to weather, waves and currents. Their drawback was high construction costs as well as the difficulty – in practice, virtual impossibility – of removing them after production ceased.

First

Statfjord A was among the first concrete giants approved for the NCS in 1976. After a series of modifications, the Norwegian Petroleum Directorate (NPD), which then embraced the PSA, found that the necessary safety standards were met. It came on stream in 1979. When operator Mobil submitted plans to build Statfjord B as a copy of the A structure, however, the NPD put its foot down and sent the company what has often been called “Norway’s most expensive letter”.

This required the living quarters to be placed on a separate structure. After many meetings and long discussions, however, Mobil won acceptance for a single platform with a longer topsides.

That made it possible to separate the accommodation from those areas where fires and explosions – and a consequent major accident – might occur.

This concept later formed the basis for the Statfjord C facility and the three Condeep platforms installed on the Gullfaks field. Adopting prudent solutions during planning was later extended to other types of risk. It became more usual, for example, to take account of employee experience when designing workplaces.

That improved the physical working environment and reduced the risk of personal injury. In turn, sickness absence declined and efficiency increased.

Installation work on Åsgard in the Norwegian Sea. Such subsea developments shot ahead in the 1990s. Photo: Equinor/Øyvind Hagen

Subsea

Technological advances led to a new shift from the 1980s, when big integrated concrete and steel facilities began to be replaced by subsea solutions tied back to existing installations.

As early as the initial phase of Norway’s oil history, small discoveries had been made which were not considered commercial on their own.

But it became clear in the 1980s that developing such marginal fields could be made profitable as well as acceptable in safety terms with the aid of seabed installations.

Specially built remotely operated vehicles (ROVs) capable of performing complex jobs on subsea Xmas trees and other equipment were also introduced at this time.

Ultimately, this made it possible under certain conditions for big fields – such as Ormen Lange in the Norwegian Sea – to produce entirely without surface installations.

Aasta Hansteen is one of the newest fields to come on stream off Norway. It has been developed with a Spar platform, seen here being transported from the yard in South Korea to Norway. Photo: Boskalis/Equinor

Biggest

A lot of facilities are still being constructed for the NCS. The world’s largest Spar platform was installed last year on Aasta Hansteen in the

Norwegian Sea, for example. Best described as resting on a big vertical steel cylinder, this installation is tailored for deep water and demanding offshore conditions.

At the same time, the Oseberg west flank 2 project marks a move in a different direction. This development includes a completely unmanned wellhead platform.

Remotely operated from the Oseberg field centre, the H facility will only have people on board for one or two annual maintenance visits. It thereby has no quarters, helideck or lifeboats – not even a toilet. Personnel will go on board from a vessel fitted with a walkway.