Women on Ekofisk

person By Ragna Ervik
Does female identity fit with a male-dominated culture? This question has been explored by Ragne Ervik for a master’s thesis in social anthropology which focused on women working on Ekofisk.
— Process engineer Liv Åshild L. Ervik photographed at the Ekofisk Center. Photo: Unknown/Norwegian Petroleum Museum
© Norsk Oljemuseum

Ekofisk was the first commercial petroleum discovery on the Norwegian continental shelf (NCS). Found in 1969, it came on stream as early as 1971.

This area lies at the southern end of Norway’s North Sea sector, about 280 kilometres south-west of Stavanger, and has been developed with a central complex and several satellite fields.

arbeidsliv, kulturmøter, sikkerhetskultur
Sunset at Ekofisk. Photo: Husmo Foto/Norwegian Petroleum Museum

Working on Ekofisk has always been and remains very unlike a job on land. The most eye-catching difference is the need to fly. A helicopter flight takes 90-120 minutes, depending on weather.

While at work, personnel are completely divorced from life on land and experience a total physical separation from “normal” society.

People on Ekofisk are part of a small but complex community where platform operation is the common denominator. Most workers do fixed tours of duty – usually two weeks on and three-four off.

Offshore jobs were originally held exclusively by men. The first women only arrived in 1978, either as nurses or as catering personnel.

But Ekofisk remains a male-dominated arena, where women are in a clear minority at less than 10 per cent of the workforce. Catering has the largest proportion of females – just under 50 per cent. The share is significantly below 10 per cent in production and operation.

Male and female jobs

Although the bulk of the women now on Ekofisk still have jobs in the service sector, they are represented across all occupational sectors – platform management, drilling, production and operation.

The various types of work differ in their standing and prestige among those employed on the field and in the rest of society.

Social anthropologist Jorun Solheim believes that every kind of work has a gender dimension.[REMOVE]Fotnote: Solheim, Jorun and Ellingsæter, Anne Lise, Den usynlige hånd. Kjønnsmakt og moderne arbeidsliv, 2003, Oslo. By this, she means that society has generalised perceptions of “male” and “female” jobs.

A male job often relates to base or core functions in a workplace, with direct participation in what is being produced, while female work is defined as social and hygienic.

This means that a woman working in base functions on a platform, such as production, holds a “male” position and is perceived in terms of her job rather than her gender.

She is therefore judged differently from women engaged in more typically female work. So women in “male” jobs acquire a different standing both among her colleagues and in society at large from female workers in service trades. A women employed in the core area of a company works alongside men and is accepted by them. Solheim puts it this way:

The central issue is how the work itself is ‘genderised’. Particular work assignments and areas of expertise will be viewed as male or female respectively.[REMOVE]Fotnote: Solheim, Jorun and Ellingsæter, Anne Lise, Den usynlige hånd. Kjønnsmakt og moderne arbeidsliv, Oslo, 2003.

In other words, the job has a gender dimension. The individual worker is defined by the work he or she does – by whether it has a male or female character – and not by their actual gender. A man’s job has more standing and prestige than a woman’s.

So the question is whether the job done by a woman on Ekofisk determines how she is assessed, or whether gender in itself is decisive for how she is regarded and her place in the hierarchy. How are these women viewed by their female and male colleagues?

Job standing and perception of women

Process engineer Liv Åshild L. Ervik. Photo: Unknown/Norwegian Petroleum Museum

As mentioned above, most people on Ekofisk work defined tours – two weeks offshore and three-four weeks at home. But differences exist. Working conditions and tour arrangements vary between operator employees and contractor/service company personnel.

Those employed by the operator – in this case ConocoPhillips, formerly Phillips Petroleum Company – have the most stable jobs. Their tours are fixed and they travel offshore with the same people every time.

Service company employees, on the other hand, will complete an assignment on one platform and then move to a different facility. So they will not be on the same installation for a long period.

Their position is also to some extent unstable. The duration of their work depends on a specific contract between operator and contractor. This may run over several years and can either be extended on expiry or transferred to another contractor with new personnel and rules.

Whether they are operator or contractor personnel can influence people’s view of the work and not least the employee’s own perception of their job and the associated social life. The point here is that operator employees are considered to have the most important jobs offshore and can thereby feel themselves to be superior to others.

kvinnene på ekofisk,
Prosessingeniør Liv Åshild Ervik på kontoret. Foto: Ukjent/Norsk Oljemuseum

Education represents another important factor in the way a worker is regarded. Those with the highest qualifications often have the same educational attainment as their own managers, and thereby hold a kind of intermediate position between colleagues offshore and the land organisation.

Women in jobs which call for a high level of education avoid having to “compete” with the men in an arena where females have traditionally done less well because they lack male strength.

People with higher education and offshore experience are also qualified for a range of positions in the company, from production engineer to the partner relations department, for example. In other words, advanced technical qualifications, work in the core areas and permanent employment with the operator confer more standing than an unskilled temporary position or a job with a contractor/service company.

A skilled female technician employed by the operator has a position which awards prestige. She works in her employer’s core area and is a permanently employee.

Offshore nurses have a professional qualification and often additional training in a specialist field. They are highly educated and permanently employed by the operator. And, even though the same job on land is perceived as a female occupation, it has traditionally been a male preserve offshore.

That could partly reflect an inheritance from shipping. The first mate on a ship – a man – is often responsible for dealing with injuries. This means that the nursing function offshore has been redefined from a caring role to an expertise-based position and enjoys high standing. On the other hand, a women employed in drilling does not work for the operator but for a service company. In theory, that should indicate the job is less prestigious.

But drilling falls within the platform’s core area – no wells, no production. These workers make “first contact” with the oil or gas before it is tamed. A drilling job has a mythic quality, since it involves a certain level of risk, a level of expertise and a portion of good luck. This has traditionally been regarded as a job for the tough “lads”, and a woman who succeeds in this environment enjoys great respect. Even if she is employed by a service company, she will have high standing because of its “manly” character.

As contractors, the catering companies cover two occupational groups – the skilled cook and the unskilled cleaner. The latter has a service job traditionally associated with women, which has a female character in itself. Many cleaning personnel begin as temporary replacements before securing permanent employment, and few opportunities are available for career advancement. The work done is taken for granted and is not noticed until it has not been carried out. This provides an example of a job which confers low standing.

Spatial relationships

The platform’s spatial organisation works differently for women and men. Since the offshore environment is male dominated, arenas will exist where just men are present. But women-only places are seldom found.

Females are more or less always in mixed company and in a minority. A women thereby has few or no locations on a platform where she can simply be herself, without playing a part.

arbeidsliv, forpleining, kninne, kvinnearbeidsplass, Forpleiningstjenesten
Watering plants in the sky lobby at 2/4 Hotel. Photo: Husmo Foto/Norwegian Petroleum Museum

Social anthropologist Erving Goffman talks about people’s need for a “backstage” area. He divides social life into this and “frontstage”, or between private and public spheres.REMOVE]Fotnote: Goffman, Erving; Vårt rollespill til daglig: en studie i hverdagslivets dramatikk. Oslo 1992.

When backstage, no demands about behaviour are made and people can relax more. Frontstage is a place where they must think through and prepare their performance.

So men do not have to reflect how they appear to women when only males are present. Using Goffman’s terms, we can say that women have few backstage areas and men have more of them. This means that females must be more conscious of their performance for more of the time they spend offshore than is necessary for males.

Process engineers and nurses are examples of solo players. They will not “make a botch” of the way men in corresponding roles and at other times have done the job.


Women often lack the natural authority men possess, but can compensate for this by utilising spatial relationships to legitimise their organisational status.

An example of such conscious use of these conditions is the female offshore installation manager (OIM) who deliberately occupies the manager’s chair because those who enter her office are used to connecting it with the OIM. She wants to be associated with this role and uses spatial relationships to emphasise this.

Even though women do not control the physical or social space directly, they nevertheless exert an influence on how space is allocated and utilised.[REMOVE]Fotnote: Ardener, Shirley  Ground Rules and Social Maps for Women: An Introduction.  Women and space : ground rules and social Oxford  1993 

According to both oral and written sources, sales of after-shave in platform shops increased dramatically when women began working offshore.

Women have also exerted some influence on the design and utilisation of tools and other equipment. The Karmøy winch was developed because a female operator maintained that it must be possible to get equipment which made it easier to open valves.

Wall decoration, also part of the spatial dimension, is another area influenced by the women. After they started working offshore, fewer picture of more or less semi-naked models have adorned work spaces and offices.

Social relations

Arbeidsliv, Organisasjon og yrker, Yrkesgrupper offshore, Sikkerhetsavdeling, helsetjeneste
Nurse Kirsten Elsebutangen checks the medicine cabinet on Tor 2/4 E. Photo: Husmo Foto/Norwegian Petroleum Museum

A platform is much more than a workplace. By extension, it is also a small but complex community on an artificial island where people live 24 hours a day.

This society is characterised by the need to perform many different functions and, in order to achieve that, people need to specialise.

Like the wider society on land, the Ekofisk community is complex because a great variety of activities have to be pursued. Some people are specialists on process, others on drilling or mud.

A complex society is also characterised by the fact that only partial identities are expressed through interactions in the various settings.[REMOVE]Fotnote: Solheim, Jorun and Ellingsæter, Anne Lise, Den usynlige hånd. Kjønnsmakt og moderne arbeidsliv, 2003, Oslo.

The expression “partial identities” means that people do not see the whole person in their job, but only that part which is “relevant” to what they are doing there.

Nevertheless, the fact that personnel live on a platform around the clock will allow more aspects of their personality to emerge.

Occupational identity is central, largely fixed – and not negotiable. What can be negotiated or personally determined is whether the time offshore will be positive, whether one is going to be social.

People put each other in social categories and simplify by creating stereotypes. Anthropologist Gregory Bateson sees this need for simplification as a result of information overload which requires us to bring things down to a more manageable level.[REMOVE]Fotnote: Solheim, Jorun and Ellingsæter, Anne Lise, Den usynlige hånd. Kjønnsmakt og moderne arbeidsliv, 2003, Oslo.

Statements such as “women in aspirational jobs … aren’t here long” about university-trained engineers reflect a stereotype of a feature or property of females with such qualifications.

It is easier to avoid leisure contacts with work colleagues on larger platforms. You can expect “somebody else” to be engaging in social interaction, so your absence will not be noticed.

Pressure to be sociable can be stronger on smaller installations, and you will feel under a greater obligation to be present in common parts.

It is particularly difficult for women to evade social relationships on a small platform because there are so few of them that their absence will be immediately noticed.

Job affiliation

Different levels of affiliation to the job appear to affect how a person integrates with the platform community. Those permanently employed offshore and in stable jobs – whether for the operator or a contractor on a long-term contract – are more assimilated.

This group includes personnel in both production and service roles – process operators, nurses, radio operators, administrators and catering employees. They are often well integrated in the platform community and also have friends among those they have met offshore.

The exception is the nurses. Even though they are well assimilated, a number of female medical personnel indicate that they avoid over-close relationships for professional reasons.

Highly educated technical personnel and service company employees are often less integrated because their jobs are not permanent.

The same seems to apply to managers in typical career posts. It appears that the higher up the hierarchy a person is, the more formal their relationships will be.

With the role structure more strictly defined, such people are required to behave more formally. Formal structures create clear divisions of roles and demands for bodily control.[REMOVE]Fotnote: Douglas, Mary; Natural Symbols explorations in cosmology London 1996.

A woman in a management position offshore seldom has female colleagues at the same level. Should the job also absorb most of her time, it is hard to become intimate with other women.

If they are at work the whole time, social interaction becomes part of the job and the boundaries between work and leisure get blurred. That applies primarily to nurses and OIMs, who are always on call.

Everything was better before

Those who have worked offshore for a long time have claimed that everything was nicer before. Typical comments include: “we were all more united then”, “there’s much more division now”, and “we had a much better time”.

The reason why earlier times were finer was that certain jobs had fewer responsibilities than today. And TV sets in cabins with masses of channels must take a share of the blame for people being less sociable.

Leisure activities

Various leisure activities are available offshore. These normalise the time spent there, and help to break up the routine of work, eat and sleep.

They help to make the time more meaningful. When a job is characterised by routine, a hobby which allows people to express their creativity can aid relaxation.

Male-female relations

Everyone believes that having both genders represented on the platforms is beneficial, even though some people were sceptical to begin with.

Where women work in relation to the men has an impact on their bonding. Those who interact closely with male colleagues usually have man-to-man types of association – friendship, collegial ties, a superior-subordinate relationship and so forth.

Most emphasise the importance of not ending up in woman-man ties, such as becoming sweethearts or lovers, because this undermines the respect they have built up at work.

Gender is toned down. The great majority of women are keen to play down their female attributes.

Loose-fitting clothes and no makeup are standard for many of them offshore – regardless of the type of job they have.

But women in catering do not have the same need to play down their femininity. Because they work in “typical” female occupations, others accept if they act as women.

Women in other roles find it advantageous that somebody else serves as the centre of male attention. Job affiliation appears to be crucial in determining which females are possible objects for chatting up. Those working in catering are considered “worth trying it on with”, while a woman who is seen as one of the “lads” is not perceived as female in the same way.

Female morality debated

Romantic relationships have arisen in the North Sea, as in other workplaces. Some have led to lasting partnerships, while other love affairs have been more transitory.

Informants make such observations as “she was a lady of the more generous type and keen on men”, or “there were some who went right off the rails from all the attention”.

Most of the stories about these transitory romances are characterised by the fact that the discussion concentrates on the woman’s behaviour.

This represents a nature-culture dichotomy, where men are regarded as closer to the culture while women are closer to nature, because female morality becomes the point at issue.[REMOVE]Fotnote: Ortner, Sherry; ed.  Rosaldo, Michelle Zimbalist and Lamphere, Louise; Is Female to Male as Nature is to Culture? Woman, culture, and society Stanford University Press, 1974.

The woman is the one who steps outside the accepted norms, and who can undermine the position of other females by giving their whole gender the stamp of immorality.

Women are felt to have only themselves to blame if they are not properly treated offshore. In other words, a woman who is subject to verbal or other harassment has given the wrong signals and brought it on herself.

Catering workers are often regarded as group which represent a social factor by definition. First, most of the females on a platform are found here, and part of their job is to create homelike conditions for the others.

These personnel are metaphorically the “mothers” in the big platform family..[REMOVE]Fotnote: Solheim, J, og  Hanssen-Bauer, J.   Kompleksitet og fellesskap på en Nordsjø-plattform : rapport fra et besøk på Statfjordfeltet Rapport / Arbeidsforskningsinstituttene, Arbeidspsykologisk institutt, Prosjektgruppe Arbeidsmiljø på kontinentalsokkelen ; 108/83 Oslo : Arbeidsforskningsinstituttene, Arbeidspsykologisk institutt.  They are the ones who create the “domestic” environment with good food and clean, tidy rooms. At the same time, they come into contact with many other occupational groups offshore.

Women in this occupation can allow themselves to categorise males by different criteria than those used by females who work closely with men because they see what lies behind the male facade. Catering gets closer to the private sphere of the other personnel.

Must fit in

Virtually all women employed offshore find it positive to be working in an environment with many men. The attitude is that “if you’re straightforward and genuine yourself, you get a lot back” and “you learn what men are like when you work in a male society”.

The woman is the one who must cope with being in a masculine workplace. “It’s good to have more females, but you must fit it,” is a frequent comment. That refers to succeeding not only in working so intensively, but also in being a woman in a relatively marginal position.

Social relations on land

arbeidsliv, sosialt liv, fritid, telefonkiosk,
Phone kiosk at Ekofisk 2/4 H. Photo: Kurt Mauer/Norwegian Petroleum Museum

A factor which is not visible offshore but very definitely present is the relationship with family and friends on land. Most of the women in this study have both husband and children.

Many were mothers when they started working offshore, or have since become so, and have had one or two periods of maternity leave.

Combining a platform job with family life on land is not regarded by the informants as particularly problematic. On the contrary, they have organised themselves in such a way that working offshore and having a good time when at home is preferable to a nine-to-five job ashore.

Some of the mothers have been single parents or shared care with the child’s father. Many have a good network of friends and family who help out when they are offshore. In many cases, it is society at large which makes a problem out of a mother being away from their offspring.

Responsibility for organising matters at home appears to rest with the women. Earlier studies of male offshore workers and feedback from such informants indicate that men employed offshore fail to accept the same level of responsibility for their family.

The helicopter flight from/to land is a key part of working offshore. This journey has been called a rite of passage, but many experience their whole time on the platforms as a marginal phase. You travel from something, spend time away from “normal” society, and reintegrate with it when your tour is over.

A number of North Sea workers start their offshore tour well ahead of flying out. The transition from normal life on land to one directed at their platform job occurs before they depart.

That applies primarily to women. Many of them plan the life of their family while they are away. They organise, clear up and put things in order to minimise the drawbacks for those staying at home. Men are more “a soul and a shirt” when they set off.

   Being visible

Everyone positions themselves and has their standpoint, including those who regard women from the outside and communicate their view. Media want to talk about the North Sea pioneers, labour disputes and special episodes.

The various magazines published by companies say something about their corporate identity: “We support women offshore, and give them opportunities, we want to come across as a company where equal opportunities are important”.

While the positive woman is presented in personal in-depth interviews, however, the negative ones get presented as a group. Females are stigmatised as grumblers and malcontents.

The women worth presenting are the distinctive individuals who become the first to hold a particular job, usually a high-status post previously reserved for men.

Different jobs carry varying weight when describing them. Stories about a hard grind in a tough masculine occupation get more attention than ones on drudgery in the physical care sectors.

Being visible can also be interpreted as others seeing what you do. Many offshore workers find that they are regarded as people who make good money and have a lot of free time – who are better off than others.

Å bli sett kan også tolkes som det at andre ser hva man gjør. Mange som jobber i Nordsjøen erfarer at de blir sett på som personer som tjener godt og har mye fri. De blir sett som folk som har det bedre enn andre.

Neighbours and friends have no idea what happens out in the North Sea, and women working offshore find little understanding in their home environment of what their job is like.

Published 2. July 2020   •   Updated 22. February 2021
© Norsk Oljemuseum
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Knut Åm – oil and gas veteran

person by Kristin Øye Gjerde, Norwegian Petroleum Museum
The special contribution made by Knut Åm to Phillips Petroleum Company was one reason for his appointment in 2014 as a Knight First Class of the Royal Norwegian Order of St Olav.
— Knut Åm in his office in 1993. Photo: Dag Myrestrand/ConocoPhillips
© Norsk Oljemuseum

Åm was born at Årdal in the Sogn district of western Norway in 1944, and grew up in Oppdal and Volda/Ørsta where he proved an able pupil at school. 

He opted to study mining engineering at the Norwegian Institute of Technology (NTH) in Trondheim, graduating with honours in 1967. 

Åm’s first job was with the Norwegian Geological Survey (NGU), again in Trondheim, where he worked and conducted research for six years. One of his jobs was to interpret aeromagnetic measurements of sub-surface rocks made from the air, which provide valuable information on geology and prospects for finding petroleum. In a series of publications, he described the big sedimentary basins identified in the Skagerrak between Norway and Denmark and in the Norwegian and Barents Seas. 

He joined the Norwegian Petroleum Directorate (NPD) in 1974, serving as a section head in the resource department and a principal engineer in the safety department. 

That was followed by three years with Statoil, where he became the state oil company’s first vice president for research and development. His appointments at the time included chairing a research programme on offshore safety, which led to legislation enacted by the Storting (parliament) and a bigger research effort. 

Joining Phillips

olje og gassveteran knut åm,
Hovedkontoret til ConocoPhillips i Bartlesville, Oklahoma. Foto: ConocoPhillips

Åm secured a job with Phillips in 1982 and was soon sent to the head office at Bartlesville in Oklahoma to get better acquainted with the company and its corporate culture. 

After a year in the USA, he returned to the company’s Tananger office outside Stavanger and became the first Norwegian to serve as offshore manager for the Greater Ekofisk Area (GEA). 

That put him in charge of 23 platforms, with responsibility for the waterflooding programme as well as the project to jack up a number of the installations. These major developments extended the producing life of the GEA and sharply increased estimates for recoverable reserves from its fields. 

Åm led this work during difficult times, with low oil prices and the need to implement cost savings and overcome substantial financial challenges. As if that were not enough, he also taught at the University of Bergen from 1985 to 1990 as an adjunct (part-time) professor of applied geophysics. 

First Norwegian chief executive

Knut åm,
Knut Åm ved kontorpulten i 1993. Foto: Dag Myrestrand/ConocoPhillips

After heading operations in the Permian and San Juan Basins at Odessa, Texas, from 1988-91, Åm became the first Norwegian president and managing director for Phillips Petroleum Norway. 

That put him in charge of 3 000 employees in the GEA as well as in Tananger, Oslo, Teesside and Emden. This was when a redevelopment of Ekofisk was planned, along with the future cessation and removal of old platforms.[REMOVE]Fotnote: https://www.fylkesmannen.no/globalassets/fm-rogaland/dokument-fmro/felles-og-leiing/brev-og-artiklar/fm-tale-til-knut-am.pdf 

By 1996, Åm was back in Bartlesville – now as vice president and head of all exploration and production in Phillips. He stayed in that job until retiring in the USA during 1999.

Offices and committees

But his working life did not end there. Appointments from 1999 to 2007 include membership of the Statoil board – and many similar posts can be mentioned. 

Åm has been president of the Norwegian Geological Council and the Norwegian Petroleum Society, and chair of the Norwegian Oil Industry Association (now the Norwegian Oil and Gas Association). 

He led the exhibition committee of the 1996 ONS oil show in Stavanger, and has chaired Bergen’s Christian Michelsen Research institute as well as the industrial council of the Norwegian Academy of Science and Letters.  

In addition to chairing Hitec ASA, he has been a director of several technology companies. 

Mention must also be made of the improved recovery committee appointed by the Ministry of Petroleum and Energy with Åm as chair. This produced a report in September 2010 which presented 44 specific measures for improving the recovery factor on the Norwegian continental shelf (NCS). 

Through his work and many appointments, Åm has been acclaimed for a combination of expertise, creativity and determination.  He also demonstrated the ability to tackle the requirements of Norway as a nation as well as the industry and its employees – not least with regard to the working environment and safety in a demanding and risky offshore industry. 


In retirement, Åm is an optimist – with regard to the climate as well. “I’m very concerned with nature, but believe we should extract the resources its given us,” he told Otium in 2016. 

“Norway could have a long and good future in the oil and gas industry if people give it more support. Exploring for new deposits is important, but we should also seek to achieve a far better recovery factor from both new and existing fields.” 

“You can naturally concentrate on life’s negative aspects. Then everything’s simply awful. I think you’ll be a far happier person if you prefer to see the positive side of life. I call that self-motivation. We need more of that in the energy sector.”[REMOVE]Fotnote: https://api.optimum.no/sites/default/files/PDF/optimum-magasinet-2016.pdf 

Published 21. October 2019   •   Updated 21. October 2019
© Norsk Oljemuseum
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Knut Ove Kristensen – veteran manager with his heart in HSE

person Kjersti Melberg, Norwegian Petroleum Museum. Based on an interview with Kristensen on 12 September 2019.
More than forty-five years of service on Ekofisk underpin Knut Ove Kristensen’s status as a pioneering leader on the Norwegian continental shelf (NCS). His involvement began in 1974 when he switched from a career at sea to become a process technician for Phillips Petroleum.
— Knut Ove Kristensen in conversation with process apprentice Fredrik Svindland Theissen (left) and operations manager Siri Friestad. Photo: ConocoPhillips
© Norsk Oljemuseum

Early promotion and trust followed, and he served as an offshore installation manager (OIM) for more than 33 years in the Greater Ekofisk Area. 


Kristensen recalls that he was a committed young man in the early 1970s – an open, curious and plain-speaking person who was not afraid to criticise health, safety and environmental (HSE) conditions. 

The working style he encountered offshore suited him well, ready as he was to speak his mind. “I’ve undoubtedly been a loud-mouth. I’m used to having zealous people in the Family With grand-parents and a father who served as mayors, which is perhaps why I don’t quite know when to keep quiet.” 

Thinking back to working conditions when he started in petroleum industry, he recalls living on Gulftide, Norway’s first production facility, and says it was fascinating. 

“This was an old jack-up rig, with the helideck installed on planks. We were four to a cabin, and things were pretty shabby. Primitive conditions prevailed, to put it mildly.” 

The workplace at the time was characterised by the presence of the Americans, and confusions frequently arose between them and those who were not particularly good at English. 

“It was very unusual,” reflects Kristensen. “We were trained up by the Americans, of course – they were the ones who knew about this business. There were a lot of misunderstandings among the Norwegians, people who pretended to understand the messages they were given about what jobs to do. Both serious and funny situations occured. Those of us who’d been to sea undoubtedly had an advantage in that we knew the language a bit better. The rest were fishermen and smallholders and ordinary people from the Districts in Western Norway who didn’t speak much English. Offshore terminology wasn’t easy for people who didn’t have the language.” 

He quickly grasped the ethos in this working environment. “The Americans often only gave you one chance. If you showed that you could cope with your job, you won trust, new opportunities and more responsibility.” 

Given his background in the Norwegian merchant marine, however, Kristensen reacted negatively to a number of the conditions which prevailed at the time. “I was one of the youngest then, and that wasn’t always easy because there were a number of older and more experienced people who felt they had a ‘monopoly of brains’,” he comments. “And quite a lot were pushy. “Working conditions weren’t orderly, with proper employment contracts like I was used to from my time at sea thanks to the Norwegian Seamen’s Union – unionisation and the like.” 

He adds that he is grateful for everything he learned from the Americans, but that they at the time were not particularly keen on unions and the Norwegian concept of collaboration between employers and employees. “They thought it was enough to enter into agreements on a mantoman basis or with the company, and saw no need to organise this via trade unions.” 


Given his views, it is not surprising that he became involved at an early stage with the Ekofisk Committee by serving as secretary to Øyvind Krokvik, who was first head of this union. 

Kristensen explains that he has been committed throughout his career to involvement and worker participation and to good collaboration between unions, the safety service and management. That was particularly important during the early years of the petroleum industry on the NCS, he emphasises. His experience of union work accompanied him into various senior posts on Ekofisk. 

With a gleam in his eye, he says the following about his promotion: “Acquiring managerial responsibility early on may have had something to do with my involvement with the union. Putting in place systems for worker participation and collaboration was particularly important in the early years of Norway’s offshore industry. 

“I played a part in establishing the parameters which govern industrial relations out on the field today, with unions and the safety delegate service.

I became the country’s youngest OIM at the age of 24, and served as a manager out there for 41 years.

They may have thought ‘he’s more trouble than we need, so we’ll just promote him up and then be quit him.” 

Kristensen reports that he has been preoccupied throughout his managerial career with ensuring that “things are genuine” – that a manager must understand and personally be part of “the home team”. He explains that as the ability to understand a position from the standpoint of the various parties involved, and adds that he has thrived offshore with a living and working community. This he defines as one “where you get close to people, where everyone is seen and heard, and where they understand that they play an important role in reaching a common goal”.[REMOVE]Fotnote: Pionèr, ONS 2018: 8. 

It did not take him long to learn how to adjust his management style to the offshore environment, but admits that this approach has developed over the years. The leadership culture which dominated on the platforms during the early years undoubtedly influenced me a bit. I was probably very inflexible and saw things in black-and-white, but have become more judicious and considered over time. 

“Nobody left my office earlier in any doubt about what I meant. I thought that saved a lot of time. But I can’t have been too bad, or I wouldn’t have held down the job for so long.” 


Kristensen’s long service makes him unique on Ekofisk, and he has thought a lot about management. His expressed strategy has been to get people on side over HSE through commitment and integrity – and without any “second agenda”. 

“Working in the Ekofisk Complex with 600-700 people is an unusual experience,” he observes. “I held the same job as the man in charge for 20 years. “That means you’re ‘on stage’ the whole time, and attend 10-12 HSE meetings every week. You’ve got to get people committed, drive a doctrine and sell a message. This involves getting what people have to concentrate on implanted in their hearts and minds so they can contribute to their own safety and that of others, he explains. 

“You must be genuine, and your own integrity must be order. You have to build trust, and not least display respect for your audience.” 

“What’s been a powerful help for me is that I’m on the home team. I’ve been a skilled worker myself and have been through most things.” 

Kristensen emphasises several times that he regarded the unions, their elected officers and the safety delegates as a resource in this work. 

“The tripartite collaboration pursued in the petroleum industry between government, companies and unions functions very well,” he concludes.  “This is about informing and involving people, and ensuring that decisions aren’t taken over their heads. Our company has achieved that in a positive way.” 

“The fact that Ekofisk is a mature field and ConocoPhillips is a mature company also has something to do with it. Cooperation with the Petroleum Safety Authority Norway and other authorities is also very good.” 

Kristensen denies that union-management collaboration has become more strained during the downturns experienced by the petroleum industry. “Strained and strained – we must adjust to external conditions and try to protect the jobs needed to safeguard the industry. But nobody’s ever been made redundant by this company. That’s worthy of respect.

Downsizing has been solved with severance packages. People have often been given early retirement. From that perspective, it’s been a privilege to work for an operator company.” 


After almost 46 years with the company, Kristensen’s commitment to continuous improvement, good safety and high production regularity is as strong as ever. Recognising that substantial progress has been made in the HSE area over the years he has worked in the industry, he affirms that this issue is closest to his heart. 

“We’ve staked out the path as we’ve advanced. We don’t accept incidents and accidents. We take a completely different approach to risk today. Accidents which do occur are used for all they’re worth in an effort to say to ourselves: ‘this has actually happened, but it’s our duty to learn from it’.” 

Kristensen has personally experienced accidents and injuries at close hand, and thereby knows the importance of preventive safety work to protect people, the environment and equipment. 

He will never forget some incidents – and immediately mentions the Alexander L Kielland disaster in 1980 With 123 casualties. An article in local daily Stavanger Aftenblad as recently as 2012, with photos of all those who have died on duty on the NCS since 1966, made a big impression on him. 

Britain’s Piper Alpha explosion in 1988, when 169 people were killed, is another major incident he recalls. His conclusion is that the petroleum sector has not been a Promised Land for all. 

The former OIM proudly mentions a number of HSE improvements which have partly been the result of technological advances in the industry during his time. But he warns about hazards which still exist, such as vessels drifting out of control. A well-known incident on New Year’s Eve in 2015 made a particularly strong impression on him. 

A 150000 tons, unmanned barge had come loose and was threatening to collide with installations on Ekofisk. Several hundred workers from this field and neighbouring Valhall were flown to safety and production was shut down. The barge passed the platforms at a distance of about one nautical mile, but Kristensen found the actual incident and the threat it posed frightening. 

“Drifting vessels which come loose in rough weather, which can get pretty challenging out there, are perhaps the biggest hazard we now face. Luckily we have good procedures to handle such challenges.” 


Such incidents and near-misses are regarded by Kristensen as a reminder that the petroleum industry is under an obligation to learn the necessary lessons. He points to the potential for learning from other industries, and emphasises the good collaboration which prevails across the company. Mechanical handling provides a good example, he says. 

“Things can go terribly wrong. After fatal accidents in the 2000s, we established a work group which held monthly meetings. I took part as technical manager for these facilities. We involved everyone in the logistics chain on land, at the base and on the platforms. That attracted so much attention and such great improvements that we’ve now managed to prevent virtually all undesirable conditions in this area.” 

Despite good systems and routines, colleagues on the installations are Kristensen’s most important reminder of the responsibility he has had as an OIM on Ekofisk. 

“Experiences from my early years meant that I have become particularly attentive to HSE – and I was involved in quite a lot, of course. But this mostly relates to the individual who gets injured on your watch and on your shift – in other words, the people you work with. They stood on the drill floor and worked so that the sparks flew around their ears. Having only two-three fingers used to confer ‘status’. 

He notes that improvements have a lot to do with technological progress. Much risk has been eliminated by automating a great deal of the work which used to be done manually. 

“But we still have more than enough opportunities to injure ourselves. This has a lot to do with awareness – being present in the real world, making sure you’re focused. That’s actually expected for 12 hours at a time.” 

A respectful attitude to his big responsibilities and duties was maintained by Kristensen to his last working day. “Emergency preparedness is like being at war – you do what you’re told. But you feel it. Although we’ve trained so long at this, you’re still conscious of being responsible for several hundred lives. Taking a wrong decision could … You must act on the basis of the information you’ve got, not what you know many months later. When you tackle it, however, you get a sense of mastery at solving the problem together with an outstanding emergency response organisation on land. Ultimately, though, you’re the skipper on your own ship.” 

Time to reflect

Kristensen has finally retired from ConocoPhillips, giving him time to reflect over his own commitment and lifestyle offshore as it affected him and his family. 

“For my own part, I must say that it’s had a price,” he admits. “I couldn’t get involved in politics or organisations, for example. I was only at home half of the time. I followed up the kids when I was at home, of course, but never felt I could be active in associations and so on, contribute the way I’d have liked. 

He has found the transition to retirement unaccustomed in many ways. “Simply remembering that I’m not going offshore is a big change, for example. I had to deal with so many challenges right up to my last day at work that it’s been impossible to prepare anything. I ought to have thought about and planned retirement a bit better, of course, but I’ll undoubtedly find something to do when I want to.” 

Published 21. October 2019   •   Updated 25. October 2019
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Ekofisk 2/4 VC

person Norwegian Petroleum Museum
Injection water from subsea installation Ekofisk VC (Victor Charlie) began to be pumped down well VC-03 on 28 September 2018. Well number two came on line just under a week later. 
Kjappe fakta:
  • Plan for development and operation (PDO) was approved by the Ministry of Petroleum and Energy on 7 September 2017.
  • Part of Ekofisk South
  • Installed September 2017
  • On stream September 2018
  • Gets electric power and signals from Ekofisk 2/4 M
  • Also called "Victor Charlie"
— Illustration of Ekofisk 2/4 VC (Victor Charlie). Illustration: ConocoPhillips
© Norsk Oljemuseum

The aim of this facility – an extension to the Ekofisk South project – was to increase waterflooding on the southern flank of the Ekofisk reservoir in order to maintain oil and gas production. 

An amended plan for development and operation (PDO) of Ekofisk South was approved by the Ministry of Petroleum and Energy on 7 September 2017. 

This involved installing a new seabed template with four water injection wells, and represented a continuation of the well-established Ekofisk production strategy based on waterflooding.[REMOVE]Fotnote: https://www.regjeringen.no/no/aktuelt/okt-utvinning-pa-ekofiskfeltet/id2570011/. 

The template was installed in September 2017, with a technical solution similar to that used on the seabed facilities already installed – Ekofisk 2/4 VA and 2/4 VB.[REMOVE]Fotnote: Pionér, no 2, ConocoPhillips, 2018.

In addition to the structure itself, including wellheads and Xmas trees, the installation comprised control modules with umbilicals connected to the existing waterflooding system. 

The 2/4 VC facility receives injection water from Eldfisk 2/7 E, while power and control signals come from Ekofisk 2/4 M. It is run from the Ekofisk 2/4 K control room. 

When fully developed, overall injection capacity for this subsea installation will be 80 000 barrels per day through the four wells. 

The water pipeline and umbilical to 2/4 VB were extended to 2/4 VC. Well operations on the latter began on 24 May 2018 with a view to starting injection before the end of the year. 

Published 15. October 2019   •   Updated 15. October 2019
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Ekofisk from 2008 to 2017

person by the Norwegian Petroleum Museum
Click through the photo carousel under the look-up from year to year from 2008 to 2017.
It shows the development of the Ekofisk area with platforms, pipelines and underwater installations.
— 2017
© Norsk Oljemuseum

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Do you want to see the development of the Ekofisk area from 1971 to 2001 click here.

Published 7. October 2019   •   Updated 14. October 2019
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Ekofisk from 1971 to 2001

person Norwegian Petroleum Museum
Click through the image carousel below the lookup image.
It shows the development of the Ekofisk area from year to year from the start with the first production in 1971 until 2001.
© Norsk Oljemuseum

To follow the development of the field further from 2008 to 2017 click here.


Published 7. October 2019   •   Updated 8. October 2019
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Getting the timing right

person by Trude Meland, Norwegian Petroleum Museum
The issue of work schedules for offshore personnel has been subject to constant discussion between government, employers and unions – leading to radical changes over 50 years.
— The offshore workers arrive at the platform for a new work period. Photo: Kjetil Alsvik/ConocoPhillips
© Norsk Oljemuseum

Different systems for rotating personnel between work and leisure functioned in parallel on the drilling rigs during the early years of oil exploration in the Norwegian North Sea. The most common practice was nevertheless one week on and one off. To get a holiday, people carried on working offshore until they were entitled to three weeks free in one go.

However, this arrangement proved impractical – particularly for workers who going offshore or returning home on a Saturday or Sunday. They never got a full weekend off. To stagger such change-overs, the schedule was extended to eight days offshore with eight days free. One work period in five was also dropped, so every fifth free spell was 24 days long.[REMOVE]Fotnote: This gave a working time which averaged 38 hours per week and 1 824 hours per year after holidays. That corresponded to shift work on land.

When Norway’s Working Environment Act (WEA) came into force in 1977, the permitted length of a continuous shift on land was cut. But there was no assurance that this would be applied offshore. In its original form, the Act did not permit the 12-hour working day normal on all offshore installations. So amendments were needed to adapt the legal provisions to fixed platforms.[REMOVE]Fotnote: The Act specified that working time was 36 hours over seven days for work carried out around the clock throughout the week. That represented 1 877 hours a year on average. Adjusting this for four weeks of holiday gave a net working time of 1 733 hours.

The Norwegian Petroleum Directorate argued that reducing working time offshore was impractical, with the “special character” of the oil industry requiring exemptions.[REMOVE]Fotnote: Ryggvik, H, 1999, “Fra forbilde til sikkerhetssystem i forvitring: Fremveksten av et norsk sikkerhetsregime i lys av utviklingen på britisk sokkel”, Working Paper, Volume 114, Centre for Technology and Culture, University of Oslo, printed edition. Oslo: Centre for Technology, Innovation and Culture (TIK), University of Oslo: 16. As early as 1975, however, Ekofisk operator Phillips Petroleum had agreed to working hours for its own personnel which accorded with the provisions proposed for the new Act. A royal decree of 9 July 1976 extended the existing Worker Protection Act, with certain exceptions, to the fixed installations offshore on a temporary basis.

The WEA was then applied to these facility in 1977.[REMOVE]Fotnote: Ryggvik, H, 1999, “Fra forbilde til sikkerhetssystem i forvitring: Fremveksten av et norsk sikkerhetsregime i lys av utviklingen på britisk sokkel”, Working Paper, Volume 114, Centre for Technology and Culture, University of Oslo, printed edition. Oslo: Centre for Technology, Innovation and Culture (TIK), University of Oslo: 18. This meant that offshore workers had their working time regulated and acquired legal safeguards against unfair dismissal. After long discussions, the North Sea schedule was by and large established as two weeks working offshore and three weeks free on land.

But the WEA was not applied to floating units such as rigs, and working time in that part of the oil industry continued to be regulated by Norway’s Ship Labour Act.

 An extra day

Norway’s legislation on paid holidays was amended in 1981 to give everyone a legal right to four weeks and one day off. The latter was nicknamed the “Gro Day” after Gro Harlem Brundtland, the Labour premier of the day. This meant the two weeks on/three weeks off schedule now imposed too many working hours. It was decided that the extra would be compensated as 25 hours of overtime per year.[REMOVE]Fotnote: Working time was reduced from 1 752 to 1 727 hours.

Agreement was reached in the 1986 collective pay negotiations on a 7.5-hour normal working day and a 37.5-hour week. Personnel both on land and offshore working a continuous shift also had their weekly hours cut 33.6.[REMOVE]Fotnote: Net working hours after deducting holidays were reduced from 1 752 to 1 727. To comply with these new terms, the offshore schedule was altered to two weeks at work, three weeks ashore, two weeks at work and four weeks on land.

When the Gro Day was introduced in 1981, the Labour government originally proposed introducing a full week’s extra holiday in stages over three years. But that failed to materialise. In 2000, the Norwegian Confederation of Trade Unions (LO) proposed a fifth holiday week for all employees, which would thereby reduce the number of hours in a work-year.[REMOVE]Fotnote: That involved an additional four free days of 7.5 hours offshore (32 hours). The hours to be worked were then reduced from 1 612 to 1 580. That demand was accepted, and most workers could thereby enjoy five weeks off. This naturally had consequences offshore, but implementing it there was not a straightforward matter.

A schedule of two weeks at work and three/four weeks at home had been 19 hours short of a normal work-year. That was overcome by deducting this time from pay or leaving the first 11 hours of overtime unpaid.[REMOVE]Fotnote: Sande, Leif, “Arbeidstiden på sokkelen”, Sysla – meninger, 11 March 2015.

The new holiday deal meant that an offshore worker would be doing 12 extra hours per year. This was initially paid as overtime, which the unions found unsatisfactory. They demanded the full holiday entitlement awarded to everyone else through the introduction of a schedule of two weeks on and four off. In 2002, the Norwegian Oil Industry Association (OLF – today the Norwegian Oil and Gas Association) allowed local deals under the offshore agreements to adopt this two-four scheme. All the companies subject to these agreements introduced the new schedule. ConocoPhillips was among the operators to do this, in its case covering the Greater Ekofisk Area.

However, the two-four system meant workers were falling short of a work-year by 122 hours.[REMOVE]Fotnote: Working 12 hours a day for 14 days, followed by four weeks off, means that an employee works 168 hours every six-week period. That adds up to 1 460 hours per year. Annual pay was thereby cut by 7.71 per cent to take account of the reduced time worked.[REMOVE]Fotnote: Norwegian Official Reports (NOU) 2016:1, Arbeidstidsutvalget — Regulering av arbeidstid – vern og fleksibilitet. https://www.regjeringen.no/no/dokumenter/nou-2016-1/id2467468/sec16. Other conditions were also set on Ekofisk. The whole offshore organisation was to be reviewed to find efficiency gains, and the agreement specified that the change would not lead to an increase in the workforce.[REMOVE]Fotnote: Pioner, “2-4-ordningen innføres”, March 2003.

Published 21. October 2019   •   Updated 21. October 2019
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Ekofisk 2/4 Z

person Norwegian Petroleum Museum
This installation is a wellhead platform in the Ekofisk Complex.
Kjappe fakta:
  • Wellhead platform
  • Installed summer of 2013, on stream 25 October
  • Also known as Ekofisk Zulu
— Ekofisk 2/4 Z. Photo: ConocoPhillips/Norwegian Petroleum Museum
© Norsk Oljemuseum

This platform rests on a steel jacket built by Dragados at Cadiz in Spain. The module support frame (MSF) and topsides were fabricated by Energomontaz at Gdansk in Poland and completed at Kværner Egersund. 

The topsides were installed in July 2013. Petroleum and energy minister Tord Lien performed the official inauguration of 2/4 Z and the Ekofisk South project on 29 October 2013,13 just four days after the platform came on stream.14 

No control room is provided on 2/4 Z, but it has a local equipment room (LER) which is not permanently manned. The platform is monitored and remotely controlled from the control room on Ekofisk 2/4 J, but can also be run from the operations centre in Tananger.

2013-10 – Historisk dag for Ekofisk og Norge åpning av Ekofisk 2-4 Z – regjeringen-no

Published 1. October 2019   •   Updated 25. October 2019
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Ekofisk 2/4 VB

person by Gunleiv Hadland, Norwegian Petroleum Museum
The 2/4 VB subsea installation began injecting water in May 2013, three kilometres south of the Ekofisk Complex. It formed part of the Ekofisk South project approved by the Storting (parliament) in 2010.
Kjappe fakta:
  • Ekofisk 2/4 VB was a part of the Ekofisk South project
  • Installed 2012
  • Producing May 16. 2013
  • Also called “Victor Bravo”
— Ekofisk 2/4 VB (Victor Bravo) lowered into the sea. Photo: Bob Bartlett/ConocoPhillips
© Norsk Oljemuseum

 So successful had the 2/4 VA facility proved to be that it was copied for 2/4 VB as an eight-well template, also delivered by FMC at Kongsberg.

Similarly, the wells on 2/4 VB were drilled by Maersk Innovator. The well operation department completed installation of the template, manifolds and casing for the eight subsea wells.

Seabed installations carried out by Subsea 7 comprised a five-kilometre pipeline for water from the Eldfisk Complex as well as a diver-installed T piece welded into the existing pipeline from Eldfisk 2/7 E to Ekofisk 2/4 K.

This assignment also covered laying three kilometres of umbilicals combining hydraulic lines and fibreoptic cables from 2/4 VA, so that 2/4 VB could also be remotely operated from land.

Published 23. September 2019   •   Updated 7. February 2020
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Sea scurf – the geology of Ekofisk

person By Björn Lindberg
The oil and gas in Ekofisk lies in a chalk reservoir composed of countless tiny shelly fragments derived from coccolithophores – microscopic algae which make calcium carbonate (CaCO3) scales.
— The image was taken using a scanning electron microscope (JEOL JSM-6330F), the colors are therefore artificial. Scale = 1.0 µm. Photo: NEON yes, colored by Richard Bartz
© Norsk Oljemuseum
havets flass
Microscope image from of cookoliths from the Ekofisk reservoir.

Known as coccoliths, these plates are so minute than 30 of them laid side by side would be no wider than a strand of hair. But what they lack in size, they make up for in numbers. 

Their colossal accumulation is helped by the fact that coccolithophores reproduce asexually. When one dies, its coccoliths sinks to the seabed at a rate of about 15 centimetres per day. 

If conditions are right, the scales remain lying and are eventually buried in their billions of billions 

Estimates indicate that coccolithophores globally produce more than 1.5 million tonnes of calcium carbonate per annum – equal to the weight of the Gullfaks C platform, which ranks as the heaviest structure ever moved by humans. 

Three things must be in place for an oil and/or gas field to form – a source rock, a reservoir rock and a cap rock which prevents the petroleum from escaping. 

In the case of Ekofisk, we know quite a bit about how these three components originated. 

Source rock – Draupne

havets flass,
Core sample from a well in the Vikinggrabenen field, with large content of Draupne shale. The Draupne formation is found over large parts of the Norwegian continental shelf. Photo: Norwegian Petroleum Directorate (Fact pages)

The Ekofisk source rock dates from the Jurassic period, 161-145 million years ago, and comprises organically rich black shales known as the Draupne formation. 

In Norse mythology, Draupne was the gold ring worn by the god Odin which formed another seven rings every ninth day – in other words, an endless source of prosperity. 

So the name is appropriate for a formation found over most of the Norwegian continental shelf (NCS), which has put huge volumes of petroleum into most of Norway’s fields – including Ekofisk. 

Cretaceous reservoir rock – Tor formation

The Cretaceous period followed the Jurassic and lasted for 145-66 million years, with the last 10 million of these forming the Campanian and Maastrichtian stages. 

Conditions then were favourable for coccolithophores over much of the southern and central North Sea as well as England, Denmark and France. 

Countless coccoliths were deposited on the seabed. Since the latter was neither flat nor stable, they were moved around by small slips, landslides and/or mud flows which could be activated by earthquakes, before being finally buried by their successors.

havets flass
Chalk cliffs along the French Channel coast (Etretat, Normandi). Photo: ConocoPhillips


The Cretaceous ended in a mass extinction event, when up to 70 per cent of all life on Earth vanished – including the dinosaurs. 

This wipe-out was unleashed by a massive asteroid strike in what is now the Gulf of Mexico, where the Chicxulub crater is about  150 kilometres in diameter and 20 kilometres deep. The asteroid itself may have measured 80 kilometres. 

havets flass,
Bioturbert chalk: Small animals on the seabed have eaten and dug into the chalk layers.

Palaeocene reservoir rock – Ekofisk formation

That impact nevertheless failed to destroy all marine life, and the “sea scurf” continued to rain down in the following Palaeocene period. 

During its first million years, known as the Danian stage, further tens of metres of calcium carbonate were deposited. But changed seabed conditions and a colder climate had an impact. 

The amount of reworking which the material experienced varied and decreased, while the content of silica derived from microscopic diatoms and radiolarians increased. 

Lower sea levels also meant an increased influx of sediments from land (terrigenous material) in the chalky plates heaping up on the seabed. 

Porosity and permeability

These sediments usually have up to 50 per cent porosity (cavities) when deposited. But this will be considerably reduced by burial and diagenesis (the physical, chemical and biological changes which occur during conversion from sediment to stone). 

In some case, that reduction can be down to well below 10 per cent. However, the good conditions around the Greater Ekofisk Area (GEA) meant that much of the porosity in the chalk was retained.  

It has been calculated at 25-40 per cent. By comparison, a good sandstone reservoir – which is the kind usually found on the NCS – has a porosity of 30 per cent. 

Permeability is also needed to get much oil out of a rock, and the “primary permeability” of Ekofisk chalk is low since the connections between its pores is poor/constricted. 

But the field has enjoyed another stroke of luck here. A large number of fractures in the reservoir have improved its permeability and provide good production properties – at least initially. See water injection. 

Cap rock and trap formation

havets flass,
Geological layers are folded and deformed. Etretate, Normandy. Photo: ConocoPhillips

After the deposition of the Ekofisk formation, conditions changed so that the overlying sediments lost all their porosity when buried and became tight (impermeable). 

That allows them to function as a cap rock which seals the reservoir formed by the Tor and Ekofisk formations. 

The fractures mentioned above were created at the same time as the rocks were subject to movement when large quantities of underlying salt shifted. This also produced large domes and thereby created trap structures where oil and gas can accumulate. 

In other words, the oil migrating from the source rocks has gathered in the reservoir formations under the cap rock – and in amounts which can be difficult to imagine. 

Havets flass – geologien i Ekofisk, Vanninnsprøyting for økt utvinning, graf
Produced and remaining oil reserves in fields on the Norwegian continental shelf. Ekofisk has the largest total oil reserves, but not the largest proportion of recoverable reserves. Source: Norwegian Petroleum/Norwegian Petroleum Directorate

The Ekofisk reservoir is as thick as the Eiffel tower is tall and covers an area of 40 square kilometres – the same size as 5 500 football pitches. 

Recoverable oil in Ekofisk totals 3.5 billion barrels, which would be sufficient to supply the whole world with crude for 35 days. 

Roughly 1.1 billion standard cubic metres (scm) of oil (about 6.9 million barrels) and 300 billion scm of gas were present in Ekofisk when production began. 

That corresponds to twice Norway’s annual water production. It also represents more than 100 times annual Norwegian energy consumption and just over 100 days of global oil usage. 

Havets flass,
Visualization of oil and water in one of the reservoir layers in Ekofisk. Red: Oil. Green: Oil and water. Blue: Water

It is impossible to get all the oil out of a reservoir, and a distinction is therefore drawn between reserves in place and recoverable reserves. 

However it is measured, though, Ekofisk ranks as one of the very largest fields on the NCS. The original estimate for petroleum recovery from the field was 17 per cent. It is now expected to exceed 50 per cent – in part through waterflooding. 

Further reading

Halbout, Michel T, Giant Oil and Gas Fields of the Decade: 1968–1978. AAPG Memoir 30, 1980.  

 Ivar B. Ramberg – Inge Bryhni – Arvid Nøttvedt – Kristin Rangnes (ed.’s), The Making of a Land, NGF 2008


Published 23. September 2019   •   Updated 9. June 2023
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