Albuskjell 1/6 A

person Norwegian Petroleum Museum
Installed in 70 metres of water during 1976, Albuskjell 1/6 A came on stream in 1979.
Brief facts:
  • Installed in 1976
  • On stream 26 May 1979
  • Production ceased 26 August 1998
  • Removed 2007-13
  • Also known as Albuskjell Alpha
— Albuskjell 1/6 A. Photo: Husmo Foto/Norwegian Petroleum Museum
© Norsk Oljemuseum

The Albuskjell oil and gas/condensate field lay 21 kilometres north-west of the Ekofisk Complex and extended across blocks 1/6 and 2/4, licensed to Norske Shell and the Phillips group respectively. It was later unitised on a 50-50 basis.

Shell drilled discovery well 1/6-1X in 1972, in cooperation with Phillips, close to the boundary with block 2/4. The Albuskjell structure formed rather differently from other fields in the Greater Ekofisk area. Deposited 22-55 million years ago over a salt dome, its producing layer comprises carbonate rocks with some thin strips of shale.

Albuskjell 1/6 A produced from 11 wells and was tied back by gas and oil pipelines via Albuskjell 2/4 F to Ekofisk 2/4 R. A separate flare stack was linked to the platform by a bridge.

Processing comprised an oil/gas separator. Gas was dehydrated and compressed before export in a 24-inch pipeline. The separated oil was exported through an 18-inch line. Before being piped away, the oil and gas passed through a fiscal metering station to measure the volumes produced.

The platform was designed in a collaboration between Cork Shipyard, Oil Industry Services (OIS), Nylands Verksted, Tangen Verft, Aker Stord and Thyssen. Morco AS was the drilling contractor.

Like that on Albuskjell 2/4 F, the jacket (support structure) for 1/6 A was unusual because its two topmost frames were filled with water to prevent them heating up in the event of a fire. It was built at Aker Verdal, with the module support frame (MSF) fabricated by Aker Stord.

The living accommodation provided 46 beds, later 96.
The water depth was 70 metres.
Total weight of platform and pipelines was 25 300 tonnes.
The tip of the flare stack was 94 metres above sea level.
The derrick was 74 metres tall.

It was originally designed as a combined production, drilling and accommodation platform, but the derrick and drilling equipment were removed as early as 1979. The accommodation module with helideck was replaced in 1983 to increase beds from 46 to 96. The actual lifting operation was performed by the Balder crane barge from Heerema/Seaway.

When the Albuskjell field was shut in during July 1998, it had produced
46 million barrels or 7.353865 million standard cubic metres (scm) of oil
15.53439 billion scm of gas
990 139 tonnes of natural gas liquids (NGL)


Once a well has been fully drilled, it is completed for either production or injection. The purpose of well completion is to isolate the oil/gas production flow (wellstream) so that the whole path from reservoir to platform topside is leak-free.

This is achieved by running production tubing inside the casing (well liner) installed during drilling. These tubes are attached to the wellhead on the platform, which seals the top of the casing and provides a system for controlling pressure in the well.

Reservoir pressure causes crude oil/gas to flow up through the production tubing to the wellhead, which contains master and choke valves. These make it possible to shut down a producer or to adjust the desired volume of flow from each producer.

The Xmas tree (so called because of its shape) is installed on the wellhead. It contains control and work valves, such as the one for injecting diesel oil and various chemicals into the production tubing. Wellhead and Xmas tree form part of well control system.

The automatic master valve sits in the vertical section of the wellhead and is kept open by hydraulic pressure. Supported by the manual master valve, it represents the first barrier for shutting down the well.

Designed to cope with a substantial pressure drop, the choke valve is used to regulate wellstream flow and pressure from the individual well. This ensures that pressures in and production rates from all the wells are virtually identical.

The wellstream flowing through the choke valve is conducted to the production or the test manifold through a block valve before entering the separator on the platform.


The wellheads delivered a mix of crude oil, natural gas and water through either the production or the test manifold to the separators. This mix had to be split into its various components for further processing on the platform.

Albuskjell 1/6 A
Production separator in module P07. Photo: Jan A. Tjemsland/Norwegian Petroleum Museum

Measuring 20 metres long, the production separator was a horizontal tank with a diameter of four metres. It worked on the principle that the heaviest components in the tank would sink to the bottom while the lighter liquids and gas remained higher up.

This was a three-phase device with a lower phase of water, a middle one of crude oil and an upper gas phase. It was equipped internally with inlet deflectors, seven perforated guide plates and a demister for the gas outlet.

The test separator worked on the same principle, but was rather smaller. Its applications included testing the production rate from a single well so that the choke in the wellhead could be correctly adjusted.

Gas compression

Compression was needed to increase the gas pressure before it entered the pipeline which ran to Ekofisk 2/4 R. The train comprised a gas cooler, suction scrubber and gas compressor.

   Gas cooler. This reduced the temperature of gas emerging from the separator in order to prevent the compressor from running too hot. The gas circulated around a set of water-cooled tubes, lowering its temperature to 27°C.

   Suction scrubber. Once the gas was cooled, some liquids had to be removed in this device. It comprised a vertical tank four metres tall and two metres in diameter.

   Gas compressor. Driven by a gas turbine, this unit increased the pressure from 465 pounds per square inch gauge (psig) to 1 305psig while also raising the gas temperature from 27°C to 100°C.

Gas dehydration

albuskjell 1/6 a,
Drying unit - also called Glycol Contactor. Photo: Jan A. Tjemsland/Norwegian Petroleum Museum

Gas piped to Ekofisk 2/4 R had to be completely free of water to avoid ice or hydrate (hydrocarbon ice) plugs forming in the pipeline during transport through the cold seawater.

The gas was first cooled from 100°C to 27°C in two stages before being mixed with triethlyene glycol – a liquid which attracts water. After it had been dehydrated in this way, the gas was reheated to 65°C in a heat exchanger.

In all, the dehydration system comprised the gas/gas heat exchanger, the gas aftercooler and the glycol contactor.

   Gas/gas heat exchanger. This had two functions – cooling down the incoming gas from 100°C to 60°C and heating up the outgoing gas from 27°C to 65°C. Two gas streams passed each other in the unit.

   Gas aftercooler. This contained a number of water-cooled tubes which the gas circulated around to reduce the temperature from 60°C to 27°C.

   Glycol contactor. This unit comprised a vertical tank 13 metres tall by two metres in diameter. The gas bubbled up through a number of vessel filled with glycol and ended up dehydrated at the top. Water-saturated glycol was circulated out and replaced by more dry chemical.

Fiscal metering

Oil and gas processed on the platform and exported to the Ekofisk Complex was metered in a metering station on 1/6 A. Data from these instruments were transmitted to a Daniel computer for processing before being transferred to the Ekofisk Complex via a telemetric link.

Corresponding meters were also provided for gas consumed on the platform and for the flare boom.

 Gas metering. The gas meter comprised a tube containing pressure and temperature gauges, a densimeter and a flow orifice. When the gas passed through the orifice, its speed rose and its pressure fell. Knowing the density and composition of the gas meant the pressure drop could be used to measure the quantity exactly.

albuskjell 1/6 a
Meter Prover (this one at Edda 2/7 C). Photo: Kjetil Alsvik/Norwegian Petroleum Museum

Oil metering. A turbine flow meter was used to meter oil. Small magnets located on the outer edge of the rotor transmitted signals to sensors in the rotor housing. The latter could then measure the speed at which the rotor turned, and thereby arrive at the exact amount of liquid flowing through the meter.

Calibration. Such turbine flow meters had to be calibrated regularly to ensure accurate measurements. Known as a meter prover, this system comprised a horseshoe-shaped test loop which contained a rubber ball.

During calibration, oil was conducted through the loop and pushed the ball ahead of it. Measuring how long the ball took to complete the circuit, given that the loop’s exact volume was known, made it possible to measure oil flow accurately. These data were then compared with the pulses from the turbine flow meter.

Albuskjell 1/6 A
Tor Hindrumsen checks the control panel in the control room at Albuskjell 1/6 A. Photo: Jan A. Tjemsland/Norwegian Oil Museum

Control room

The control room was the platform’s heart, monitoring and controlling all important processes on board.


Glycol regeneration Glycol coming from the gas dehydration facility had a pressure of 1 205psig and was saturated with water and gas. After its pressure had been reduced, the gas was removed in a degassing pot.

The glycol was then filtered and heated in the regenerator to evaporate the water, and passed through pumps to reach the same pressure as the dehydration unit before being returned to it.

Gas pipeline pigging. To remove slag and water from the gas pipeline, a sphere was launched into it at 1/6 A and followed the gas flow to Ekofisk 2/4 R where removal took place.

Oil pipeline pigging. The pig in the oil pipeline had a different shape to the unit used for the gas pipeline, but otherwise functioned in the same way.

Power supply

Electricity for the platform came from the generator room, where four generating sets were driven by Kongsberg gas turbines. Two of these turbines were later removed and replaced by a diesel engine. Electric switchboards were installed in the module above the generators. The working voltage was 480V.

Other utilities

Other utilities on the platform included fire extinguishing and rescue systems, instrument air, chemical injection and drinking water.

Also provided were diesel and lube oils, gas lift equipment, a workshop, helideck, accommodation module, flare boom, radio communications and so forth.

Production ceased in 1998, and the platform became unmanned in 1999 with remote monitoring from Ekofisk 2/4 K. After the processing plant had been cleaned and the wells were plugged and secured, the platform was removed during 2013.

Published 24. March 2017   •   Updated 25. October 2019
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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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