Building the Statfjord A topside

person by Trude Meland, Norwegian Petroleum Museum
The Aker group had been commissioned by Mobil in August 1974 to fabricate and outfit the topside for Statfjord A. It had already undertaken similar contracts – Vindholmen Verft in Arendal had built the topside for Beryl A and Aker Verdal north of Trondheim was building a similar structure for Shell/Esso’s Brent B. Both these platforms were destined for the UK sector of the North Sea.
— The Statfjord A topside under construction in the dry dock of Aker Stord. Two old hulls, named Tom and Tina, were used as "foundations" for this work. Photo: Tor Resser/Norwegian Petroleum Museum
© Norsk Oljemuseum

Under the letter of intent signed between Mobil and Aker, the module support frame (MSF) for Statfjord A would be fabricated at Aker Verdal with outfitting by Aker Offshore Contractors (AOC). The latter also had the contract for mechanical outfitting in the shafts of the concrete gravity base structure (GBS).

When it turned out that the topside would be larger and heavier than first agreed, the Aker Verdal yard ran into capacity problems.[REMOVE]Fotnote: Haga, T. (1993). “Stordabuen går offshore” : Arbeid og faglig politikk ved A/S Stord verft 1970-83 (Vol. 1993-4, AHS (trykt utg.)). Bergen: Gruppe for flerfaglig arbeidslivsforskning, Universitetet i Bergen: 260. Stord Verft south of Bergen, which had only built ships – primarily oil tankers – before, was hit when the tanker market collapsed in the wake of the oil crisis. An order for 11 supertankers was cancelled, leaving the yard short of work.[REMOVE]Fotnote: Grove, K., Heiret, J., & Stord jern- & metallarbeiderforening. (1996). I stål og olje : Historia om jern- og metallarbeidarane på Stord. Stord: Stord metall- og bygningsarbeider[e]s fagforening: 161. og Myklebust, A., & Aker Stord A/S. (1994). 75 år på Kjøtteinen : 1919-1994 : Jubileumsbok for Aker Stord. Stord: [Aker Stord].

Bygging av A-dekket,
Statfjord A topside under construction at Stord Verft. Photo: Aker Mekaniske Verksted/Norwegian Petroleum Museum

Aker accordingly submitted a proposal to Mobil in February 1975 to transfer the job of building the Statfjord A topside from Verdal to Stord. Mobil accepted this, and Stord Verft thereby acquired its first offshore assignment. The contract was signed on 5 April 1975.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 178.

But Stord Verft was soon to discover that fabricating offshore structures differed significantly from shipbuilding. While the latter was a form of mass production, a platform had to be custom-built.

Bigger than expected

The original contract allowed Stord Verft to take on a wider scope of work. As initially conceived, the topside was to comprise a single MSF where the equipment was installed in modular form – almost like a large Lego construction.

Bygging av A-dekket,
The Statfjord A topside is starting to take shape. Foto: Aker Mekaniske Verksted/Norwegian Petroleum Museum

Since the yard had spare capacity, however, Aker initiated negotiations with Mobil on a new integrated structure. Rather than all the modules forming a conventional modular system, the support structures for a number of these would be incorporated in the MSF, and their equipment then installed in them.

The contract with Aker’s Stord Verft embraced the following elements.

Design and fabrication of the steel topside, with an estimated weight of 6 800 tonnes. This included steel procurement, towing the topside to the mating site and mating with the Condeep GBS.

Design and fabrication of the MSF for the integrated M6, M8, M11, M12, M14, M17, M18 and UM7 modules and installation of the deck, with an estimated weight of 1 828 tonnes. This also included steel procurement.

Outfitting the cellar deck and the above-mentioned modules. This would be done to the extent that approved drawings, specifications, equipment and materials were available at Stord Verft.

While contract negotiations were under way between Aker and Mobil, appraisal wells being drilled on Statfjord revealed that the field was larger than originally thought. On the basis of that knowledge, it was resolved to double production capacity on the platform from 150 000 barrels per day to 300 000. In order to be able to handle such large volumes of oil, the topside facilities had to be expanded from one to two process trains. That naturally doubled the size and weight of the equipment. This in turn meant that the MSF had to be strengthened to handle the weight.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 141.

A partially integrated topside would be significantly more complicated, but Aker justified the design changes submitted to Mobil on 6 February 1975 by noting that steel weight would be reduced. Mobil accepted the revised design and a new contract was signed on 5 April 1975.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 178.

This meant a welcome increase in the scope of work for Stord Verft. A number of the modules were originally due to be fabricated at other yards and engineering works in Norway and abroad which were also struggling with the after-effects of the oil crisis. Because Stord Verft was now going to integrate these modules in the MSF, the other fabricators lost sorely needed work.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 183. Modules were built by Kværner/Sterkoder in Egersund and Kristiansund (M1A, M1B, M2, M10, M13, M16, UM8, UM9 and the toolroom), Nordland Offshore A/S in Sandnessjøen (UM9B and the telecommunications module), Bodø Mekaniske Verksted (UM2 and M10 top), Wilson Walton, Middlesbrough (M3, M5 and M9), and Curtis Wright/RSV in Rotterdam (M4A, M4B, UM5 and UM6). In addition, Norway’s Leirvik Sveis completed M9. 

In retrospect, it is clear that the local management at Stord Verft took an unrealistic view of the transition from shipbuilding to platform construction. A topside for what then ranked as the world’s largest offshore installation was far more complicated, and new standards had to be met – particularly for welding.

The amount of engineering design work was greatly underestimated, and detailed design proved the first casualty. While the yard had been accustomed to using its own drawing office, it now received detailed drawings from Matthew Hall Engineering (MHE) in London. The latter had the contract for the technical design of outfitting and process equipment.

Design job too extensive

MHE had won an engineering management contract (EMC) for the Statfjord A topside (see the section on the construction contracts for more details). This job embraced conceptual and technical design, management of process equipment and modules – including procurement – award of fabrication contracts and construction site supervision.

Although the EMC had been put out to competitive tender, a tight market meant that Mobil received only two bids. The operator had been concerned from the start about MHE’s lack of experience with similar projects, but had no choice but to award it the contract if the schedule was to be maintained.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 168.

It quickly transpired that the design work failed to meet the required standard and would be delayed. MHE had estimated 400 000 hours for the work, with 90 per cent completed by the end of 1975. But the company ran into problems.

In addition to insufficient experience with such projects, it lacked enough personnel and had up to 80 per cent contract workers at one point. When the decision was taken to change the concept to a partly integrated topside, MHE had already been working for nine months on planning the process equipment. A completely new concept meant that the company had to start all over again, and many working hours were wasted.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 169.

Only 50-60 per cent of the design work was completed in January 1976, and the number of hours was four times higher than the estimate. Mobil resolved to cancel the contract with MHE and brought in a US engineering contractor – Brown & Root – to replace the London-based company on a gradual basis. Mobil regarded Brown & Root as the best qualified candidate for the job, and awarded the contract without competitive tendering.

In October 1975, Brown & Root also took over the contract for planning, management and execution of offshore hook-up work from MHE. It already had the job of technical design and management for work on the loading buoy, flare boom and flowlines.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 156. This meant that the company now held all three of the major assignments for completing Statfjord A.

Topside weight increases

The factor which caused the biggest problems in planning and building Statfjord A was a massive underestimating of the weights involved.

Bygging av A-dekket,
Stord Shipyard estimated the hours of extra work as result of the weight problems to 150,000 hours, which corresponded to about NOK 75 million including materials. Another consequence of the reinforcement work was failure in the supply of materials. The amount of steel ordered was based on the initial estimates and was therefore too small. With a tight market, delivery time was long. Photo: Aker/Norwegian Petroleum Museum

A platform’s weight can be measured in two ways – wet and dry. Wet weight is measured in operating condition with the various process components are filled with liquids. The GBS and topside are designed to cope with a given weight, and the wet weight must not exceed that level. The dry weight is the sum of MSF and equipment alone. A platform is towed out fully or partly outfitted, and the dry weight of the topside must not exceed the tow-out value.[REMOVE]Fotnote: Rolstadås, A., & Norges tekniske høgskole Institutt for verkstedteknikk. (1981). Prosjektstyring. Trondheim: Tapir: 137.

MHE lacked a satisfactory system for either wet or dry weight control. The most accurate possible weight estimates for both MSF and production equipment were already required in early 1975 in order to design the topside. But the wet weight calculations produced by MHE were too low.

Disputes arose between the design company on the one hand and Stord Verft/Aker on the other about the loadbearing capacity of the topside. MHE’s estimate was 34 500 tonnes, while the contract with Stord Verft stipulated 41 500 tonnes. The overall weight ultimately came to 49 500 tonnes. Extensive design work was required to ensure that the MSF could bear this weight. That in turn led to big delays and significantly more expensive fabrication work.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]: 164.

During the fabrication period, MHE’s engineers fell behind with the design work. In an attempt to speed up progress with the technical design, MHE issued incomplete drawings. This meant that the number of drawing revisions and fabrication changes increased. When drawings were amended, structures already installed had to be ripped out and the work done again.

Tow-out weight restriction

The tow-out or dry weight also caused problems. The loadbearing capacity of the Condeep imposed restrictions on the amount of equipment which could be positioned topside before departure for the field.

It turned out that the maximum tow-out weight was significantly lower than the hardware to be installed. Modules accordingly had to be removed for installation once the platform had been positioned on Statfjord. Such assembly and disassembly, both for this reason and because of revised drawings, had a negative effect on the motivation of the workforce at the Stord yard.

Welding is not just making welds

Welders were the largest group of workers involved in fabricating the Statfjord topside. They quickly discovered that welding tankers and oil installations were two different exercises. The former demanded other material types and thicknesses than were used on ships, and the new kind of steel demanded a different welding technique. In addition, the quality of the work had to be improved and its accuracy improved.

Mobil required that all the welders were certified to specified standards. Instead of the earlier approval by Norway’s Det Norske Veritas (DNV), the American ASME norm was introduced. This was divided into six levels, from 1G as the lowest up to 6G. To secure a 6G certificate, a welder had to be able to weld around a pipe positioned at an angle of 45 degrees while welding “through” – in other words, so that the joint is filled.

Many former ship welders failed to pass the tests for the new certificates, and the yard eventually had problems securing sufficient skilled personnel. Since the work was already behind schedule, the management wanted to bring in foreign welders. But this had first to be cleared with the unions. Welders were brought in from other Aker companies to help out. The shortage of welders meant that prefabrication lagged behind, and delays there had a knock-on effect on assembling the topside.

Welds were carefully X-rayed and checked. The yard was told that each weld had to be marked with a number, so that possible faults could be traced directly back to the welder who had done the job. As the work progressed, it became clear that a number of welds had to be redone. If the checks showed more than five per cent error in a weld, it was rejected. A welder who had too many rejects had to be recertified.[REMOVE]Fotnote: Grove, K., Heiret, J., & Stord jern- & metallarbeiderforening. (1996). I stål og olje : Historia om jern- og metallarbeidarane på Stord. Stord: Stord metall- og bygningsarbeider[e]s fagforening: 170. By March 1976, fabrication was far behind schedule.

Pipework

The pipefitters also found that their work changed with the transition from ships to platforms. There was considerably more pipework and it was more monotonous. The piping was prefabricated and much of the work previously done by the fitters arrived ready-made. Piping was lifted on board from the warehouse by crane.

When ships were still being built, detailed drawings were supplied by the yard’s own engineers, but the individual foreman or fitter could change them if he found it appropriate. That was no longer the case.[REMOVE]Fotnote: Grove, K., Heiret, J., & Stord jern- & metallarbeiderforening. (1996). I stål og olje : Historia om jern- og metallarbeidarane på Stord. Stord: Stord metall- og bygningsarbeider[e]s fagforening: 169. Drawings supplied from London had to be followed to the smallest detail, and all changes had to be reported. The independence and scope of the work was reduced.[REMOVE]Fotnote: Myklebust, A., & Aker Stord A/S. (1994). 75 år på Kjøtteinen : 1919-1994 : Jubileumsbok for Aker Stord. Stord: [Aker Stord].

Working conditions in the workshops were also poor. The worst problem was the heat. The platform steel had to be preheated to 150°C before it could be welded. Although fresh air was blowing into the welding areas to thin out the gases, no effective ventilation was in place. There were smoke and fumes everywhere, while greater use of angle grinders and carbon rod welding increased the noise level.

The Stord Verft workforce noted the transition to the offshore industry directly. Their work became less independent, delivery times were shorter and physical working conditions deteriorated. The many change jobs had an unfavourable impact of their morale, and productivity declined.[REMOVE]Fotnote: Grove, K., Heiret, J., & Stord jern- & metallarbeiderforening. (1996). I stål og olje : Historia om jern- og metallarbeidarane på Stord. Stord: Stord metall- og bygningsarbeider[e]s fagforening:172.

To offset this decline in efficiency, the workforce was expanded to 950 people between June and December 1976. But this did not increase the amount of work actually done.

Designing equipment which was to last “for ever”, and which would never again be seen or accessed, was unusual and challenging. No design codes existed for offshore petroleum projects in 1975. When mechanical engineer Einar Jensen at AOC worked on the rotating machinery, he and his team used design codes developed by Mobil for use on land and DNV codes for shipboard use.

Nobody had ever designed such a large and complex structure as Statfjord A, with all its criss-crossing pipes.[REMOVE]Fotnote: Interview with Eilef Lynghaug, Einar Jensen and Jan-Henry Larsen, former platform managers on Statfjord, by Trude Meland, Norwegian Petroleum Museum, 18 September 2008.  To begin with, all the piping was marked. But these marks were subsequently covered with insulation, so the work was wasted.

Postponement

Bygging av A-dekket,
The Statfjord A topside at Stord Verft. Photo: Aker Mekaniske Verksted/Norwegian Petroleum Museum

Mobil eventually grasped the seriousness of the position, and realised that tow-out of the platform would have to be postponed for a year. It could not go out to the field before the summer of 1977.

In statements to the media, the company emphasised that more of the work on the installation could thereby be done inshore rather than more expensively and lengthily out on the field:

“The more equipment which can be installed on the platform while it is inshore ¬– according to plans, at Stord, the better. In this way, the time at land can be exploited and difficult and expensive work avoided on the field in the North Sea.”[REMOVE]Fotnote: Stavanger Aftenblad, 13 May 1976.  “Størst mulig last en fordel”. 

Because of the maximum tow-out weight, however, this plan could not be fully implemented.

Despite the problems, the MSF was eventually completed. This work had taken place in the yard’s dry dock, but the gates were opened on 30 July 1976 and the structure was towed out into the fjord. At the same time, the GBS was on its way from Stavanger to Stord.

The MSF had been built on two redundant tankers – known as Tom and Tina. When the topside was to be mated with the GBS, the latter was ballasted down until it was almost entirely submerged and the two tankers were manoeuvred between the concrete shafts.

Deballasting the storage cells then raised the GBS, so that the topside was carefully positioned on and then lifted by the shafts.[REMOVE]Fotnote: Godø, H. (1980). Plattformutbygging til havs (Vol. Nr 11-1980, Sosialdepartementets sammendragsserie (rapportsammendrag : trykt utg.)). Oslo: Sosialdepartementet: 45. This mating operation took place on 8 August 1976, and work then continued out in Digernessundet.

Leaks

But the problems were not over. Cracks in the GBS were discovered in 1976 during maximum submersion in connection with the mating operation. They had arisen as a result of excessive temperature fluctuations and a weak section in the concrete. It took two months to repair the damage.[REMOVE]Fotnote: Hanisch, T., Nerheim, G., & Norsk petroleumsforening. (1992). Fra vantro til overmot? (Vol. 1). Oslo: Leseselskapet: 392. Einar Jensen experienced this episode:

“It was a Friday evening, I think, and we were on our way home to Stavanger. When the high-speed ferry berthed, the project manager was standing there and waving us to one side. We went directly to Sola [airport] and into a specially booked plane. Statfjord A was listing. The platform was shipping water in its cells. Four-five of us were involved. There was little drama, but we took in a good deal of water and didn’t know where it was coming from.”[REMOVE]Fotnote: Interview med Einar Jensen by Trude Meland, Norwegian Petroleum Museum, 2 October 2008.

It transpired that there were two cracks, each 20 centimetres long, in the concrete between one “star” cell and a storage cell. The GBS was taking in 15 000 litres of water per hour or 20 buckets a minute.[REMOVE]Fotnote: Stavanger Aftenblad, 14 September 1976. “20 bøtter i minuttet”. But the structure was never in any danger of tipping over or sinking. The pumps installed in the GBS were capable of discharging a million litres per hour, and had no problem controlling the water intrusion. Without the pumps, the GBS would have sunk 60-70 centimetres per day because of the extra displacement caused by the water.

People from AOC and Norwegian Contractors (NC) devoted the weekend to identifying what had happened. When the cracks were located, NC – the company responsible for the concrete structure – injected them with epoxy, a special and elastic form of concrete. Sealing the cracks was a big job, and the incident led to delays. Installing such modules as the living quarters and the helideck had to be postponed until the damage was repaired.[REMOVE]Fotnote: Hanisch, T., Nerheim, G., & Norsk petroleumsforening. (1992). Fra vantro til overmot? (Vol. 1). Oslo: Leseselskapet: 392.

Two months later, Statfjord A listed again while it was lying in Digernessundet. A test of the emergency shutdown procedure for the ballast system went wrong. The living quarters had been installed at one end of the topside, and differing levels of ballast water in the various cells was used to compensate for the added weight. A service operative from the Swedish factory which had delivered the ballast system was going through the procedure for testing the hydraulics. Einar Jensen reports what happened:

“The procedure involved placing each valve in a semi-open position, and then pressing a red button and timing how long it took to shut down. There were 16 cells with ballast water. He tested first one valve and then another. Everything seemed to be working fine. The final stage in the procedure was to place all the valves in a semi-open position and then press the big button. Since we had varying water levels, things began to happen and the platform started to list. The alarms sounded, and the big button fortunately worked. We had a well-qualified man in the control room who pressed the button as soon as he saw the platform begin to list.”[REMOVE]Fotnote: Interview med Einar Jensen by Trude Meland, Norwegian Petroleum Museum, 2 October 2008.

The procedure followed would have been correct for a system which was not in operation. Since the system on Statfjord A was in fact operational, the final stage should have been left out.

This was a serious incident. The platform listed by three degrees, which means that the topside sank by eight-nine metres along one side.[REMOVE]Fotnote: Gjerde, K., Ryggvik, H., & Gooderham, R. (2014). On the edge, under water : Offshore diving in Norway. Stavanger: Wigestrand: 158. It was evacuated, and nobody was hurt. Subsequent reports have alleged that people jumped from the topside, but Jensen denies this:

“People didn’t jump from the topside, but a scaffolding ladder was installed on each side down to a barge on the water. When the platform listed, the stair on one side became far too short, so that when you reached the bottom step the surface was still some way down. It’s possible that some people who went down those stairs jumped, but I can’t confirm it.”[REMOVE]Fotnote: Interview med Einar Jensen by Trude Meland, Norwegian Petroleum Museum, 2 October 2008.

When Mobil decided that the tow-out of Statfjord A should be postponed by a year, a new date was also set – 3 May 1977. That deadline was met, and the platform was in position on the field by 8 May.

Grouting – filling the space between the GBS base and the seabed with gravel – started two days later. The remaining work of completing Statfjord A and readying it for production could then begin. Much work and many challenges were still to come.

Published April 5, 2018   •   Updated May 13, 2020
© Norsk Oljemuseum
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The Statfjord B letter

person by Trude Meland, Norwegian Petroleum Museum
Preparations for building the Statfjord B platform were well under way in the autumn of 1976. But the Norwegian Petroleum Directorate, as the regulator responsible for offshore safety, had its own views on the project. It expressed these in a letter sent to operator Mobil on 11 November 1976, which came to change all the plans.
— Norway's most expensive letter, it was called, the letter that instructed the Statoil/Mobil group to change the structure of Statfjord B.
© Norsk Oljemuseum

At that time, contract negotiations had been pursued with Norwegian Contractors on building a four-shaft Condeep gravity base structure (GBS). They were at the point where a letter of intent was ready.

The recently established Norwegian Petroleum Consultants (NPC) joint venture had also signed a contract on project management and engineering design for Statfjord B. Read more about NPC in the section on Statfjord B – the first plan.

While the contract for building the platform topside and mechanical outfitting of the GBS shafts had yet to be awarded, an option agreement had been secured with the Aker group.

So all the main contracts for the project appeared to have been put in place. The Storting (parliament) had also approved phase II of the development plan in June 1976, and most people assumed that it was simply a case of starting to build.

Until the NPD letter arrived

The Vogt commission

brevet,
The Statfjord B topside. Photo: Mobil Exploration Norway Inc./Norwegian Petroleum Museum

New safety regulations for the Norwegian offshore industry had been adopted on 9 July that year. A key issue for Statfjord B and the field licensees was the introduction of a more restrictive attitude towards simultaneous drilling and production combined with living quarters on a single integrated platform.

The new rules had been developed by a commission of inquiry appointed by the government as early as 22 May 1970 with a mandate to propose regulations for the safety of production and storage facilities on the seabed and of exploiting petroleum deposits.[REMOVE]Fotnote: Norsk Oljerevy. (1976). no 2. Kontroll med sikkerheten fordelt på ni instanser. 

Work in the commission progressed slowly and its chair, Jens Evensen, asked to be relieved. He was replaced in November 1972 by director general Lars Oftedal Broch, who was replaced in his turn during May 1974 by Nils Vogt from the NPD.

The latter gave his name to the commission’s report, which was submitted to the Ministry of Industry on 12 July 1975. It was then circulated for consultation to affected companies and institutions.[REMOVE]Fotnote: Hanisch, T., Nerheim, G., & Norsk petroleumsforening. (1992). Fra vantro til overmot? (Vol. 1). Oslo: Leseselskapet: 324.

Adopted by royal decree of 9 July 1976, the new safety regulations were based on the recommendations of the Vogt commission and on comments received in the consultation process. One provision of the decree was that the NPD would bear primary responsibility for supervising fixed offshore installations.

Safety issues on Statfjord were viewed by the directorate through the prism of the new regulations. It kept the industry ministry informed about its work, and wrote the following in a letter dated 7 July 1976:

“Given the work being done on safety conditions, it has been found necessary to adopt a more restrictive attitude to those concepts which are based on combined drilling and production, where the living quarters are also placed on the same platform. The main intentions of the Vogt commission’s recommendations run counter to both combined activity and the above-mentioned placement of living quarters … The NPD would emphasise that combined drilling and production will only be accepted following individual analyses and assessments. The same applies to living quarters which it is proposed to place on a drilling/production platform. No final choice of concept has been made for Statfjord B, so no specific safety analysis has been submitted. Comments from the NPD will accordingly have to wait until it the actual conditions have been presented.”[REMOVE]Fotnote: Norsk Oljerevy.

In other words, the ministry had been informed of the NPD’s work and of its scepticism about the plans for Statfjord B. As the letter indicated, the regulator could not adopt a final position until the Statfjord Unit Operating Committee (SUOC) had approved the concept chosen for the B platform in late August 1976. Only then could the NPD conduct its own safety analysis.

Brevet,
It was called Norway's most expensive letter. The letter instructed the Statoil/Mobil group to change the structure of Statfjord B.

The results of the latter were presented to the Statfjord licensees in the above-mentioned letter of 11 November 1976, where the NPD questioned the safety of an integrated platform and ordered the construction of a separate quarters platform:

“The NPD is currently assessing the concept for Statfjord B on the basis of a general evaluation of the safety rules on the field in the light of the new regulations (royal decree of 9.7.76)

“Statfjord B is expected to involve:

  • particularly complex and extensive production facilities concentrated on a single platform
  • a large number of producing wells with high capacity, along with water and gas injection
  • permanent living quarters for 200 occupants, which will be used by 400 people during the construction phase and possibly the drilling phase
  • possible simultaneous drilling and production.

“The total risk is characterised by the contributions from each of the activities and processes which include the examples given above. The NPD’s assessment is that the total risk associated with these conditions lies at too high a level.

“In the NPD’s view, the best way to reduce the total risk would be to reduce the number of people who are present on the platform at any given time. The NPD has accordingly concluded that a separate quarters platform connected to Statfjord B should be built.”

This safety assessment was not confined to Statfjord B. Questions were also posed about the A platform, construction of which was far advanced at the time. It was due to be towed out to the field in six months.

“The considerations mentioned above also apply to Statfjord A, if to a somewhat lesser degree. The NPD would accordingly, on the basis of the provisions in the royal decree of 9.7.76, request that the company undertakes a new overall assessment of safety conditions [on this installation] in relation to the planned drilling and production programme, with particular attention paid to the accommodation issue.”

This letter was signed by Gunnar Hellesen, chair of the NPD board, and director general Fredrik Hagemann.

New concepts proposed

Statfjord B was intended to be a virtual copy of the A platform, but with four support shafts instead of three. The process facilities would be equally large and complex, with a production capacity of 300 000 barrels per day, and the 200-berth quarters module was to be installed on the platform.

It was the last feature in particular that the NPD wished to prevent. The regulator took the view that cutting the number of people on the platform at any given time would reduce the overall risk.

As the letter indicates, the desirable solution was seen to be the construction of two platforms – one for production and drilling, and the other for accommodation. The NPD also emphasised the need for overall safety thinking, and wanted a separate safety study carried out before detailed planning began.

Statoil and Mobil expressed surprise at the letter, and claimed they had not heard that such assessments were being made. Arve Johnsen, then Statoil’s chief executive, described his reaction to the letter in his book Utfordringen (The Challenge): “As chief executive of Statoil, I received many kinds of letters … I have forgotten most of them, but I will remember one to my dying day … It sent a shock wave through the licensees in the Statfjord group.”[REMOVE]Fotnote: Johnsen, A. (1988). Utfordringen : Statoil-år. Oslo: Gyldendal: 202.

It might seem incomprehensible that the partners had failed to see this coming. They had long been aware that the NPD was looking at problems associated with simultaneous drilling and production, and the Vogt commission’s report had been through a consultation process. Comments in the latter as well as the report itself formed the basis for the new safety regulations.

Adopted in June, four months before the letter was despatched, the regulations specified that simultaneous drilling and production was prohibited without special permission. This should have sent certain signals that the plans for Statfjord B might be more difficult to implement than Mobil and Statoil thought.

As late as 12 October, section head Harald Ynnesdal had explained the NPD’s view on the issue in a speech he gave in Kristiansand:

“The new platform types are particularly complex and difficult to assess from a safety perspective with regard to these combined activities. As far as possible, fields should be planned with separate quarters platforms. The production platforms could then, with their combined activities, be assessed purely as industrial plants.

“In an assessment of simultaneous drilling and production in the Statfjord project, for example, the problem would have been much simpler if separate quarters platforms had been adopted. The cost of such platforms would have had little effect on profitability for this project, but would have meant a great deal for overall safety and the desire for an early start to production.”[REMOVE]Fotnote: Norsk Oljerevy. (1976). no 9. Statfjord – planer og virkelighet. On the basis of this letter, an extraordinary meeting of the SUOC was called on 26 November. It decided that all activities related to Statfjord B would be halted. The project would have to be re-evaluated, and extensive conceptual studies were to be carried out for every option from one to three platforms.

brevet,
" two giants become four little ones" Headline from Aftenposten 25. juni 1977

A meeting of the Statfjord field engineering committee (SFEC) – the technical project team – took place in January 1977. A 35-strong sub-committee was appointed to study and assess various conceptual solutions for Statfjord B, and came up with 39 variants for consideration.

When the SUOC met again on 18 March, Statoil expressed concern at the progress made. The project had a tight timetable, and order books at the Norwegian shipyards were empty. To speed up the process, the company proposed a separate drilling platform linked by a bridge to a combined production and quarters unit.

A drilling platform supported on a steel jacket, for instance, would be relatively cheap to build and could be ready for tow-out as early as 1979. Drilling of production wells could start as soon as the platform was in place, and continue while the associated production and quarters facility was under construction.

As soon as the latter had been installed, oil and gas could thereby begin.[REMOVE]Fotnote: Norsk Oljerevy. (1977). no 5. Industrien må fortsatt vente på Statfjord B.  This meant in turn that the original schedule set in the field development plan could be met.

Mobil and Saga were strongly opposed to this plan, but did not have enough votes to block it. Their interests added up to only 25 per cent, while resolutions in the SUOC needed 70 per cent support. The Statoil proposal was thereby adopted – against the operator’s vote.

Esso also proposed its own solution at the meeting, comprising an integrated production, drilling and quarters (PDQ) platform but with processing capacity halved to 150 000 barrels per day. This facility would be simpler, since only one process train was required rather than the original two, and overall safety would be improved.

Mobil supported the Esso proposal. The two companies were uncompromising in their opposition to two platforms, and maintained that this would provide no safety benefit. A factor in their assessment was the poor seabed soil conditions on Statfjord, which meant that installing two platforms so close to each other and linked by a bridge carrying high-pressure pipelines would pose a safety risk.

The thought of the substantial capital investment required for two platforms also worried the operator. On the other hand, experience from other North Sea projects suggested that a capacity of 150 000 barrels per day would be sufficient. Such a solution would reduce construction costs by simplifying the platform, and production could also start earlier.

Threats

A further meeting of the SUOC was held on 28 April, when Mobil proposed an integrated platform with a single process train and an average capacity of 180 000 barrels per producing day. This size had been chosen in the hope of avoiding a separate quarters platform.

The change to the original concept was so large that a completely new field development plan might have to be produced. According to the proposals approved the Storting in the summer of 1976, three platforms with a combined capacity of 900 000 barrels per day were to be installed.

Reducing the size of the process facilities on each platform would either require more structures to maintain the planned output, or a slower pace of production.[REMOVE]Fotnote: Norsk Oljerevy. (1977). no 5. Industrien må fortsatt vente på Statfjord B.  Fresh consideration by the Storting could delay the project further.

At the same time, Mobil vetoed a separate quarters platform.[REMOVE]Fotnote: Moe, J. (1980). Kostnadsanalysen norsk kontinentalsokkel : Rapport fra styringsgruppen oppnevnt ved kongelig resolusjon av 16. mars 1979 : Rapporten avgitt til Olje- og energidepartementet 29. april 1980 : 2 : Utbyggingsprosjektene på norsk sokkel (Vol. 2). Oslo: [Olje- og energidepartementet]. With strong support from Esso, the operator noted that it could not accept a solution which complied with the NPD’s principle that drilling and production should not take place simultaneously on the same installation.

Brevet,
" Platform living quarter confrontation" Headline from Aftenbladet 28. juni 1977

Clear instructions had been sent from Mobil’s head office in New York that a compromise solution which would involve an acceptance of the NPD principle was out of the question. It feared that conceding this demand from the Norwegian regulator could lead to similar requirements on other continental shelves, which would have major consequences for both Mobil and its fellow oil companies.

A telex from New York emphasised that, the way things looked, concrete platforms on the scale of Statfjord A had outplayed their role on this field. Mobil was willing to renounce the operatorship for Statfjord B if a two-platform solution was adopted. This attitude took Statoil and the Norwegian government by surprise.[REMOVE]Fotnote: Norsk Oljerevy. (1977). no 5. Industrien må fortsatt vente på Statfjord B. 

Statoil explored the possibility of another operator, but none of the other partners was willing to take on the role without a reallocation of licence interests. Mobil and Esso had staked their prestige on the issue, and they finally managed to convince Statoil of the technical problems posed by a two-platform solution. The argument that this could affect later developments in deeper water was central to the Norwegian company’s change of mind.

The discussion on one or more platforms and the studies of various concepts were paralleled with the presentation of new seismic data for the field. These cut its estimated oil reserves from 3.9 billion barrels – equivalent to 527 million tonnes – to 3.2 billion or 432 million tonnes. That reduced the need for two process trains on Statfjord B.

Clarification

On 5 August, the SUOC approved plans for a platform with the capacity to process 180 000 barrels per day. It was resolved on 29 November to apply to the NPD for permission to build such a structure. The application, accompanied by a separate safety study, was submitted on 1 December.

Plans now called for Statfjord B to be installed in 149 metres of water at the southern end of the field. Seabed conditions were poorer there than over the rest of Statfjord, and the base area of the GBS accordingly had to be increased.

While Statfjord A had 19 cells, the B version would have 24. Planned topside space would expand correspondingly, from 5 200 square metres to 7 800. The platform would still have four shafts even though only one process train was to be installed. With the fourth shaft reserved for risers, space was freed up in the others.

Additional safety barriers were introduced by the decision to make the decks and modules open, reducing the danger of an explosion and possible damage from such an incident. The various functions would also be positioned in such a way that no hazardous operations were close to or beneath the living quarters. And the quarters modules would be protected by an additional fire wall. These plans were approved by the NPD on 19 December.

The project had been delayed by a year and incurred substantial costs through a number of conceptual studies and reports. According to Henrik Ager-Hanssen, deputy chief executive of Statoil, the letter from the NPD was the most expensive in Norwegian history and cost the project NOK 25 million per word.

Viewed from a different perspective, former Statoil staffer Bjørn Vidar Lerøen has noted that oil prices reached record levels over the next few years. That meant the letter became one of Norway’s most profitable.[REMOVE]Fotnote: Lerøen, B., Gooderham, R., & Statoil. (2002). Drops of black gold : Statoil 1972-2002. Stavanger: Statoil: 149.

Published May 23, 2018   •   Updated May 5, 2020
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Gas pipeline agreements

person By Håkon Lavik, former Statoil employee
The sale of gas from Statfjord made it necessary to connect the platforms with flowlines to gather gas for export via the Statpipe system. Oil flowlines also linked the platforms, but these had been installed as part of the field development.
— Statfjord field with associated gas pipelines. Source: Storting Report 39 1984–85
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A separate project, the Statfjord intrafield pipeline system (Sips), was established to engineer and install the gas lines. Once the work had been completed, Sips was taken over, owned and operated by the Statfjord Unit. In formal terms, Sips
forms part of the Statfjord Facilities – in other words, all the platforms, flowlines, wells and so forth which have been developed to operate the field.

Since the British licensees in Statfjord were not allowed to sell their gas to continental Europe, a separate UK Gas Offtake pipeline was laid as part of Sips from Statfjord B to the UK side of the boundary. There it tied into the Northern Leg Gas Pipeline (NLGP), a gas gathering line for fields north of Brent. The Statfjord Unit owns that part of the UK Gas Offtake line which lies within its boundaries, while the British licensees own the section to the west, including the NLGP tie-in. The UK government demanded the inclusion of a non-return valve in this line, so that British gas could not be conducted to Statfjord B.

This line was regulated by the Agreement for Installation and Tie-in of the UK Pipeline to the Statfjord B Platform and to the Northern Leg Gas Pipeline , which entered into on 1 February 1983. The UK Statfjord Gas Offtake Operating Services between Mobil Exploration Norway Inc and Conoco (UK) Ltd service agreement was also signed on 27 September 1985. A gas pipeline was laid from Gullfaks A to Statfjord C under a separate Agreement for Tie-in and Operation of the Gullfaks Pipeline to the Statfjord C Platform between the two sets of licensees,   dated 27 September 1984.

Gas from Gullfaks was carried via Sips before entering Statpipe until the end of the 1990s, when Gullfaks acquired a new tie-in to Statpipe south of Statfjord. Gas transit via Statfjord accordingly terminated, but the pipeline from Gullfaks is still intact and usable and the tie-in agreement remains operative.

Statpipe tie-in

Gassrøravtaler,
Statpipe map from Gullfaks brochure 1984. Illustration: Equinor

Although the Statpipe system starts from the field, it does not form part of the Statfjord Unit. A separate pipeline and transport company was established after the gas from Statfjord, Gullfaks and Heimdal had been sold in 1982.

The purpose of this joint venture was to install pipelines and build the Kårstø processing plant north of Stavanger in order to export gas from the Norwegian continental shelf (NCS) via Ekofisk to Emden in Germany. Where Statfjord was concerned, this meant that a contract was signed on 12 July 1984 between the Statfjord Unit and Statpipe concerning the tie-in of the pipeline to Statfjord and its subsequent operation.

 Statfjord B serves as the starting point for Statpipe, and the valve system on the seabed is operated from that platform. But it was Statfjord C, via Sips, which was responsible for maintaining pump pressure in the pipeline and ensuring that the gas flowed to Kårstø.
Statpipe later became part of the Gassled joint venture, and the section from Statfjord to Kårstø now lies in Gassled’s tariff zone 1. In connection with the Statfjord late life (SFLL) project, the connection between Sips and Gassled was severed in 2007. Statfjord B now provides the connection with Gassled.

Statpipe-Statfjord transportation agreement

Dated 30 September 1985, this contract secured transport rights in Statpipe for the Norwegian share licensees in Statfjord. The agreement still exists in principle, but was converted on 1 January 2003 to individual contracts for each licensee following the adoption of the EU’s gas directive. Each company accordingly has its own transport agreement. That was also the original position, but based on a single contract.
Similarly, each of the licensees in the Norwegian share of Statfjord had separate sales agreements for its proportion of the gas with the buyer consortium in continental Europe. These contracts were terminated in 2007, since the volume sold under them was deemed to have been delivered. Statfjord gas, including output from the SFLL project, is sold today to the UK.

Tampen Link

Gassrøravtaler,
Tampen Link. Illustration: Equinor

As part of SFLL, the decision was taken to lay a new pipeline from Statfjord to tie into the Far North Liquids and Associated Gas System (Flags) in the UK North Sea. The latter runs from Brent to St Fergus in Scotland.
Tampen Link is a separate company operated by Gassled. Dated 22 February 2005, the contract related to Statfjord has a long name: Agreement Between the Tampen Link Joint Venture and the Statfjord Group for the Installation and Tie-in of the Tampen Link Transportation Facilities to the Statfjord Facilities and the Operation of the Tampen Link Statfjord Facilities and the Operation of the Tampen Link Statfjord Facilities and the Transit Services at the Statfjord Facilities.
This agreement makes it possible to transport gas from Statfjord directly to Flags and the UK, and from other fields in transit via Statfjord to the same destination.

Crossing agreements

Since Statfjord is a hub for oil and gas exports from the northern North Sea, a number of pipelines large and small have been laid. Where these cross over each other, a crossing agreement has to be established. You cannot simply lay your pipeline over one belonging to somebody else and possibly cause damage. This must be regulated.

The following agreements have been established so far:

  • Crossing of the Statfjord B Pipeline and the Statfjord Control Umbilical by the Penguin Pipelines and Cable , dated 22 March 2002. (Penguin is a small UK field tied back to Brent.)
  • Pipeline Crossing and Laying Agreement Between Statfjord Unit and Sygna Unit , dated 14 April 2000.
  • Pipeline Crossing Agreement Between Statfjord East and Statfjord North Flank , dated 1 April 1999. (the north flank is the northernmost part of Statfjord, developed with subsea wells).
  • Pipeline Crossing Agreement Between Tampen Link and Statfjord Unit , dated 20 November 2006.

Published October 30, 2019   •   Updated February 18, 2020
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Changing the operator

person By Håkon Lavik, former Statoil employee
Transferring the Statfjord operatorship from Mobil to Statoil ranks as one of the biggest controversies in Norwegian oil policy. The 1973 licence allowed a change of operator to be requested 10 years after a discovery was declared commercial, and Statoil asked to exercise this right in 1984. Mobil was opposed, and felt it would suffer a huge loss of prestige from such a transfer.
— Statoil takes over operator responsibility from Mobil. Martin Bekkeheien and Mike Smith pictured together with a model of Statfjord A. Photo: Leif Berge/Equinor
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The US major at least wanted a visible compensation for the loss of the operatorship. It asked first to become operator for block 30/6, which proved to contain the Oseberg field.

When that failed, Mobil “declared war” on Statoil and began to fight to retain the operator role. It argued that the state oil company had gone behind its back by securing the exploration operatorship for 30/6.

Although Mobil secured an interest in the block, it felt that this was not enough. Moreover, the operatorship for 30/6 was transferred from Statoil to Norsk Hydro in 1982 – Norway’s first political decision on such a change.

Mobil next sought to secure the operatorship for block 34/7, where Snorre, Vigdis, Tordis and Borg were to be discovered, but again without success. Norway’s Saga Petroleum became the operator – and Mobil was not even offered a holding in the block.

The Statfjord operatorship became a hot political issue during the early 1980s. That was because it involved Statoil and the size of that company, and because “clipping Statoil’s wings” had been a manifesto commitment for the Conservative Party in the 1981 general election. That promise in turn led eventually to the creation of the state’s direct financial interest (SDFI) in 1984, in effect from 1985.

Before that, however, the operator issue had to all intents and purposes been settled in 1983, with a formal decision in 1984. The question was considered by the standing committee on industry of the Storting (parliament) in 1983 in connection with the annual Statoil report to the committee.

Both Mobil and Statoil were asked to submit their arguments. The former decided to devote its time to rubbishing the state oil company. That annoyed so many members of the committee that its chair, Reidar Due, noted afterwards that a majority already existed for the fastest possible change of operatorship.

Operatørskiftet,
Kåre Kristiansen. Photo: Stortingsarkivet/Scanpix

Kåre Kristiansen from the Christian Democratic Party, who became petroleum and energy minister in 1983, was opposed to a transfer. So were prime minister Kåre Willoch and finance minister Rolf Presthus, both Conservatives.

However, a majority recommendation from the industry committee in favour of a transfer was backed by members of the Centre and Christian Democratic parties. Since these were both part of the governing centre-right coalition, this act was political dynamite.

The outcome was that Willoch himself contacted the committee and had the recommendation revised before the document was submitted to the Storting’s presidium. This meant in practice that Due and the other members of the coalition party – including Arnljot Norwich and Svein Alsaker – agreed to postpone the issue for a year. Kristiansen failed to grasp that.

When the issue came up again in the autumn of 1984, the fronts had consolidated. Mobil was battling desperately to retain the operatorship, while Statoil fought just as hard to secure it.

In an attempt to resolve the question without bringing down the coalition, local government minister Arne Rettedal asked the two companies to agree on a collaboration agreement.

Such a deal was actually drawn up, but rejected the following day by Mobil before it could be submitted to Rettedal and Kristiansen. This was because the US company had received clear signals from Kristiansen that a decision on the operatorship would be postponed, perhaps for a decade.

Before Mobil rejected the agreement, it asked Kristiansen whether he stood by his word. He did. But things fell apart when the deal was turned down. The government could no longer prevaricate, and the message from the industry committee was once again clear. Both the Centre and Christian Democratic Parties would support Labour and ensure a majority for a change.

If the issue was not resolved that autumn, the government would be defeated and might fall apart or have to resign. Faced with that prospect, the coalition resolved unanimously on the following day that the operatorship would be transferred.

The Storting followed up with a decision in December 1984, and the transfer was implemented painlessly during 1986. Statoil became operator on 1 January 1987. The transfer decision marked the end of the last major Norwegian political controversy over Statfjord.

Published October 30, 2019   •   Updated February 14, 2020
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