In the beginning was …

person Finn Harald Sandberg, Norwegian Petroleum Museum
Before oil companies can start searching for petroleum in a region, they need to prospect unexplored areas which look promising in terms of hydrocarbon deposits. The information acquired in this way must then be interpreted and assessed by experts who can determine the opportunities for and probability of discoveries in this potential province.Finally, the companies must apply for a licence from the owner or owners of the area – in Norway’s case, the government acting on behalf of the state – and hope for a positive answer.
— A group from Statoil's exploration department studying maps of the Trænabank area. From left Egil Tveit, Rolf Magne Larsen and Erik Håvarstein. Photo: Statoil/Norwegian Petroleum Museum
© Norsk Oljemuseum

Seismic data

Geophysical and geological maps must be created in order to form a picture of the chances for finding oil and gas in a region. These determine whether seismic surveys should be conducted.

In addition to studies and measurements of the Earth’s crust, geophysical surveys cover determination of the local gravitational and magnetic fields.

Seismic surveying is the most important method used in geophysical investigations. Exploring for oil in this way involves transmitting powerful sound waves into the sub-surface and recording the echoes which bounce off the various strata.

That makes it possible to construct a picture of conditions beneath the Earth’s surface. Although seismic surveys can identify reservoirs, they cannot determine whether these are aquifers (water-filled) or contain hydrocarbons.

All information about how long the sound waves take to travel through the Earth’s crust is stored for later processing – done today by powerful computers.

During the 1960s and 1970s, however, computer technology had not advanced that far, and seismic interpretation was conducted by entering coloured lines on print-outs of the recorded data.

Seismic shooting is the oil industry’s most important tool for identifying possible petroleum deposits many thousands of metres beneath the Earth’s surface.

The actual work involved in such surveys is very considerable, and the consequences of positive signals are so great that such activity is defined as petroleum-related in Norway’s Petroleum Act.

International companies were conducting seismic surveys in the Norwegian sector of the North Sea as early as the summer of 1963. At that time, national jurisdiction had not been established beyond the fisheries limit of 20 nautical miles from the coast.

Norway declared its sovereignty over the continental shelf in that year, and thereby acquired authority over all prospecting for and exploitation of undersea natural resources. But it was 1965 before the UK, Norway and Denmark agreed their mutual boundaries in these waters.

Stavanger Port Authority records reveal at least 140 calls by 40 or so vessels participating in the race to find “black gold” in 19963-65. America’s Sonic was the first recorded seismic survey ship to arrive. It took on fuel in Stavanger on 8 August 1963.

American Overseas Petroleum Ltd received the first official permit from the Norwegian government to undertake seismic surveying in national waters on 7 June 1963.

Represented in Norway by Norsk Caltex Oil A/S, this company had applied to the Ministry of Industry but secured the award from the Ministry of Foreign Affairs over the signature of E F Ofstad.

On 5 September, this company notified the Norwegian government that it intended to begin surveying an area which subsequently turned out to embrace Valhall.

The contract for this work was awarded to Western Geophysical Company of America, which conducted the survey with Cynthia Walker and Linda Walker .

This technology was important when petroleum operations began on the Norwegian continental shelf (NCS), and domestic companies rapidly acquired a key role in further developing and adapting it for offshore use.

Norwegian factory trawlers proved very suitable for conversion to seismic vessels and were quickly adapted to this role. The former crew stayed with the ships, providing the geophysicists and engineers with valuable knowledge about handling equipment derived from the fishing fleet.

A clear indication that the Norwegian government was not perhaps entirely familiar with the new technology – or confident that it was – was provided when Norsk Hydro applied on behalf of the Petronord group to conduct seismographic surveys in May 1964.

In addition to a detailed technical explanation, this application contained an appendix with drawings (figure 1) to show the difference between the refraction and reflection methods.

Interpreting data

Generally speaking, three conditions must be met if petroleum reservoirs are to be created.

  1. A source rock where hydrocarbons can form. Claystone and shale are the commonest source rocks in the North Sea.
  2. A porous rock which the hydrocarbons can migrate to and accumulate in. Examples of such reservoir rocks include sedimentary deposits such as sand, sandstone and chalk (Valhall).
  3. A cap rock which overlies the reservoir rock and prevents further migration of the hydrocarbons.

Geologists interpret seismic and well data in an effort to understand the complex structure and formation of the NCS. In order to identify recoverable oil and gas resources, they must map “traps” which may contain hydrocarbons and estimate the possible size of such resources.

Overall seismic surveys were conducted during the early years on the NCS by commercial companies. Since the Norwegian Petroleum Directorate (NPD) was established in 1972, it has been responsible for doing such area studies. Their results are sold to companies wanting to assess opportunities for finding oil or gas.

Such sales also give the government an indication of the strength of interest in various parts of the NCS. In addition to its own assessments, the NPD’s specialists follow up geological interpretations made by the companies.

Applying for a production licence

Over more than five decades of petroleum exploration, licensing policy has been the Norwegian government’s most important instrument to controlling the level of offshore activity and ensuring optimum management of hydrocarbons on the NCS.

The licensing system represents a key element in the operating parameters governing Norway’s petroleum industry – in other words, the terms and conditions licensees on the NCS must comply with.

A division of the NCS into rectangular blocks with their short sides facing north was carried out in 1964 on the same pattern adopted by the other North Sea countries.

Each Norwegian block covered 500 square kilometres, about twice the size of its counterparts in the UK sector, but the international oil companies had wanted them to be even bigger.

They argued that an unknown geological region like the NCS should put large areas on offer in order to attract sufficient interest but failed to win full acceptance for this view.

The first licensing regulations for the NCS were established by royal decree on 9 April 1965. Later the same month, 278 blocks were put on offer. Block 2/8, embracing much of Valhall, was awarded as production licence 006 on 17 August 1965.

This initial licensing round is also by far largest in Norwegian oil history in terms of both the number of blocks offered and the total acreage involved.

The second round was announced on 21 May 1968 and extended over several years. Fourteen of the 68 blocks put on offer were awarded in all. One of these was 2/11, containing the rest of Valhall as well as Hod, which was handed out as PL 033 on 30 May 1969.

Today’s system is regulated by the Act of 29 November 1996 no 72 relating to petroleum activities (the Petroleum Act). This specifies that the state owns the undersea petroleum resources on the NCS.

Government permits and licences are required for all phases of petroleum operations, from the award of prospecting and production licences, through seismic surveys and exploration drilling, to plans for development and operation and for cessation of production.

Production licences are normally awarded through advertised licensing rounds. Applications can be made singly or in groups. Details they must contain and the procedure for seeking production licenses are regulated in the Petroleum Act and associated statutory regulations.

Securing an award

Production licences are issued to companies by the Ministry of Petroleum and Energy after a thorough assessment of the applications received.

Awards are made in accordance with published criteria which are unbiased, objective and non-discriminatory, and usually to a group of companies.

One company is appointed operator for the group, responsible for the operational activities covered by the licence. The other licensees are also intended to function as an internal check on the operator’s work.

A licence regulates the rights and duties of the companies in relation to the government. It confers a sole right to conduct prospecting, exploration drilling and production of petroleum in the geographical area covered.

The licensees become the owners of the petroleum produced. Each licence applies in the first instance to an initial period defined as the exploration stage, which can last up to 10 years.

First licences for Valhall

PL 006 was awarded on 17 August 1965 to Amoco, Amerada, Texas Eastern and the Norwegian Oil Consortium (Noco). It covered the three contiguous blocks 2/2, 2/5 and 2/8 as well as the nearby but not adjacent block 3/4.

This acreage added up to 2 279 square kilometres. The one-off area fee to be paid was NOK 1 139 500, or NOK 5 000 per square kilometre.

Chapter 4 specified that “the Licensee has undertaken to carry out a work programme which will be completed in its entirety by 1 September 1971. The following provisions apply to this work programme and its implementation.

“The Licensee will drill four wells with the purpose of finding oil and gas in the licenced areas covered by production licences 004, 005 and 006. At least one well will be drilled in the blocks covered by this licence.”

Chapters 7-10 set stringent requirements for conducting seismic surveys, especially with regard to shipping and aviation activities but very particularly to fishing. These rules related to equipment as well as the use of explosives. Notification and reporting were also covered by separate provisions.

No reserves had been proven in blocks 2/2 or 3/4 up to 2015. A promising reservoir was discovered in block 2/5 in 1970, which was given the name Tor.

This structure extended into block 2/4 and turned out later to be part of the Ekofisk area. It has accordingly been “unitised” – treated as a single unit – with interests divided in accordance with the estimated hydrocarbons in each block. That gave 75 per cent to PL 018 and 25 per cent to PL 006.

The field which was eventually to be given the name Valhall was discovered in 1975 in block 2/8. This reservoir again extended into a neighbouring block, 2/11, which had proved the year before to contain the Hod field. That acreage was awarded to Amoco and its partners in 1969 as part of the second licensing round.

PL 033 was awarded on 30 May 1969 to the same companies, and covered blocks 2/9 and 2/11. For some reason, only 2/11 was geographically defined.  That did not prove a problem subsequently, however, since this represented the only acreage where recoverable reserves have been found.

The defined area covered 208 square kilometres, and the area fee was NOK 104 000 – in other words, the same price per square kilometre as four years earlier.

Chapter four specified that “the Licensee has undertaken to carry out a work programme which will be completed in its entirety by 1 September 1971. The following provisions apply to this work programme and its implementation.

“Further seismic surveys will be conducted. Furthermore, [the Licensee] will drill one well in this block with the purpose of finding petroleum. This well will aim to test the base of the Zechstein formation, which is currently assumed to lie at a depth of 12-15 000 feet, unless abnormal conditions are encountered during drilling which make drilling to such a depth impractical on technical or economic grounds.”

One provision not included when PL 006 was awarded in 1965 concerned the section in chapter 6 on state participation. This stated that:

“The Licensee will pay 10 per cent of the net profit achieved by the Licensee from the sale of produced petroleum, etc, from this licence. The more detailed content of this participatory right is specified in the “Agreement” with annexes attached as appendix 1 and forms part of this production licence.”

The “Agreement” specifies in part that “no payment will fall due until the Licensee has covered the costs and investments incurred in connection with exploring for and producing petroleum in this licence.”

Magnetometric methods are based on the fact that all rocks contain a certain amount of magnetic particles. This content varies from rock to rock, and the differences can be measured with sensitive instruments. Magmatic (igneous) and metamorphic rocks contain far more magnetite than those derived from sedimentary deposition. That makes it possible to identify areas of extensive sedimentation which could contain hydrocarbons.

Gravimetric methods are based on measuring changes in the Earth’s gravitational force which derive from the varying densities of different rocks. Gravity will be stronger over a dense rock than over lighter sediments. Gravimetry was used with great success in the Ekofisk area to which Valhall belongs.


Published 14. September 2018   •   Updated 10. August 2020
© Norsk Oljemuseum
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Technical Drawings and Documentation of the Valhall Platforms

person Filip Fremo Minge
Here you will find technical drawings and technical documentation of the platforms on the Valhall field.
— 00-07-00-PP-012-001 Elevation south
© Norsk Oljemuseum

Drilling Platform (DP)

Process and Compression Platform (PCP)

Quarters Platform (QP)

Riser Platform (RP)

Published 28. July 2015   •   Updated 26. January 2023
© Norsk Oljemuseum
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Privacy Statement

person Norwegian Petroleum Museum
Some internet users are concerned about data confidentiality and the use of cookies downloaded to their computers from websites they visit. These small files are designed to store information about pages accessed, but cannot steal information from the visitor or their computer system.

The Norwegian Petroleum Museum utilises the Google Analytics tool, which installs cookies to collect and assess information about how visitors utilise its website.

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More information on cookies and how they are used can be found by clicking on help in the browser menu.

Published 9. August 2019   •   Updated 14. October 2020
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About Project

person The Norwegian Petroleum Museum
This website is one result of the Valhall Industrial Heritage project, pursued in 2013-15 to document the Valhall and Hod oil and gas fields on the Norwegian continental shelf (NCS).

The work has covered the platforms on these two fields as well as the pipelines carrying their production to market. Physical structures above and below the waves are detailed ­– exteriors, interiors, machinery and equipment as well as significant modifications. A systematic selection of documentary sources related to Valhall from 1962 to 2012 covers documentation and depictions of characteristic features of the field’s development. These include technological advances, special projects, historical events, negotiations and decisions underlying development decisions and choices, political decisions and debate.

Work has been pursued by the Norwegian Petroleum Museum, the Regional State Archives in Stavanger and the National Library of Norway in Mo i Rana, in cooperation with BP Norge and Hess Norge.

The project has been led by the Norwegian Petroleum Museum , reporting to a council with representatives from the bodies listed in the previous paragraph.

Photographs, films, publications and objects have been preserved by the museum, whose staff has written articles for the website which help to create a context for the archival material.

The National Library and Seeds Consulting have delivered the technical platform for the website, based on the eZ Publish tool and adapted to provide the desired functionality. A search function has also been developed by the National Library to make the digital

material searchable across the whole website. This means that photographs, films, radio clips, books, scanned magazines, objects and other interesting material are now readily accessible.

The National Library has also ensured the preservation of digital radio clips, scanned magazines and digitised film.

The Norwegian Oil and Gas Archive/Regional State Archives in Stavanger has been responsible for the sub-project relating to archives. This has identified, selected, organised and catalogued the records covered by the project.

As operator of the Valhall field, BP Norge has collaborated on the execution of the industrial heritage project with support from fellow licensee Hess Norge.

National Library of Norway

The National Library of Norway is one of the most important sources of information about the country, its people and Norwegian conditions.

Activities at the National Library are pursued in part through collaboration with other institutions, such as libraries, media, educational bodies, research institute, archives, museums and artistic bodies. New services for the public are also developed. The library ranks as an important resource in a number of areas, such as the infrastructure for Norwegian research – including its role as a research library. Others include serving as a cultural policy tool, as a body responsible for the long-term preservation of Norway’s cultural heritage, and ensuring the celebration of author anniversaries.

The library has also been given an expanded responsibility for linguistic policy through the job of establishing, building up and running a Norwegian language bank. In addition, it has been made responsible for developing the library sector in Norway. Digitisation, long-term storage of digitised materials and the development of digital library services represent a key part of the library’s activities.

It has launched an extensive programme to digitise its whole collection – a job expected to take 20-30 years to complete. Materials held by the library are made available in accordance with the Norwegian Copyright Act or under agreements with the holders of intellectual property rights. The National Library has almost 450 employees and is headed by a director general. Its operations are split between Oslo and the north Norwegian town of Mo i Rana.

Role of the National Library in Valhall Industrial Heritage

A copy of all information made available in the Norwegian public domain must be deposited with the National Library, which is in the process of digitising its whole collection. It is accordingly equipped to make available that part of its collection which relates to the field via the search page on the Valhall Industrial Heritage site. Books, newspapers, radio programmes and minor printed works found here have been digitised by the National Library, which has also received digital files and metadata for photographs and objects (from the Digital Museum ) as well as films.

The library also operates the complete web solution used by the Valhall Industrial Heritage site, and has implemented the search engine for the site. This makes it possible to search both metadata (name, title, author, etc) and the actual content of a book or other printed work. Users can also view or listen to the relevant digital object. In addition, they can find other digital material in the National Library’s own digital collection .

Norwegian Oil and Gas Archive

The Norwegian Oil and Gas Archive has national responsibility for preserving records from this industry and making them accessible. These materials come from operator companies as well as suppliers, unions, government bodies and key people in the sector.

Among suppliers come such players as Moss Rosenberg Verft, Teekay, NorSeaGroup and Norwegian Contractors, while organisations include the Norwegian Union of Industry and Energy Workers (IE), the Norwegian Union of Energy Workers (Safe) and the Norwegian Oil and Gas Association. Archives have also been preserved from an extensive downstream industry, other organisations such as the Petroleum Wives Club, and a number of individuals.

Handling of materials

The various documents received by the archive go through an important process before they are ready for long-term deposition in the storage facility. This includes removing plastic sleeves, files, binders and other covers which could damage the paperwork, and replacing packaging with a new acid-free material for optimum preservation. Such purging and repacking reduces the volume of the archive by 40 per cent on average, without any scrapping of the actual records. Once the process has been completed, the material is placed in the climate-controlled store. That creates the best possible conditions for indefinite preservation. Finally, the material is registered in the Asta database maintained by the National Archives and published in the catalogue at .

Such registration makes the records searchable and simplifies access to it by the public. However, the material is not initially open to all. Permission to study an archive must be granted by its owner on the basis of a written application. All the records will ultimately become public in a 100-year perspective.

Archives with information on Valhall

Records about and from the field are found in a number of different government and private archives, providing a comprehensive picture of Valhall’s development and social role.

Public-sector archives derive, for example, from the Ministry of Industry’s oil office, the NPD, the Petroleum Safety Authority Norway (PSA) and the police relating to their specific areas of responsibility. The NPD, as the successor to the oil office, has served as the regulator for the petroleum sector, originally covering both safety and resource management. Established in 2004 by separating the safety department from the NPD, the PSA has yet to deliver records to the oil and gas archive.

Among private companies, BP Norge – as operator for Valhall – has deposited the largest volume of archival material about the field. That originally totalled 145 shelf-metres, reduced to just under 100 after sorting and registration. This is the old Amoco Norway Oil company archive, and is registered as private archive 1740 at the Regional State Archives in Stavanger. Its contents cover a period of more than 30 years, from 1965 to 1999, documenting Amoco Norway’s operations in Norway and on the NCS. The materials cover the company’s relations with government, licence partners, Norwegian society as a whole and employees, and range widely. They document everything from major technological achievements to smaller triumphs – such as a successful Christmas party.

The important decisions taken in Amoco Norway over the years can often be found in the abundant selection of minutes from meetings in various bodies. These include the operating committee, management committee, exploration committee, Valhall unit committee, bid committee and partner meetings. The deliberations of these bodies provide a good insight into the history of the company, revealing how decisions were discussed, assessed, justified and implemented. Although the archive documents the whole range of Amoco Norway’s operations, the bulk of the material naturally enough deals with the Valhall and Hod fields. The section dealing with the latter covers such aspects as Hod development and planning reports, administration, engineering, fabrication and transport/installation, and the Hod saddle project.

More than a third of the whole archive deals directly with Valhall, including development and planning, committees, meetings and minutes, economics and safety. In addition come details on the living quarters, drilling, process and compression, wellhead and riser platforms as well as on engineering. Other topics include daily activity reports, production operations, field development, oil and gas pipelines and incoming/outgoing correspondence. The language in the archive varies between Norwegian and English, with most reports, correspondence and minutes of meetings in the latter. The file index uses English terms.

Since it largely follows Amoco Norway’s file index, the archive is simple to navigate – which eases retrieval and searches. All the same, a good many reports and the like fail to comply with the file index. However, they are searchable by key word, title and year. Hess Norge, which is BP Norge’s fellow licensee in Valhall, has so far deposited only a small quantity of records with the Norwegian Oil and Gas Archive. This material, both paper-based and electronic, has been mapped. It contains interesting information related to Valhall, but also to Hess in general. So further deposits are possible.

In addition to the oil companies, the Amoco Company Union (ABC) has transferred a great many of its files. It was established in 1982 as a “house” union for Amoco employees. After the merger between Amoco and BP, it changed its name to the Employees Company Union – retaining the same initials in Norwegian. It is now the BP branch of the IE union. The records deposited with the Regional State Archives in Stavanger amount to six-seven shelf-metres, and consist largely of correspondence, minutes of various meetings and printed materials.

Published 9. August 2019   •   Updated 14. October 2020
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