Norwegian oil and gas giant Equinor is extending the life of the Heimdal gas centre, located in the North Sea, to 2023.

New wells at Valemon will extend profitable operations at Heimdal, which is processing gas from Valemon. The field partners have now decided to extend operations at Heimdal to 2023, Equinor said on Thursday.

Equinor and its partners have already received consent from the Petroleum Safety Authority for life extensions for the Heimdal platform with associated pipelines and wells.

Since its start-up in 1985, Heimdal has produced 46 billion standard cubic metres of gas and 7 million cubic metres of liquid (oil/condensate), corresponding to 332 million barrels of oil equivalent. In addition, Heimdal has processed approximately the same volume of oil and gas from the satellite fields Huldra, Skirne, Atla, Vale, and Valemon.

Production from Valemon is expected to increase in the future as 3-4 new gas wells will be drilled for Valemon in 2021 and 2022. This enables Heimdal to maintain profitable operations somewhat longer than originally communicated (2021 or 2022).

As explained by Equinor, the extension will enable the production of the remaining reserves in Vale and Skirne and increase production from Valemon.

“Heimdal is an important field that has repeatedly led the way for the Norwegian petroleum industry. First by contributing to the construction of Statpipe, which is a cornerstone for Norwegian gas export to Europe. Then by capturing value also after its own resources were produced. Heimdal illustrates how investments in infrastructure offshore drive future value creation opportunities”, said Geir Sørtveit, Equinor’s senior vice president of Exploration and Production West.

Sørtveit added: “When Heimdal is shut down the field will have produced and processed about 700 million barrels of oil equivalent and generated revenues estimated at about NOK 260 billion for the partners processing at Heimdal and for Norway”.

Heimdal and Norwegian gas history

Located in the northeastern part of the North Sea, Heimdal was found in 1972, when an exploration well proved a 120-metre gas column in Palaeocene sand. Although considerable gas resources were struck, it was long uncertain whether the field could be developed. No transportation system for gas export from the Norwegian continental shelf had been established, which was an important challenge. But the solution was found in 1981.

With gas from both Heimdal and Gullfaks, in addition to gas from Statfjord, there was a sufficient resource basis for the construction of Statpipe – the new European Highway for gas from Norway to the continent, and in addition the construction of the onshore plant at Kårstø.

The field development concept included an integrated processing, drilling, and accommodation platform with a steel jacket. An export pipeline for condensate was laid to the Brae field on the UK continental shelf. In 1985, the Kårstø plant delivered the first gas to the continent. Statpipe and the Kårstø plant have later become key to the Norwegian gas machine.

In 2020, Kårstø exported energy in the form of gas and oil products corresponding to about 400TWh/year. By way of comparison, all Norwegian waterpower production accounts for about 137 TWh/year.

At the end of the 1990s most of the gas in the Heimdal reservoir had been produced, and it was uncertain how long the operations could continue. However, Equinor (then Norsk Hydro), who had had a small interest in Heimdal from the start, saw new opportunities and took over the operatorship after ELF (TotalEnergies).

Under Equinor’s management, Heimdal was in 2001 reconstructed to a gas processing hub. This involved tie-in of the Huldra, Skirne and Vale gas fields for processing, in addition to the use of Heimdal as a transit point for gas export from Oseberg to the UK. In order to accomplish this, a new riser platform must be built next to the old main platform.

At about the same time, the Norwegian gas transport systems were combined in a new joint venture (Gassled) operated by the newly established national company Gassco. For Heimdal, this meant that Equinor transferred the operatorship for the new riser platform to Gassco, and since then there have been two operators at Heimdal.

Heimdal was in 2001 reconstructed to a gas processing hub. (Photo: IKM Testing)
Heimdal was in 2001 reconstructed to a gas processing hub. (Photo: IKM Testing)

In 2011, it was decided to bring the gas from the Valemon field to Heimdal for processing. Valemon took over the gas pipeline from Huldra, where production had ended. Thanks to the Valemon agreement, Heimdal’s productive life could be extended, which in turn enabled extended profitable production from Skirne and Vale, and the development of the small Atla field. The Vale and Skirne fields have produced better than expected.

Shutdown & removal

Equinor has appointed a dedicated project to prepare for the decommissioning of the field and removal of the two platforms. The removal project is working for both the Heimdal licence (the main platform) and for Gassled (the riser platform).

This spring contracts for platform removal were awarded to Heerema – the same company that installed the Heimdal platform on the field in 1985. The platforms are scheduled to be removed in the period 2025-2027 and brought ashore at Eldøyane, Stord, for scrapping, reuse and recirculation – more than fifty years after the field was discovered by the drilling of well 25/4-1 in 1972.

When the operations at Heimdal end in 2023 the remaining gas reserves at Valemon will be transferred to Kvitebjørn and Kollsnes for processing. Gassled will reconnect the dry gas pipelines currently passing over Heimdal to a subsea bypass.

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