ONS: A hard nut to crack

Great expectations are riding on the development of the Ormen Lange field west of Kristiansund on the Møre coast. The field with the second-biggest gas reservoir yet discovered on the Norwegian shelf is located in a very demanding area, with ocean depths of between 700 and 1100 metres. The biggest challenge is to get the technology qualified so that the field can be commercially exploited. This means that the solution must be profitable with current gas prices, since the field has a low quantity of condensate and no oil at all.

Norsk Hydro is the responsible developer for Ormen Lange; it was also Norsk Hydro that originally took an interest in the area and made the necessary preliminary investigations. Norsk Shell AS will be responsible for the actual operation of the field. It is no secret that Shell wanted to give priority to the development and operation of the so-called President Block first, while Norsk Hydro pressed for development of Ormen Lange.

15 years ago

As early as in 1985 the geologists in Norsk Hydro took an interest in the area that later became known as Ormen Lange. They thought that there were clear signs that there might be hydrocarbons in the area. After having shot seismics on Haltenbanken, the geologists decided to make seismic investigation of Blocks 6305/5 and 6305/7 on their way southwards and homewards. The seismics were taken secretly to Hydro’s offices at Sandsli outside Bergen and studied by a small group of geologists.

Sure enough, after thorough investigation the geologists found traces of hydrocarbon-water contact. This formed the basis for a licence application for the blocks that were released in the area. In the 15th Licensing Round (1996) Norsk hydro was allocated Licence 209, while BP Amoco got Licence 208. Well 6305/5-1 was drilled about 140 kilometres west of Kristiansund in 1997; gas was found here, in sandstone strata of the ridge formation dating from the Palaeocene. Subsequently a further two wells, of which 6305/1-1 was dry but 6305/7-1 proved major gas reserves.


It soon became clear that the field stretched southwards into Block 6305/8. Norsk Hydro applied for that block and thought it more or less certain that it would be allocated it out of turn in 1999. All the greater was the disappointment when the Ministry of Petroleum and Energy allocated Production Licence 250 to Shell. Hydro felt this as a slap in the face.

A battle then developed between Norsk Hydro and Shell over who was to get the operatorship and operational responsibility for the field when the development was to be planned and implemented. A strong constellation backed Shell on the grounds that it was important to keep the big oil companies active on the Norwegian shelf. Norsk Hydro, which had discovered the field and had always seen it as a major task, naturally thought itself the best-suited. “All the innovations we developed for the Troll field, inter alia the seabed separation, were preparations for the Ormen Lange project. We wanted to implement the project on the basis of the experience we had gained from Troll”, emphasises the director of Norsk Hydro Production and Research in Central Norway, Bengt Lie Hansen.

Norsk Hydro heaved a huge sigh of relief when the Ministry finally decided for a split, with Hydro responsible for the development and Shell for operations.

Difficult seabed conditions

The Ormen Lange field has a very difficult location: the seabed above the reservoir has extreme relief. For the reservoir is right under Storeggaraset, a subsea landslip that occurred about 7,000 years ago. The seabed slopes very steeply, almost like a mountainside in the West Norwegian fjord country, from 350 metres to 1100 metres depth. Norsk Hydro’s main objective is to achieve a solution corresponding to that used at Kollnes for the Troll platform, that is, for the actual processing plant to be shore-based. The difference between Troll Gas and Ormen Lange is that the latter will be developed with subsea solutions. There is currently no technology available to lay this pipeline along the seabed and into a processing plant. Building a road on the seabed is quite out of the question. “In Norway we can build submersible tunnels that are anchored in the seabed, so we should be able to manage this with oil and gas pipelines too”, says Technology and Expertise Director Bjørn Rasmussen. “We have initiated projects linked to the Demo 2000 programme that can qualify the necessary technology for the Ormen Lange development,” continues Rasmussen. “Almost all the development work we will be doing in the next few years will be with a view to developing Ormen Lange.”


One of the big problems is the severe environmental stress to which the equipment will be exposed. On the seabed the water temperature sometimes falls as low as minus 1.9° C, as opposed to a normal temperature of minus 1.4° C. This is the temperature that is ideal for hydrate formation in a two-phase stream of gas and condensate/water. Hydro is therefore working intensively to find methods of preventing hydrate formation.

A subsea solution may mean an underwater processing plant like on Troll C. “A precondition for subsea production is the existence of a fully practicable distribution system for electrical energy that can be used under the conditions encountered on Ormen Lange.” A project associated with Demo 2000 being developed by ABB, the Subsea Power Distribution System (SEPDIS), will be crucial for our ability to develop and use a subsea production system.

Hydro is also considering other development solutions, including one based on a floater with dry wellheads and with transport of gas to the actual gas processing plant on shore. Together with the research institution Marintek, Umpoe has been commissioned to develop a Spar buoy that can withstand the conditions obtaining on southern Haltenbanken. “The environmental conditions are much tougher than in the Gulf of Mexico. Wind and wave stresses are about nine times heavier. Experience is not directly comparable”, emphasises Rasmussen.

A single drainage point.

The reservoir itself is like a dome in the rock. Hydro does yet know its precise extent, but has shown that its original survey of the area accords with the results the company has so far obtained from the well tests. “We must drill another well this year to find the number of drainage points for any development,” says Lie Hansen to Teknisk Ukeblad, “We hope that one will be enough”.

Current conditions in the reservoir will determine this. A single drainage point will limit costs. “What we know so far is that we will not need water injection for pressure support in the reservoir for a long time yet, perhaps not for ten years after commissioning.”

The county takes the lead

Any gas will be landed on the Møre coast. Møre og Romsdal County Council has taken an initiative, “Ormen to Møre”, to find and prepare the best possible reception site for the gas. In the middle of May Hydro’s project workers visited 14 different sites that could be of interest with a view to the landing of gas. “We have an excellent collaboration with the County. The fact that they are helping to find a solution eases our work considerably, “ says Project Manager Thor A. Tangen. “It is always useful to have the local authorities on board when the landing decision is to be taken.”

He emphasises that no development solution has yet been chosen for Ormen Lange: “We can go for subsea production. We can use floaters and it is conceivable that a production and drillrig platform will be a solution. The road forward is long and complicated. I think we will find the right solutions, and are looking forward to production start in 2006.”