The installation this weekend of the first of Ormen Lange's two 1,150 tonne well templates on the sea floor at 850 meters deep breaks a Norwegian water-depth record.
"The installation is a significant milestone for the Ormen Lange project. Hopefully the weather will be good enough to install the second template next week. Then we’ll have really made a long stride towards realizing one of the world’s most technologically demanding gas developments," says Hydro’s Einar Kilde, responsible for the offshore part of the Ormen Lange project.
Once the wells are drilled and connected and the field starts producing in 2007, Ormen Lange will supply the UK with up to one-fifth of its gas demand for several decades. The production operation will not be visible at all from the sea’s surface. Hydro’s sub-sea solution on Ormen Lange has lifted Norway’s offshore technology capabilities to new heights. Ormen Lange gas will be produced at an extreme sea depth with pipelines to shore along an extremely uneven seabed, in strong currents and at sub-freezing temperatures.
The installation/lifting operation, carried out by the world’s largest crane barge "Thialf" of Heerema, has been precisely planned for the past two years and went off without a hitch. The forces required for the installation, including the stress on the crane wire, were calculated with detailed data models, and then additionally tested in simulation sea basins at Marintek in Trondheim, Norway. The seabed was also mapped to the smallest detail. The positioning of the templates was assisted by sound signals produced from 10 acoustic transmitters installed earlier.
Enormous dimensions
The well templates, which are 44 meters long, 33 m wide and 15 m high, will be 3.6 kilometers away from each other on the sea floor. Each template has slots for eight wells, which will be drilled down into the reservoir and hooked up to a manifold consisting primarily of valves and pipe. The well stream (gas, condensate and water) will be transported from the templates in two 30-inch diameter multi-phase flowlines, up the steep "Eggkanten" embankment and to the onshore gas receiving facility at Nyhamna on the west coast of Norway.
There the gas will be treated and sent further on to the southeast coast of England through the Langeled pipeline system. Light oil from the field will be separated from the well stream at Nyhamna and stored in tanks for later transport by ships.
In addition to installation of the two well templates, a 350 tonne pipeline connection box will be placed on the seabed some 50 meters away from one of the templates. The templates and manifolds, constructed by the Norwegian Grenland Group’s fabrication yard in Tønsberg, Norway, is a sub-contract to FMC’s main contract with Hydro for Ormen Lange’s sub-sea production systems, valued at about NOK 1.3 billion.
The first phase of Ormen Lange development is planned with two sub-sea well templates in the central part of the field. The pre-drilling of up to eight wells will begin in early November of this year. After familiarity with the reservoir and its geological faults is established, a decision will be made regarding the total number of wells.
Demanding pioneer project
Ormen Lange is a pioneer project in the Norwegian offshore sector operated during the development phase by Hydro. The field lies in an area of the Norwegian Sea that is notorious for temperamental climatic and oceanographic conditions, making Ormen Lange one of the world’s most demanding offshore gas field development projects.
The combination of extreme water depth, a fractured sea bottom, difficult sea currents and sub-freezing temperatures below with high winds and waves on the surface, has placed enormous demands on all parties involved with this extraordinary project.
The development of Ormen Lange is calculated to cost a total NOK 66 billion, making it Norway’s largest ever. The project currently proceeds according to plan – on budget and on time.