Tyrihans is located on the Haltenbank in the Norwegian Sea, 35 km southeast of the Kristin field in roughly 285 m of water.
The discovery comprises of two structures - Tyrihans North and Tyrihans South. Part of the Tyrihans South field extends into production licence 091, while Tyrihans North lies exclusively within production licence 073.
Recoverable reserves are put at roughly 182 mln bbl of oil and condensate, and 34.8 bln m of rich gas.
Statoil has a 46.8 percent interest. Its partners are Total with 26.51 percent, Hydro with 12 percent, Eni with 7.9 percent and ExxonMobil with 6.75 percent.
Gas and Liquid Export
In July 2005, Statoil submitted a PDO (Plan for Development and Operation) for Tyrihans and began procurement. A 43-kilometer pipeline will carry the wellstream to the platform for separation. The rich gas from both fields will then be exported via the Бsgard Transport system which runs to KМrstн, north of Stavanger. There, the gas will be processed before onward transmission to European customers.
Meanwhile, the liquids production - condensate and crude - will be combined with Kristin output after stabilisation and piped to the Бsgard C storage ship for export by shuttle tanker.
Development
Statoil will use a total of 12 wells, some multilateral, breaking down to nine for production, two for gas injection and one for the injection of unprocessed seawater. The wells will also include the use of smart well technology for improved recovery from subsea-completed fields.
These wells will be connected to five subsea templates. Statoil has entered a three-year agreement to use the Transocean Arctic semisubmersible for drilling and completion.
Subsea pumps will be used for injection of seawater, while gas will also be injected from the Бsgard field. Statoil awarded FMC Kongsberg a contract for the subsea systems. This covers assistance and maintenance of the facility during installation and operation.
Pipelines
An electrically heated pipeline will link Tyrihans with the Kristin platform. Statoil let a contract to Butting of Germany for the December 2006 delivery of steel pipe for the pipeline, laying of which is expected to begin in 2007. Ramboell Denmark SA will conduct engineering for the pipelines and their routes.
The pipeline for the wellstream is to be made of special steel. It will consist of an outer carbon pipe and an inner stainless steel pipe. This will be the first time that Statoil has installed such a pipeline. The operator awarded Stolt Offshore the work to lay two pipelines from Tyrihans to Kristin.
Production
The Бsgard B platform will require modification, as will Kristin, although some modifications were made while the platform was under construction. A 250-ton processing module will be built and installed on the platform in 2008.
Plateau production for gas is expected to be about 13 MMcm/d, while plateau production for liquid is expected to be 13,000 cu. m/d. Plans envisage the field coming on-stream in 2009, when spare capacity will be available in Kristin's topside facilities. It will cost an estimated NOK 14.5 bln in nominal value to bring the field on stream. Tyrihans is expected to produce oil up to 2025.
New Technical Solutions in the Tyrihans Development
A cable for direct electrical heating (DEN) will be used on the production pipeline at the Tyrihans field. The length of the cable will exceed 40 km and is much longer than previous projects, max length approximately 20 km. This technology developed by Statoil jointly with the suppliers is a significant step forward in the area of multiphase product (oil, water and gas) transportation for large distances. This technology could be of special interest in the realization of projects in the Arctic zone.
Tyrihans is the first field where untreated seawater is injected for formation pressure maintenance. In cooperation with Aker KvНrner Subsea, Statoil designed 2.3 MW sea-water pumps for subsea installation.
The new generation equipment is designed for the Tyrihans field with the aim of more efficient remote monitoring and control of the field operation from shore. Application of the previously existing and new technologies will enable operators to achieve reserves recovery factor at the Tyrihans South reservoir close to 55 percent.
Industrial Cooperation Across the Borders
For the project realization, it will be necessary to perform additional upgrading on Бsgard B and Kristin platforms. Aker Reinertsen was granted a contract on the modification work related to said platforms. Major engineering work is being done in Trondheim, but certain work on piping design is being done also at Reinertsen branch in Murmansk. In addition, Murmansk branch will be responsible for main part of structural steel work for construction of the module which will be installed at Kristin (Fig. 2). The possibility of piping prefabrication manufacturing by this company is also under consideration.
