Kristin, a Norwegian semi-submersible platform, will begin bringing gas and condensate to the surface in October next year. Enormous preparations are required before the first gas can start flowing from the seabed. Pon Power Oil & Gas, a joint venture of Pon Power Netherlands, Pon Power Denmark and Pon Power Norway, supplied the back-up generator sets on the Kristin platform. Project manager Henk Metz explains how this exceptional contract was undertaken.

Kristin is being built under an order placed by Statoil, the principal shareholder and operator. The platform will be part of the plan for development and operation (PDO) for the Kristin gas and condensate field in the Norwegian Sea . The first contacts between Pon PowerOil & Gas and contractor AkerKvaerner were established in 2001. Henk Metz: “It took us a few months to prepare the offer and conduct the contract negotiations. The order was defined in a specification document that came to more than 1,000 pages. The project was started up in May 2002 and we began determining the exact layout of the generator sets and peripheral systems. We co-operated closely with the customer, end-user and suppliers during this period. The deliverables were defined in about 250 documents and drawings that took us around 3,000 hours to complete compared with the usual 400 hours. The design has been embedded optimally within the space available on the platform. In two sub-deliveries we supplied equipment that weighed more than 100 tons in all.”

Commissioning

The motors were the only standard element of the order. Other components had to be custom-built. At present Kristin is still in the Aker Stord yard on the west coast of Norway. The units and peripherals have already been installed on the platform in the yard. The generator sets will be put into service next summer. In autumn, the topside of the platform will be placed on the hull. In addition to the living quarters of the operators, the topside houses all machines and the modules supplied byPon Power Oil & Gas. The ‘Essential Unit’ of 5.2 MW (see sidebar) will be used continuously from the time of commissioning until gas production gets underway. By the time the platform becomes operational in October 2005, the unit will already have been running for thousands of hours.

Megapower

Pon PowerOil & Gas supplied two modules: an ‘Essential Power Unit’ and an ‘Emergency Power Unit’. The Essential Power Unit will supply power for essential processes on the platform during faults and maintenance. A Caterpillar 3616 marine auxiliary diesel engine was combined with an ABB AMG 710 generator for this purpose. The set’s total electrical output comes to 5.2 MW, which makes it the largest single generator set that Pon PowerOil & Gas has built to date.

Pon PowerOil & Gas also supplied the Emergency Power Unit, which has a total electrical capacity of 1.6MW. The set comprises a Caterpillar 3516B marine auxiliary diesel engine and an ABB AMG 500 generator. The set will be used to protect platform and crew in the event of emergencies. A special requirement was that the generator set had to continue working if the platform topples over. Fulfilment of this requirement has been guaranteed for tilting angles of up to 22°.

The two generators were delivered complete with various peripheral systems for purposes including cooling, ventilation air, exhaust gas and fuel. Special materials were selected for these systems. 

Kristin facts & figures

• The Kristin gas field is situated 240 kilometres off the west coast of Norway
• The reservoir pressure is 910 bar and the temperature 170 °C.
• The gas field is expected to yield 42 billion m³ of gas and 219 million barrels of condensate (light oil).
• The expected lifetime of the platform is 30 years.
• Kristin’s on-board equipment includes two 30 MWe gas turbines for the platform’s power supply.