Ekofisk II, North Sea Central, Norway

The original Ekofisk area development consisted of eight oil and gas fields, namely Cod, Ekofisk, West Ekofisk, Tor, Albuskjell, Eldfisk, Edda and Embla. This complex also formed a transportation hub for Valhall, Hod, Gyda, Ula, Statfjord, Heimdal, Tommeliten and Gullfaks. The infrastructure consisted of 27 permanent installations, ten of which were located in a central Ekofisk complex.

Approximately 560,000b/d oil was piped 354km to the Phillips terminal in Teesside, while around 2 billion cubic feet per day of gas was piped 440km to the Emden terminal.

In December 1993, Phillips Norway submitted a 20 billion Norwegian Kroner expansion plan to bring oil and gas to market until 2028.This envisaged:

• Taking the northern part of the complex out of production
• Refurbishing platforms 2/4C, 2/4Q, 2/4FTP and 2/4W
• Constructing two new platforms at the Ekofisk complex

EKOFISK 2/4X

Ekofisk 2/4 J became the central platform in the Ekofisk area. It consists of an 11,400t, eight-leg steel jacket held in place by sixteen piles totalling 5,500t. The jacket supports a 23 500t topside sub-structure with module support frame, process module, separation (transport) module and utility module. Like the 2/4X, it stands in a water depth of 76.1m although it is rated for 90.1m to obviate potential subsidence problems in the chalk reservoir. The platform has a processing capacity of 260 000b/d oil (total export capacity of 420,000b/d), 21.2 million cubic metres per day of gas and 31,800 million barrels per day of water.

When 2/4 J became fully operational, a number of platforms started to be decommissioned. Production from third party fields such as Valhall, Gyda and Ula were merged at 2/4 J and then piped to Emden and Teesside. Statpipe gas production flowed via a new line directly to booster platform B-11 on the Emden pipeline. By 2006, only two of the original Ekofisk Centre platforms will be operational.

REFURBISHMENTS

The 2/4 Q and 2/4 FTP platforms are currently used as bridge supports. Water flooding is planned to continue from 2/4 W while 2/4 H will remains as the hotel platform at the complex. Platform 2/4 C will continue to flow until the wells collapse, after which it will also be used for bridge support.

PIPELAYING

Existing pipelines connected to either 2/4 R, P or G platforms have been re-routed and connected to the 2/4 J platform, requiring over 63km of new lines to be laid. A total of 23 tie-in spools are already in place on the seabed.

EKOFISK 2/4 J

The jacket and the utility module was built by Aker Verdal, while the module support frame and the process module was built by Amec Process and Energy. The separation module was built by Umoe Haugesund. The generators came from Dresser Rand in Norway and turbines were from by Nouvo Pigone.

EKOFISK 2/4X

The jacket was built by Aker Verdal, the drilling module by Hitec/Dreco and topsides by Umoe Haugesund.