Ringhorne subsea production to match Balder's output decline

Esso Norge's decision to order subsea facilities for its Ringhorne development from ABB represents a repeat order.

Esso Norge's decision to order subsea facilities for its Ringhorne development from ABB represents a repeat order. ABB also supplied the subsea facilities for the Balder Field to which Ringhorne will be tied back. The contract, the value of which has not been divulged, calls for the supply of five subsea production systems - three for production and two for water injection - and modifications to the subsea control system on the Balder floating production, storage, and offloading (FPSO) vessel.

The contract has been awarded to a consortium of three ABB companies, which will act as an EPC team, accord ing to Mathias Owe, who is project manager for the contract. The consortium will be managed from Norway. Subsea trees and controls will be manufactured by ABB companies in the UK, while a new master control station system will be supplied by ABB in Norway. There are options for the supply of further subsea production systems for the project.

With first production scheduled for late 2001, as Esso confirms, the project can be classified as fasttrack. As Balder itself comes off peak, production from Ringhorne will come up, enabling utilization of the FPSO's production capability to be kept high. To meet this demanding schedule, ABB's deliveries are due to be completed by the end of this year.

The customer gains the benefit not only of rapid delivery but the costs saved by using the same functional specifications. The same subsea production systems have also been supplied to Esso's Blackback development in Australia.

The Balder concept also provides good flexibility, Owe says. The individual well systems can be easily daisy-chained to each other, and disconnected and reconnected as required. One of the Ringhorne producer systems is to be daisy-chained to one of the Balder systems, while the other two producer systems will be daisy-chained to each other.

There is therefore no need for redundancy in the overall system, which adds cost. If a problem arises with one system, it can be individually disconnected while the other systems are maintained in operation. The components of each system can also be individually retrieved for maintenance or repair.

Only one new umbilical will be required, to serve three of the subsea systems which are located at a new site. The other two systems will be located at one of the Balder subsea centers, where they will be connected by jumpers to the existing umbilical.

Ringhorne is not a single field as such, but consists of eight finds altogether, including the Forseti Field, to the north of Balder in Esso's part of block 25/8. Some of the reserves, which in total are estimated by Esso at 280 million bbl of oil, will be produced through a fixed platform due onstream until 2002, and which will also be tied back to the Balder FPSO.

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