Ekofisk 2/4 W
- Installed in 1989
- Operational 12 September 1990
- Ceased operation 2009
- Fully removed 2011
- Also known as Ekofisk Whiskey
The 400-tonne module was built by Heerema in the Netherlands and lifted onto the bridge support by the DB 102 crane ship. Danish jack-up Mærsk Guardian drilled the eight injection wells.
Waterflooding is used to improve petroleum recovery by maintaining pressure as oil and gas originally in the reservoir are removed through production.
While Ekofisk 2/4 K provided such pressure support in the northern part of the Ekofisk structure, 2/4 W did the same for the southern area.
The platform was unmanned, with waterflooding initially controlled from Ekofisk 2/4 FTP and later by 2/4 K. A 12-inch high-pressure pipeline with a maximum capacity of 120 000 barrels (about 18.8 million litres) of water per day was laid from 2/4 K to 2/4 W by the Loreley laybarge.
A leak in the pipeline was discovered in 1993. The Safe Lancia flotel had been located nearby with a bridge to Ekofisk 2/4 S, and one of its anchor chains had caused the damage. The leak was located with the aid of a remotely operated vehicle and repaired.
Well stimulation vessel Big Orange XVIII collided with 2/4 W on 8 June 2009, causing extensive damage to platform and wells. The installation was shut down, and had been fully removed by the summer of 2011.