Apache proposes to remove the NCC BUOY from the East Spar field (Figure 2.1). The field is located in 96 in water depth, approximately 36 km west of Barrow Island and 63 km west of Varanus Island. Gas and condensate production commenced in 1996 via Varanus Island and was suspended in 2006 upon exhaustion of the field reserves and the NCC BUOY cease operation. The Halyard field was connected to the East Spar manifold and export pipeline to Varanus Island in 2011 and control of the Halyard well provided via an Electro-hydraulic umbilical from the John Brookes platform. Today, Halyard remains in production and another well (SPar-2) is scheduled to tieback through this connection. The gas produced from the Halyard well passes through the East Spar manifold, but all East Spar wells (i. e. ES-I, ES-3 and ES-6) are shut in and operation from the NCC Buoy is no longer required. The NCC is due for relifing in 2016, therefore Apache Energy, on behalf of Apache Oil Australia Pty Ltd (the East Spar Joint Venture operator) intends to remove the NCC Buoy from the East Spar field.
The NCC BUOY is located in the East Spar Field. The East Spar Field consists of subsea wells and production facilities connected to a Subsea manifold with 62km of 350mm production pipeline to Vl. The operational area is classified as the 500m exclusion zone surrounding the buoy location. The buoy location is 36 km from the nearest land at Barrow Island, and 95 km from the nearest mainland, and 101 km north of the nearest town at Onslow.
The NCC Buoy provided a means of controlling and operating the subsea wells. It included storage and pumping of corrosion and hydrate inhibition chemicals and relayed operating data from the facilities to the control room on Varanus Island. Equipment on the buoy includes:
Corrosion and hydrate inhibitor storage tanks and pumps;
Hydraulic fluid storage, Hydraulic power unit, accumulators and controls for the subsea wells (connected from the buoy to the wells by umbilicals;
Power generation and associated support utilities;
Diesel storage tanks c/w pumps to fuel generators;
Subsea control system and associated power supply;
Communications system relaying information to Varanus Island and receiving control signals from shore.
The activity will be carried out over approximately 2 weeks in quarter four of 2015. The latest completion of the activity is 31 December 2015. Operations will be 24 hours per day, seven days per week.
