East Spar NCC Buoy - Advancing Remote Technology

Abstract

Abstract The East Spar gas and condensate field, located off the North West coast of Australia, has been developed using a subsea production system operated and powered by an unmanned Navigation, Communication and Control Buoy (NCC Buoy). The NCC Buoy is tethered next to a subsea manifold in 95m of water. The activities on the NCC Buoy and subsea equipment are controlled and monitored from the gas plant on Varanus Island, 63 kilometres away, by means of a peer-topeer UHF link between the control system on the NCC Buoy and the Island. This type of system allows the control and monitoring of the field to be carried out from any convenient location. The innovative packaging of the facilities and the total integration of the control and communications systems allow completely unmanned operation, with up to six months between planned maintenance visits. The use of the NCC Buoy and other innovative technology, such as subsea horizontal xmas-trees, subsea heat exchangers, subsea multiphase flow meters, subsea pipeline corrosion monitoring and subsea pig launching, collectively advance the capabilities of remote technology for oil and gas developments. Introduction The East Spar gas field is located sixty three kilometres southwest of Varanus Island, off the north-west coast of Western Australia in 95 meters of water (Fig.1). Discovered in March 1993, this condensate rich gas field has estimated recoverable reserves of 12.5 billion cubic metres of gas and 28 million barrels of liquid. The discovery came as the gas marketplace in Western Australia was rapidly being deregulated and this presented a window of opportunity for gas sales, if the development could meet the delivery deadlines. These delivery targets forced the field and facilities development on to a fast track schedule and prompted investigation by the East Spar Joint Venture (ESJV) partners, into a contracting strategy which would compliment this rapid development approach. The outcome was an operator/contractor alliance between Western Mining Corporation (WMC), field operator, Kvaerner RJ. Brown, and Clough Engineering. This union of expertise formed the East Spar Alliance, where each position in the team was filled by the best person for the job, irrespective of their company of origin. The result was a seamless team of high performance individuals. The East Spar Alliance commenced work on the detail design in February 1995. First gas was achieved by the East Spar Alliance in November 1996, ahead of the original target of January 1997. (Since the completion of East Spar, WMC have sold their interests in the field. Apache Energy, a member of the ESIV, have taken over as operator and Kvaerner R.I. Brown have changed their name to Kvaerner Oil & Gas Australia.) The major advantage of the Alliance concept was the flexibility to vary the development concept, whilst maintaining schedule and cost. The approach was non-adversarial with common goals and there was a joint owner/contractor attitude to safety and environmental objectives. A fundamental principle of the Alliance concept was the shared risk/reward approach. The emphasis was placed on rewarding contractors for reducing whole of life costs and not just capital costs.