Page 138: of Offshore Engineer Magazine (May/Jun 2014)

137 139

Zafro, off Equatorial Guinea; a control limited or to power stranded felds where

SeaProducer buoy for Mossgas’ current E-M devel- they can be tied back but do not have Ocean Resource has an agreement with opment off South Africa, in partner- local control. ABTechnology to license SeaProducer ship with Mentor Subsea, a division of “They are a proven entity,” Lack says. technology for oil production systems.

Dubai-based McDermott subsidiary J Ray “This is why we are seeing now an up- The SeaProducer is the frm’s produc-

Vessels

McDermott; and the East Spar control turn in offshore activity. There is strong tion buoy concept, aimed at felds able buoy offshore Australia. interest in the buoys, not so much in the to produce 1-20,000b/d. Its design differs

Ocean Resource also designed a 5MW North Sea, but in many other regions. from previous Ocean Resource designs in power buoy for CNR International’s One area with a lot of interest right now that, for installation, the buoy would be

Lyell feld, in the North Sea, to provide is Perth, Australia, and the areas driven towed to the location upright, instead of power generation for up to 16 downhole out of Australia, southeast Asia and to horizontally, to protect production equip- electrical submersible pumps. The proj- some extent West Africa. Buoys are one ment. This means the design is wider ect stalled during fnal construction. In of the lowest cost structures you can than previous designs, and also with addition, the frm has designed and seen put in to water to do a job, including in fewer decks, better facilitating integration installed 10 other monitoring buoys over deeper waters.” of production equipment.

the last 20 years. In total, the frm has fve different buoy The system is designed to last 25 years,

Dr. Lewis Lack, commercial director concepts: SeaCommander, SeaPower, and and comprises a semisubmersible buoy, for Ocean Resource, says buoy tech- SeaSentinel, for oil and gas well control, taut-moored with tethers, to a gravity nology is proven and there is growing electrical submersible pump power and base, with a subsea riser connecting the demand, be it for control and power control, and offshore monitoring, the production facilities to subsea wells. buoys, which can be used for local power SeaProducer, for production, and the An example of a confguration, the or control, where space on a facility is SeaSequestor, for CO injection. frm says the foating buoyant structure, 2 could be 57m-high, weighing 650-tonne (dry), with a 20m hull diameter, moored to a self-installing, 4000-tonne, concrete gravity base. The production facilities, which could be stored across three or more decks, will house frst and second stage separation facilities, heat generation and process control systems.

“The production process used will depend on the clients’ preferences and also the produced fuid, plus availability and reliability requirements, Lack says. “As well as temperature, vacuum separa- tion has been considered.”

Up to 4.1MW of power could be gener- ated through six 820kW on board die- sel generators, using one generator as a standby, to power, via a subsea riser and seabed umbilicals, up to eight electrical submersible pumps (ESPs), or other func- tions requiring power. Associated gas could also be used to provide power, as well as heat for separation. ESP control will be through eight onboard variable speed units, with a ninth installed as backup.

The number of wells produced will depend on the tie-in system used, and will be driven, in most cases, by the selection of subsea system, Lack says.

The unit would include a 3m diameter access shaft for maintenance. The buoy could support a helideck. Produced liquids would be stored in subsea storage tank, positioned up to 500m away, or exported to a host facility. The storage tank size will depend on production rate and offtake frequency. Typically, Ocean

Resource says it will be a 200,000 bbl concrete storage tank, weighing 13,000-

Ocean Resource’s production buoy concept under construction. Photo from Ocean Resource.

tonne, using an oil water interface

May 2014 | OE oedigital.com 140 138_OE0514_Vessels4_unmanned.indd 140 4/19/14 10:33 AM