Working FPSO numbers are set to double in the next five years. Their flexibility and re-use potential are now taken for granted. Operators, however, still see scope for restrain-ing capital outlay through standardizing equip-ment packages and construction procedures.
These were some of the main issues that emerged at IBC's Floating Production Systems conference in London last December. Some of the fresher thinking came from Peter Noble, floating systems manager at ConocoPhillips Marine. As head of a newly merged global giant, he is overseeing five simultaneous development projects in different countries based around monohulls. Two of these were due to go out to bid this year:
- Corocoro, Venezuela, a large FPSO incorporating onboard water flood facilities. Associated shallow water production barge, also due to be contracted in 2003
- Belanak, Indonesia, a turret-moored FSO to be stationed alongside a large spread-moored FPSO with onboard processing, presently under construction in China.
Elsewhere, an FPSO for the company's Su Tu Den project off Vietnam is being built in Korea, while an LPG FPSO taking shape in the same country will be deployed to the Bayu Undan field off East Timor.
The fifth project involves a large FPSO for Bo Hai Phase 2, China, with a soft yoke connection to a mooring tower.
"All of them are newbuilds," Noble said, "and the way we're going, ours are mostly double-hulled units.
"We haven't yet found a suitable [tanker] conversion candidate, particularly for long-term projects."
Despite the widespread proliferation of FPSOs in new projects in recent years, the industry still views floaters as "one-offs," Noble said, "leading to a lot of wasted activity and reinventing of the wheel for each project." It is true that FPSOs fall into a unique category, he said, in between transportation vessels, mobile offshore drilling units, and fixed offshore installations. Nevertheless, many of the components and systems in floaters are derived from traditional ship designs.
But there are significant design issues that need to be resolved, he maintained. For instance, unlike tankers, which are usually full or empty, FPSOs nearly always operate with slosh tanks, which can cause problems with stability. Also, FPSOs are generally afforded less latitude on heel and trim than tankers due to their processing system needs – in Belanak's case, large fractionating towers. Third, while tankers load up from shore-based tanks, FPSOs take crude directly from the process deck. This means that FPSOs have more solids to take care of, and that can cause knock-on problems such as tank corrosion.
The overriding challenge in Noble's view was the interface between marine, topsides, and subsea systems.
"Spectacular cost overruns tend to come in projects where this is not handled well." Disagreements between project partners often complicate matters further. Once the field is onstream, what often ensues is not in the project's best interest, he added. The team is often disbanded, rather than staying with the asset for life.
ConocoPhillips, like ExxonMobil and others, is now looking at ways of standardizing FPSO construction to cut capital expenditure and improve scheduling, uptime, and safety. Tanker conversions are unsuited to the "standardization" process, he claimed. "But this is not the case with the new generation of new-build vessels, which tend to fall into one of three categories, i.e., turret-moored, spread-moored, or with external turrets. There are always unique requirements, such as the need to build in national yards near to the projects. But even in this case, there's still scope for standardization.
"One of the most significant costs comes in engineering the hull for a new FPSO. If one generic design could be developed, that would save millions of dollars. It could also cut equipment lead times by three months," he said.
Noble pointed out that FPSOs generally slip into three size categories suitable for most production volumes. The norm is for accommodation at the fore and power generation aft. It should be possible, therefore, to develop common specifications for these modules, and perhaps also for cargo handling, ballast, seawater, and off-take systems.
For all ConocoPhillips' FPSO projects, each team currently has to draw up separate submission approvals relating, for instance, to cargo pumps. This is not efficient, he said. Instead, there should be a company-wide procedure recognizing common systems and specifications. That would allow the teams on both its current Far East projects to draw on the same stocks of spares held, say, in Singapore.
ConocoPhillips Marine has devised a concept known as global floating asset integrity management program, covering hull structural and pressure envelope integrity, and mechanical/electrical systems reliability. Among its goals are creating consistent procedures for the company's various projects and establishing a shared database, which would, for instance, allow the team in West Africa to pass on tips on long-lead items to its counterparts in Venezuela and Vietnam.
This concept becomes more relevant when the vessels in question are of similar size, he added. In practice, however, what is the incentive for a contractor in Indonesia to share beneficial information with a counterpart in Venezuela? Noble admitted that the company had not crossed this particular hurdle.
Angola hulls
One group working along some of the lines Noble discussed is the Angola Deepwater Consortium, comprising Sonangol, Doris Engineering, and Pride-Foramer. This trio has been cooperating on a variety of new drilling and production concepts over the past three years. In 2001, they conducted a study of a newbuild FPSO, which concluded that there are cost advantages in procuring the hull and living quarters from a shipyard as opposed to an offshore yard. They also found that treating the hull as a long-lead item improves the contractor's working arrangements.
The Atlantic Deepwater Consortium's computer-generated view of a generic-hull FPSO for operations offshore Angola.
A second study was initiated last July and completed this February. The aim was to issue an outline specification suitable for tendering of an FPSO hull and living quarters offshore Angola. This specification could then act as a reference basis for a generic hull and accommodation for future deepwater Angolan FPSOs, which again could be built at a shipyard.
The hull scope included typical topsides, electrical and telecommunications items, mooring system strengthening, riser support, export systems, and vessel motion analysis. The study scope extended to the tendering process, i.e., clarifying the operator's requirements prior to detailed design and providing recommendations on supply of equipment packages for integration by the shipyard.
Both studies were performed for the major deepwater operators in Angola. According to Doris' CEO Dominique Michel, "We have almost finished our design for a hull for this 'generic FPSO.' It will feature 2.2 MMbbl of storage, with 38,000 tons operating deck load, and accommodation for a crew of 160. But ADC's really interesting achievement is providing a standard deck design that permits connection of the topsides to the hull and management of load transfer into the hull structure. This works for any modular topsides lay-out.
"From the operators' point of view, they want a standardized hull because each time they embark on a big new deepwater development, they have to pay afresh for basic engineering of the hull. This process can often consume up to 20,000 manhours, and they are not happy about this. Also, they believe this hull would be easier for the shipyard to build as it would have a clearer picture of exactly how they want the hull built."
