Designs for the future

Jeannie Stell speaks with classification organizations ABS and DNV GL to discuss today’s trends in new pipelay vessels.

Mike Sano

Bigger is better, when the object of discussion is offshore pipelay vessels. Today’s generation of pipelay vessels, and almost all of the associated on-deck equipment components, have been upsized because, for example, larger reels equate to more pipe that can be spooled into place with less reloading required. Larger and more robust engines and highly developed geo-positioning technologies mean the pipelay vessels can remain in place for long work periods – even in harsh environments. And new engine designs bring fine-tuned efficiencies to the forefront of operations to ensure fuel conservation for economics and reduced emissions.

“In the past five years, we have noted the growing demand for pipelaying vessels in deeper waters,” says Mike Sano, manager of energy development for ABS. “As a result, large pipelaying assets were designed and delivered to satisfy this demand. One of those was Saipem’s Castorone.”

The Castorone is an ABS ice-class pipelay vessel built for Saipem. The Navalimpianti Tecnimpianti Group was contracted to design and assemble the vessel’s pipe handling and storage system. Engineering assistance for the completion of the design was provided by ship design firm Navalprogetti.

With a handling capacity of more than 500m/hr of pipe, the vessel’s pipe-deck receivers, handling and storage systems minimize the transfer time between the pipe barge and pipelay vessel holds. A full contingent of 702 workers can be accommodated onboard the vessel, and it has a 4300sq m of cargo deck area.

With a handling capacity of more than 500m/hr of pipe, the Saipem Castorone pipelay vessel’s pipe-deck receivers, handling and storage systems minimize the transfer time between the pipe barge.  Photo from HGG Group.

The Castorone is fitted with a knuckle boom crane that has a safe working load at a 30m outreach at 600-ton, and at 46m, the outreach is 350-ton. Additionally, the vessel includes two gantry cranes, each with 52-ton capacity at 35m, three tensioners of 250-ton each and an abandonment and recovery winch.

For dynamic positioning (DP), Castorone has eight side thrusters, two bow thrusters, six azimuth thrusters, and a fully redundant class-3 control system comprising two HiPAPs (high precision acoustic positioning) for 3000m of water depth and two differential global positioning system reference systems.

“It was designed to have both S-lay and J-lay capabilities in deepwater, and can handle up to 48in diameter pipes,” Sano adds. “That vessel has been working for a couple of years now. It had a tremendous backlog of work.” On her first assignment, the new vessel performed marine activities for the development of the Chevron-operated Jack/St. Malo fields in the US Gulf of Mexico (GoM).

Even as owners, operators, shipbuilders and designers geared up for an exciting new generation of pipelay vessels, with some record-breaking megastars already delivered, the vessel market began to recede as a result of the oil price crash.

“The level of offshore activity has dropped significantly,” Sano says. “This has impacted the offshore support vessel fleet, such as pipelay vessels, because many of the oil companies’ projects have been put on hold or significantly moved to the right.”

Arnstein Eknes, special ships segment director for DNV GL, agrees.

“The oil prices will have the effect that many new or planned offshore fields with a high break-even level will be delayed or put on hold,” he says. “The situation today is that the backlog for companies engaged with planned subsea activities is quite good for this year, then very much weakening next year. Many of the EPC companies utilizing pipelay vessels are reducing their manning to adapt to a reduced cost and activity level, hence making it more likely that the market for newbuild vessels will remain weak.”

The Castorone.Photo from Saipem.

New designs

When the economics recover, or possibly even before then, some new pipelay vessel designs could be brought to the market. “I think we will probably see more pipelay vessels designed specifically to work in harsh environments,” Sano says.

“For example, Shell has proposed a drilling program in the Arctic that will need pipelines to flow well production to midstream facilities,” he says. “But, currently, there are no harsh environment pipelay vessels. I think that is something we will probably see in the future, because subsea pipelines make sense, to keep the lines away from ice formations and bad weather.”

Another new development is the inclusion of liquefied natural gas (LNG) as vessel fuel. “This is a new focus for the industry,” Sano says. “ABS has been involved with LNG as fuel for OSVs for more than five years now. In fact, earlier this year, Harvey Gulf International Marine introduced the first LNG-fueled supply vessel in the GoM.”

Shell contracted the Harvey Energy, a 302ft offshore supply vessel to carry equipment, drilling hardware, fluids and other supplies to Shell’s deepwater operations in the GoM. The Harvey Energy sets an example for future pipelay vessels, with its three dual-fuel Wärtsilä engines that can be powered by 99% LNG fuel and can be operated for nearly seven days before refueling.

“If used in pipelay vessels, LNG fuel could enhance fuel efficiencies, reduce costs and abide by new sulfur and nitrogen oxide emissions regulations necessitated in the North American Emission Control Area,” Sano says. “LNG produces less emissions. It also is cleaner as it burns inside an engine, so it helps to lower maintenance costs. Diesel and other liquid fuels leave behind residual particulate matter in the engine that causes contamination of the lube oil and abrasives that wear down the cylinder liners over time.”

But, the technical challenge will be to refuel LNG-powered pipelay vessels offshore. “There will need to be some type of LNG bunker barge that is capable of delivering LNG fuel offshore,” Sano says.

“The lack of bunkering vessels can explain why 16 out of 17 offshore vessels presently fueled by LNG are operating in the North Sea where they now have good and close access to LNG bunker terminals onshore,” Eknes says. “Without a proper market within a region for a bunker vessel, a pipelay operator will need to build alliances with the LNG distributor directly in order to safeguard own bunker supply. Technically, this is fully possible. The key question will be if the players find it commercially attractive to lead the race knowing that the full benefit will come when you have at least two bunker suppliers available. This is why we do a lot of scenario building together with operators and ship designers assessing the long term economics of different fuel alternatives.”

Diesel-electric engines

Another efficient technology is diesel-electric engines. “These can be used to provide the right level of power to the vessel when it needs it, which results in more efficient operations,” Sano says.

Earlier vessel designs had a direct-drive diesel engine powering the propulsion. With a diesel-electric design, all of the propulsion is electric. As a result, the engines can produce energy as efficiently as possible while also having access to additional power when needed. Also, the response time, in relation to the variation in power demands, is significantly shorter, which drives the quicker transfer of power to the ship.

DNV GL’s Eknes agrees. “With the currently reduced oil price, the necessity to reduce cost is evident,” he says. “A natural consequence of this will be to reduce the amount of fuel being used onboard. The opportunity to implement more flexible power systems onboard, such as a combination of different engines to ensure a flexible and capable power plant configuration, is one of the key trends happening these days.” Battery technology is also a buzz word these days, adding electrical storage and availability of power as key features. “To gain full benefit from batteries onboard, operating alone or in a hybrid mode with other engines, it is still important to maintain a reliable DP function and power during a critical pipelay operation,” Eknes says. “Together with the guidelines for maritime battery systems (2014), DNV GL’s new rules for propulsion and power generation published this year will act as a guide for how to safeguard operation while tapping into the benefits of reduced engine running hours, less emissions and a more flexible & reliable system onboard.”

No silver bullet

“There is no silver bullet in this market, as far as we are aware, with regard to design or equipment for pipelay vessels,” Eknes says. “The drivers toward deeper and harsher environments will continue in the long run, but the most pronounced driver supporting pipe-laying activity

is probably the strong trend to develop more subsea, and also shallow water with tie backs to existing installations.”

Offshore evolution necessitates the incorporation of new technology, Sano says. “Pipelay vessel capabilities will con- tinue to expand as industry moves into new frontiers – becoming not only larger, but faster, safer, and more efficient.”