DNV has developed a new pipeline concept, called X-Stream, that can significantly reduce the cost of a deep- and ultra-deepwater gas pipeline while still complying with the strictest safety and integrity regime. X-Stream is based on established and field-proven technologies which have been innovatively arranged.

 

X-Stream can reduce both the pipeline wall thickness and time spent on welding and installation compared to deep-water gas pipelines currently in operation. The exact reduction in the wall thickness depends on the water depth, pipe diameter and actual pipeline profile. Typically, for a gas pipeline in water depths of 2,500 m, the wall thickness reduction can be 25 to 30 percent compared to traditional designs.

 

"It's essential for DNV that the new concept meets the strict requirements of the existing safety and integrity regime, and I'm pleased to confirm that this concept does," said Dr. Henrik O. Madsen, DNV's CEO.

 

Current deep-water gas pipelines have thick walls and, due to quality and safety requirements, the number of pipe mills capable of producing the pipe is limited. When installing pipelines, the heavy weights are difficult to handle and the thick walls are challenging to weld. And finally, the number of pipe-laying vessels for deep-water pipelines is limited too.

 

New offshore oil and gas fields are being developed in deeper and deeper waters and export solutions for the gas are critical. New exploration activities are also heading for ultra-deepwaters. The distance to shore is increasing too. The X-Stream concept can for such fields represent an alternative to e.g. floating LNG plants combined with LNG shuttle tankers.

 

By controlling the pressure differential between the pipeline's external and internal pressures at all times, the amount of steel and thickness of the pipe wall can be reduced by as much as 25-30 percent - or even more compared to today's practice and depending on the actual project and its parameters. This will of course make it easier and cheaper to manufacture and install the pipeline.

 

The DNV study is a concept study, and a basic and detailed design will need to be carried out before the X-Stream concept is realised on a real project. DNV intends to work further with the industry to refine and test the concept.

 

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