courtesy Aker Arctic

Total may have sealed its 25 percent stake in the company developing the Shtokman gas field in the Russian Barents with a remote control buoy, judging by slides seen at the Deep Offshore Technology conference in Stavanger.

A buoy that “chews” 17-metre-thick pack ice as it converts DC current or supplies AC current to sub-sea facilities could only have been of interest to Gazprom, according to conference goers polled by Scandoil.com.

Total E&P development engineer, Yann Bouger, said “time-consuming and expensive” ice-testing at the ice labs of Force Technology in Denmark showed exactly the results hoped for. A 1:40-scale model of a 3,500-tonne “inverted cone” was shown by underwater views and time-lapsed photography to efficiently “open its own sea lane” with the passage of ice flows, a noisy operation.

“I’m glad it’s unmanned,” Bouger said.

A “kilowatt” control buoy powered by fuel cell and a “megawatt” version to convert DC current for actuating valves are two configurations already conceived.

“Everyone is thinking it, but no one is saying it,” one industry onlooker said, adding, “Gazprom must surely have been interested for their own long offsets and seabed compression thoughts.”

The control buoy must be manned to be disconnected should any of the region’s million-tonne bergs appear on a collision course. A helicopter pad and docking “hatch” shelter for emergency fast craft allow for emergency crews.

The onrush of an iceberg puts the buoy in disconnect mode, and “simple hydraulics” disengage the umbilical, which remains in suspension. An ice skirt protects 800 metres of anchor wire and chain and, together with 2,000 tonnes of liquid ballast, adds seaworthiness.

The worst Barents Sea waves, at 23 metres, are never as bad as in the open Atlantic Ocean, or even the North Sea. The Barents’s one-knot current is the main ice-breaking force, judging by a video Scandoil saw.

A “co-author” of the report on the buoy’s performance is Marc Leblanc of Force Technology in Norway. Leblanc’s work is behind a great many of the jacket designs offshore Norway.

A long, “sub-sea-to-beach” concept is believed to be among the frontrunner concepts for developing the giant gas field Shtokman in the Russian Barents Sea.

ws@scandoil.com