Developing the deep sea

Following a successful subsea installation project in Australia, Maersk Supply Service aims to develop its expertise in sub-zero, pitch-black waters kilometres below the surface of the ocean.

Captain Sylvi Hansen on the bridge of Maersk Nomad: “Sometimes we have waited weeks for a perfect weather window.”

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Key planks of the Maersk Supply Service strategy

  • Outperform competitors on safety and profitability
  • Outperform competitors on safety and profitability


million USD – cost of one Christmas tree.

Captain Sylvi Hansen scans the horizon from his position on the bridge of Maersk Nomad, as a giant metal contraption weighing almost 90 tonnes hangs ready to be submerged above the surface of the ocean.

He is waiting for the perfect ‘weather window’ before giving the crew the go-ahead to begin slowly winching the device – known in the industry as a ‘Christmas tree’ due to its tree-like shape and decorative dials – down towards the seabed.

The tree is one of ten being installed by Maersk Nomad on a series of wells drilled by Exxon in the Jansz-lo gas field, 1,350 metres under the sea, offshore Western Australia.

It will form part of a complex network of subsea infrastructure used for production and transportation of gas from the field.

Highly specialised work

Installing this infrastructure at remote depths, in pitch-black waters kilometres below the ocean surface is highly specialised work, and an area that Maersk SupplyService has set its sights on for future expansion.

“As oil companies go to greater and greater depths in their search for oil and gas we see good opportunities in the subsea sector and are investing heavily in new vessels to grow our presence in this market,” says Niels Elmbo, Head of Projects and Subsea, Maersk Supply Service.

While Maersk Nomad was specially modified to carry out the work for Exxon by widening the vessel to accommodate a huge crane capable of lifting 200 tonnes, four new vessels are now on order specially designed for subsea work up to depths of 3,000 metres.

The vessels will join the fleet in 2016 and have been carefully specified to meet future industry requirements, with space for 120 people on board, each with their own cabin.

“We are setting a new trend in the industry, as most vessels currently have double cabins. It’s important that we offer our crew a good working environment,” says Elmbo.

Remote-controlled robots
Powerful sea swells, freak waves and storms are a frequent occurrence in this part of the Indian Ocean so it’s no surprise that Sylvi Hansen has his expert eye trained on the weather.

“The swell coming from the Southern Ocean can be pretty big sometimes. If the vessel is rolling too much as we lower the crane, the danger is that the tree starts swinging back and forth and could smash into the ship. We would never go ahead in a rough sea. Sometimes we have waited weeks for a perfect weather window,” says Hansen.

Poster image
The Christmas tree on deck before being winched down to the sea bed. The Christmas tree will be attached to a well and used to control the flow of gas out of the well.


tonnes – weight of one Christmas tree

Stormy weather isn’t the only challenge. With the pressure on the sea floor far too great for a human diver, remote-controlled submarine robots – known as Remotely Operated Vehicles (ROVs) – have to perform the task of connecting the tree to the well.

The ROV crew monitors the robots on a screen and controls their movements like a video game, carefully manipulating the arms to clean dust and sand from the well, before guiding the tree into position and switching on the valves and dials ROVs also help the crew in steering clear of any marine life, including sharks which could be circling the murky depths. Hansen recalls one operation during which the crew spent four hours prising a giant squid from the top of the well head with a high-pressure hose.

Lift-off to lockdown

Installation of the tree usually takes just a couple of hours, but the specialised nature of the job means a large crew of around 50 people is involved. Ensuring its smooth running and safety requires precision, planning and teamwork, says Hansen.

“We have a number of meetings to go through procedures and safety before beginning the operation. It is a very intense time when we lower the Christmas tree into the sea, but everyone has their own job to do. Once the tree is securely locked down and in position, then we can celebrate.”

Developing these specialisms is key to Maersk Supply Service’s strategy going forward, says Elmbo, who sees bright prospects for the future of the subsea sector.

“We see another big market opening up in this sector further down the line as oil companies start to decommission projects. When the oil wells dry out, companies will have to kill the wells and take out the entire subsea infrastructure. Our vessels will be ready to take on that job.”