By Alexander Wardwell, Det Norske Veritas

Scheduled for delivery in March 2012, the most recent addition to Stena Drilling’s fleet will be the industry’s first ice class +1A1 dual-mast ultra deepwater drillship for arctic conditions. But is the industry ready for offshore arctic drilling?

Based in part on Stena’s proven DrillMAX design, the new drillship, now under construction at Samsung Heavy Industries in South Korea, represents the company’s most ambitious project to date. According to Tom Welo, Managing Director of Stena Drilling, the project was conceived to meet the evolving demands of the industry. “Increased global demand for oil has encouraged energy companies to focus more on exploration,” he says. “And since many of the most promising fields are increasingly found in deepwater and harsh environments, including the arctic, we saw an opportunity to build a drillship to reflect the market.”

Tom Welo Stena Drilling

Tom Welo, Managing Director, Stena Drilling. Photo: Alexander Wardwell

Welo acknowledges that DrillMAX ICE represents a significant investment for the company and so far, the drillship has not secured a contract. “Any newbuilding project built on spec is a risk, but in our view, the greater risk would be to sit still,” he says. “We anticipate continued growth in this segment, and want to strengthen our position as a leading provider of drilling units equipped to operate in harsh environments.”

Flexible operational profile
At present, Stena Drilling operates four semisubmersible drilling platforms and three drillships. While these units have been active all over the world, including the North Sea, US Gulf of Mexico, South East Asia, Mediterranean, Caribbean, South America, North America & Greenland: Atlantic Front, Australia, North Africa and West Africa, the company has earned a strong position as a leading provider of drilling services in harsh environments. While similar to the company’s existing fleet of drillships, the design of DrillMAX ICE has been optimised for ultra deepwater arctic operations.

However, Welo is quick to note that once completed, the unit will be suitable for any job. “While we expect the vessel will be active in the polar region, the design doesn’t limit the drillship to waters above the Arctic Circle,” he says. “Rather, it expands the vessel’s operating parameters to almost any depth or environment.” Welo adds that the new drillship is capable of operating in water depths up to 10,000 feet.

Managing risks in the Arctic
The unit has been optimised for Arctic conditions. Six ice-classed 5.5MW azimuth thrusters, providing maximum manoeuvrability, propel the ice-strengthened hull. Below deck escapeways port and starboard side connect the aft engine rooms with FWD accommodation. Designated moon pools port and starboard allow for installation of two separate ROV systems. Anti-icing equipment protects the unit’s anchors, deck piping, lifeboat escape exits, scuppers and drains while enhanced de-icing machines keeps decks, gangways, and handrails clear. Steam heating coils warm the ballast tanks and drill water tanks and windwalls and cladding offer enhanced protection to the drill floor and dual mast derrick. “Most accidents and near-misses are related to human error, so we have worked hard to ensure the safety and comfort of our crew.”

In total, costs related to adapting the DrillMAX unit for Arctic conditions are calculated somewhere between USD 220 to 240 million. “We did consider adding icebreaking capabilities, but were concerned that the moon pool would collect ice and the cost would be prohibitive,” says Welo. “Instead, when operating in the Arctic, the drillship will have an escort of OSVs to help manage the ice.”

A relative threat
Operating in icy seas and low temperatures, which can drop to –20°C degrees in the Arctic in summer, is challenging, but Welo notes that different environments have different threats. “Operating in the North Sea is complicated by frequent storms and heavy seas and as we saw with Hurricane Katrina, the Gulf of Mexico is hardly a benign environment,” he says. “Icebergs and extreme cold certainly represent a risk in the Arctic, but there is less of a threat from heavy seas and large waves.” Still, Welo adds, DrillMAX ICE can survive waves as high as 30 metres.

While the drillships hull form is based on Stena’s proven DrillMAX design, some topside modifications were included. The drillship is likely to operate in the environmentally sensitive Arctic region, so space was created on deck for an extra six-RAM BOP, providing critical redundancy. “The additional BOP will also help us avoid delays between drilling projects related to the BOP workovers and maintenance.”

Proven concept
While there have been drilling operators active above the Arctic Circle for decades, most notably in the North Sea and the Barents Sea, energy companies have approached exploration in the region with some caution. To help generate more confidence in the Stena DrillMAX ICE concept, the company has worked with a broad range of key suppliers, with extensive experience in harsh environments.

DNVFor example, the drillship is equipped with DP3 station-keeping and related automation systems provided by Kongsberg for operating in ice conditions, knuckleboom deck cranes rated for -30°C conditions, and six-RAM BOPs provided by Cameron. The company conducted extensive Ice Model Testing, and worked closely with DNV to achieve ICE 10 Certification, among other notations. “Stena and DNV have worked together for decades,” says Welo. “Like Stena, DNV has extensive experience in the North Sea managing risk in harsh environments. DNV were thus natural choice to class the unit.”

With the build going well at Samsung Heavy Industries, Welo is looking forward to welcoming DrillMAX ICE into the Stena fleet. In the meantime, he says the company is in dialogue with a number of energy companies that have expressed interest in the concept. “I am confident we will secure a charter soon,” he says. “After all, DrillMAX ICE is coming out of the yard during a time when energy companies are expanding their deep and ultra deepwater exploration programmes. With this unit, we can offer the flexibility to go anywhere.”

Republished with permission, (c) 2011 Det Norske Veritas

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