Usually a sailing rig is used to drill test holes and find oil. It is held in place by anchor chains or computer-controlled propellers.

Royal Dutch Shell plans to deploy the world’s first sailing liquefied natural gas plant, at the Prelude and Concerto gas fields off the coast of northwestern Australia. The gigantic vessel is much larger than an aircraft carrier, weighing 600,000 metric tons and measuring 1,574 feet long and 246 feet wide. Even the U.S. Navy’s new nuclear supercarrier would only barely top 100,000 metric tons. The world’s largest passenger ship also only reaches a tonnage of 220,000 metric tons.

Floating LNG plant is increasingly being considered as a way to commercialize stranded gas resources too small to support the construction of more expensive onshore LNG terminals and their associated pipeline infrastructure. LNG is natural gas super-cooled to liquid form so it can be transported by ship to places not connected by pipeline.

Such a monster ship would be able to reach “stranded” gas fields far out in the oceans, whereas usual operations require long undersea pipelines to reach the gas fields. The mobile gas processing planet also has the advantage of not going obsolete when gas fields run dry. The untested method is a “game-changer,” allowing discoveries that are small and too far from the coast to justify onshore plants to be profitable.

The Hague-based Shell’s plans to employ what it called the biggest ship in the world are backed by the largest exploration budget of any oil company, estimated at $31  billion this year and $28 billion in 2010, the company’s executive director, Malcolm Brinded said. The project is among more than a dozen that may propel Australia to second among global suppliers of the fuel from fifth now.

Shell in July awarded a contract to Samsung Heavy Industries Co. and Technip to design, construct and install floating LNG facilities over 15 years. Shell may order as many as 10 units worth about $5 billion each, Samsung Heavy estimated in a July statement.

The vessel is designed to withstand a “one-in-10,000-year” tropical cyclone, Brinded said.