Before leaving Newfoundland waters, the rig will stop at Marystown where it will undergo inspections and recertification, a process required for drill rigs every five years.
The Eirik Raude is likely to return to the Orphan Basin in 2008 or 2009 to continue exploration. The Great Barrisway hole was drilled in 2,350 metres of water, deeper than any other well drilled so far offshore Newfoundland and Labrador.
Initial estimates were that the exploration well would cost $140 million based on an estimated four months drilling. As completed, the well took seven months.
On top of the harsh ocean environment offshore Newfoundland, the water depth in the Orphan Basin calls for cutting edge technology. Pressures at the depths involved can be as much as 200 times the atmospheric pressure at the ocean surface.
Great Barrisway F-66's water depth rivals those in the Gulf of Mexico. Chevron's Jack 2 field in the Gulf of Mexico was discovered at a water depth of 2100 metres and 6100 metres below the sea floor.
But drilling to such depths provides many daunting engineering challenges.
Such equipment, for example, must be built to handle tremendous weight.
"The way the drilling process works is that you put sections of pipe together one at a time as you run [the pipe] through the water and down into the earth," Hadden said. [Steve Hadden, senior vice president of exploration and production at Devon Energy in Oklahoma City, quoted in the National Geographic story linked above.]
"You keep adding to the drill string until you reach the total depth of the well. So [in this case] you've got a 30,000-foot-long [9,144-meter-long] string of pipe hanging off a floating rig," he added.
"You can imagine the weight requirements, and you have to have the ability to lift it to the surface to change the drill bit."
Twenty thousand feet (6,096 meters) of the large diameter pipe that encases the drill hole tops the scales at over a million pounds (453,000 kilograms).
The enormous pressures found in deep wells are another major hazard.
Too much pressure can make it difficult to control the drill bit. Or the pressure could collapse the hole altogether.
Drillers must therefore use seismic readings while drilling to predict how high pressures will be at future depths in order to keep the hole viable.
