What happens when an irresistible iceberg meets an immovable oil rig?
St. John's, Newfoundland
Dat Duthinh, an engineer, wants to bash a berg against a rock. The plan, to pull an iceberg against a steep cliff at Deepwater Point near St. Anthony, at the northern end of this island, is part of a study of the threat that icebergs pose to offshore oil rigs.
With the announcement this summer that the governments of Canada and the Province of Newfoundland would provide financial assistance to a group of oil companies to begin commercial production on the offshore Hibernia oil field, the research by the Centre for Cold Ocean Resources Engineering (C-CORE) here has taken on more urgency.
Hibernia, on the Grand Banks 200 miles southeast of this capital of Newfoundland and Labrador, is smack in the middle of what is sometimes called ``iceberg alley.'' A production platform in this field, or in any others discovered in the same region, must be able to survive a collision with an iceberg.
The big question is: Does the platform or the iceberg give ground? If the platform does, the result could be damage, an oil spill, or at worst, the crew being thrown into the frigid waters of the Labrador.
Scientists here have conducted extensive research on the strength and other characteristics of ice. Mona El-Taham, an Egyptian-born senior research engineer at this research facility on the campus of Memorial University of Newfoundland, has devised a computer-based model that she believes enables her to forecast the path an iceberg will take for 24 hours or so. (Some scientists here question whether the model is pragmatic, given the need to know in advance the speeds of ocean currents and winds, and the shape of the berg.)
Dr. Duthinh, who immigrated here from Vietnam, heads the ice engineering group at C-CORE. In four months, he and a colleague will fly to Terre Ad'elie, in Antarctica, to help carry out iceberg experiments in cooperation with the French Antarctic Expedition. In this area, south of Tasmania, icebergs bob up and down in the waves, frequently bumping onto the rocky seabed. The researchers plan to put ``motion packages'' onto icebergs to measure the deceleration when they hit the ocean bottom. The shape of the bergs will have been recorded by sonar and photography.
In earlier research for the Hibernia Partners, Duthinh and colleagues landed on an iceberg frozen into sea ice in Pond Inlet in Canada's far north. Thus the berg was stable. They dug several tunnels in the berg with chain saws. Then, with an air compressor, they used one wall of the tunnel as the backing for forcing under high pressure a large metal ball against the other ice wall at an appropriate speed of about one knot. The impact covered just 3 square meters (3.6 square yards).
The experiment showed that ice crushes under severe pressure into fine particles and flows like a viscous fluid. But these researchers aren't certain that these results can be multiplied to get the impact of, say, a 5 million-ton iceberg - the largest size that has been spotted on the Grand Banks in the past eight years - against a platform.
Public Works Canada, a federal department, gave C-CORE the money to study the feasibility of a ``large-scale iceberg-impact test.'' But the government has not yet come up with the $3 million needed to carry out a real test with a modest-size iceberg, say 50,000 tons to 100,000 tons.
The present idea is to tow a suitable berg close to the cliffs at Deepwater Point. That is no special trick. Scientists here and elsewhere have towed icebergs before. The towing boat simply runs a rope (one that floats) around the berg, joins the two ends, and pulls. Once near shore, the rope would be hooked up with a powered pulley on shore. Then the iceberg would be pulled against the rocks. Various scientific devices on the rocks would measure and photograph the impact. Here the impact area would be several hundred square meters.
The results, it is hoped, would provide a better idea of what sort of giant, concrete bumper would be needed around a gravity-based production platform.