Memorial University & Understanding Icebergs
By Tom Peters
They can come in all shapes and sizes, silently shuttled along by the currents. The larger versions are white, glistening and beautiful and a potential disaster waiting to happen.
Icebergs off the coast of Newfoundland and Labrador are one of the many products of a harsh North Atlantic environment and a hazard to offshore exploration rigs, drill ships, and platforms. In any given year there could be thousands of bergs, ranging in size from several feet in height and weighing hundreds of thousands of tons to the smaller size, known as Bergy bits, but all equally as dangerous.
Keeping an eye on these floating giants is a full time job several months of the year and requires an action plan by those operating in this environment to thwart off any pending collision.
Suncor, Husky Energy, Statoil and the various shareholders of the Hibernia platform, presently operate off the Newfoundland coast, some at more ice risk than others, but all potentially a target.
“We require all of the operators to have ice management plans which are submitted to us as part of the authorization process and you can’t get authorization to operate offshore unless you have an ice management plan,” said Sean Kelly with the Canada-Newfoundland and Labrador Offshore Petroleum Board, who also noted the industry “just came out of a pretty heavy ice season.”
He said ice management is just one of a number of plans required, all identifying potential risks and what the measures would be to address those risks.
Husky Energy, which operates the Sea Rose FPSO, a floating production vessel for the White Rose field, has dedicated ice observers on offshore facilities during ice season and liaise with a number of companies in terms of monitoring, said Husky’s Colleen O’Connell. She said the number of icebergs Husky would deal with annually varies according to ice conditions.
And Suncor, the major partner and operator of the Terra Nova field, just over 200 miles southeast of St. John’s, has an ice management program that monitors and deflects icebergs when required. Support vessels can encircle the berg with a cable or net and change its direction or use water cannons or wash from a vessel’s propellers to put the iceberg on a different course.
Neil Riggs, an iceberg expert and senior project manager, Autonomous Ocean Systems Laboratory (AOSL), Faculty of Engineering and Applied Sciences at Memorial University, in St. John’s, NL, put some perspective on the iceberg count.
“If you draw a line of latitude from St. John’s, going eastward, that is almost 48 degrees north latitude, that is the index line that the International Ice Patrol uses and the Canadian Iceberg Service to determine how severe an iceberg year is. So the number of icebergs that cross the line south, that is the measure. So if the number is a 1,000 or more or even a few hundred or more, these installations are in potential jeopardy,” he said.
“These people who operate these things (offshore operations) are obsessed with iceberg management which means detecting icebergs that are going to come upon you at some point,” Riggs said. “They go quite far north to look for them and then they track them by aerial surveys and sometimes satellites. As the bergs get closer they are using modeling software to predict how the bergs are going to drift and come up with a probability that there could be a collision or what will be the closest point of the iceberg to the installation. They will deploy various mitigation strategies, depending on what the models are telling them. Mitigating may mean towing the icebergs to maybe going out and attacking them with a fire hose to make them go away or take a different drift path,” Riggs said.
Nearly 100% of the icebergs heading down the Newfoundland and Labrador coast come from the west coast of Greenland, said Riggs. Actually, one glacier, the Jakobshaven glacier, is the most productive. The icebergs, some weighing millions of tons, calve off glaciers flowing into Jakobshaven fjord and then drift out into Baffin Bay. “They start heading northwards because that is the way the current flows and then when get around the Lancaster Sound area they basically hang a left and go west and start down Baffin Bay past the Labrador Coast and then to the Grand Banks,” said Riggs. Their size is reduced considerably subject to melting in the water but can still be quite large when they reach the Grand Banks.
“Even the small ones can be dangerous. The big bergs can be detected with radar and other means. The smaller ones are not easily seen on radar and often confused with something called sea clutter which is basically reflections from the top of waves. A bergy bit, as they call them, might be two to four metric tons so you can imagine that thing moving a couple of knots and then striking the hull of ship. So the threat is wide in scope,” Riggs said.
Tracking the Ice
Helping to determine iceberg flows and developing iceberg behavior modeling are what bring AOSL into the picture. AOSL has undertaken a long-term study into modeling the behavior of icebergs that includes acquiring real world data that will increase the accuracy of predicting the rate and direction of their drift. It will be information that will be available to offshore operations.
”What our lab is about is unmanned systems and using unmanned systems to solve problems for people,” said Riggs. “The unmanned systems we use are the autonomous underwater vehicles (AUVs) and more recently for us autonomous surface craft. The work we are doing here involves using a combination of both of these, using them to measure the above water and underwater shapes of the icebergs and also to measure the current field and in the vicinity of the icebergs as they are drifting along. We want to get that information as we measure it to the folks who want to use it as quickly as possible. It is all in the research and development stage but we are having some good results and hopefully we may be doing some trials in a year or two,” he said.
“One thing we are doing is learning about high persistence, that means unmanned systems that can stay out there for a long time without needing attention,” said Riggs, and AOSL has done some work in that particular field.
The concept was developed at ASOL by director Dr. Ralf Bachmayer and his team.
“It is an unmanned surface craft and it is in the shape of what we call a spar, like a spar buoy or telephone pole. We are now building a propelled spar that will be able to operate by remote control or under its own control. It will be equipped with a lot of instrumentation for measuring above water things like dimensions, size and shape of the iceberg but also weather, sea state, that sort of thing,” Riggs said. “It will also be equipped with a sonar system and other instruments for underwater that will be able to measure the shape of the berg, at least to a certain depth. We have other technology we are developing in concert with that (the spar) that will allow us to see the whole iceberg. We are adapting a particular type of underwater autonomous vehicle to be able to circumnavigate an iceberg underwater, like a corkscrew,” said Riggs. The vehicle is equipped with sonar and will be able to look at the sides of the iceberg as it circles around plus know its position. It will collect data that can be processed later into a shape and size estimation. With information collected from the surface craft and the sub-surface craft “we can put all the data together and come up with an estimate of underwater size and shape,” Riggs said. The technology also measures currents and other vital data pertaining to the icebergs with the view to get it to people who want to use it as quickly as possible.
AOSL hopes to have the spar technology in the water for testing in early 2015 and have it ready for testing in the North Atlantic by summer of 2015.
Riggs said AOSL also works co-operatively with the National Research Council of Canada which has also developed new iceberg modeling.
“They have put together the biggest database of underwater shapes of icebergs probably in the world,” said Riggs. “They have shared that with us and we have used in our R&D work. Basically we have developed a technique in processing it in such a way that when we make a measurement underwater on the shape of an iceberg, we can use their experience in the data they have collected on how accurate our estimation is on the underwater shape and size.”
Aside from industry benefitting from the AOSL work, the International Ice Patrol (IIP), which falls under the U.S. Coast Guard and has a mandate to monitor iceberg danger in the North Atlantic and provide relevant iceberg warning products to the maritime community, may also see some benefit.
Michael Hicks, with the IIP, said the ice patrol “would benefit from the availability of actual iceberg drift (and deterioration) data to validate the iceberg drift model that we presently use as well as to assess the operational effectiveness of other models that come available.”
He said the IIP has used satellite tracked beacons deployed on icebergs but that has not proven to be totally effective because iceberg surfaces are irregularly shaped and the icebergs tend to roll and break apart.
He said data from an autonomous vessel that can reliably detect and track and iceberg over a lengthy period would be a useful model for validation purposes.
(As published in the APRIL 2015 edition of Marine Technology Reporter - http://www.marinetechnologynews.com/Magazine)
February 2024
