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Improving the mouse trap MMS requires capability to respond to an oil spill; research is finding improved ways to trap and remove oil from the Arctic offshore Alan Bailey Petroleum News
While continuing research is improving the efficiency of cleanup techniques for oil spilled in ice-laden water, existing techniques for oil spill response in Arctic offshore waters have been proven to be effective, Jeff Walker, U.S. Minerals Management Service regulatory supervisor, field operations, told Petroleum News Oct. 2.
“Our regulations and our regulatory programs establish a planning standard for spill response,” Walker said.
A company operating on the U.S. outer continental shelf has to be able to demonstrate that it has available the equipment and personnel necessary to clean up the total volume of oil that could be discharged in a worst-case scenario oil spill, Walker explained. And in assessing that spill response capability, MMS uses capacities for equipment such as skimmers derated below the manufacturer’s nameplate capacity. Derating the equipment capacity allows for the likelihood that equipment will not operate with maximum possible efficiency during an oil spill response, Walker said.
MMS views an oil discharge contingency plan as acceptable if the operator has a sufficient inventory of response equipment with the capability of operating in the offshore environment where the operator will be working, said Christy Bohl, MMS oil spill program administrator. The operator needs sufficient personnel to mount a 24-hour-per-day response operation, with adequate protections for sensitive sites and animals in the area of the response scenario, Bohl said.
Mechanical recovery The use of skimmers — devices used to remove oil from water — in conjunction with surface boom has for long been a widely used technique for recovering oil from open water. But skimming techniques can also be used in icy water, Bohl said.
“Skimming and mechanical recovery is the preferred method for oil spill response because you’re actually removing the oil from the environment,” Bohl said. “And there are very good skimmers that work in broken ice.”
There is a wide variety of skimmer designs, with each design intended for a particular type of oil recovery situation. Skimmer designs known as rope mop skimmers and brush skimmers include material that attracts oil from the water and have been demonstrated to work in icy water, Bohl said.
That’s not to say that skimming oil from icy water doesn’t present problems.
“The big thing with ice is that it has the potential to block the action of the skimmer,” Bohl said.
Bohl said that the techniques used to operate the skimmers play a critical role in mounting a response in icy water. For example, some trials in 1999 and 2000 using a large barge-based system for collecting and skimming oil proved problematic.
“That was not overly effective if you had heavy concentrations (of ice) to cope with,” Bohl said. The ice could tear up the boom or endanger the skimmers, she said.
That experience has led to a technique that involves the use of small, single vessels that deploy relatively small amounts of boom to mop up pools of oil from water between the ice. And with this type of technique it is possible to use the edges of ice floes as natural containment for oil on the water.
“The smaller vessels are much more maneuverable there and can access in between floes along the ice edge,” Bohl said.
New skimming technologies Meantime, research is progressing into new and improved skimming technologies. MMS has, for example, funded research at the University of California Santa Barbara into a new material for drum skimmers that increases skimming capacity by more than 200 percent, Bohl said. That technology has been tested successfully in a cold-water tank and is now being developed into a commercially available product, she said.
The new drum skimmers could skim oil from the surface of, say, slush ice during freeze up, Bohl said.
Oil herders — chemicals that when added to an oil slick cause the slick to contract and thus become more concentrated — also show great promise. The use of herders in icy conditions has been successfully tested at the U.S. Army Cold Regions Research and Engineering Laboratory, Bohl said.
“A chemical herder, essentially, is a surfactant,” Bohl said. “It’s placed in the oil at very, very low dosages. It … changes the surface tension and forces the oil slick to contract.”
By concentrating the oil into a relatively small slick, the herders increase the recovery rate during skimming operations. And there is also the potential to use herders in conjunction with in-situ burning or oil dispersant techniques, Bohl said.
Research to date has proven the effectiveness of herders. But another study that is up for funding should take that research to a point where approval for the technique can be sought from regional response teams and the State of Alaska, Bohl said.
MMS has also sponsored quite a bit of research and experimentation into the use of chemical dispersants to remove oil slicks, Bohl said. The relatively low energy of frigid Arctic seas has traditionally been considered a major obstacle to the use of dispersants in the Arctic offshore. But tests have now shown dispersants to be a bit more effective in cold water than was originally thought, Bohl said. MMS is currently working through some peer review comments on experiments done in the Ohmsett testing facility in New Jersey, she said.
“Our initial testing went through peer review with the National Science Academy,” Bohl said. “They came out with where they thought there were problems or it needed additional clarification — we’re working through that now.”
In-situ burning MMS has also done a great deal of research into the in-situ burning of spilled oil.
“MMS has a long history of in-situ burning testing,” Bohl said. “… In-situ burning is a very operational technique.”
From the perspective of in-situ burning in the Arctic offshore, MMS has researched the limitations of the technique in freeze-up conditions.
“A few years ago we conducted another research program, defining what the burn limits were in freeze-up conditions, to see how far you could push it before you lost the ability to burn the oil,” Bohl said.
In-situ burning could prove particularly valuable in spring conditions, when melting ice allows open water leads to form and oil trapped in or under the ice during the winter rises through brine channels into surface pools. In fact an experiment at Svalbard in Norway has tested this type of technique.
“We put in I think about 10 drums of oil under the ice in February,” Bohl said. “… And then in May it surfaced up through the brine channels and then we estimated we burned about 96 percent of the oil.”
However, the North Slope Borough has raised concerns about the potential environmental impact of the burn residue, a tarry mat that can be removed mechanically from the water but which could sink to the seabed.
“So we’ve now got another project up for consideration for funding, on improving methods to collect in-situ burn residue,” Bohl said.
Alaska Clean Seas, the North Slope oil spill response cooperative, has an oil recovery technique that involves mining oil that has become trapped in sea ice during the winter. During the winter freeze up ice closes up and encapsulates the oil, Bohl said.
“Also when it’s encapsulated it’s removed from the environment,” Bohl said. “It’s not going to weather.”
Ground-penetrating radar And new techniques that use ground-penetrating radar to detect oil under solid winter ice have been tested both in the laboratory and in the field. The radar is shot through the snow and ice and can detect the water-oil-ice interface, Bohl said.
One major concern is the potential for an oil pipeline to leak underneath the winter Arctic ice pack — without the radar technique people have had to drill holes through the ice above a pipeline to make sure that no oil had escaped from a line. A big concern is that a small but long-lasting leak during the winter could, if not detected, result in a major oil spill by the time the oil surfaces during the spring thaw, Bohl explained. And, even in the area of a known oil spill, the radar technique will help delineate the location of the oil under the ice.
“You can delineate the spill much faster,” Bohl said. “You’re essentially protecting industry personnel because they’re not out there auguring holes through the ice and being exposed to the elements and whatever critters might be wandering around out there.”
Researchers are now investigating techniques for carrying out radar surveys from aircraft, rather than having to pull the radar equipment across the ice.
But, given the current state of fully operational oil spill response technology, how well is industry prepared for an oil spill in the Arctic?
The oil industry has developed a very extensive inventory of equipment and tactics, Walker said.
“Industry and the spill response organizations on the North Slope have really gone a long way to develop a response structure that could mount a credible response,” he said.
But that doesn’t preclude the need for further research.
Techniques continue to evolve “to try to improve the mousetrap,” Bohl said.
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