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The burning question in ice conditions Arctic oil spill JIP publishes report on the effectiveness of in-situ burning in a response to an oil spill in ice-laden water Alan Bailey Petroleum News
As companies such as Shell turn their eyes to the Arctic seas as a new frontier for the discovery and development of oil resources, some people are skeptical about the possibility of cleaning up an oil spill, should some accident occur in the ice-laden waters of the far north. Can oil realistically be removed from between ice floes? And what if oil becomes trapped under a continuous ice sheet?
One technique that the oil industry has proposed for responding to an Arctic offshore spill is the in-situ burning of oil, a technique that the industry says has the potential to remove large volumes of oil from the sea, depending on sea and ice conditions.
An Arctic oil spill technology joint industry program, or JIP, has published a new report overviewing current knowledge of in-situ oil burning in ice-affected waters and providing insights into the feasibility of the technique and into some of the issues involved in the technique’s application.
According to the JIP website the JIP, with a membership composed of nine major oil companies including Shell, BP, ExxonMobil, Statoil and ConocoPhillips, was formed in 2012 as a collaborative venture under the International Association of Oil and Gas Producers, to expand industry knowledge of Arctic oil spill response. The JIP is conducting laboratory research projects into the use of oil dispersants, environmental effects, oil slick trajectory modeling, remote sensing of oil and in-situ burning. The program may also at some time involve Arctic field testing of response techniques, the website says.
Current knowledge The JIP’s new in-situ burning report presents a synthesis of current knowledge about this technique, rather than the results of some new laboratory or field research done by the JIP. The objective is to encourage the consideration and acceptance by industry, regulators and other stakeholders of in-situ burning as a viable technique in ice-affected waters, the report says.
“In general, in-situ burning has proved effective for oil spills in ice conditions and has been used successfully to remove oil spills in ice-covered waters resulting from storage tank and ship accidents in Alaska, Canada and Scandinavia since the 1970s,” the report says.
The report says that, while in-situ burning has rarely been used in dealing with marine oil spills, success with the technique in eliminating 220,000 to 310,000 barrels of spilled oil from the Gulf of Mexico following the Deepwater Horizon disaster has increased interest in the technique’s use.
Depends on ice conditions But the feasibility of burning oil in a situation involving sea ice would depend on the precise ice conditions, the report says. In the presence of floating pack ice or drift ice, the concentration of ice on the sea surface would determine whether spilled oil could be burned. In the case of consolidated land-fast ice, the process of encapsulation and migration of the oil would be a determining factor.
“Mid-winter, although associated with long periods of darkness and cold temperatures, provides a stable ice cover that not only naturally contains oil within a relatively small area but also provides a safer working platform for surface oil removal,” the report says.
There is a range of effective burning options that could enable high oil removal rates from spills under or on fast ice, the report says.
But burn options in moving pack ice are more limited, with a likelihood of highly variable removal rates, depending on the ice conditions.
“In these conditions it is often only possible to track the oil until it is released from the ice the following spring and ignite and burn it then,” the report says.
The report reviews the history and the results of research and development for a number of technologies that could be used for oil burning in ice-infested water, including oil igniters, fire-resistant boom, floating burners and additives for assisting the burn procedure. The report says that the following technologies are currently commercially available: two types of igniter for use with oil pools contained by fire booms; two aerial ignition systems; four types of fire boom for us in open water and in light drift ice; and two chemical agents that can herd uncontained oil in pack ice conditions.
Environmental tradeoff In-situ burning has the effect of removing oil from the sea and ice by converting the oil into a plume of soot and combustion gases, while leaving a residue in the sea. And so the merits or otherwise of using burn techniques revolve around the tradeoff between the environmental harm caused by leaving the oil spill untreated and the environmental impact of the burn’s airborne plume and remaining residue.
The report says that, while a number of studies have pointed to burn emissions such as particulate carbon and sulfur dioxide having the potential to pose a threat to wildlife or human health downwind of an oil burn, exposure to these materials would fall below thresholds for health impacts within a few kilometers of the burn site. The use of prescribed separation distances between burn sites and sensitive downwind areas can mitigate any smoke hazards, the report says.
In addition, burn residues remaining at a site after a burn appear to pose little threat to either aquatic resources or people, with the residues representing a small proportion of the original oil slick and consisting of material equivalent to highly weathered oil.
“Case studies of burns in major spills have revealed no significant impacts to human or ecological resources,” the report says.
And hypothetical risk evaluations support the view that in almost all circumstances burning crude oil on water poses a lower risk to humans and the environment than does leaving the oil in place, unburned, the report says.
Issues to consider But planning and implementing a safe and effective controlled burn of spilled oil in ice-laden water requires the consideration of several issues involving the feasibility of the burn, the resources needed to carry out the burn and the procedures to avoid or minimize health risks and environmental impacts. The report comments that operational experience of in-situ burning in open water conditions is somewhat limited and that experience in ice-affected water mainly stems from field experiments of limited size. However, in-situ burning has a potential role in a number of Arctic offshore scenarios, including in open water; in various conditions of drift and pack ice; and in a near-solid ice cover, the report says.
Editor’s note: Part 2 of this story will appear in the March 2 issue.
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