Reliable and Effective Tools to Fight Oil Spills in Arctic Conditions
a report by
Vince Mitchell
Executive Project Manager, Lamor Corporation Ab
The unprecedented seasonal retreat of sea ice in the Arctic has been observed and is currently taking place. If this continues it has the potential to drastically increase the amount of worldwide marine activity in Arctic waters for the foreseeable future. This may include an increase in shipping of all types, including tankers, bulkers, container ships, tugs with barges and fishing vessels, in addition to the passenger cruise vessels, research vessels and ice-breaking vessels currently plying these waters. This increased activity will also include oil and gas exploration, development and production activities. This will present a whole host of new considerations and challenges for Arctic nations and will increase the chances of oil being spilled in these regions. These increased risks will include both persistent oils (many crudes and heavy refined products) to non-persistent oils (diesel and petrol). This article will examine the reliable and effective tools, equipment and common tactics available to fight oil spills under Arctic conditions in offshore environments.
Behaviour of Spilled Oil
The foremost physical properties effecting oil when spilled is its density (specific gravity – the oil’s ability to float) and its viscosity (the oil’s ability to flow and its thickness). The behaviour of any oil spilled in Arctic conditions will be different from oil spilled in more temperate climates. The major differences that will affect the oil spill responders include the following.
Evaporation
This occurs when the lighter, more volatile components are lost mainly due to the speed of the wind, the temperature and the thickness of the oil slick. Evaporation rates of spilled oil in the Arctic are less than in warmer sea and air temperatures.
Spreading
Discounting the presence of ice, the spreading of oil on the surface of the sea is primarily a function of the water temperature and to a lesser degree the air temperature. Oil spilled in the Arctic will be more viscous and spread less than oil spill in warmer waters. These factors will cause differences in the behaviour of the spilled oil that may affect the equipment selection and tactics available for use by the responders. It can be generally stated that the presence of ice reduces the overall efficiency of spilled oil recovery operations. There may be other considerations that may in fact be favourable for spill responders when operating in Arctic regions. These may include an increase in the thickness of the spilled oil, reduced weathering and formation of emulsion (water-in-oil mixture), reduction of the waves due to the dampening effects of ice and the blockage of shoreline impact due to the presence of land-fast ice.
Safety of Responders and Equipment
In any response to spilled oil the safety of the spill responders is paramount. In addition to the marine safety hazards all responders may be exposed to on oil spill in any location that may include noise, fire and
© TOUCH BRIEFINGS 2010
explosions, ergonomic, crane operations, chemical and respiratory exposures, wildlife and aircraft operations. Additional concerns in Arctic regions may also include cold stress (including hypothermia), small boat operations, which may involve ice and icing conditions, and increased risks of slips, trips, falls and even sunburn. Ample consideration should be given, ahead of an event if possible, to mitigate or design out, wherever possible, the effects of any potential hazards.
Mechanical Containment and Recovery Equipment
This is the most ‘traditional’ of the oil combating techniques and involves what commonly comes to mind when one thinks about response to oil spills: the use of oil containment booms and oil recovery skimmers. The vessel platforms selected for this offshore mechanical containment and recovery should be suitable for the harsh environmental conditions, provide adequate facilities for sustained operations and ideally at a minimum be ice-classed and equipped with controllable pitch propellers for sustained slow-speed operations. Equipment selected for use in the Arctic should be robust, simple and ideally fitted with cold temperature adaptations to prevent equipment freezing (engine oil heaters, hydraulic oil heaters, hot water or steam heating) and the ability to avoid or process any ice that may be encountered.
Oil Containment Booms
Oil booms can be used to collect oil, contain oil, protect areas at risk and assist in shoreline clean-up if needed. For the offshore, open water use in Arctic regions (~1–2/10 ice), oil booms can be used effectively to collect and contain spilled oil, increasing the oil thickness for collection by skimmers. All oil booms have common components that give the boom its freeboard-, draft- and buoyancy-to-weight ratio. The most common boom construction materials include polyvinyl chloride (PVC), polyurethane/polyvinyl (PU) and rubber-coated (neoprene). All oil booms have some type of floatation material, which can range from air to solid foam, and some type of tension member/ballast weight, which commonly ranges from chain to lead weights. It should be noted that all oil booms will eventually fail in increasing ice conditions due to the tremendous forces produced by the ice on the boom system. Generally, for offshore use in Arctic regions a heavy-duty neoprene fabric boom with air floatation and a chain tension member/ballast weight provides the highest strength, best performing and most robust boom suitable for offshore service. As the concentration of ice increases, the spreading of the oil will be impeded and reduced as the ice acts as a natural booming material, concentrating the oil into the narrow channels or into pockets in the ice.
Oil Recovery
Once oil is collected in a sufficient thickness, it can be removed or skimmed from the surface of the water. Skimmers are either stationary or advancing and the most common type of oil skimmers include weir,
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Regional Focus – Arctic
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