Critical factors in Arctic oil spill preparedness

Time is the most critical factor when dealing with an Arctic oil spill, says Steve Potter, principal consultant, SL Ross. Small spills can usually be handled by onsite personnel with rig- or platform-based boats and booms. Larger spills require more resources, so land-based or pre-positioned equipment is critical to any response.

Shell’s oil spill response crews practice laying out nearly 600m (1500ft) of a floating, curtain-like device designed to contain oil from the Nanuq response vessel near Valdez, Alaska, in May 2012.

In the Arctic, remote locations and limited resources hinder a rapid response as does the cold environment. API Bulletin D16: Suggested Procedure for Development of a Spill Prevention Control and Countermeasure Plan (2010) recommends a tiered responsive:

• Equipment for small spills.
• Equipment from regular sources for medium-sized spills, difficult in remote areas.
• National/international efforts for large spills or long lasting events.

The key separator is the time needed to activate and move equipment into position to address the spill.

There are three main strategies to manage spills: containment and recovery using vessels of opportunity towing booms and skimmers; in situ burning using vessels towing fire-resistant booms coupled with ignition of the gathered oil; and dispersants for widely spreading or high-volume spills.

Containment and Recovery

Containment and recovery is the preferred approach, but is limited by the available equipment. A large area must be covered in a short time. In a large spill this strategy may only be able to address 1-2% of the total spill area. It is also problematic in open water and shoulder seasons due to the presence of ice.

Even traces of ice limit the effectiveness of containment and recovery. Skimmers need to be able to process ice and have rotating brushes for cleaning closely packed ice. Smaller, single-sweep, oleophilic skimmers work well in more open waters, are more maneuverable, and minimize water pickup.

Containment and recovery is the least effective technique with only 0-30% of the slick recovered.

In-Situ Burning

In-situ burning is best for open water and where there is concentrated ice. It is highly effective with low equipment and manpower requirements. It can reduce slick thickness with 90% effectiveness, and can achieve a burn in thick ice with melt pools at the surface. However, it does involve an environmental tradeoff, since the consuming fire will send smoke and partially burned hydrocarbons into the air.

Dispersants

Dispersant application is an open water technique that can be used with some ice concentrations. It chemically breaks the slick into small droplets, diluting and dissolving the slick into the seawater, so that naturally occurring, oil-consuming bacteria can neutralize the oil. Dispersant effectiveness is dependent on the spilled oil’s properties.

This technique requires minimal equipment and manpower, since dispersants can be applied by air in a short time. The environmental tradeoff is protecting surface resources (birds, sea mammals) versus subsurface resources (fish). As the oil is broken into minute droplets by dispersant and diluted by seawater, its toxicity rapidly drops to low levels.

Effectiveness

Of the three techniques, in-situ burning is the most effective, removing 70-90% of the spilled oil. Next are dispersants, with 30-70% effectiveness. Containment and recovery is the least effective at 0-30% recovery.

Equipment delivery, personnel support. and waste handling must be considered and plans developed to address an oil spill. In addition, it is best to get pre-approvals for use of burning or dispersants, since regulations are unclear or non-existent in many arctic jurisdictions.

Industry’s Response

The industry is well aware of the need for additional Arctic technology development to address oil spills in the high latitudes. There is a need for of new chemistries, equipment and experimental spills to test their effectiveness.

To meet this need, the Arctic Response Technology Joint Industry Project was formed and has developed a series of projects to investigate key problems.

According to Joe Mullin, JIP program manager, there are nine projects underway investigating:

• Dispersed oil under ice. The goal is to develop a numerical model for oil plumes; a contract was awarded 4Q 2012 for a turbulence model and data gathering to validate the model.
• Dispersant testing under realistic conditions. The goal is to understand the needs, develop lab experiments, and define regulatory requirements.
• Environmental impacts. Net Environmental Benefits Analysis framework will be used requiring an information base, a review of historical impacts, and prioritization of impacts. This is presently underway and is to be delivered 1Q 2013.
• Trajectory modeling. This project will expand on the oil spill modeling with the addition of high resolution ice modeling to develop an oil trajectory model.
• Remote sensing. This project will develop ways to detect and map oil spills and plumes on the ocean’s surface using airplanes and satellite data. For the subsurface, it will develop a test program using ROVs and AUVs to gather data. The JIP is presently working with Woods Hole Oceanographic Institute to develop this program.
• Mechanical Recovery. The goal is to develop remote recovery units, explore new vessel designs, develop onboard oil/water/ice separator equipment, and develop an onboard oil incinerator.
• In-situ burning. Review and define the state of knowledge and prepare educational materials.
• In-situ burning. Develop improved systems of aerial ignition.
• In-situ burning. Develop improved chemical ‘herders’ (to enable in situ burning without the use of booms) with application systems and basin testing.

The JIP also wants to create opportunities for field research with other groups, to test their results.

Resources:

Arctic Response Technology JIP
Spill Response in the Arctic Offshore – February 2, 2012