AGI/AIPG SUMMER INTERNS
costs drove many companies to abandon their projects, despite successfully finding oil.2 Exploration also slowed following the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 and the end of Royal Dutch Shell’s exploratory drilling in 2014.1,3
More recently, however, interest in offshore Arctic resources has rebounded despite falling crude prices.4
Challenges to Drilling and Oil Spill Response in the Arctic
The Arctic is rapidly changing: Arctic annual average temperatures are increasing at nearly twice the rate of mid- latitude temperatures, and sea ice is quickly retreating.1 Increasing interest in Arctic exploration and drilling requires an appreciation for the unique challenges posed by the harsh Arctic environment, particularly in the event of an oil spill.
The first of these challenges is lack of infrastructure. The nearest U.S. Coast Guard station is more than 1000 miles away from the North Slope of Alaska, where the majority of drilling takes place. This makes supplying equipment in the case of an emergency, such as an oil spill, difficult, dangerous, and time consuming.1 Moreover, once on site, responders could face shortages of housing, freshwater, food, waste facilities, communications infrastructure, and medical support.1
Environmental factors present additional challenges. Proper oil response requires a strong understanding of surface ocean circulation, yet surface ocean currents in the Chukchi Sea have complex flow patterns that can reverse direction in a matter of hours and vary in magnitude and direction over small spatial scales.1 Wind, as well as high wave heights dur- ing the open-water season, can also limit the effectiveness of many oil recovery and clean-up techniques. Meanwhile, low temperatures (-35°C) and icy conditions can lead to equip- ment malfunction, prevent aircrafts from flying, and present conditions too dangerous for response crews to work outside.1 Such frigid conditions also occur in combination with seasonal darkness; off the Beaufort coast, there is no daylight from November to January.1 Finally, any activity in the Arctic must also be wary of rapidly changing ice conditions and seasonal ice cycles. Even in the summer, ice can intrude on drilling locations and shipping routes, and ice-free regions can transi- tion to ice-covered regions in a matter of days at the start of fall freeze-up.1
Nevertheless, conditions in the Arctic do offer some advan- tages for oil spill response efforts. For example, sea ice can contain oil spills in a localized area, while cold temperatures and reduced wave energies during the winter months slow oil weathering, which can extend the window of opportunity for effective spill response techniques.6 Additionally, ice frozen along the shoreline can keep oil from impacting coasts from the fall freeze to spring thaw periods that last up to 9 months in many areas.1,6
Options for Clean Up Operations in the Arctic
Fortunately, oil can naturally degrade under several weath- ering processes. Evaporation can occur quickly for lighter, less viscous products (e.g., diesel and gasoline), but can be limited
1. 2. 3. 4.
5. 6.
7.
under subfreezing conditions or with heavier fuels (e.g., bunker fuel oils and emulsified oil).1 Emulsification (oil and water mixtures) and natural dispersion are driven by wind and wave action, but the presence of pack ice can dampen waves and slow both processes.1 Alternatively, naturally-occurring bacteria can degrade petroleum compounds and photoxidation can also occur as chemical compounds are broken down by sunlight energy during long summer months.1
However, given the relatively slow rate at which these natu- ral processes occur, active clean-up techniques often must be employed. The most widely used option for oil spill response is containment and recovery. This involves physically removing oil from the surface of the water by containing it with a boom, recovering it with a skimming device or sorbent material, stor- ing it on a vessel or barge, and then disposing the recovered liquids and contaminated materials.1,6
Unfortunately, sea ice concentrations and reduced wave intensity during Arctic winters can diminish the effective- ness of traditional containment and recovery strategies. Conventional booming strategies are most effective in open water or with ice concentrations <10%, 1 and dispersants that facilitate biodegradation require high levels of wave intensity to be effective.
The most promising oil spill response techniques for the Arctic is In-situ burning (ISB): the controlled burning of oil in the area it was spilled.1,6 Controlled ISB has been employed on a number of oil spills since the 1950s, including the Exxon Valdez spill in Prince William Sound, Alaska, in 1989.1
The key to effective IBS is thick oil slicks, which act as insu- lation from colder underlying water and keep the surface at a high enough temperature to maintain combustion.1 Closely packed ice floes (70-90% ice coverage) can contain oil and keep slicks thick, but under 30-70% ice coverage, slicks are often too dispersed. In these scenarios, chemical “herders,” or surface surfactants, can be used to drive oil to contract into slicks 3- to 5-mm thick prior to ISB attempts.1,6,7
Under the right conditions, ISB techniques can be very successful, eliminating oil with efficiencies greater than 90 percent.1,4 Additionally, this technique reduces demands on equipment and personnel, making it suitable for regions with limited infrastructure or dangerous conditions.1
Yet, it is critical to recognize that ISB is not a perfect solu- tion. Although 85–95% of burned oil becomes carbon dioxide and water, 5–15% is converted to heat-absorbing particulates like soot, which can land on ice and decrease ice reflectivity, causing ice melt.1 An additional 1–3% includes byproducts such as nitrogen oxide, sulfur dioxide, carbon monoxide, and polyaromatic hydrocarbons (PAHs) which contribute to global warming and acid rain.1 Meanwhile, smoke plumes from ISB can obstruct visibility and may pose safety hazards to people, ships, aircrafts, and motor vehicles in the immediate vicinity and downwind of the fires.1
http://www.nap.edu/catalog/18625/responding-to-oil-spills-in-the-us-arctic-marine-environment.
https://www.wilsoncenter.org/sites/default/files/Artic%20Report_F2.pdf
http://news.nationalgeographic.com/news/energy/2014/04/140404-coast-guard-blames-shell-in-kulluk-rig-accident/ http://www.nytimes.com/interactive/2016/business/energy-environment/oil-prices.html.
http://www.boem.gov/Five-Year-Program-2017-2022/ http://www.arcticresponsetechnology.org/wp-content/uploads/2012/11/FINAL-printed-brochure-for-ATC.pdf.
http://www.arcticresponsetechnology.org/research-projects/field-research-using-chemical-herders-to-advance-in-situ-burning/at-a-glance.
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