Dealing with oil slicks, cleaning up the crude

The black days of the Tory Canyon, Exxon Valdeez and Prestige may seem to be a thing of the past thanks to double-hulled tankers and higher standards, but the industry is still constantly improving clean-up technology

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By  Nicholas Wilson Published  July 4, 2006

technology|~|spills200.jpg|~||~|There have been enough well-publicised major oil spills with devastating consequences to highlight the danger that they represent, such as the Exxon Valdez incident 17 years ago in Alaska. However, according to the International Tanker Owners Pollution Federation (ITOPF), the incidence of large spills around the world and in the Middle East in particular, is relatively low and has decreased significantly over the past 30 years.

The average number of large spills per year during the 1990s was less than one-third of that in the 1970s, and those that do occur are mostly small—less than seven tonnes. Of the 20 major oil spills since 1967 only two have occurred in the Middle East.

The low incidence of spills in the Gulf region, including the Strait of Hormuz, the Gulf of Oman and into the Arabian Sea, is impressive given that more than 45% of the world’s sea-borne crude oil trade passes through the area. There have been relatively few major accidental spills from tankers, partly because there are comparatively few navigational hazards.

ITOPF says the main navigational threat is linked to possible collisions resulting from traffic congestion, in particular around Fujairah and other oil loading and bunkering facilities. To this end, traffic separation schemes have been established in the approaches to and within the Gulf and been adopted by the International Maritime Organisation (IMO).

The Gulf’s shallow marine waters can, however, create problems for deep draft tankers that travel for considerable distances with limited under-keel clearance. In addition, prolonged winds in a constant direction can cause surges and a significant change in water depth, also creating potential navigational problems.

ITOPF adds that concerns have arisen recently about the number of illegal discharges from the large volume of shipping within the region and the frequency of oil spills because of sub-standard vessels illegally transporting oil from Iraq. Unofficial records show that nearly 26,000 tonnes of oil ended up in the sea from these illegal and risky operations.

Most spills from tankers occur during routine operations such as loading, discharging and bunkering, which are normally carried out in ports or at oil terminals. These are more easily dealt with, but it is the risk of major spills at sea or even the cumulative effect of many, smaller spills that is the main concern of the industry.

According to ITOPF, marine oil spills used to be considered “unavoidable accidents” resulting from adverse environmental conditions or functions of catastrophic events. However, it points out that more than 80% of all spills are, in fact, due to human error. Many billions of dollars have been spent over the past decade on research and development, leading to new safety procedures and technological improvements in tanker operations, as well as in response practices and clean-up procedures.

Clean-up practices depend on the location and size of the spill. However, there are several common technologies used. These include chemical dispersants to break down the oil and distribute it throughout the water column; biological agents that speed up degradation rates; and occasionally burning.
Dispersants can be applied from vessels or aircraft—fixed wing and helicopter. Booms, skimmers and pumps are also deployed from vessels at the scene of the slick to remove the spill from the water surface. Other technologies such as high-pressure washing or vacuuming get rid of the oil once on shore.

Rob Self, is the Bahrain-based head of Oil Spill Response Limited (OSRL), a United Kingdom-based organisation owned by 30 oil companies, including most of the majors. “When we get a call about a spill we have to quickly determine what the situation is. From that information, we work out whether the oil is going to come ashore and what resources are at risk; for example, desalination plants, power stations, refineries, fisheries and, increasingly in the Gulf, tourist areas, he said Also, something that’s specific to this region is coral—which, for example, means that we would avoid the use of chemical dispersants.”

Self says that if the spill is offshore then the main priority is to contain the slick and recover the oil. For this, large inflatable booms—inflatable devices towed through the water to contain spills—are towed out to the area and the oil is trapped within them and then recovered and held in storage tanks onboard vessels. Chemical dispersants can also be applied via spray systems from ships, helicopter under-slung buckets and—in OSRL’s case—a Hercules aircraft when the situation demands it.

“The general rule of thumb is one part dispersant to 20 parts of oil, but using it depends on coral, fisheries and most importantly on the permission of the regulatory authority, which owns the waters you’re spraying in. A decision on whether to use dispersants needs to be taken quickly because the longer the oil is at sea the more likely it is to become heavier, and more viscous oil is less amenable to dispersity,” Self said.

The oil slick can also be burned. However, this creates a very dense, black smoke that pollutes the air and does not remove all the oil. “As with all fires, there’s always something left and the oil that doesn’t burn can sink which causes problems further down the line,” Self says.

Response practices for spills near the coast are different. “A major oil spill will eventually come onshore, so the important thing is to keep it where it has impacted. Resources are focused on keeping it in one place and to recover as much as possible,” he said.

The first stage is to remove the bulk oil liquid product, and secondly all oiled material debris on the beach. “Then it receives a final polish to get it back to how it was.” This polish stage does not, however, always occur as depending on the size of the spill, a natural clean up can occur via the marine environment. An alternative method, Self notes, is the use of a bio-remediation agent usually applied along the affected shoreline adding nutrients or micro-organisms that “eat” the oil.

While most oil response practices are standard, new technology is being developed to improve the existing processes. Erik Schobesberger is the sales manager Middle East & Northern Africa for Lamor Corporation, a Finnish-based supplier and manufacturer of oil spill recovery equipment. His company has developed advanced skimmers for clearing up marine spills. “These are mounted on vessels with sweeping arms on both sides that extend and are driven through the slick guiding the oil to the skimmer,” he said.”

Lamor has also developed a brush wheel that rotates in the water and attracts more oil because of its larger surface area compared to a traditional disk or drum.

Changes are also being made to traditional booms. “Customers now want these to be deployed more quickly,” Schobesberger says. “The response time is a crucial element in oil spills and we have developed a boom that is inflated automatically from just one point rather than individually through its various chambers. It’s safer to deploy as well because there’s no need for personnel to be involved at the boom. There’s quite a significant time saving as well; previously it would take 15 minutes to inflate a 300-metre boom but the self-inflatable ones only take six minutes.” Another new development is equipping traditional skimmers with thrusters so they can become more manoeuvrable and be operated either from a vessel or an onshore line.
Key to any spill response is preparedness and communication. The Gulf has established an industry co-operative body, the Regional Clean Sea Organisation (RECSO), formed in 1972 by regional oil companies including Saudi Aramco, ADNOC, Kuwait Oil Company, Dubai Petroleum Company, Bahrain Petroleum Company, Qatar Petroleum, Petroleum Development Oman and the Iranian Offshore Oil Company, amongst others.

According to its chairman Khamis Juma Bu Amim, the main aim is to protect the environment from oil pollution emanating from members’ operations. “Each member shares the responsibility of ensuring a long-term commitment to the ‘Clean Gulf” concept.” RECSO’s aim is to prevent operational oil spills, stop tanker discharges, ensure safe ships and stop all industrial waste discharge into the sea.
Bu Amim claims that the low level of oil production-related spillage in the region is due to the fact that companies have “always taken the environment and potential risks into consideration [and] applied stringent measures and control over any possible harmful discharge.”

He also says that there is a sufficient level of response practices for oil spills. “This has been a major area where we invest a lot of time and effort in order to share ideas and know-how. Soon we hope to finalise the Gulf Incident Command, which will maximise the effectiveness of dealing with any incident.”||**||

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