Oil Spills and Blowouts - Click here for info on the Terra Nova Oil Spill, November 2004
Troubled History (Extracts from Strong et al., 2002; SFU, 2004 )
| The history of oil spills associated with onshore and offshore petroleum industry is well documented. The United States Minerals Management Service (MMS) recorded over 31 million barrels lost in spills between 1974 and 1997 (U.S. DOI 1997a). The largest oil spill in history was caused by the June 1979 blowout from the Ixtoc-I offshore production facility which released more than three million barrels of oil into the Gulf of Mexico by the time it was finally brought under control in 1980. The largest tanker spill occurred when the Atlantic Empress spilled over two million barrels of oil off Tobago in the West Indies. The Exxon Valdez spill, the most famous spill within in the past two decades, in which roughly 260,000 barrels of oil were spilled into Prince William Sound in Alaska in 1989, ranks 34th in size worldwide. |
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In Eastern Canada there have been three significant examples of offshore damage within the last 30 years. In February 1970 the huge (100,000 ton) “Arrow” bunker oil spill in Chedabucto Bay in Nova Scotia was brought ashore by winds to the south-eastern area of Cape Breton Island. Shorelines exposed to wind and wave action were cleaned up in less than five years, however sheltered bays remained contaminated much longer. Toxicity was acute in local areas (that is, in areas close to the spillage site), affecting the re-colonisation of certain species in the most heavily oiled waters. In March of 1979 the same area of Cape Breton Island and also southern Newfoundland were affected by wind-driven slicks from the “Kurdistan” bunker oil spill in Cabot Strait. This time the slicks took several weeks to come ashore and relatively little biological impact was observed other than to sea birds.
The last major occurrence in Eastern Canada took place in February 1984 with the “Venture” gas/condensate blow-out near Sable Island. In this case the chemicals had a short “residence time” in the water column (several hours to a few days). No adverse biological effects were recorded and no tainting of locally caught fish was observed. Of these three incidents, only the “Venture” blow-out was directly related to offshore exploration. The “Arrow” and “Kurdistan” spills were associated with the transportation of bunker oil, a heavy oil that has already undergone some processing.
Since the 1970’s, Canada has developed very stringent offshore regulations. These were not influenced by the “Arrow” and “Kurdistan” accidents, but rather by the “Ocean Ranger” disaster in 1982. The “Ocean Ranger” was a production platform on the east coast of Canada that went down in an extremely heavy storm resulting in the loss of 84 lives.
Sinking of the tanker Erika which broke up in gail force winds and spilled 10,000 tons of crude oil on France's coast in December, 1999. |
The Piper Oil Production Platform in the North Sea caught fire, releasing an estimated amount of energy equal to 1/5 that of the consumption of the UK. 167 workers died. |
Oil spewing from a bullet hole in the TransAlaska pipeline. |
Marine petroleum disaster. |
Improvements
Despite increases in total hydrocarbon production and transportation, spill frequency and volumes have been decreasing steadily over the past several decades due to improvements in practices (RSC, 2004; JWEL, 2001; Shrimpton, 2004). In 2002, the National Research Council (NRC) of the National Academy of Sciences completed “Oil in the Sea III”, it's third examination in a series (1975, 1985, 2002) of petroleum inputs into marine waters worldwide. Petroleum inputs other than natural sources have decreased significantly over the past three decades, from 43 million barrels per year (MMbbl/yr) in 1975 to 9 MMbbl/yr by 2002.
The study also examined total petroleum input sources worldwide, with offshore oil and gas development responsible for 4% of the petroleum in the world’s marine environment. This value drops to 2% when examining North American marine environments. Natural seepage remains the largest single source, contributing 47% of the total worldwide and 63% of the total in North America. Municipal and industrial waste is next at 12% worldwide and 22% in North America. Marine transportation shows the greatest disparity with 33% of worldwide petroleum inputs and only 3% of inputs in North American marine waters.
Of the 77 spills recorded by the Canada-Newfoundland Offshore Petroleum Board in the four-year period from 2000 through 2003, only 19 were greater than 10 litres. Of the 13 spills greater than 150 litres, the largest was 23,700 litres of low toxicity synthetic drilling fluid. The major component of this fluid is a food-grade synthetic oil similar to baby oil.
Of the 61 spills recorded by the Canada-Nova Scotia Offshore Petroleum Board between 2000 and 2003, only 12 were greater than 10 litres and of these just four were greater than 150 litres. The largest of these was 7,290 litres of conduit fluid which disperses quickly and is considered non-toxic in the marine environment. Eleven of the 18 spills recorded off Nova Scotia in 2003 involved small releases of kerosene by a seismic vessel that was called back into port for additional inspection and measures to prevent further such releases.
SFU (2004) proposed that an assessment of oil spill risk for a potential BC development could be obtained by comparison to the one provided in Cook Inlet's environmental assessment (EA) for proposed expansion of the Alaskan industry (U.S. DOI 2002a). The proposed project includes the drilling of four exploration wells and production of 140 million barrels of oil and 190 billion cubic feet of gas over about a 20-year production period. This is considered comparable to probable development scenarios for BC (Bridges 2003a). The Cook Inlet study, which uses a more recent analysis than FEP, predicted that there will be 484 small spills (less than 1,000 barrels), and a 19% probability of a large oil spill greater than 1,000 barrels over the life of the project (U.S. DOI 2002a).
Declining rate of oil spills (from US Coast Guard data)
Oil spilled from tankers worldwide, 1970-2002 (www.itopf.com)
Blowouts (Extracts from Strong et al., 2002; SFU, 2004 )
Blowouts occur when well control is lost and the protection system fails as the last line of defense. Well control is lost when sufficient hydrostatic pressure is not maintained by using drilling muds in the drill column and pressurized fluid (gas, oil or water in combination) in the porous rock being drilled enters the well bore and flows to the surface. In the event that the mud system cannot be brought under control, the blowout preventer (BOP) stack is a further line of defense. Once the BOP has been used to seal the well, they are designed to withstand any pressure that the well contains. On occasion, the BOP stack fails and human experts and special equipment must be brought in to regain well control. This usually entails drilling a relief well that intersects the initial well and allows heavy mud and cement to be introduced to the blowing well (WCOEEAP, 1986).
The Federal Expert Panel (FEP) (RSC, 2004) provided probability assessments of blowouts based on industry estimates in its report. The information illustrated that the risk of a blowout is small, ranging from 1/6,666 during exploratory drilling to 1/40,000 during production for spills greater than 10,000 barrels. This is generally consistent with other estimates (U.S. DOI, 2002a; Johnston and Hildebrand, 2001; U.S. DOI, 1997a; ). The FEP pointed out that these risk estimates may be high because they are based on averages over a longer period that do not take into account the declining rates of spills (RSC, 2004).
Impacts (Extracts from Strong et al., 2002; SFU, 2004 )
Specific impacts from spills or blowouts are difficult to predict because several factors that determine the exact impacts are unique to the nature of an individual spill and the local environment in which it takes place. Hydrocarbon toxicity is directly related of the chemical composition of the spilled petroleum. Certain classes of compounds (e.g. aromatics), have more toxic effects than others (e.g. alkanes). Hydrocarbons are have a low water solubility and thus tend to accumulate at interfaces: at the sea surface (air/water), at the sediment surface (sediment/water), and on beaches (water/land). Obviously organisms most at risk are those occupying interfaces, such as sea birds and mammals at the surface, and prawns, crabs and other species that dwell on the sea-bed and beach surface sediments.
Organisms living at the sea surface, in intertidal zones and in river estuaries and other coastal habitat—such as seabirds, juvenile salmon and larvae—are impacted most severely (Strong et al., 2002; GESAMP, 1993). In addition, organisms that are immobile—such as mollusks—are particularly vulnerable. Organisms that cannot detect pollution—such as Dungeness crab larvae—are even more vulnerable. In some cases, organisms may not be able to leave a contaminated area, even if they can detect the pollutants and are thus adversely affected (Husky Oil 2000 in JWEL, 2001; AGRA, 1998; GESAMP, 1993). Early life stages in marine life are very susceptible to the impact of spills (Birtwell and McAllister, 2002; GESAMP, 1993; Kovaleva and Mazmanidi 1978 in Leonov, 1999). Early life stages are up to 10 times as sensitive as adults to hydrocarbon pollution and are adversely affected at concentrations less than a part per billion (Carls, Rice, and Hose, 1999; Leonov, 1999; U.S. DOI 2001, Rice 1985, Moore and Dwyer 1974 all in JWEL, 2001; Howarth 1991 in Kenchington, 1997).
The effects of a spill or blowout on marine mammals can be from physical contact to sensitive tissues such as eyes, noses and blowholes or through indirect effects such as loss of habitat or food. Species such as otters, northern fur seals and young sea lions that depend on fur for warmth are likely the most sensitive to oiling since the matting of their fur could result in loss of warmth and buoyancy. Similar to birds, grooming may also cause the direct ingestion of hydrocarbons that could have unknown sub-lethal effects. Further, if prey species are greatly affected by the blowout, the predator species would also be affected. In the area of interest, marine mammals such as cetaceans (whales, dolphins, porpoises) and pinnipeds (seals, sea lions, walruses) form the top of the food chain. This is another area that bioaccumulation studies would need to be initiated. Again, sensitivity mapping to identify areas frequented by marine mammals would help in prevention and mitigation of the effects of a spill (WCOEEAP, 1986).
Bird species vulnerability depends on its behavioural characteristics. For example, species that tend to swim a lot have a greater chance of encountering oil slicks. The effects of such encounters can be catastrophic even if minimized, since even a small amount of oil can cause matting and heat loss leading to hypothermia and even death. Further, the sub-lethal effects of ingestion of oil due to preening are not well understood. Similar to effects on fish, it is important that contingency planning and sensitivity mapping take place in order to minimize the effects of a spill and a quick reaction if one occurs. Oiled birds can be cleaned but it requires trained individuals and this training must be included in planning for oil spill mitigation (WCOEEAP, 1986).
Impact on Fisheries (Extracts from Strong et al., 2002; SFU, 2004 )
A good portion of the concern in BC about offshore hydrocarbon production focuses on the threat to local fisheries. The severity of the ecological effect of a spill on the fisheries off of the northern coast of British Columbia would depend not only on the kind and volume of hydrocarbon extracted, the mode of exploration and production employed and the climate and weather patterns experienced in the region, but also on the location and characteristics of the species occupying the local interface areas. For example, pelagic (open ocean) species such as salmon, herring, tuna and mackerel, which are highly mobile and feed near the water surface, are usually the most unaffected by oil spills. Greater damage to fisheries can be expected in the case of less mobile, bottom-feeding species such as cod, haddock, plaice, halibut and flounder. Oil pollution, therefore, poses a more serious threat to shallow-water groundfish stocks such as those which constitute the bulk of the fisheries of Atlantic Canada than to the stocks off the narrow shelf of British Columbia. Most at risk are benthic (“bottom-dwelling ”) species, including all molluscs and crustaceans such as clams, oysters, scallops, crabs, squid, lobsters and shrimp, and the eggs of many pelagic and demersal (bottom-feeding) species that derive their food directly from the sea-bed where hydrocarbons tend to accumulate after a spill.
The effects of hydrocarbons on fish species are being studied in Canada and throughout the world. Salmon are a particularly important commercial species on the west coast. Salmonids could be especially susceptible to an exposure to hydrocarbons when the juveniles enter the sea from their fresh water spawning grounds. Exposure to hydrocarbons at this stage could cause developmental abnormalities, if not death. Groundfish eggs and larvae are pelagic and drift with water currents. If a spill were to occur near an area of high concentration of these early life stages, they could be exposed to the spill for long periods of time as both the oil and organisms drift and disperse with the water current.
Similar to the eggs and larvae of groundfish, many species of invertebrates and shellfish spend their early life stages as pelagic and passive drifters and therefore could also be exposed for long periods of time. Sinking oil could affect adult and juvenile groundfish while they rest on and generally inhabit the sea floor. This sea floor contamination could also affect the health of benthic populations that inhabit the sea floor both above and below the sediment surface. Herring are also at particular risk because their spawning, incubation and nursery life-stages take place in nearshore areas. Beach contamination could cause the death of the herring or their eggs and larvae. It could also result in deaths, loss of habitat or food and thus result in stress in the adult populations of shellfish (WCOEEAP, 1986). It is obvious that the specific effects will depend on the organisms and life stages present and the spatial distribution of the spilled oil.
Countermeasures (Extracts from Strong et al., 2002; SFU, 2004 )
There are several methods used to mitigate the effects of a hydrocarbon spill or blowout. Spills on the ocean surface are sometimes contained by floating booms so that specially equipped boats can skim oil from the water. Another technique involves the spraying chemical control agents called dispersants over the spill or impacted area. Dispersants speed up the natural degradation of oil in the water column. Bioremediation works in a similar manner by using specialized bacteria that accelerate the breakdown of oil molecules in water. Dispersants are also applied to shorelines prior to their contact with hydrocarbons to minimize adhesion. Affected shorelines may sometimes need to be cleaned by hand in a very labor-intensive process.
Depending on its location relative to environmentally sensitive areas, sometimes the most effective option is to monitor a spill’s movement and allow evaporation, wind and wave action to naturally disperse and break down the oil. On rare occasions, companies will use drastic measures such as igniting the oil, but only after the governments have approved such action.
Major clean-up efforts to date have had poor success. A mass balance estimate of the Exxon Valdez oil 2.5 years after the spill found that the intensive clean-up effort removed only 14% of the oil (Spies et al., 1996). Others report that only 5-15% of oil from spills is ever recovered or cleaned up (Ocean Conservancy, 2003; Clarke, 1990; Holing, 1990). There is also concern that clean-up efforts can injure wildlife and hamper recovery (Burger, 2003; Peterson et al., 2003; Strong et al., 2002; Houghton et al., 1996; Spies et al., 1996). Dispersants can damage water repellency and insulating capacities of fur- or feather-bearing animals, and have a toxic effect on young life stages of fish and other biota (Strong et al., 2002; U.S. NAS, 1989). Dispersed oil can also penetrate sediments and thus may lead to contamination over longer terms (GESAMP, 1993). Manual cleaning of seabirds has proven ineffectual to date; “cleaned” birds rarely resume breeding and have low survival rates (Burger, 2003). In summary, clean-up efforts can prolong and/or complicate recovery (U.S. NOAA, 1997; Spies et al., 1996). More research is necessary in order to guide appropriate use of clean-up strategies and to assess their impacts.
Spill Modeling - From OSRIS Web Site, 2004
Another important countermeasure after a spill has occurred is tracking and modeling of the spill trajectory. This is done in order to minimize the impact to areas identified as particularly sensitive (e.g. shorelines, marine protected areas). A spill can be monitored using visual spotting from aircraft, remote sensing technology (satellites), buoys and drifters.
BC began in 1992 to develop a computer-based Marine Oil Spill Response Information System. OSRIS and the Coastal Inventory system includes multiple data-types such as satellite images, digital maps (topographical/bathymetry), and geographically referenced information. The information within OSRIS relates to more than 50 coastal resources, including the physical character of the shorelines and the biological species that interact with the shoreline such as fish, birds and marine mammals. The database also includes human activities that occur in the coastal zone such as sport and commercial fisheries, aquaculture, native harvesting, tourism, recreation and commercial enterprises. Special status areas, such as archaeological or heritage sites and ecological reserves and parks are also included. Coastal inventory and human uses are linked independently to a uniquely defined shoreline unit. Each shoreline unit is based on its geomorphology: sandy beach, rock platform, cobble, rock cliff, etc.
Based on this inventory, a sophisticated computer modeling program ranks the sensitivity of each shoreline unit. The modeling program takes into account such aspects as oil residency, the coastal resources present, species rating, seasonality, human-use rankings, etc. Identification of the most important and vulnerable coastal areas enables priorities for shoreline protection from oil pollution to be decided. Based on this sensitivity determination, OSRIS also identifies countermeasure strategies such as protection booming. During a spill event, OSRIS has a spill trajectory model that can simulate the spread of oil on water depending on wind direction, time and current/tidal regimes. Where shoreline oiling occurs, OSRIS determines the most environmentally sound cleanup strategies. Post-spill functions of OSRIS include long-term monitoring, resource impact assessment, and damage evaluations.
Emergency Response Plans - Legislation
The provincial department responsible for environmental protection is the Ministry of Water, Land and Air Protection (WLAP). Legislation and emergency response plans concerning marine oil spills are currently addressed under the environmental emergency management program. This program prevents, plans for and responds to environmental emergencies in BC, including oil and hazardous-material spills, pipeline gas and gas leaks, water-related debris flows, erosion and accretion, and submarine (underwater) slides. Due to the existing moratorium, BC does not have a regulatory process in place for managing offshore oil and gas projects. As mentioned elsewhere on this site, any management framework designed to oversee offshore operations in BC would use the examples from the East Coast as a starting point. Thus a joint BC-Canada offshore petroleum board would likely be given similar authority to place conditions upon development in matters pertaining to environmental protection as that on the East Coast.
Usually in the event of a spill the operator bears the initial responsibility and cost of cleanup (polluter-pays). However, if the operator is unable to effectively cleanup, the government may accept responsibility although the company will subsequently be billed for the costs. This spill cost recovery is detailed under the provincial Waste Management Act. This and other environmental legislation will need to be updated to specifically address concerns associated with offshore oil and gas development. Both levels of government and the offshore industry will need to develop contingency plans for the cleanup (and mitigation) of potential spills together. British Columbia is currently involved in international partnerships such as the Pacific States/British Columbia Oil Spill Task Force with the mission to strengthen State and Provincial abilities to prevent, prepare for, and respond to oil spills. There is also the West Coast Marine Oil Spill Reporting Program (1-800-OILS-911 or 1-800-663-3456) from BC to California.
Some credit from above text to Review of Offshore Oil and Gas Development by Simon Fraser University, 2004 and Royal Roads University: BC Offshore Oil and Gas Socio-Economic Papers, 2004
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