Oil pollution in the North Sea

1981 ◽  
Vol 7 (4) ◽  
pp. 172-172
1977 ◽  
Vol 1977 (1) ◽  
pp. 45-52 ◽  
Author(s):  
D. R. Blaikley ◽  
G. F. L. Dietzel ◽  
A. W. Glass ◽  
P. J. van Kleef

ABSTRACT The reasons are introduced for the development of a simulator sufficiently simple to enable weather data normally acquired for E & P operations to be used. “SLIKTRAK,” developed by Shell, applies a slick description and combat concept, developed within the E & P Forum for well blowouts in the North Sea, but applicable to other areas. This concept includes costs for cleanup, damages and the effect of phenomena such as evaporation and natural dispersion. These factors are based on industry experience and vary primarily with sea conditions. The computer programme simulates the continued creation of an oil spill and applies weather data to predict movements of each day's spillage for successive days at sea and quantities of oil left after each day until the oil either disappears or reaches a coastline. Cumulative probability curves for the oil volumes cleaned up, oil arriving at specified shores, total costs, etc., are produced by random selection of input variables such as well location, weather data, the possibility of well bridging etc., and repetition of simulated spill incidents over a large number of cycles. Trace-plots of individual spills may also be generated. In association with the E & P Forum's position as technical advisers to the North West European Civil Liability Convention for Oil Pollution Damage from Offshore Operations, a study based on the North Sea areas has been made. These results and further developments of the program are discussed.


The history of large and well-publicized incidents of seabird mortality resulting from oil pollution from tanker accidents (such as the Torrey Canyon in 1967) and from unattributed oil slicks at sea, gave rise to real fears that the development of North Sea oilfields would result in serious mortality and declines in the large populations of seabirds breeding and wintering in and around the North Sea. The oil industry recognized the problem and attempted to minimize pollution risks in all exploration, production and transport operations. Preliminary maps were prepared showing the distribution of vulnerable concentrations of breeding and wintering birds to facilitate contingency planning, and, particularly in Shetland, Orkney and the Moray Firth, extensive and long-term programmes are established to monitor: (1) the numbers of breeding birds; (2) wintering concentrations (particularly of sea ducks); (3) the distribution and abundance of seabirds at sea; (4) the numbers, and percentage oiled, of birds found dead on beaches. The feared increase in oil pollution incidents has not materialized. The few accidents associated with offshore production have had little effect on seabirds. Tanker accidents have been few, but have had large, temporary and local effects (e.g. the Esso Bernicia at Sullom Voe in 1978-79). Breeding seabird populations in the area have increased, although in recent years, in some places, some species may have declined, but these declines cannot be attributed to oil activities in the North Sea. The Beached Bird Survey suggests that chronic oil-induced mortality is at a relatively low level.


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