Offshore Europe 1983, Aberdeen 6–9 September

Conference Report Offshore Europe 1983, Aberdeen 6-9 September This year, for the first time, the Society of Petroleum Engineers of the AIME were sponsors to the Offshore Exhibition and conference, held in Aberdeen. Under the patronage of the UK Offshore Operators Association (UKOOA), and in its tenth year, the exhibition is now only second in size to the massive OTC event held annually in Houston. Although the event is largely European in terms of subject coverage, it is truly international in terms of both delegates and exhibitors present. Despite the fact that the event is primarily one for promoting the interests of the operators and service industries involved with hydrocarbons exploration and production, the SPE saw fit to include in the technical program a number of papers on safety and health, of which those on the environmental effects of diesel-based and low-toxicity drilling muds were of particular interest to the readership of the Journal, not least in that they precede the UK Government's attempt to regulate pollution from these sources. Both biological and legal aspects of dieselbased drilling mud pollution were discussed in a paper by a working group incorporating Britoil, Marathon Oil, BP and Shell for the operators, and the Ministry of Agriculture, Fisheries and Food (MAFF), Department of Agriculture and Fisheries for Scotland and Department of Energy (DOE) for the Government. During the 1970s, only 10-20 wells were drilled using oil-based muds, whereas in 1982, 110 were drilled using this method, and it is a problem which has been under study for the last four years. Mainly from literature sources it has been possible to establish the major inputs of oil to the environment local to the platforms studied, and to estab-

lish the biological effects of this pollution. In terms of overall inputs to the northern North Sea, drilling muds represent some 60% of the total from all sources, being on average 10% by weight of all cuttings disposed of from platforms, or 100 tonnes oil per well drilled. The biological effects of this suggest that most species around a platform up to 500 m away on the seabed suffer adversely, communities becoming highly modified and impoverished and only beyond a zone up to 800 m away are benthic fauna unaffected. It is not yet possible to determine the relative effects of organic enrichment, burial by cuttings or toxicity as the agents of change, but it can be surmised that local to the structure, recovery of the seabed community may be limited in the long term. No long-term studies exist, however, to elucidate this problem, and it appears that at present, the lack of concrete evidence has caused the UK Government to postpone the imposition of rigid limits to disposal of muds of this type, in favour of the operators voluntarily installing cleaning equipment on platforms intending to continue using diesel-based drilling muds. This is partly as a result of the official findings that manufacturers have widely differing views as to the realistic efficiency of the equipment available. Until an accepted limit can be established on this basis, no legal limits will be imposed, although it seems widely accepted that a maximum figure of 10% must be achievable. For low-toxicity muds discharge will not be regulated, although the EPA have not approved the dumping of such materials in US waters. Amongst the exhibitors at the event were some 26 companies and organisations directly involved with oil pollution and spill control, and this along

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with the presentations suggests that both companies and manufacturers will recognise the importance of pollution control, although it seems

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that the identification of the sources of pollutants may be a most important matter for study in the future.