Monitoring in the vicinity of oil and gas platforms: results from the Norwegian Sector of the North Sea and commended methods for forthcoming surveillance

Abstract

Note: The book’s editors note that peer reviewer’s raised considerable doubt about the validity of this study and its conclusions.

From the Abstract: “Studies on the environmental effects by oil activities in the Norwegian sector of the North Sea show that significant contamination from oil and trace metals are found around all installations using Oil-based mud (OBM). Contamination is greatest along the direction of the primary current axis and effects are found to distances beyond those previously reported. At one field significant contamination was observed as far out as 7000 and 12000 m and a change infauna was found out to 5000 m. Indications are that this is an effect due to discharges of oil-contaminated cuttings. There is a clear relationship between the amounts of oil-contaminated cuttings discharged and the are of seabed affected. The depth to which sediment is contaminated varies, but 2000 m from one field the contaminated layer was more than 9 cm.

Despite the change from diesel-based muds to low aromatic muds (low toxicity muds) there has been no concomitant improvement in the benthic communities studied. There are, however, signs that following cessation of drilling activities degradation of oil has occurred and the benthic communities show signs of recovers. The degree of degradation seems to be correlated to the concentration of hydrocarbons in the sediment.

In the vicinity of platform using OBM the base oil discharged with the cutting sis found accumulated in fish livers of near bottom feeders but not in pelagic fish.

In the Norwegian surveys there were large variations from field to field and form year to year both within and between surveys. This was shown to be largely due to methodological differences and it was felt necessary there, to introduce a standardized monitoring programme, which is presented here.