The environmental effect of oil based mud drilling in the North Sea

Abstract

From Conclusions: “This paper has considered the immediate and longer-term effects that can be measured around single well sites, at platforms during development drilling, and in the phase after drilling has ceased….The evidence discussed in this paper suggests that the major deleterious benthic effects are confined to an inner zone within 500 m of development drilling operations and within 250 m of single well sites. Beyond this, more subtle biological changes are seen in the transition zone generally extending to around 1000 m from development site and 500 m from single well operations…The monitoring around UK platforms where drilling discharges have ceased indicates that recovery and recolonisation of the transition zone begins with 1–2 years, accompanied by degradation of the oil hydrocarbons, and that the biological transition zone begins to move inwards, despite some outward redistribution of oil-contaminated materials…One sublethal effect which has been examined is that taint. No oily taint was found in round fish caught 400–2000 m around major oil production platforms or in flatfish harvested from outside 1000 m of an oil producing platform. It is apparent, however, that for flatfish caught closer to platforms, some assessors detected an oil taint, indicating a tendency towards taints by petroleum hydrocarbons in flatfish caught up to 850 m from platforms.”