Petroleum hydrocarbons in sediment resulting from drilling discharges from a production platform in the North Sea

Abstract

From the Abstract: “The chemical impact on the environment of hydrocarbons associated with discharged cuttings from production drilling at the Statfjord A platform was investigated. The drilling was started in December 1978. Samples of the top layer of the seafloor sediments were collected in July 1978 and in July 1979. At the latter date three production wells, out of a total of 32, had been largely completed, and drilling of the fourth well was in progress. An approximate amount of 1,250 m3 drill cuttings, containing about 300 m3, or 250 tons, of oil had until this time been discharged to the sea. Hydrocarbons resulting from the discharges were detected over an area of 5 square kilometers. Although the hydrocarbons were spread very unevenly, the general pattern of distributon corresponded largely with the directions of water transport. The detected amounts ranged from more than one thousand milligrams total hydrocarbons per kilo wet sediment in the vicinity of the platform down to less than 10 mg/kg. A change in the composition of the polluting oil was observed as the distance from the platform increased, the relative amounts of the lightest and most soluble components had decreased. This implies that physio-chemical and probably also biological processes are effective in removal of the oil from the sediments.”