Offshore oil platforms

Today, offshore oil extraction makes up nearly a quarter of worldwide production, with more than 20,000 platforms of all sizes and designs, found in four main areas: the Gulf of Mexico, the Persian Gulf, West Africa and the North Sea.

The US National Academy of Sciences estimates the volume of operational discharge and accidental spills from this sector of activity at 80,000 tonnes in 1979, 50,000 in 1981 and 100,000 in 2000.

The accidents mostly involve the spillage of a few cubic metres to a few tens of cubic metres, resulting from pipes bursting or from human errors. These incidences are mainly concentrated in areas where the material is old and the safety procedures deficient (Caspian Sea, Black Sea, Red Sea and China Sea). Occasional major accidents caused by an oil well eruption or an act of war can be added to the list of causes of large-scale oil slicks. One of these incidents holds second place in the ranking of oil spill world records.

An oil terminal accident

On 7 August 1997 at 12:20 am, the oil tanker the Katja was berthing when she hit a wharf in the oil terminal of Le Havre, and 190 m3 of propulsion fuel spilled into the port. Despite immediate intervention, part of the pollution was carried out of the port with the receding tide, causing small-scale pollution of the surrounding area. The prevailing weather conditions saved the British coastline, but caused the pollutant to be washed up on the French shores of Calvados.

The Ixtoc I blow out

On 3 June 1979, in the Gulf of Mexico, the offshore platform Ixtoc 1, run by the national company Petroleos Mexicanos, was destroyed by a blow out. A fire broke out. The blow out was not reduced until 23 March 1980, by which time half a million to possibly even a million tonnes of oil had been released. Between a third and half of this oil burned. The remainder spread out to form drifting slicks in the Gulf of Mexico. Some of the slicks reached the coasts of Texas, triggering the activation of a regional oil spill response plan on 9 July. Localised clean-up operations were undertaken, followed by an in-depth impact study, involving the analysis of over 4,000 samples (water, sediment, flora and fauna).

Oil eruption in the Gulf of Mexico

 

Former practices

In an article from 27 March 1998, Lloyd’s List, a daily paper on the world of maritime insurance, quotes the testimony of a former captain of an oil tanker on the practices in the early 1950s, when vessels barely hit the 25,000 tonne mark. The following extract is of particular relevance.

"...She was not only single hulled but riveted, and leaked a small and regular proportion of her cargo into the ocean from many loose rivets as she steamed from load port to discharge port... Tank cleaning before drydocking in Todd’s Yard at Brooklyn was quite remarkable by today’s standards. The ship steamed at slow speed up and down the east coast of the US, just outside the 50 mile limit, for about 10 days while the crew were busy cleaning tanks and dumping all the sludge straight over the side..."

Ship-building and common practices have since changed, thankfully.

This article appeared in Lloyd’s List on March 27 1998. For more information visit www.lloydslist.com.
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The prevention of incidents on offshore platforms relies on two complementary measures: reinforced safety for accidents and rigorous checks for the discharge of drilling mud and exploitation fluids.

The North Sea oil fields, located in the centre of one of the richest fishing areas in the world, are particularly advanced in terms of prevention and safety.

The platforms there operate under permanent surveillance by satellite, remote sensing planes and specialised, mainly Norwegian and British, vessels. Personnel from the safety services and the oil industry meet periodically to research new and improved safety solutions. The laboratories financed by the oil industry study the potential long term effects of exploitation on the marine populations.

Large-scale response exercises are carried out regularly by specialists from the industry and the administrations in charge of spill response at sea.

Pollution response exercise in the North Sea