Mixed report on offshore sector's performance

The amount of oil released into the sea by the UK's offshore oil and gas industry dropped to its lowest figure in 1997 since the early years of North Sea oil following an effective ban on discharges of oil-based drilling muds. Offsetting that positive trend was a sharp increase in the tonnage and number of oil spills, while some new synthetic drill fluids have been found to be no more biodegradable than oil-based muds and are to be phased out.

Details of the sector's environmental performance were set out in May in the Department of Trade and Industry's annual "Brown Book" on the UK's offshore oil and gas resources.1Announcing the publication, Energy Minister John Battle said that he wanted the UK "to be at the forefront of setting oil industry environmental standards." The Government has just rectified its predecessor's lengthy failure to apply the 1985 EC Directive on environmental assessment to offshore oil and gas projects and, Mr Battle pointed out, has signalled its intentions by implementing the 1997 amending Directive several months ahead of schedule (see p 40 ). But the Minister chose not to highlight adverse features of the industry's record last year.

On oil spills, two records were set in 1997: the number of installations reporting spills and total reports of spills were the highest ever (see table ). However, the latter figure has been inflated to an unknown extent in the past two years by the inclusion of spills detected by official aerial surveillance flights.

The quantity of oil spilled in 1997 was, at 866 tonnes, the highest since 1990. Last year also saw the largest single spill since 1988, with Texaco losing 685 tonnes of oil from its Captain field in August. The incident led to a temporary ban on fishing in 756 square kilometres off the Moray Firth (ENDS Report 274, pp 35-36 ). Texaco is one of three firms referred to the Scottish Procurator Fiscal for possible prosecution.

A predictable statistic was the further small increase in the amount of oil discharged in "produced water" extracted from production wells and discharged to sea. Produced water increases in volume as oil fields mature, and the amount of oil discharged in this way has doubled over the past ten years.

However, offshore operators have reduced the average oil content of produced water from a peak of 36ppm in 1992 to 25ppm last year - well within the 40ppm target set by the Paris Commission. But six out of 63 installations breached this limit in 1997. The industry has now agreed to aim for a target of 30ppm on a company basis.

The industry's largest source of oil was eliminated last year under another Paris Commission rule. This bans dumping of oil-based drilling cuttings containing more than 10mg/kg of oil, a limit currently unachievable. In the 1980s, oil discharges from this source exceeded 20,000 tonnes per year.

However, one problem has been replaced by another. The report says that "several" synthetic drilling fluids have been found to be no more biodegradable than the oil-based muds which they have replaced. Almost 35,000 tonnes of these fluids were discharged to sea in 1996. Companies have been told to eliminate these discharges by the end of 2000.

The report contains only a paragraph on chemicals discharges, commenting that the official chemicals notification and usage reporting scheme "has had a positive effect on the types of chemicals being discharged offshore." A recent parliamentary answer revealed that offshore discharges of alkyl phenol ethoxylates, which have suspected oestrogen disruption properties, have increased over the past four years (ENDS Report 279, p 31 ).

The DTI, which polices the offshore industry, has come under fire over its inspection record (ENDS Report 261, pp 3-4 ). The report reveals that 62 inspections were carried out in 1997/98, suggesting that about one-third of the 186 installations in place at the end of 1997 were inspected. The industry's environmental performance was "in the main" found to be "satisfactory", with "only minor comments" being made by inspectors about record-keeping and chemicals storage.

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