Environmental Report 1999 Index

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Accidental Oil Spills Preventing oil or gas leaks is a priority, both for safety and environmental reasons. The mandatory Safety Cases prepared for each installation help to ensure both that the prevention of oil and gas releases is considered systematically, and that control systems are in place to minimise the risk of any inadvertent loss. Offshore operators are required to report every oil spill, to carry out an investigation into the cause and, where possible, to put steps in place to avoid a recurrence. Oil spills are reported to the DTI, the Coastguard Agency and the JNCC. In the unlikely event of a major spill, UKOOA members have arrangements in place to be provided with oil spill combat services from independent contractors. Spill Types And Quantities Oil spill reports are sent to the authorities in a specified format that includes the cause and source of the spill; the type and quantity of oil spilled; the area affected; the weather conditions; and any actions taken to control the spill or mitigate its effects. Where appropriate, more detailed investigations are conducted. Offshore installations are routinely monitored by surveillance aircraft, which over-fly offshore oil fields on behalf of various authorities. Figure 1 shows the types and quantities of oil spilled during 1998. Figure 1 Type Number of spills Quantity (tonnes) Base Oil 4 35.003 Condensate 17 0.26 Crude Oil 232 78.651 Diesel/Fuel Oil 67 16.619 Graphite Grease 1 0.001 Hydraulic Oil 31 2.401 Lube Oil 9 0.332 Oil Based Mud 1 0.006 Unknown 14 3.224 TOTAL 376* 136.497 Figure 2 shows the three-year trend in the number of spills reported and the quantities spilled. Figure 2 Year Number of Spills Quantity (tonnes) 1996 300 127 1997 349 866 1998 376* 137 * (The total number of oil spills reported in the 1998 Energy Report (Brown Book) differs from the number of oil spills reported to UKOOA's Environmental Emissions Management System (EEMS) and recorded here, although the tonnage reported is the same in both cases. DTI has indicated this difference was caused by several spills being counted more than once by DTI. A correction will appear in next year's Energy Report.) Large spills are uncommon, but when they occur they tend to dominate the record and make it difficult to discern trends. For example, the anomalous peak in 1997 was caused by a single accidental spill of 685 tonnes from an offshore installation. When large spills such as this one, are factored out, the records reveal that more than 90% of spills involve less than one tonne of fluid, with many measured in a litres. This reflects the effectiveness of the industry's drive to encourage a culture of reporting and investigating each and every spill. The Advisory Committee on Pollution of the Sea publishes the annual spills of oil from all reported incidents in the UK. The reported spills into the marine environment for 1998 are shown in Figure 3. Figure 3 Source Quantity in Tonnes *Open sea 175.9 Oil and gas operations 136.5 Vessel casualties 114.9 Ports 72.6 Rivers and estuaries 25.8 (* Excludes oil and gas operations) Environmental Effects Of Oil What happens to oil after it is spilled into the sea depends on many factors, including the type of oil (particularly, on whether it is volatile or persistent), and the wind, wave and tidal conditions at the time. In the open sea, natural processes lead to a progressive removal of the oil and lessen its potential effects on marine life and seabirds. In the worst circumstances, however, oil may be driven ashore, where it can pose a serious threat to coastal marine wildlife and commercial resources. On the evidence gathered from major coastal oil spill sites, most marine populations are able to recover from the effects. Offshore, it is difficult to be precise about the damage an oil spill may cause to marine wildlife. While seabirds tend to be most at risk, there have been no recorded mortalities among seabirds or other marine life that can be directly associated with spills from the offshore industry.