With the development of the Gulf of Mexico's deep-water fields, helicopter transportation is being required to serve larger offshore platforms located at greater distances from the shore. Although the weather climate is relatively benign, the helicopter operations to these new platforms are becoming more akin to North Sea operations. In particular, the requirement to evacuate large and distant platforms in advance of a hurricane may put a particular premium on demonstrating the safety of such operations in worsening weather conditions.
The paper outlines progress and gives example results from a number of research themes aimed at improving the safety of helicopter operations on the UK continental shelf. The themes include ways of minimising the risk posed by the aerodynamic hazards in the vicinity of helidecks on large offshore platforms, improving the emergency flotation systems for helicopters forced to ditch in the sea, and improving the crashworthiness of such systems so that helicopters which crash into the sea are more likely to float following impact. New motion criteria being developed for operations to helidecks on floating vessels and improvements to helideck lighting schemes are also described.
Helicopters are an essential part of offshore oil and gas industry operations. On the UK continental shelf (UKCS) 90,000 hours and about 200,000 sectors are flown each year. Since 1976 there have been 12 fatal helicopter accidents associated with UKCS offshore operations which have claimed a total of 92 lives. The accident rate for UK registered helicopters operating offshore in 1999 was 3.69 per 100,000 hours (see Table 1). There has not been an offshore fatal accident since 1992. The five-year moving average in 1999 was a total accident rate of 1.74 per 100,000 hours. 1999 was a particularly bad year with 3 non-fatal accidents. The five-year moving average for the previous year was 1 per 100,000hours. In view of the fact that these operations are performed over long distances, and in an often-hostile environment, this is considered to be a good safety record. Three of the accident soccurred in close proximity to an offshore installation.
Table 1 - Offshore helicopter accident statistics.
Gulf of Mexico helicopter operations have historically been rather different. The majority of the offshore installations are located quite close to shore, and many services are performed using small single engine helicopters, some not required to be fitted with emergency flotation equipment. About 1,500,000 sectors are flown each year, and the total accident rate for 1999 was 2.29 per 100,000 hours with a fatal accident rate of 0.25 per 100,000 hours. The five-year moving averages in 1999 were 1.4 and 0.46 per 100,000 hours respectively [1, 2].
The discovery and development of hydrocarbon reserves in the ultra-deep waters of the Gulf of Mexico has led to a new generation of offshore facility being developed. The new installations are much larger, and much further from shore than the present ‘shelf’ developments.