Another gas alarm

This leak was one the largest experienced to that date on the A platform. It shut down immediately and most of the people on board were evacuated to the Polycrown flotel moored alongside. The incident began as an oil leak from a valve flange on a pipeline in the utility shaft, about 70 metres above the seabed. This in turn caused large volumes of gas to accumulate in the shaft, which was easily ignitable in the dry space.

Gas leaks represented a growing problem on Statfjord A at this time. While 11 oil or gas escapes were recorded in 1991 and 1992, this figure had risen to no less than 20 in 1993. Operator Statoil initiated a special programme to reverse the trend. Nor was Statfjord the only field struggling with leaks. The number of gas escapes on the Norwegian continental shelf (NCS) in general had increased dramatically in recent years. No less than 106 had been reported to the Norwegian Petroleum Directorate (NPD) in 1992 from fixed installations and mobile units, compared with only 55 the year before.

Improved monitoring and alarm routines were among the reasons for the rise in reported leaks. Reporting routines had been tightened up by the NPD after Britain’s Piper Alpha disaster in 1988. From nine a year, the number rose to 47 in 1989 and 48 in 1990. A total of 97 hydrocarbon leaks were recorded in 1993.

The figures nevertheless revealed an increase in large and medium-sized incidents, while the number of installations and production had both risen. Technical errors, such as faulty assembly and handling of flanges and valves, stood out as a significant cause. Failures in technical equipment accounted for 44 of the 1993 cases, human error for 17 and design faults for 23. The final leak that year occurred in 1993, when gas flowed from a valve during maintenance work.