Hydrocarbon leaks are categorised for the RNNP report in three groups based on the rate of escape: more than 10 kg/s, 1-10 kg/s and 0.1-1 kg/s.
Even a gas leak with the lowest registered leak rate – 0.1 kg/s – has a substantial accident potential.
These are among the conclusions drawn in the 2009 edition of the annual Trends in risk level in the petroleum activity (RNNP) report from the Petroleum Safety Authority Norway (PSA).
A total of 15 gas leaks were reported from installations on the Norwegian continental shelf (NCS) in 2009. That is more than 50 per cent above the industry’s target, which was a maximum of nine leaks in the course of the year.
The increase was greatest for leaks in the 1-10 kilograms per second category (see right-hand margin for information on leak rates).
“After a number of years when the industry could report a progress on reducing the number of leaks, the trend appears to have reversed,” comments Øivind Tuntland, the PSA’s director of professional development.
“We accordingly consider it crucial that the industry now joins forces on new measures, and thereby contributes to a new drive in this area. Purposeful and not least continuous efforts are needed to turn developments around.”
Major accident potential
Hydrocarbon leaks have a major accident potential, as was shown by the destruction of Britain’s Piper Alpha platform in 1988 with the loss of 167 lives.
Escapes of gas have the biggest potential for causing damage because of the danger of explosions posed by the spread of the gas cloud.
After observing a negative trend for gas leaks around 2000, the Norwegian Oil Industry Association (OLF) took action in 2003 under pressure from the authorities.
The resulting gas leak reduction project (GaLeRe) achieved its initial goal of halving the number of escapes to less than 20 per year by the end of 2005.
Work by the OLF continued, with a further halving by 2008 as its goal. This was attained as early as 2007 when there were 10 leaks. An even bolder target was set – a further 25 per cent cut from the 2008 level by the end of 2011.
However, developments on the NCS have moved in the wrong direction over the past two years. A total of 14 leaks were recorded in 2008, and the 2009 figure was 15 as mentioned above.
A comparison of leak frequencies per operator continues to show relatively big differences between the companies. Comparing with figures from the UK continental shelf also shows a potential for leak reductions on the NCS.
By contrast, the trend for land-based plants is positive. The number of hydrocarbon leaks at these facilities declined significantly in 2009 compared with earlier years.
No marked change in major accident risk
The indicator related to well control incidents has developed positively in recent years, but showed an increase in 2009 for both production and exploration drilling.
Incidents involving ships on a collision course with installations have continued to decline.
Other indicators which reflect incidents with a major accident potential are at a stable level, with no or small changes.
Disappointing noise status
The indicator for exposure to noise on offshore installations has been more or less stable throughout the decade, leading the PSA to doubt whether the companies are using the indicator actively in their risk reduction work.
“Risk associated with noise exposure is known and noise conditions have been established,” says Tuntland.
“The potential for noise-reduction measures is therefore substantial. What’s lacking is action in the form of good, risk-based measures.”
Personal injuries down
One fatal accident occurred within the PSA’s area of regulatory authority in 2009, during disassembly of scaffolding on Oseberg B.
Serious personal injuries have shown a positive trend in recent years on offshore installations. A total of 25 cases were registered in 2009, seven on mobile units and 11 at land-based plants.
The personal injury frequency on mobile units has displayed a particularly marked decline compared with earlier years, and the level in 2009 was a third of that in 2007 and 2008.
Intended to analyse employee experience of HSE conditions and developments over time, the latest biennial questionnaire survey was the fifth involving offshore workers and the second in which personnel at land-based plants also participated.
Roughly 7 000 personnel offshore and just under 2 000 on land took part. That corresponds to a response rate of just over 30 per cent, sufficient for statistical analysis.
The survey shows that employee experience of safety is developing in a positive direction. A clear improvement, for instance, was shown by the index for both negatively and positively formulated statements about the HSE climate.
There was also a slight improvement from the previous survey in 2008, related to assessments of a number of working environment indices.
The survey has also identified some challenges.
RNNP and prevention of acute pollution
The goal of the RNNP study is to create a refined picture of risk level trends so that the effects of overall safety work can be gauged. That in turn allows resources to be concentrated where they have the biggest effect.
This reflects the philosophy that no single indicator can pick up all relevant aspects of risk. Developments are accordingly measured by utilising a number of relevant indicators and methods, such as the collection and analysis of incident indicators and barrier data, interviews with key informants and a major questionnaire survey every other year.
Risk monitoring is important because it helps to identify possible negative trends at an early stage and thereby allows better priorities to be set for accident prevention measures.
Extensive data have been gathered since 2000, and this material has so far been used to follow up trends in the risk to people.
Groundbreaking work began in 2009 as part of the RNNP process on exploiting a large part of this information to describe trends in the risk of unwanted incidents which may cause acute pollution.
The goal in 2010 is to continue developing relevant risk indicators and methods, and to present a first report this summer on the development of the acute pollution risk since 1999.
That will provide the basis for measuring trends in the risk of acute environmental emissions/discharges in coming years and strengthen future work on preventing petroleum-related accidents.
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