Increasing dangers of exposure to hydrogen sulphide

Paul Boughton

The oil and gas industry faces increasing dangers of exposure to hydrogen sulphide as the North Sea reaches maturity and decomissioning work rises. As companies look for measures to mitigate the threat, Phil Saxton looks at what the firm is doing to improve awareness and training

With the decommissioning of assets now under way in the North Sea, hydrogen sulphide is one of the global top priority risks and that’s why active monitoring for hydrogen sulphide gas and good planning and training programmes for workers are crucial to prevent injury and death.

Hydrogen sulphide, H2S - or sour gas as it’s commonly referred to - is colourless, highly flammable, toxic and explosive. It can deaden a worker’s sense of smell rapidly and exposure to high levels of it can quickly lead to death. As it’s heavier than air, it will settle in poorly ventilated or low-lying areas, dissolving in any water or oil present.

Workers in oil and natural gas drilling could be exposed to it when pumping seawater into rock formations as part of work to maintain pressure. This can lead to a build-up of H2S as organic matter degrades and produces the gas in the absence of oxygen.

As higher sulphide levels occur in increasingly depleted wells, well expirations are going to be key growth markets for H2S training and safety services in the future.

A report by the Energy Division of UK's HSE’s Hazardous Installations Directorate, suggests the decommissioning of offshore installations could accelerate from 2017, involving many installations, up to 5,000 wells and 10,000km of pipelines.

This difficult process means risk assessments are vital. These need to be carried out early with escape, evacuation and rescue measures put in place, as many assets have remained in situ for years and taking them apart brings with it new safety challenges.

Metal fatigue, including hydrogen embrittlement or sulphide stress cracking, can result in a release of hydrogen sulphide gas if it’s not tackled effectively. When entering a well that’s been abandoned, maybe for years, workers need to prepare for the worst-case scenario because they will be dealing with a lot of unknowns.

As production declines in the UK Continental Shelf, the most easily accessed fields have been exhausted. With new fields in deeper waters, under higher temperatures and pressures, as well as longer pipelines, logistics are becoming increasingly difficult which not only challenges the integrity of assets, but means workers are faced with a more dangerous environment in which to operate.

While there has been significant investment in new infrastructure, around half of offshore platforms are beyond their original design life with many assets commissioned in the early 1970s now forecast to continue operating to 2030 and beyond. Investment in new assets and the extension of the life of existing plants present both safety and commercial challenges.

There is no doubt about the health effects of breathing air contaminated with H2S and although most people can smell very low concentrations of H2S, it is dangerous to assume that odour would provide adequate warning. In a perfect world, the safest exposure to H2S would be none at all.

Preparing the next generation

It’s vital that anyone working in an area where concentrations of hydrogen sulphide may be present should have the very best training. Just seconds of exposure at low concentrations can be lethal, shutting down the system that regulates breathing.

There should also be a contingency plan to ensure all staff have been shown how to use hydrogen sulphide safety equipment correctly in all hazardous areas. Gas detection equipment should be present wherever hydrogen sulphide might exist, as well as respiratory protection for normal and emergency use.

Training should include recognising the characteristics, sources and hazards of hydrogen sulphide and knowing how to react in response to H2S warnings in the workplace. It should also include rescue techniques and first-aid procedures in light of H2S exposure, especially with regards to confined space entry procedures.

Workers should have a plan ready at the time, because if the H2S sensor alarm goes off, they need to know how to react immediately. Having a plan and equipment at the ready ultimately saves time and money, which otherwise could be lost due to inactivity if the platform has to be abandoned.

Changing face of offshore industry

Advancements in gas detection methods over the years and new technology  means hydrogen sulphide safety is easier to get to grips with than ever before for today’s offshore operators.

Innovations such as wireless gas detectors and autocalibration methods have changed the face of oil field H2S safety within the last decade.

Training also helps workers recognise the dangers of H2S and today we are not just better at educating workers, but they are also better equipped.

The oil and gas industry as a whole is making tremendous efforts to raise awareness of H2S in order to have incident-free and environmentally-safe operations now and in the future.

Phil Saxton is Dräger Marine and Offshore general manager. Dräger Marine and Offshore UK works alongside industry partners to pioneer safety solutions for the future. It offers training at any location and work closely on training solutions with our four North Sea countries; the UK, the Netherlands, Norway and Denmark. It can deliver the H2S basic safety training course accredited by the Offshore Petroleum Industry Training Organisation (OPITO) at its dedicated Training Academy and Service Centre in Aberdeen.

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