Communities keep watch as industry strives to contain a deadly gas

Bill Roman learned the hard way to respect sour gas as a young engineer in the early 1950s. Half a century later, the lesson remains a vivid memory

April 01, 2009

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He was removing a gauge from a valve at Shell Canada’s Jumping Pound natural gas processing plant about 40 kilometers west of Calgary. “There was a small amount of gas trapped in the tiny space between the valve and the gauge. I got a whiff of that and I learned pretty quick. It took a couple of hours to recover.”

Those were the days when little was known about the dangers of the naturally occurring nasty ingredient in some of Alberta’s richest natural gas deposits, hydrogen sulphide. The chemistry and the poison hazard were well understood, but not details such as how leaks behave in western Canadian winters.

Roman and other pioneers of the sour gas industry helped pave the way for elaborate management of this potentially risky field which today makes up a quarter of Alberta’s natural gas production. How well the hazard has been tamed shows in the durability of the operations.

New sour gas drilling proposals invariably arouse fear and protest. But few Calgarians realize their city is ringed with wells and plants handling high volumes of the material because accidents and injuries are exceedingly rare. The credit for making the field a cornerstone of the province’s resource wealth and employment belongs to a three-sided, at times uneasy partnership of industry, the Energy Resources Conservation Board and the public.

H2S is not rare. Oil and gas production has no monopoly on the substance. It is also found in sewage, swamps, pulp and paper plants. Its trademark rotten-egg smell becomes apparent at atmospheric concentrations as low as fractions of parts per million (ppm). Exposures to levels between one and 10 ppm can cause nausea, stinging eyes and headaches.

The latest ERCB directives require emergency evacuations at 10 ppm. Above that, danger territory begins. At concentrations over 150 ppm, health effects can be severe and lengthy exposures can kill.
According to ERCB records, approximately 6,000 sour gas wells, 240 processing plants and 12,500 kilometers of sour gas pipeline stud the Alberta landscape. The province accounts for around 85 per cent of total Canadian sour gas production.

Shell had a leading role in advancing the technology of sour gas drilling, production and processing. “It’s both the materials of construction – the metallurgy or chemistry of the steel and the types of gasket material – and also the actual gas treating process and the running of that process,” explains David Kidd, operations manager at the Jumping Pound gas plant.

“Some of the properties of steel when it comes in contact with H2S combined with water can cause cracking and accelerated corrosion.” He says in the early days a lot of research was going on, and many solutions were first tried and tested at Jumping Pound.

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