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

By Graham Chandler

April 01, 2009

If you have been knocked out by sour gas, go see a doctor even if you think you are fine, was the moral of that story.

These stories are not tall tales. They are genuine experiences, preserved and told to communicate unforgettable lessons about how deadly sour gas is and how careful and aware you have to be when working anywhere you risk exposure.

Sour gas is a naturally occurring substance. In Western Canada it is encountered primarily by the oil and gas industry in drilling or well service and stimulation operations. Most of the students attending this course were rig workers.

The toxic gas stinks like rotten eggs at low concentrations. At higher concentrations, it temporarily knocks out your sense of smell.

“A lot of guys would smell it, then the smell seemed to go away and they thought the danger had passed and kept working,” noted Williams. “Then – bang – they are on the ground.”

Released sour gas can dissolve in water, oil, sludge, emulsions, well fluids and molten sulphur. It can also creep into tool boxes and be released when workers open them off site.

The gas is measured in parts per million relative to air because surprisingly miniscule amounts can cause great damage. Respiratory protection is required at any level above 10 parts per million. At 200-500 ppm, or less than .05 per cent, the gas will kill you within hours. At 500 to 700 ppm, it affects the central nervous system and stops your breathing within minutes. Above that, there is immediate loss of consciousness and permanent brain damage.

Most of the course focused on rescue and resuscitation. When seeing a co-worker fall down, most people react by running over and seeing what is wrong, Williams says. This response, while honorable, is the quickest way to multiply the number of casualties in a sour gas mishap. Numerous incidents have ended with a pile of corpses on-site as worker after worker ran over to see what was wrong only to get immediately knocked out, said Williams.

The response strategy taught to the class is a seven-part approach where the rescue comes in at number five. Before going in to save a co-worker, the scene must be evacuated, authorities need to be alerted, an assessment must be done – starting with a headcount and ending with a check as to the direction of the on-site windsock – and breathing apparatus must be put on. After the rescue, the victim is revived and receives medical aid.

These seven steps were repeated and the class chanted them like a mantra before coffee and lunch breaks. Students painstakingly applied the strategy to many case scenarios.

At the end of the day, students were tested on their new knowledge and if they scored above 70 per cent, they were certified to work on sites that may have sour gas. Wherever they were going, at least two things were bound to stay in their minds: check your equipment for rodents and don’t always follow your instincts – doing so might lead to an ugly death.

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