Sour gas is natural gas containing more than one percent hydrogen sulphide (H2S), and in low concentrations is identifiable by a strong 'rotten eggs' smell. It is commonly found in deep, high-pressure natural gas deposits such as those in the foothills of Alberta's Rocky Mountains region.
What is sour gas used for?
Almost 99 per cent of the sulphur in Western Canada sour gas is recovered and converted into elemental sulphur, which is used in the manufacture of fertilizers, paper, pharmaceuticals, steel and other products. Canada is one of the world's leading producers of sulphur and a global leader in the technologies for safely handling and developing the resource.
Sour gas makes up about one-third of the gas produced in Alberta; the province also accounts for nearly 85 per cent of Canada's sour gas production. British Columbia's natural gas industry contributes most of the remainder of Canada's sour gas. There are over 6,000 sour gas wells and 18,000 kilometres of operating sour gas pipelines in Alberta. Sour gas is processed at approximately 250 plants in Alberta, including more than 50 larger facilities that produce elemental sulphur.
Is sour gas an issue?
An increasing number of residents in areas adjacent to sour oil or gas producing or processing operations are actively opposing sour gas development because of the perceived risks to human health and safety.
What are the risks of sour gas?
H2S is toxic to humans and animals at very low concentrations. At concentrations between 10 - 750 ppm H2S becomes increasingly toxic. It is deadly to humans in concentrations of greater than 750 ppm. Most people can smell the distinctive 'rotten eggs' odour of the gas at concentrations between 0.1 and 0.3 ppm. At concentrations of 20 ppm or more, people may begin to experience slight discomfort in the eyes and nasal passages, and workers are required to wear breathing apparatus. At higher levels, around 100 ppm, the gas becomes more dangerous because it quickly numbs the sense of smell. Health effects such as dizziness and slight respiratory difficulties begin with exposure for an hour at 150 ppm, and fatalities can result from exposure to levels above 750 ppm unless the person is immediately evacuated and resuscitated.
Primary responsibility for the integrity and safety of sour gas operations falls to the Alberta Energy Regulator (AER) formerly the ERCB, which regulates oil and gas wells. The AER regulates sour gas with stringent regulations for sour oil and gas producing, processing and transportation.
The Alberta Energy Regulator (AER) has more information on Public safety and sour gas including a report with 87 recommendations for the development of sour gas from the Provincial Advisory Committee on Public Safety and Sour Gas (PSSG).