Hazards associated with Sour gas

Gas contains components that form acids when mixed with water which in turn corrode steel and most other metals used to line wells and make pipelines

"Sour gas" is natural gas containing components such as hydrogen sulphide and carbon dioxide that form acids when mixed with water. The technical problems this poses for gas producers is that acids corrode steel and most other metals used to line wells and make pipelines, as well as other gas production and processing equipment. They also eat through the plastic seals in most gas pumps.

There are serious health problems associated with hydrogen sulphide, a deadly constituent of most deep gas deposits. At tiny concentrations, it is associated with the smell of rotten eggs. At concentrations as low as 700 parts per million, the gas instantly paralyses the respiratory system of any person or animal unfortunate enough to inhale it. The concentration of hydrogen sulphide in Abu Dhabi's Shah field is a hefty 23 per cent, according to engineers who have worked on the project. That is near the top end of concentrations found in other high-sulphur gas deposits that have been developed in countries such as Canada and Kazakhstan.

There has been high human cost wherever sour gas has been produced. In the 1920s, hydrogen sulphide exposure killed 30 oil and gas workers in Texas over two years. In 1982, a blowout at a Canadian sour-gas well killed two people and hundreds of cattle, while thousands more people complained of headaches, eye irritation, nosebleeds and "flu-like" symptoms. The world's worst sour-gas disaster occurred in 2003 in central China, when a toxic cloud from a well blowout near the city of Chongqing killed 243 people.

The environmental costs of sour-gas production can also be high. Pumping it always results in at least some emission of sulphur dioxide, a pollutant linked to poor air quality and acid rain. The carbon dioxide found in sour-gas deposits, at a 7 per cent concentration at Shah, causes more environmental problems if vented to the atmosphere. [e-mail]