American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.


Drilling for and producing hydrocarbons containing hydrogen sulphide gas from deep, high pressure reservoirs can be a profitable venture, but its presence presents hazards that are abnormal to routine oil field operations. A drilling venture of this type can be safely conducted if all personnel concerned are aware of the unusual risk involved and are trained in proper safety procedures. Hydrogen Sulphide, synonymous with such names sour gas and H2S, is a poisonous gas that can destroy life in very low concentrations and can also cause the instantaneous failure of high-strength steels and other metals. This means that all personnel must not only be thoroughly familiar with safety procedures and safety equipment but, also, the kinds of materials that are safe for use in hydrogen sulphide environments. This paper will deal with the safety aspects of sour gas operations.


Personnel involved in the drilling, testing, Personnel involved in the drilling, testing, and completion of wells containing hydrogen sulphide gas should first of all be familiar with the characteristics of this gas and its principal hazards. The following points principal hazards. The following points should be learned and discussed by everyone involved.

  • A. Characteristics of H2S

    1. Extremely toxic (poisonous).

    2. Heavier than air, and colorless. Specific gravity of 1.192.

    3. Has odor of rotten eggs, in smallamounts.

    4. Burns with a blue flame and produces Sulphur Dioxide (SO2) gas, which is very irritating to eyes and lungs. The SO2 is less toxic than H2S, but can cause serious injury.

    5. H2S forms explosive mixtures with air, between 5.9% and 27.2% by volume.

    6. H2S is soluble in water but becomes less soluble as the water temperature increases.

    7. H2S is almost as toxic as hydrogencyanide and is between 5 and 6 times as toxic as carbon monoxide.

    8. Produces irritation to eyes, throat and respiratory tract.

    9. Threshold Limit Value (TLV) maximum of eight hours exposure without protective respiratory equipment - 10 PPM.

  • B. Principal Hazard - Poisoning by Inhalation

All personnel involved in sour gas operations should become extremely familiar with the H2S toxicity contained in Table 1.

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