Logging Operations In Sour Gas Wells

Formidable technical and operational problems arise in the course of drilling, testing, and producing wells which contain appreciable amounts of hydrogen sulfide. Though not the worst of such problems, wireline operations are certainly rendered more difficult and dangerous. Logging equipment is designed to perform properly in the high temperatures and pressures found in oil and gas wells. The presence of hydrogen sulfide has thrust forward a new hostile environment problem. The troubles are twofold: the threat of personnel overexposure, and the deterioration of metal components which are exposed to HS. Industrial plants have long known of the dangers to personnel who are exposed to hydrogen sulfide. Steps were taken to learn the procedures necessary for personnel safety. These procedures were then adapted for use by our logging crews, and have been effective in that no case of hydrogen-sulfide poisoning has been reported. The downhole problem created by the presence of hydrogen sulfide is harder to correct. The solution to the problem was evidently either to protect vulnerable steels from contact with the gas, or to use other materials which were not vulnerable. Both measures have been successfully applied. Protective coatings are good enough to permit the use of standard cables and downhole tools in cases of low HlS concentration, but special H2Sresistant cables are needed for severe conditions. In no case, however, should sour-gas logging operations be looked upon as routine. HS-resistant pressure-control equipment is also available. Pressures to 15,000 psi can be controlled.