Field handling of sour gas and condensate

The handling of low-pressure sour gas has been with us since the sour crude fields were discovered, but the discovery of sour-gas reservoirs and a need for means to satisfactorily drill and produce them began in the late 1950's. It became necessary to experiment to find suitable materials and develop techniques to safety handle sour gas at pressures exceeding the rating of ANS Class 150 flanges. It was found that low carbon steels with a Brinell hardness no higher than 230 to 242 are the most satisfactory steel for pipe, flanges, and fittings in sour-gas service. The proper welding procedure is also an important part of a successful sour-gas system with adequate measures being taken to anneal the welds such as controlled cooling or stress relieving. All pipe used in the construction of a sour-gas system should be given an appropriate type nondestructive test to insure that the pipe is free of gas pockets, gouges, laminations, and inclusions. During the construction period, each field weld should be checked by nondestructive inspection. Means should be provided to detect internal corrosion after the system is placed in service and adequate facilities need to be installed to mitigate this condition. It is essentialmore » that provisions be made to automatically shut down a well or wells being served by the sour-gas system should a leak occur.« less