Galvanic corrosion behavior in sour and sweet well environments for
combinations of materials from carbon steels to high nickel alloys was investigated by using electrochemical methods and immersion tests. Basically, the results obtained by electrochemical methods coincided with those by immersion test. The ratio of a corrosion rate of a material in coupled to that of uncoupled defined as galvanic effect index (GEI) was studied with different surface ratios. GEI increased with an increase in the weight loss of the “uncoupled specimen” and is at most 2.0 in both sweet and sour environments when a surfhce area ratio of anode site to cathode site was 1:1. GEI increased with increasing stice ratio but almost independent on surface ratio at temperatures more than 100°C. Galvanic corrosion was not selious as expected from the theory.
Keywords: galvanic corrosion, oil country tubular goods, carbon steel, stainless steel, corrosion rate, sour gas, CO2 gas