Evaluation of environmentally friendly corrosion inhibitors vs traditional corrosion inhibitors in oil and gas industry

摘要

Carbon and low alloy steels are widely used construction materials for oil and gas process and transportation facilities. In order to guarantee the integrity of plants a very effective corrosion management strategy is mandatory with these materials. The most extensively used method in controlling internal corrosion threats is represented by chemical inhibition. A large number of commercial corrosion inhibitors is available to handle a lot of different corrosive conditions. Unfortunately, most of the chemical molecules, more effective as corrosion inhibitor, are non-biodegradable and toxic for marine and terrestrial living species. That is why international regulations are changing, forcing chemical manufacturers and operators to dismiss harmful and hazardous chemicals in favour of eco-friendly compounds. Concerning eco-friendly corrosion inhibitors the main questions arising between operators are: Are the environmentally friendly corrosion inhibitors as effective as traditional ones? Are they really environmentally friendly? In the attempt to answer these questions a laboratory testing activity was carried out by eni e&p with the support of specialized laboratories. This paper describes the applied testing protocol and the results of the comparative evaluation of eight different corrosion inhibitors, both traditional (red) and environmentally-friendly (green). Four service companies were asked to provide two different corrosion inhibitors, a red and a green one. The efficiency (ξ), in corrosion control, of the eight chemicals was evaluated, at the same conditions, by means of weight loss and electrochemical techniques, both under static and dynamic conditions. The toxicity of the chemicals was evaluated by means of the assessment of their specific EC50 value. A comparison of the different laboratory test results was carried out between products of the same supplier. The results of the laboratory testing campaign indicated that the efficiency of environmentally friendly corrosion inhibitors is mostly comparable, and in some cases even better, to that of traditional products. In terms of environmental impact, most of the green inhibitors showed a better behaviour than the corresponding red ones.