Internal Corrosion Causes of Nickel Plated Drill Pipe

Before drilling down operation, severe internal corrosion was discovered in two nickel-plated drill pipes. In order to find out the causes of the drill pipe corrosion, macro and micro morphology analysis, micro-composition analysis of corrosion product were taken. The results showed that the presence of leaks and microscopic pores on nickel plated layer were the main reasons which leaded to drill pipe corrosion. H2S of crude oil dissolved in water and formed hydrosulphuric acid and thus also accelerated drill pipe corrosion, and the presence of chloride ions made the localized corrosion further. Standardizing the production process, improving the quality of plated-layer, and avoiding the leaks, microscopic pores or other defects in plated-layer were proposed to improve the corrosion resistance of drill pipe.