Corrosion Analysis of Down-Hole Device in a Nitrogen Injection Well and Relevant Countermeasures

The down-hole device was corroded seriously after application of nitrogen injection technology in Tahe oil field. In order to determine the corrosion reasons, the down-hole corrosion products were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The results show that the main elements of corrosion product were Fe and O, and the main composition was Fe₃O₄. Oxygen carried in nitrogen injection process was the main corrosion reason of the device. According to the corrosion mechanism of oxygen some countermeasures to control oxygen corrosion were proposed, such as changing the nitrogen production method to control the content oxygen, choosing proper materials, and corrosion protection of coating, inhibitor and anodic protection.