Corrosion Characteristics of Oil Well Tube in Multivariate Flow Thermal Fluid Containing Cl^-

The corrosion test of multi-element hot fluid containing O₂ and CO₂ was carried out in a high temperature and high pressure reactor, combined with SEM, EDS and XRD tests, the micro morphology and reaction mechanism of the corrosion samples were also analyzed, and the effect of the change of Cl^- concentration on the corrosion of J55 pipe was studied. The results showed that:in an oxygen-containing multi-element thermal fluid environment, with the increase of Cl^- content, the corrosion rate of J55 first increased and then decreased. When the NaCl mass fraction was 1%, the corrosion rate of J55 was the largest. Under the condition of CO₂ in the multi-element thermal fluid, when the Cl^- content was low, the corrosion rate of J55 decreased with increasing temperature; when the Cl^- content was high, the corrosion rate of J55 increased with increasing temperature. Therefore, there was a critical Cl^- concentration. In the oxygen-containing chloride ion corrosion system, J55 exhibited the corrosion characteristics of O₂ and Cl^- competing with each other. When the Cl^- content was low, O₂ played a major role in promoting the initial stage of corrosion reaction; when the Cl^- content was high, Cl^- became the main factor affecting the corrosion rate.