The Synergistic Influence of Trace Impurities and Temperature on the Corrosion Behavior of Tubing in Supercritical CO2 Environment

Carbon dioxide capture, utilization, and storage for enhanced oil recovery (CCUS-EOR) represents an effective strategy for reducing CO2 emissions while improving oil recovery efficiency. However, harsh environmental conditions during the process can induce a supercritical state in captured CO2, which may undermine the structural integrity of tubular components through corrosion. This study systematically investigated the corrosion behaviors of two tubing steels (P110 and Super 13Cr) in 20 MPa supercritical CO2 containing trace H2S/O2 impurities at 60–120 °C using weight loss tests and surface analysis. The results demonstrate that in water-unsaturated supercritical CO2 with ≤500 ppmv H2S, both steels exhibited low general corrosion rates (P110: 0.03 mm/y; S13Cr: 0.01 mm/y), with incomplete surface films partially covering grinding traces. However, S13Cr suffered pitting corrosion at >500 ppmv H2S. Oxygen introduction triggered severe general/localized corrosion characterized by cracked, non-protective surface films. Reducing O2 to 500 ppm yielded thin, continuous protective films, eliminating pitting. Temperature critically influenced S13Cr corrosion: decreasing from 120 °C to 60 °C increased the corrosion rates from 0.0031 mm/y to 0.08 mm/y due to enhanced water precipitation and impurity gas dissolution. These findings establish impurity thresholds to ensure acceptable corrosion performance.