CO
2-enhanced oil recovery (CO
2-EOR) technology is the process of capturing CO
2, transporting the captured CO
2 to a storage site, and injecting the captured CO
2 into an oil field to enhance oil recovery. CO
2-EOR technology can greatly increase the profitability of oil fields. It is also a promising method for reducing CO
2 emission and improving the environment. For these reasons, this technology has become increasingly important for the development of the global oil industry and has been widely explored. However, CO
2 injection significantly increases the risk of corrosion failure of tubing steel. As such, the effect of CO
2 on the stress corrosion behavior of tubing steel should be investigated. In this study, the effect of CO
2 partial pressure (
P_\rmCO_2 ) on the stress corrosion behavior of N80 steel was examined using an immersion test, a surface analysis technique, and an electrochemical technology. Results reveal that the influence of
P_\rmCO_2 on the corrosion rate has an inflection point of approximately 1 MPa. When
P_\rmCO_2 is <1 MPa, a corrosion product film (FeCO
3) forms slowly, and the coverage rate is low. As
P_\rmCO_2 increases, the corrosion current density of N80 steel increases. When
P_\rmCO_2 is >1 MPa, the corrosion product film can form at a faster rate, and the corrosion current density of N80 steel decreases as
P_\rmCO_2 increases. The pH of the solution decreases continuously when CO
2 is dissolved in solution. Consequently, the stress corrosion cracking (SCC) of N80 tubing steel occurs in an annulus environment. The SCC mechanism of N80 steel in the annulus environment of CO
2 injection wells is the combination of anodic dissolution (AD) and hydrogen embrittlement (HE). Localized AD (pitting) is dominant in SCC at the initiation stage, and SCC is most likely initiated at
P_\rmCO_2 of 1 MPa. At the crack growth stage, HE has a stronger effect on SCC than AD, the SCC easily grows with a high
P_\rmCO_2 , and SCC sensitivity further improves.