The role of Ca2+ ions on Ca/Fe carbonate products on X65 carbon steel in CO2 corrosion environments at 80 and 150 °C

Abstract

This is a repository copy of The role of Ca2+ ions on Ca/Fe carbonate products on X65 carbon steel in CO2 corrosion environments at 80 and 150 °C.

Fundamental insights into the stabilisation and chemical degradation of the corrosion product scales

“…Figure 5 shows the SEM images and XRD patterns of the prepared corrosion products formed in 60°C conditions with/ without the addition of Ca salts, and Supplementary Figs 3b and 4 illustrate the thickness of the corrosion scales prior to dissolution experiments. The presence of Ca 2+ in the solution resulted in the peaks for naturally formed corrosion products shift to the left from FeCO 3 (purple dash lines) and toward a mixture of Fe-Ca carbonates (green dash lines), which consistent with our previous studies 21,22 . The shifted peaks from XRD measurement correspond with the increase of d-spacing for the plane (1 0 4) for iron-calcium mixed carbonate according to Bragg's law as shown in Eq.…”

“…First-principles thermodynamics based on DFT were used to calculate the optimised atomistic and electronic structure of the naturally formed corrosion products. To simplify the model, typical corrosion products were selected, which are FeCO 3 (siderite), Ca 0.25 Fe 0.75 CO 3 , Ca 0.5 Fe 0.5 CO 3 , Ca 0.75 Fe 0.25 CO 3 , and CaCO 3 (calcite) based on the experimental results via XRD, more details calculation of Ca and Fe mole fraction within the crystals can be found in our previous publications 21,22 .…”

“…Similar work done by Hua et al 21 indicated that the associated effects of Cl -, Ca 2+ , Mg 2+ , and CO 2 within brine solution on the growth of the corrosion scales, they reported that the presence of Ca 2+ prefers to co-precipitation within the crystalline FeCO 3 and accentuates the total penetration rate of carbon steel. Shamsa et al 22 verified the addition of Ca 2+ led to the growth of a less protective Ca 1−x Fe x CO 3 scale which not only accelerated the pit growth but also increased the general corrosion rate.…”

“…Recent studies found that simplified corrosion products such as FeCO 3 can misestimate the corrosion product protection to the steel [19][20][21][22] . Esmaeely et al 20 revealed that the presence of high concentration Ca 2+ to be responsible for the growth of Ca 1-x Fe x CO 3 on the surface.…”

Corrosion Control in CO2 Enhanced Oil Recovery From a Perspective of Multiphase Fluids

“…A complicated corrosion product layer may be formed owing to the incorporation of Ca 2+ and Mg 2+ cations, which may have improved protectiveness or increased pitting susceptibility (Esmaeely et al, 2013;Tavares et al, 2015). Recently, Shamsa et al (2019) identified the corrosion products on X65 carbon steel as Fe x Ca y CO 3 in the presence of Ca 2+ cations. The stoichiometry of Fe x Ca y CO 3 could vary with immersion time.…”