Influence of a small velocity variation on the evolution of the corrosion products and corrosion behaviour of super 13Cr SS in a geothermal CO2 containing environment

Abstract

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Formation and Evolution of the Corrosion Scales on Super 13Cr Stainless Steel in a Formate Completion Fluid With Aggressive Substances

“…5) dominates the cathodic reactions in this case. The initial corrosion rate was relatively high under such hightemperature conditions, which can be attributed to the fast metal dissolution in the absence of the protective layers (solid/insoluble products), and the results are in agreement with our previous research (Yue et al, 2020a;Yue et al, 2020b;Yue et al, 2020c):…”

“…The previous literature has reported that the formation of the FeCO 3 and Cr(OH) 3 on S13Cr SS was controlled by the dissolution-precipitation process and resulted in relatively high defections (Guo et al, 2012;Zhao et al, 2019). However, the formation of the compact structures for spinel products such as Fe 3 O 4 and FeCr 2 O 4 was considered to provide better corrosion protection than that of the precipitation type (Yue et al, 2020a(Yue et al, , 2020b(Yue et al, , 2020cLiu et al, 2021). Besides, the outer corrosion products with sheet-shaped clusters characterized as a looser structure which may cause pore connectivity within the outer layer.…”

“…The Tarim Basin, where exists abundant natural gas in the depth between 6,500-8,000 m, has been constructed with 52 wells in Kuqa from 2012 (Liu et al, 2019a). Due to the high pressure , high temperature (170 °C-190 °C), and complex corrosive medium, the corrosion issues of highly dense brine-based completion fluids on tubing and casing materials in ultra-deep high-temperature wells have become a research hot spot in the course of oil and gas exploitation (Yue et al, 2020a;Li et al, 2020;Zhao et al, 2020). The considered competition fluids are mainly the bromine salt completion fluids (KBr, ZnBr 2 , and CaBr 2 ) (Liu et al, 2014;Liu et al, 2019b) and/or formate brines (NaCOOH, KCOOH, and CsCOOH) (Bungert et al, 2000;Leth-Olsen, 2004;Zhu et al, 2011b).…”

“…Hakon (Leth-Olsen, 2004) found that the formation of the corrosion product scales on 13Cr SS in formate fluids did not act as an effective barrier against corrosion, showing high-corrosion rates after several weeks of exposure, and the surface was covered by nonuniformed crystalline FeCO 3 , especially at 180 °C (Leth-Olsen and others, 2005). Although the formation of the FeCO 3 layer plays a dominant role in retarding the corrosion rate, the corrosion resistance of S13Cr SS corresponds to a complicated corrosion product scales formation and evolution process, and that the amorphous/nanocrystalline inner layer provides better corrosion protection than outer FeCO 3 precipitation [21][22][23][24][25] under the ultradeep well conditions [temperatures beyond 180 °C (Zhao et al, 2018;Yue et al, 2020aYue et al, , 2020bYue et al, , 2020cZhao et al, 2021a)]. The systematic study on the formation and evolution of the corrosion product scales on the S13Cr SS surface immersed in a formate fluid under HTHP condition, especially with the presence of aggressive substances such as sulfide or CO 2 is rare.…”

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

“…Many studies have proved the growth of the carbonated corrosion scales by the precipitation/dissolution processes 10,[30][31][32] . The steel substrate beneath the carbonates suffered localised corrosion since the naturally formed corrosion scales are porous and local dissolution of the corrosion scales can occur at the material interface.…”