Experimental Investigation of CO2‐ and Fe3O4‐Assisted Corrosion at the Cement–Casing Interface. Issue 10 (15th July 2022)

• Record Type: Journal Article
• Authors: Wang, Shuliang; He, Xujia; Wang, Shidong; Yao, Mengjun; Zhang, Jiaji; Wu, Mingyu; Liu, Li; Zhang, Xingguo; Xiang, Dinghan
• Is Part Of: Steel research international. Volume 93:Issue 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-15
• Subjects: cement–casing interfaces -- CO2 corrosion -- galvanic corrosion -- magnetites -- steels; Steel -- Periodicals; Steel -- Metallurgy -- Periodicals; 669.142
• DOI: 10.1002/srin.202200209
• Languages: English
• ISSNs: 1611-3683

Abstract

Abstract : In this study, CO2 ‐ and Fe3 O4 ‐assisted corrosion of the cement–casing interface for the magnetite (Fe3 O4 ) high‐density cement–casing steel system in simulated formation water is investigated under the normal and high CO2 pressure conditions. Results show that the degradation of the cement–casing interface is affected by the competition of cement hydration and CO2 corrosion. The migration of CO2 and corrosive species to the cement–casing interface is facilitated under the high pressure condition, resulting in enhanced corrosion rate as compared to the normal pressure condition. The casing steel is in active corrosion state while the corrosion rate gradually increases with time. After long term of immersion, a layer of thick corrosion products with multiple cracks/microgaps forms at the cement–casing interface, which can hardly protect the casing steel from further corrosion. The corrosion products on the steel surface are mainly FeCO3 accompanied by a small amount of CaCO3 and Fe3 O4, suggesting the prevalence of CO2 corrosion. The mechanism of the CO2 ‐ and Fe3 O4 ‐facilitated corrosion of the cement–casing interface for the magnetite high‐density cement–casing system is proposed. Abstract : The integrity of the cement–casing interface is critical to the safe exploitation of oil and gas resources, especially when the interface undergoes high‐pressure CO2 corrosion in ultradeep wells where magnetite (Fe3 O4 ) is widely adopted for the cementing safety. Herein, both high‐pressure CO2 and Fe3 O4 facilitating degradation of the cement–casing interface by Fex Ca1− x CO3 ‐assisted cracking and Fe3 O4 ‐induced galvanic corrosion are reported.