Abstract
CO2 geological utilization and storage (CGUS) is an effective method for reducing greenhouse gas (GHG) emissions and mitigating their global warming effects. Wellbore cement is a crucial component of the CGUS system, but it exhibits chemical instability when exposed to CO2-rich environments, which can lead to potential CO2 leakage from wellbores. Maintaining the integrity of the wellbore cement is essential for preventing CO2 leakage, ensuring the long-term containment of CO2 in subsurface formations, and ensuring the success of CGUS projects. The objective of this study is to evaluate the impact of different CO2-resisting additives on the corrosion depth, compressive strength, and the pore structure of wellbore cement when exposed to CO2-saturated brine under geologic CO2 storage conditions. The mineralogy, microstructure, and morphology of specimens with different additives were analyzed using XRF, XRD, SEM and micro-CT. The results show that the cement containing supercritical CO2-modified Ca-montmorillonite (CM) was more effective in resisting CO2 corrosion than biochar (BC), crystalline admixture (CA), and geopolymer (GP). The corrosion inhibition efficiency, when compared to the reference sample (00-RF), followed the descending order of CM (44.04%), GP (26.17%), and BC (6.49%). Adding CA to the cement not only failed to inhibit corrosion but also increased the carbonation depth within the wellbore cement by 35.78%. The analysis of CM indicates that its reinforcement mechanisms stem from micro calcite-induced carbonate growth and montmorillonite swelling, and the prevention of CO2 infiltration is attributed to the structure of montmorillonite after supercritical CO2 modification. Regarding compressive strength, all samples with different additives exhibited a decline after CO2 corrosion. The sample containing supercritical CO2-modified CM showed the smallest reduction in compressive strength (10.40%) after carbonation while the sample with GP has the highest reduction (54.63%). In summary, compared to the other additives, CO2-modified montmorillonite has the most promising application prospect.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
