Hydration characteristics of phosphoaluminate cement for carbon capture, storage and utilization(CCUS) well cementing and the mechanism of pore and compressive strength evolution

• Published in: Ceramics international Vol. 51; no. 8; pp. 10273 - 10282
• Main Authors: Yang, Shuo, Yuan, Bin, Xu, Bihua, Wen, Dayang, Feng, Qinghao, Chen, Zhiming, Zheng, Danzhu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2025
• Subjects: 1H low-field nuclear magnetic resonance; Compressive strength; Hydration process; Phosphoaluminate cement; Pore volume; Hydration process; Pore volume; Compressive strength; 1H low-field nuclear magnetic resonance; Phosphoaluminate cement
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2024.12.459

Phosphoaluminate cement is the most promising material for cementing CCUS wells due to its high early strength, stable late strength and corrosion-resistant characteristics. Currently, there is no relevant study on its hydration and strength development at conventional temperature (90 °C) in oil and gas wells, resulting in unclear evolution of mechanical properties. Therefore, in the present study, pore size changes during the early hydration of phosphoaluminate cement at 90 °C were analyzed by using 1H low-field NMR, and the dynamic change behaviors of the compressive strength, hydration degree, hydration products and functional groups were also analyzed. The results indicate that the pore diameter of phosphoaluminate cement stone decreases gradually as the maintenance time increases, and the pore volume decreases firstly and then increases, but the compressive strength increases all the time. Dissolution of reactive minerals (CAP and CA), crystal transformation of hydration products (C3AH6 and C2AH8), and crystals of hydration products (CAPH, CPH, C3AH6, and C2AH8) occur during the hydration of phosphoaluminate cements. Synergistic interactions among the three induced the hydration process of phosphoaluminate cement, controlling the dynamic changes of pore size, pore volume and compressive strength. Phosphoaluminate cement hydration process is classified as dissolution stage, preinduction stage, acceleration stage, induction stage, secondary acceleration stage and deceleration stage, six stages. At 90 °C, Ca5(PO4)3OH still does not participate in the hydration reaction, which ensures a stable increase in the compressive strength of the phosphoaluminate cement stone, giving it the potential to become a new material for cementing CCUS wells.