Research on surface modification of polypropylene fiber and its application evaluation in oil well cement

Abstract

In order to improve the compatibility and dispersibility of polypropylene fiber (PPF) in oil well cement and enhance the mechanical properties of cementing cement sheath, the surface modification of PPF was carried out in this study. After surface impurity removal of PPF, reaction of catechol with polyamines, and subsequent treatment with γ- aminopropyltriethoxysilane (KH-550) and Ethyl orthosilicate (TEOS), modified polypropylene fiber (MPF) was obtained. The MPF was characterized and analyzed using FTIR, XPS, SEM, and EDS, showing a transformation in the surface properties of the fibers. The most significant change was that the contact angle between MPF and water decreased from 123.87 ° to 46.32 °, marking the successful transition of the fiber from hydrophobicity to hydrophilicity. Image analysis showed that the dispersion of MPF improved significantly. The dispersion coefficient of MPF in water and cement stone was increased by 86.90% and 14.48% compared with PPF, respectively. The effect of MPF on mechanical properties of oil well cement stone was studied. The comparative analysis results showed that MPF can significantly improve the flexural and compressive strength of the cement matrix. The flexural and compressive strength of cement stone mixed with MPF were increased by 10.25% and 6.43%, respectively, compared to cement stone mixed with PPF. SEM, MIP, and fiber single fiber pull-out experiments showed that the porosity of cement stone added with MPF was lower, the rough surface structure of MPF enhanced the bonding between fibers and cement stone, and the bridging effect of fibers in cement stone ultimately improved the mechanical properties of oil well cement stone.