Improving Strength and Toughness of Oil Well Cement with Modified Basalt Fiber

Due to the influence of complex downhole conditions and inherent brittleness of cement, cement is easily broken, resulting in interlayer sealing failure. To solve this problem, basalt fiber is used to enhance the mechanical properties of cement paste. However, due to the weak adhesion between the fiber and the cement base, the excellent mechanical properties of the basalt fiber cannot be fully exerted. Therefore, the surface of the basalt fiber was modified. The basalt surface was treated by KH-550, the surface of basalt fiber was loaded with silica by the sol–gel method. The chemical structure and elemental composition of the basalt fiber were analyzed with IR and EDS, and the morphologies of the fiber surface and composite material were analyzed with SEM. The fiber monofilament is drawn to analyze the performance of the basalt fiber interface, and after modification, the bonding performance between the basalt interface and the cement is enhanced. The flexural strength and compressive strength of cement-based composites were tested. The results showed that the flexural strength and compressive strength of modified fiber cement were 27.7% and 25.2% higher than those of blank cement and 10.7% and 16.1% higher than those of the unmodified basalt fiber cement. The interface bonding performance between modified basalt fiber and cement matrix was enhanced. The analysis showed that the modified basalt fiber cement effectively improved the toughness of oil well cement and cementing quality.