The influence of multi-scale tough liquid fiber toughening agent on the mechanical properties of oil well cement-based composite materials

Abstract Cementing is a key process in drilling engineering, and the cement sheath in cementing can sometime have problems such as significant brittleness, low toughness, and low resistance to impact damage, especially in perforation and fracturing environments where the cement sheath is more susceptible to damage. In response to the above issues, three types of inorganic carbon fibers, including 1 mm carbon fiber, 2 mm carbon fiber, and nanocarbon fiber, were studied indoors to investigate the influence of their ratios on the mechanical properties of cement paste. The optimal mixture of 1 mm carbon fiber, 2 mm carbon fiber, and nanocarbon fiber in a ratio of 3:2:1 was selected, and a multi-scale liquid fiber toughening agent BS-54 was obtained through special liquefaction process treatment. The liquid fiber toughening agent BS-54 has good water dispersibility and can evenly disperse in the slurry water, effectively improving the dispersion and addition of multi-scale fibers in cement slurry. The cement slurry prepared with multi-scale dispersed liquid fiber toughening agent has good rheological properties, water loss, and thickening properties. The addition of multi-scale dispersed liquid fiber toughening agent to cement slurry significantly increases the tensile strength, impact strength, and compressive strength of cement paste, effectively reduces the elastic modulus of cement paste, improves the strength of cement paste, and achieves toughening effect. Microscopic analysis shows that the active nanoparticles dispersed by multi-scale dispersed liquid fiber toughening agents can interweave between gaps, and the dense cross-linked structure formed by their multi-scale micro nano structure improves the toughness and strength of cement slurry. Moreover, the multi-scale dispersed liquid fiber toughening agent cement slurry ensures that the cement stone sample has good integrity under external impact, which is conducive to improving the impact resistance of the cement stone.