Improving the mechanical properties of oil well cement stones by incorporating nano TiO2-modified waterborne epoxy resin

To enhance the interface bonding performance of cement sheaths in oil and gas wells, this study developed nano TiO 2 -modified waterborne epoxy resin (NTWER) as a cement slurry additive. The mechanical properties and microstructural characteristics of the resulting cement stones were systematically examined. Results indicate that an optimal concentration of nano TiO 2 (NT) in waterborne epoxy resin (WER) improves the stability of the cement slurry. The inclusion of NTWER notably enhanced the shear bonding strength while slightly decreasing uniaxial and triaxial compressive strength and reducing Young’s modulus. When the nano TiO 2 (NT) content in the WER reached 3 %, substantial improvements in shear bonding strength were recorded at both the casing (1st interface) and borehole wall (2nd interface) interfaces after curing for 1, 2, and 7 days, compared to plain cement. Specifically, the shear bonding strength at the 1st interface increased by 23.9 %, 33.5 %, and 31.0 %, while at the 2nd interface, it rose by 25.3 %, 42.5 %, and 37.4 %. Notably, the 2nd interface consistently exhibited higher bonding strength than the 1st. Mechanic studies suggest that NTWER facilitates improved bonding by mitigating early hydration inhibition, reducing macropores, and decreasing overall porosity within the cement matrix. This densification effect and enhanced bonding properties indicate that NTWER effectively addresses the limitations of conventional epoxy resin in oil and gas well cementing applications, offering a promising approach for achieving durable zonal isolation and increased well integrity.