Influence of nano-TiO2 on the wellbore shear bond strength at cement-formation interface

This research investigates the wellbore shear bond strength of nano-TiO₂-containing oil-well cement pastes with particle sizes of 20 and 40 nm. The nanoparticles were picked by the weight of cement at proportions corresponding to 1, 2, 3 and 4%. Test results indicated that nano-TiO₂ significantly enhanced the interfacial shear bond strength. The results also revealed that the strength enhancement was reliant on the nano-TiO₂ particle sizes. The specimens containing nano-TiO₂ 40 nm provided greater strength compared to 20 nm, due to effective pozzolanic activity. By fluctuating the nano-TiO₂ dosages, the optimal replacement content was 3% for all particle sizes. The particle size did not affect the appropriate dosage of nano-TiO₂, it only impacted the bonding strength of the interfaces. With 3% (40 nm) nano-TiO₂, the 3, 7, 14 and 28 days strength increased by 557.38, 504.17, 528.57 and 412.04% respectively. The scanning electron microscope, X-ray diffraction and thermogravimetric technique were used to examine the influence of nano-TiO₂ on the cement-formation bonding.