Impact of nano-Al2O3 particle size on shear bond strength in petroleum and low-temperature geothermal wells

This study examines the shear bond strength of cement paste at the wellbore interface in petroleum and low-temperature geothermal wells. Class G cement enhanced with nano-Al 2 O 3 (NA) particles (20 nm and 40 nm) was used for wellbore simulations at 80°C. The particles were chosen in percentages of 1, 2, 3, and 4% based on the weight of cement. According to the research results, the interfacial shear bond strength was considerably increased by NA. The findings also demonstrated that the size of the NA particles influenced the strength improvement. The specimens with NA 40 nm offered more strength than those with 20 nm due to their notable pozzolanic effects. By adjusting the NA doses, the optimal replacement content was found to be 3% across all sizes of particles. The size of the particles solely affected the interface bonding strength, it did not affect the ideal dosing of NA. By incorporating 3% (40 nm) NA, the strength improved by 557.14, 525.00, 514.75, and 421.30% at 3, 7, 14, and 28 days, respectively. Overall, NA boosts shear bond strength through microstructure refinement. Its smaller dimensions provide multiple benefits to improve well integrity for prolonged zonal isolation. The effect of NA on cement-formation bond was investigated using a scanning electron microscope, X-ray diffraction, and thermogravimetric method.