Penetration of imidazoline derivatives through deposited scale for inhibiting the under-deposit corrosion of pipeline steel

Effective penetration of corrosion inhibitors through deposits is vital for controlling under-deposit corrosion (UDC) in oil/gas production. Herein, the penetration of three imidazoline derivatives across a CaCO3-based scale in CO2-saturated brine was examined, along with the resulting protection effect on mild steel. Real-time spectral monitoring revealed the correlation between inhibitor structures and penetration ability, with a maximum permeability of 24.1 %. Imidazoline's affinity with water, indicated by coordination number, significantly influenced the penetration. The intrinsic efficacy of imidazoline derivatives determined actual UDC inhibition efficiency, reaching a maximum of 92.33 %, under conditions of sufficient penetration.