Abstract: Magnesium ions, which exist in formation water and injection water under downhole conditions in the oil and gas production industry, are a key determinant in the CaCO₃ scale formation.Many studies have focused their attention on the effect of magnesium on the kinetics, the morphology and the content of Mg in the CaCO₃ scale.Little attention has been paid to the effect of Mg²⁺ on the initial stages of CaCO₃ formation on a metal surface.In this study, an electrochemical technique was used to study the influence of Mg²⁺ on the initial stages of CaCO₃ scale formed on a metal surface.With this electrochemical technique, the reduction of the dissolved oxygen in an analysis solution is considered on the surface of a rotating disk electrode (RDE) under potentiostatic control.The rate of oxygen reduction on the surface of the RDE enables the extent of surface coverage of scale to be assessed.With this electrochemical technique, a new insight into the effect of Mg²⁺ on CaCO₃ scale formed on a metal surface is given.

Key words: Calcium carbonate, Magnesium, Scale, Levich analysis, Rotating disk electrode