CO 2 sequestration in saline aquifers has been proposed as one of the most practical options for reducing CO 2 emissions into the atmosphere. Massive CO 2 injection into an aquifer would alter the geochemical equilibrium between the rock-forming minerals and the formation water. In this work, a novel and simple predictive tool is presented to estimate the formation of calcium carbonate scaling as a function of pH, temperature, ionic strength of the solution, calcium cation concentration, bicarbonate anion concentration and carbon dioxide mole fraction when the water mixture is saturated with a gas containing CO 2 , to evaluate the effect of solution conditions on the tendency and extent of the precipitation. The proposed simple method covers concentration for calcium cation concentration, or bicarbonate anion concentrations up to 10000 mg/L, temperatures up to 90°C, total ionic strength up to 3.6 and pH values ranging between 5.5 and 8. The predicted values are found to be in good agreement with the reported data with average absolute deviations being less than 2.6%. The proposed tool is superior owing to its accuracy and clear numerical background based on Vandermonde matrix, wherein the relevant coefficients can be retuned quickly for various cases. Key words: Calcium carbonate, Scale, Saturation index, CO2 Sequestration, Carbon dioxide, Global warming
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