This paper presents a reliable model for the solubility products of scale-forming minerals. Our model solubilities are in relatively good agreement (±5% to 10%) with the most reliable solubilities in aqueous solutions of up to twice the seawater concentration at temperatures of 20 to 150°C and pressures up to 40 MPa. An equilibrium model for the reactions responsible for scale formation is developed. The CO2 equilibria between the gas, oil, and water phases and in the water phase itself are considered. By combining a hydrodynamic model for the transport of water through an oil reservoir during waterflooding with the proposed equilibrium model, we can estimate the amount of precipitate formed in the reservoir.