Scale Formation in Reservoir and Production Equipment During Oil Recovery: An Equilibrium Model

Abstract

This paper presents a reliable model for the solubility products of scale-forming minerals. Our model solubilities are in relatively good agreement ({plus minus}5% to 10%) with the most reliable solubilities in aqueous solutions of up to twice the seawater concentration at temperatures of 20 to 150{degrees} C and pressures up to 40 MPa. An equilibrium mode for the reactions responsible for scale formation is developed. The CO{sub 2} 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.