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 CO 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.

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Summary In this paper, we discuss experimental and theoretical studies on the effects of disproportionate permeability reduction (DPR) (i.e., the ability to reduce relative permeability to water more than to oil). The theoretical part discusses DPR effects by simple analytical arguments, supported by simulations. DPR causes buildup of water saturation in the treated zone to accommodate the water/oil ratio, Fwo, delivered by the reservoir. Core flooding experiments were also carried out, with a DPR gel placed in one half of the core. There is excellent agreement between theory and core flooding results. It was observed that the water saturation in the treated zone increased. Saturation profiles were measured with a CT scanner and is well matched by simulation.

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