Recovery of acidic crude oil from porous media can be enhanced by injection of alkaline agents. For this process we have analyzed the detrimental effect of alkali adsorption on the mineral surface. The model, which is an extension of our earlier inert solid model, was formulated by conserving three independent species. The previous solution procedure is shown to fail and a new analysis of composition paths is necessary. By introducing the notion of critical point, a short-cut procedure is developed.

The predicted profiles and effluent histories are discussed. A new result is that adsorption on the solid surface could change the ultimate recovery even for an infinite slug of alkali due to the reduced influence of the optimal region in displacing oil. Further, the influence of a favorable viscosity ratio in displacing oil is also shown to be reduced by adsorption.