MECHANISMS FOR THE INTERFACIAL REACTION BETWEEN ACIDIC OILS AND ALKALINE REAGENTS

Alkaline reagents are increasingly added to flood water as a means of improving cumulative oil recovery from heavy oil reservoirs. The effectiveness of these reagents rests with their ability to interact with reactive species (such as acids and phenols) resulting in the formation of surface-active soap species. The in situ produced surfactants are responsible for the lowering of the interfacial tension and the subsequent mobilization of residual oil. In this paper, a physico-chemical model based on convective diffusion, sorption kinetics and electrical interfacial phenomena has been proposed to account for dynamic interactions between single carboxylic acids and caustic reagents over a wide range of both acid and alkaline concentrations. The primary objective of the work is to obtain a mechanistic interpretation of the dynamic interfacial tension arising from simple reacting systems. In view of inadequate knowledge of crude oil chemistry, oleic and aqueous phases of known composition have been employed. The model equations applicable to single carboxylic acids such as oleic and lauric contacted with a spectrum of NaOH solutions have been fully developed. A novel combination of sensitivity analysis with nonlinear regression has resulted in reliable parameter estimates. The dynamic interfacial tension predicted by the model compares favorably with the experimental data over a wide range of acid and caustic concentrations. © 1990.