Investigation of alkaline–crude oil reaction

One of the mechanisms of alkaline flooding relies on alkaline reaction with organic acids (saponifiable components) in the crude oil to produce an in situ surfactant called soap that lowers interfacial tensions. However, this mechanism is not quantified in the literature. For example, what is the fraction of acid components which react with alkaline solution to generate soap? How much soap can be generated?In this paper, this mechanism and related issues are discussed, analyzed or quantified. In particular, the numerical simulation approach is used. The results show that only a fraction of acid components can be converted into soap; the amount of generated soap could be low. A minimum pH (e.g. 9) is needed for the acids to be converted to soap. The literature information on the effect of amount of acid components (total acid number) on oil recovery is also discussed.