Studying the interactions between an Arabian heavy crude oil and alkaline solutions

An experimental study to examine the effectiveness of alkaline flooding for the recovery of an Arabian heavy crude oil is presented. The interfacial tension (IFT) behavior of crude oil/alkali systems over a wide range of parameters (pressure, temperature, alkali concentration and time) was studied. These alkaline reagents react with the acidic species in crude oil to form surface-active soaps in-situ. This leads to a lowering of interfacial tension (IFT) and subsequently the mobilization of residual oil. The equilibrium IFTs obtained through alkaline flooding are compared with the IFTs when a synthetic surfactant (dodecyl benzene sulfonic acid sodium salt) is used in FOR recovery. A mathematical model representing the complete chemistry of the transient process is also presented. The model consists of a set of differential equations describing reactions, diffusion, and adsorption at the oil/alkaline solution interface. The kinetic-parameters in the model are obtained through a differential algebraic optimization technique. The concentration of the surface active species are related to the measured IFTs through an independent step that is based on isolating the surface active species formed by the reaction between the acids in the crude oil and the alkaline solution. A sensitivity analysis using the model is carried out to study the effect of surface potential and alkaline concentration on the transient interfacial tensions.