Study of immiscible oil displacement in unconsolidated porous media with and without chemical reaction.

Abstract

After the waterflood (secondary oil recovery) various techniques known under the generic name of Improved Oil Recovery (IOR) processes are employed to achieve the ultimate goal-increase of recovery of oil. Among IOR processes, alkaline flood is viewed as one of the most promising methods due to its ability to dramatically decrease the interfacial tension between the aqueous phase (alkaline solution) and oil which, in turn, causes a better mobilization of oil from the reservoir to be achieved. This study was made in continuation of other studies performed in Chemical Engineering Department of University of Ottawa. Its aim was to obtain additional information regarding the process of immiscible displacement of oil by water in a cell containing an unconsolidated porous medium, namely sand. Gathering more information in this vast field of research is an important factor that leads to a better understanding of the complex phenomena involved in the process of oil recovery. Throughout this study, distilled water and sodium hydroxide solutions with a concentration of 25 mM were used as the displacing fluids and light paraffin oil both pure and doped with 10 mM linoleic acid was used as the displaced fluid. The cell used to perform the displacement was built from glass plates and contained 53 mesh silica sand inside, allowing pictures of the moving interface between the oil and aqueous phase to be taken during the displacements. Flow rates of displacing fluid ranging between 100 cm$\sp3$/h and 400 cm$\sp3$/h, were used covering the three domains, i.e. capillary, intermediate and viscous. The results of the displacements showed a strong dependency of breakthrough recovery on flow rate (its decrease with the increase of the flow rate) and on interfacial tension between the two immiscible phases (decrease of recovery in order neutral oil $>$ acidic oil $>$ alkaline displacements).