Investigation of interfacial tension of surfactant in low salinity water for enhanced oil recovery application

Abstract

Surfactant flooding is known as a very good method to improve oil recovery. Many experimental studies in laboratories have shown the effectiveness of this method to increase the percentage of oil coming up from the core ? a substituted reservoir. Regardless the reservoir, and focusing on interaction between oil and water in presence of a surfactant and salt, the thesis ?Investigation of interfacial tension of surfactant in low salinity water for enhanced oil recovery application? was implemented. Interfacial tension between oil and water was the only investigated parameter, and it was measured by the spinning drop tensiometer. Four ENORDET products containing different internal olefin sulfonate (IOS) surfactants were used at different concentrations in low salinity salt solutions. The model oil was heptane. The result showed that the IOS surfactant in low salinity solution decrease significantly the interfacial tension, but how significant IFT decreased depended on the hydrocarbon chain length of the surfactant. The shortest chain length IOS surfactant can decrease the most the IFT. Keeping the same ions strength at the same low salinity, the composition of salt changed by substituting a part of sodium ions by double valence calcium ions to find the effect of bivalent electrolytes on the surfactant?s activity. The interfacial tension decreased when Ca2+ was present, and the stronger decrease was found for the shorter chain length surfactant. In addition, the influence of pH on interfacial tension was investigated, and the result showed that the IFT increased with increasing pH.