Publications

Sodium lignosulfonate (SLS) is a kind of surfactant used to recover the residual oil in Enhanced Oil Recovery (EOR) operations. SLS reduces interfacial tension between oil-water and inhibits oil flow to the surface. SLS in brine water can reduce the interfacial tension (IFT) number from 10-1 to 10-2. Ability of SLS to lower IFT number to 10-3 can be achieved by reacting SLS with soap from saponification reaction between fatty acid and base. This study aims to determine both the optimal composition ratio among SLS, fatty acid, and base as well as to determine how temperature and salinity affect the IFT. Procedures of the study: Injection fluid was made by mixing SLS, oleic acid and NaOH at 70°C for 3 hours. Afterwards it was desiccated into powder. The powder was dissolved into brine water with 1% (w/w) concentration and stirred. IFT measurement was carried out by injecting dissolved mixedsurfactant and an oil droplet into the capillary tube, followed by rotating the capillary tube. The IFT number was obtained by reading the result on software TX500. Steps above were repeated for the other samples with some variations in composition ratio, temperature, and salinity. The result of the IFT measurement showed the optimal composition ratio among SLS, oleic acid, and NaOH is at 1:5:5 (mol/mol). At that condition, the IFT number was 0.0041396mN/m. The higher the operating temperature is, the lower the IFT number will be. Higher temperature results in higher solubility. On the other hand, IFT number will increase in higher salinity of brine water due to addition of NaCl.